MyBatis is a lightweight Java persistence layer framework that provides database manipulation methods through the Mapper interface and implements configuration and mapping relationships using XML or annotations. MyBatis is capable of mapping Java objects to database tables, allowing developers to complete database operations by writing simple SQL statements. The advantages of MyBatis include: 1. Easy to use: MyBatis has a simple configuration, low learning cost, and provides rich documentation and sample code. 2. High flexibility: MyBatis allows developers to use annotations or XML to configure SQL statements to adapt to different project and team requirements. 3. Provide high performance: MyBatis uses a caching mechanism at the bottom, which can improve query performance and manually control and configure caching policies. 4. Easy integration: MyBatis can seamlessly integrate with various Java frameworks and support multiple databases. The drawbacks of MyBatis include: 1. XML configuration is complex: When using XML to configure SQL statements, it is necessary to manually write SQL statements, and the configuration is relatively cumbersome. 2. Not suitable for complex business: For scenarios with complex business logic, MyBatis' flexibility may bring certain development and maintenance costs. The following is a Java sample code that uses MyBatis to add, delete, modify, and query: 1. Define the data table: ```sql CREATE TABLE user ( id INT PRIMARY KEY AUTO_INCREMENT, name VARCHAR(50), age INT ); ``` 2. Define the entity class User. java: ```java public class User { private int id; private String name; private int age; //Omitting getter and setter methods } ``` 3. Define the Mapper interface UserMapper.java: ```java public interface UserMapper { void insertUser(User user); void deleteUser(int id); void updateUser(User user); User getUser(int id); } ``` 4. Define the Mapper configuration file UserMapper.xml: ```xml <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.example.mapper.UserMapper"> <insert id="insertUser" parameterType="com.example.entity.User"> INSERT INTO user(name, age) VALUES(#{name}, #{age}) </insert> <delete id="deleteUser" parameterType="int"> DELETE FROM user WHERE id = #{id} </delete> <update id="updateUser" parameterType="com.example.entity.User"> UPDATE user SET name = #{name}, age = #{age} WHERE id = #{id} </update> <select id="getUser" resultType="com.example.entity.User"> SELECT * FROM user WHERE id = #{id} </select> </mapper> ``` 5. Configure the MyBatis configuration file mybatis config.xml: ```xml <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration> <environments default="development"> <environment id="development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver"/> <property name="url" value="jdbc:mysql://localhost:3306/mybatis_test"/> <property name="username" value="root"/> <property name="password" value="password"/> </dataSource> </environment> </environments> <mappers> <mapper resource="com/example/mapper/UserMapper.xml"/> </mappers> </configuration> ``` 6. Use MyBatis for database operations: ```java public class MyBatisExample { public static void main(String[] args) { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession session = sessionFactory.openSession(); try { UserMapper userMapper = session.getMapper(UserMapper.class); //Insert Data User user = new User(); user.setName("John"); user.setAge(25); userMapper.insertUser(user); //Query data User fetchedUser = userMapper.getUser(user.getId()); System.out.println(fetchedUser.getName() + " " + fetchedUser.getAge()); //Update data fetchedUser.setAge(30); userMapper.updateUser(fetchedUser); fetchedUser = userMapper.getUser(fetchedUser.getId()); System.out.println(fetchedUser.getName() + " " + fetchedUser.getAge()); //Delete data userMapper.deleteUser(fetchedUser.getId()); fetchedUser = userMapper.getUser(fetchedUser.getId()); System.out.println(fetchedUser); } finally { session.close(); } } } ``` Note: The above code uses the core dependencies of MyBatis and needs to be added to the pom.xml file: ```xml <dependencies> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.6</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.26</version> </dependency> </dependencies> ``` Framework official website link: [MyBatis official website]（ https://mybatis.org/mybatis-3/zh/index.html ）

Hibernate is an open source Java Persistence framework, widely used in Java projects to simplify database operations. It provides a solution for Object Relational Mapping (ORM), which establishes a mapping relationship between Java objects and database tables. In programming, only Java objects need to be manipulated, without directly manipulating the database. The advantages of Hibernate include: 1. Simplify database operations: Hibernate encapsulates the complexity of the underlying JDBC API. When using Hibernate, developers do not need to write complex SQL statements, and only need to directly manipulate Java objects to complete database addition, deletion, modification, and query operations. 2. Improve development efficiency: Hibernate follows the object-oriented development principles and provides rich object Query language (HQL) and criteria Query language (Criteria) for data query. Developers can operate the database in an object-oriented way, greatly simplifying the process of code writing. 3. Cross database support: Hibernate's access to databases is based on JDBC and can adapt to different databases without the need to modify application code. 4. Provided transaction management: Hibernate provides a transaction management mechanism to ensure the consistency and integrity of data operations. The drawbacks of Hibernate include: 1. The learning cost is relatively high: The Hibernate framework is relatively complex and requires mastery of certain ORM technology and Hibernate APIs. 2. Performance issue: Hibernate may result in performance loss in order to provide adaptability to different databases. For scenarios with high performance requirements, performance optimization may be necessary. The following is a complete sample code for implementing database operations using Hibernate: 1. Create a data table First, create a data table called "users", which contains three fields: id, name, and email. CREATE TABLE users ( id INT PRIMARY KEY, name VARCHAR(50), email VARCHAR(50) ); 2. Create Java entity class User Create a User class to map the users table in the database. @Entity @Table(name = "users") public class User { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private int id; private String name; private String email; //Omitting getter and setter methods } 3. Add Hibernate configuration file Add Hibernate's configuration file hibernate.cfg.xml to the project, configure database connections, and other related information. <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test_db</property> <property name="hibernate.connection.username">root</property> <property name="hibernate.connection.password">password</property> <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> <mapping class="com.example.User" /> </session-factory> </hibernate-configuration> 4. Write database operation code Use Hibernate in Java programs to add, delete, modify, and query databases. // HibernateUtil.java public class HibernateUtil { private static SessionFactory sessionFactory; static { try { Configuration configuration = new Configuration().configure(); StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()); sessionFactory = configuration.buildSessionFactory(builder.build()); } catch (Exception e) { e.printStackTrace(); } } public static SessionFactory getSessionFactory() { return sessionFactory; } } // UserDao.java public class UserDao { public void saveUser(User user) { Session session = HibernateUtil.getSessionFactory().openSession(); Transaction tx = null; try { tx = session.beginTransaction(); session.save(user); tx.commit(); } catch (HibernateException e) { if (tx != null) { tx.rollback(); } e.printStackTrace(); } finally { session.close(); } } public List<User> getUsers() { Session session = HibernateUtil.getSessionFactory().openSession(); Transaction tx = null; List<User> userList = null; try { tx = session.beginTransaction(); Criteria criteria = session.createCriteria(User.class); userList = criteria.list(); tx.commit(); } catch (HibernateException e) { if (tx != null) { tx.rollback(); } e.printStackTrace(); } finally { session.close(); } return userList; } //Omit other methods of adding, deleting, and checking } 5. Testing Write a test class to verify the correctness of database operations. public class HibernateTest { public static void main(String[] args) { User user1 = new User(); user1.setName("Alice"); user1.setEmail("alice@example.com"); UserDao userDao = new UserDao(); userDao.saveUser(user1); List<User> userList = userDao.getUsers(); for (User user : userList) { System.out.println(user.getName() + " - " + user.getEmail()); } } } The above is a simple example code for implementing database operations using Hibernate. Through Hibernate's configuration files and APIs, we can easily perform database addition, deletion, modification, and query operations. Framework official website link: https://hibernate.org/

Eclipse Link is an open source Java Persistence framework, which is one of the Reference implementation of the Java Persistence API (JPA). It provides a powerful set of tools and functions for mapping Java objects to relational databases and achieving object-oriented data persistence. The advantages of the Eclipse Link framework include: 1. Easy to use: Eclipse Link provides a simple and intuitive API that allows for easy database operations, including creating, updating, deleting, and querying data. 2. High performance: Eclipse Link has powerful caching mechanism and query optimization function, which can significantly improve the performance of data access. 3. Support for various databases: Eclipse Link supports various relational databases, including Oracle, MySQL, PostgreSQL, etc., as well as NoSQL databases. 4. Dynamic Query: EclipseLink allows users to dynamically generate query statements as needed, providing more powerful query capabilities. 5. Scalability: EclipseLink provides a plugin architecture that facilitates the integration of other frameworks and tools, while also supporting customized development. The drawbacks of Eclipse Link include: 1. High learning costs: Compared with other Persistence framework, such as Hibernate, using Eclipse Link requires more concepts and technologies. 2. Insufficient documentation: Compared to frameworks such as Hibernate, EclipseLink has relatively less official documentation and community support, and may need to rely on other resources for assistance and problem-solving. The following is an example of Java code for implementing database operations using Eclipse Link: Firstly, we need to define an entity class to map the table structure in the database. Suppose we have a table called 'User' that contains fields' id 'and' name ': ```java import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table(name = "user") public class User { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private int id; private String name; //Omitting getter and setter methods } ``` Next, we need to configure Eclipse Link to connect to the database. Create a configuration file called "persistence. xml" and place it in the "src/main/resources/META INF" directory: ```xml <?xml version="1.0" encoding="UTF-8"?> <persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_2.xsd" version="2.2"> <persistence-unit name="example-unit"> <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> <class>com.example.User</class> <properties> <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/example_db"/> <property name="javax.persistence.jdbc.user" value="root"/> <property name="javax.persistence.jdbc.password" value="password"/> <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/> <property name="eclipselink.logging.level" value="FINE"/> </properties> </persistence-unit> </persistence> ``` Please note that the above configuration needs to be modified based on your own database connection information. Next, we can use the following code example to add, delete, modify, and query data using Eclipse Link: ```java import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.EntityTransaction; import javax.persistence.Persistence; public class Example { public static void main(String[] args) { EntityManagerFactory emf = Persistence.createEntityManagerFactory("example-unit"); EntityManager em = emf.createEntityManager(); //Insert Data User user = new User(); user.setName("John Doe"); em.getTransaction().begin(); em.persist(user); em.getTransaction().commit(); //Query data User result = em.find(User.class, 1); System.out.println(result.getName()); //Update data em.getTransaction().begin(); result.setName("Updated Name"); em.getTransaction().commit(); //Delete data em.getTransaction().begin(); em.remove(result); em.getTransaction().commit(); em.close(); emf.close(); } } ``` It should be noted that the "example unit" in the above code needs to match the name of the persistence unit in "persistence. xml". Maven dependency configuration (added in pom.xml file): ```xml <dependencies> <dependency> <groupId>org.eclipse.persistence</groupId> <artifactId>javax.persistence</artifactId> <version>2.2.1</version> </dependency> <dependency> <groupId>org.eclipse.persistence</groupId> <artifactId>eclipselink</artifactId> <version>2.7.7</version> </dependency> <-- Other dependencies --> </dependencies> ``` For more information and documentation on Eclipse Link, please visit the official website: https://www.eclipse.org/eclipselink/

Spring Data JPA is a subproject under the Spring framework. It simplifies the process of using JPA for database operations, provides a series of CRUD methods, and reduces the number of template codes written by developers. Through the Naming convention of annotation and query methods, common database operations can be automatically generated. The following is an analysis of the advantages and disadvantages of Spring Data JPA: Advantages: 1. Simplify development: Spring Data JPA can achieve database addition, deletion, modification, and query operations with a small amount of configuration and annotations, reducing template code for traditional database access, and improving development efficiency. 2. Avoid duplicate code: Spring Data JPA provides an automated code generation method. Through Naming convention and annotation based methods, the corresponding database operations can be automatically generated according to the naming of the method, avoiding the duplication of writing similar code. 3. Provide transaction management: Spring Data JPA uses Spring's transaction management mechanism to easily manage transaction consistency and isolation, ensuring the atomicity of data operations. 4. Support for complex queries: Spring Data JPA provides powerful query functions, which can easily perform complex database queries by defining method names, annotations, or using QueryDSL. Disadvantages: 1. High learning threshold: If you are not familiar with JPA and Spring framework, you may have a certain Learning curve when you start using Spring Data JPA. 2. Limited query flexibility: Although Spring Data JPA provides rich query methods, it may not be able to meet some complex query requirements and requires the use of native SQL or other query frameworks. The following is the complete sample code for implementing data addition, deletion, modification, and query using Spring Data JPA: Firstly, you need to create an entity class as a mapping for the database table, such as the User class: ```java @Entity @Table(name = "user") public class User { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; private String username; private String password; // getters and setters } ``` 2. Create an interface that inherits from JpaRepository to define database operation methods, such as UserRepository: ```java @Repository public interface UserRepository extends JpaRepository<User, Long> { User findByUsername(String username); } ``` In this interface, common database operations can be defined through simple method declarations, such as the findByUsername() method. 3. In the configuration file application.properties of Spring Boot, configure the database connection related information: ``` spring.datasource.url=jdbc:mysql://localhost:3306/test spring.datasource.username=root spring.datasource.password=123456 spring.jpa.hibernate.ddl-auto=update spring.jpa.show-sql=true ``` Among them, spring. datasource. URL is the database connection URL, and spring. datasource. username and spring. datasource. password are the username and password of the database. 4. Add the @ Enable JpaRepositories annotation to the startup class of Spring Boot to enable Spring Data JPA: ```java @SpringBootApplication @EnableJpaRepositories("com.example.repository") public class Application { public static void main(String[] args) { SpringApplication.run(Application.class, args); } } ``` 5. Example code for data addition, deletion, modification, and query using Spring Data JPA: ```java @Service public class UserService { @Autowired private UserRepository userRepository; public User createUser(User user) { return userRepository.save(user); } public User updateUser(User user) { return userRepository.save(user); } public void deleteUser(Long userId) { userRepository.deleteById(userId); } public User findUserByUsername(String username) { return userRepository.findByUsername(username); } } ``` In this example code, by injecting an instance of UserRepository into UserService, the defined database operation methods can be directly called. Maven Dependency: ```xml <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> ``` The above example uses Spring Boot and MySQL databases, so it is necessary to add dependencies for spring boot starter data jpa and mysql connector Java. Spring Data JPA official website link: https://spring.io/projects/spring-data-jpa

Apache Cayenne is an open source Persistence framework that provides simple, powerful and flexible ORM (Object–relational mapping) and database access tools. The Cayenne can help developers more conveniently perform database operations, including data addition, deletion, modification, and query, as well as transaction management. At the same time, the Cayenne supports multiple databases, including MySQL, PostgreSQL, Oracle, and more. Advantages: 1. Simplify database operations: The Cayenne provides a series of APIs and tools that can greatly simplify the amount of code required for database operations, enabling developers to focus on the implementation of business logic. 2. Powerful object mapping function: The Cayenne can map tables and columns in the database to Java objects and attributes, allowing developers to directly perform database operations by manipulating Java objects. 3. Flexible query function: The Cayenne supports various types of queries, including simple queries, complex queries, native SQL queries, etc. It also supports dynamic queries and can dynamically generate SQL statements based on conditions. 4. Automatic database table creation: The Cayenne can automatically create database tables based on the Java object model, eliminating the tedious process of manually operating the database. 5. Support for transaction management: The Cayenne provides transaction management function, which can ensure that database operations are atomic and ensure data consistency. Disadvantages: 1. High learning cost: Due to the rich functionality of the Cayenne, learning may require a certain amount of time and effort. 2. Complex configuration: The configuration of the Cayenne is relatively complex, and it is necessary to understand the structure of its configuration file and the meaning of its parameters. 3. Integration difficulty: For existing projects, integrating the Cayenne may require some modifications, especially for the reconstruction of the database access layer. The following is an example of Java code for using Apache Cayenne to add, delete, modify, and query data: 1. Add Maven dependencies for the Cayenne to the pom.xml file in the project: ```xml <dependency> <groupId>org.apache.cayenne</groupId> <artifactId>cayenne-server</artifactId> <version>4.2.1</version> </dependency> ``` 2. Create the Java class User. java to represent the user table in the database: ```java import org.apache.cayenne.CayenneDataObject; //Using Apache Cayenne annotations to define entities and attributes @Entity @Table(name = "user") public class User extends CayenneDataObject { //Defining Entity Properties @Column(name = "user_id", primaryKey = true) private Long userId; @Column(name = "username") private String username; //Omitting getter and setter methods } ``` 3. Create a configuration file cayenne.xml for configuring database connection information and entity mapping: ```xml <?xml version="1.0" encoding="UTF-8"?> <cayenne-project xmlns="http://cayenne.apache.org/schema/4.0/cayenne-project.xsd"> <cayenneRuntime> <dataSource> <name>MyDataSource</name> <url>jdbc:mysql://localhost:3306/test</url> <driver>com.mysql.jdbc.Driver</driver> <connectionPool min="1" max="5"/> <schema name="public"/> <login userName="root" password=""/> </dataSource> <mapping> <map ref="com.example.User"/> </mapping> </cayenneRuntime> </cayenne-project> ``` 4. Create a data access class UserDAO. java to implement data addition, deletion, modification, and query operations: ```java import org.apache.cayenne.Cayenne; import org.apache.cayenne.ObjectContext; import org.apache.cayenne.query.ObjectSelect; import java.util.List; public class UserDAO { //Get Data Context private ObjectContext context = DataContext.createDataContext(); //Add User public void addUser(User user) { context.registerNewObject(user); context.commitChanges(); } //Delete User public void deleteUser(User user) { context.deleteObject(user); context.commitChanges(); } //Update Users public void updateUser(User user) { context.commitChanges(); } //Query Users public List<User> queryUser(String username) { return ObjectSelect.query(User.class) .where(User.USERNAME.eq(username)) .select(context); } } ``` 5. Use the UserDAO class for database operations in the application: ```java public class Main { public static void main(String[] args) { UserDAO userDAO = new UserDAO(); //Create a new user and add it to the database User user = new User(); user.setUsername("Tom"); userDAO.addUser(user); //Query all users List<User> users = userDAO.queryUser(null); for (User u : users) { System.out.println(u.getUsername()); } //Query users based on username List<User> users = userDAO.queryUser("Tom"); //Omit other operations } } ``` In this example, suppose there is a table named "user" in the database, which contains two columns: "user_id" and "username". By using the annotations provided by Cayenne to map the Java object User to the table in the database, data addition, deletion, and modification operations can be performed. Cayenne official website link: https://cayenne.apache.org/

JOOQ (Java Object Oriented Querying) is a database framework used to build type safe SQL queries in Java. It generates Java code based on the table and field structures in the database, allowing developers to use type safe Java methods to write SQL queries instead of manually writing strings. The advantages of the JOOQ framework are as follows: 1. Type safety: Using JOOQ can capture many common SQL errors during compilation, such as spelling errors, non-existent columns, etc. 2. Highly composable: JOOQ's query builder allows developers to combine query conditions as needed, making queries more flexible and maintainable. 3. Simple API: JOOQ provides an intuitive and concise API, making writing SQL queries easier and more efficient. 4. Generate code based on database structure: JOOQ automatically generates Java code based on database tables and field structures, making it easier to maintain synchronization with the database structure. The drawbacks of JOOQ are as follows: 1. The Learning curve is steep: for beginners, it may take some time and effort to become familiar with the use of JOOQ. 2. The generated code is relatively lengthy: Due to the consideration of many details and type safety, the generated code may be relatively lengthy. The following is the Java sample code for implementing database operations using JOOQ: 1. Add JOOQ Maven dependency: ```xml <dependency> <groupId>org.jooq</groupId> <artifactId>jooq</artifactId> <version>3.15.1</version> </dependency> <dependency> <groupId>org.jooq</groupId> <artifactId>jooq-meta</artifactId> <version>3.15.1</version> </dependency> <dependency> <groupId>org.jooq</groupId> <artifactId>jooq-codegen</artifactId> <version>3.15.1</version> </dependency> ``` 2. Configure the parameters for generating JOOQ code and connecting to the database, and add the following configuration to pom.xml: ```xml <build> <plugins> <plugin> <groupId>org.jooq</groupId> <artifactId>jooq-codegen-maven</artifactId> <version>3.15.1</version> <executions> <execution> <goals> <goal>generate</goal> </goals> </execution> </executions> <dependencies> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.26</version> </dependency> </dependencies> <configuration> <jdbc> <driver>com.mysql.jdbc.Driver</driver> <url>jdbc:mysql://localhost:3306/your_database_name</url> <user>your_username</user> <password>your_password</password> </jdbc> <generator> <name>org.jooq.codegen.DefaultGenerator</name> <database> <name>org.jooq.meta.mysql.MySQLDatabase</name> <includes>.*</includes> <excludes></excludes> <inputSchema>your_database_name</inputSchema> </database> <target> <packageName>com.example.generated</packageName> <directory>src/main/java</directory> </target> </generator> </configuration> </plugin> </plugins> </build> ``` This configuration will generate JOOQ entity classes and DAO classes in src/main/Java. 3. Assuming we have a table called "users" with three fields: id, name, and age, the following is a complete example code for using JOOQ to add, delete, and modify data: ```java import com.example.generated.tables.Users; import com.example.generated.tables.records.UsersRecord; import org.jooq.*; import org.jooq.impl.DSL; import static com.example.generated.tables.Users.USERS; public class Main { public static void main(String[] args) { String userName = "your_username"; String password = "your_password"; String url = "jdbc:mysql://localhost:3306/your_database_name"; Connection conn = null; try { conn = DriverManager.getConnection(url, userName, password); DSLContext create = DSL.using(conn, SQLDialect.MYSQL); //Insert Data create.insertInto(USERS, USERS.NAME, USERS.AGE) .values("John Doe", 30) .execute(); //Update data create.update(USERS) .set(USERS.AGE, 31) .where(USERS.NAME.eq("John Doe")) .execute(); //Query data Result<UsersRecord> result = create.selectFrom(USERS) .where(USERS.NAME.eq("John Doe")) .fetch(); for (UsersRecord record : result) { System.out.println("Name: " + record.getName() + " Age: " + record.getAge()); } //Delete data create.deleteFrom(USERS) .where(USERS.NAME.eq("John Doe")) .execute(); } catch (Exception e) { e.printStackTrace(); } finally { if (conn != null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } } } ``` This example code demonstrates how to use JOOQ for data addition, deletion, modification, and query operations. You need to replace 'your username', 'your password', and 'your databasename' with the actual database connection parameters. JOOQ official website link: https://www.jooq.org/

Querydsl is a Java domain specific Query language framework, which can be used to write type safe and intuitive database queries. Advantages of Querydsl: 1. Type safety: Querydsl generates query statements based on Java code, so Syntax error can be captured during compilation to reduce runtime errors. 2. Intuitiveness: Querydsl uses domain specific internal domain language (DSL) to write queries, making the query statements more concise and readable. 3. Scalability: Querydsl supports multiple databases and can easily switch database types without the need to modify Java code. 4. ORM integration: Querydsl can seamlessly integrate with multiple ORMs (such as Hibernate, JPA, JDO, etc.), providing more powerful query functions. Disadvantages of Querydsl: 1. Learning costs: The syntax and usage of Querydsl require a certain amount of learning costs, especially for developers without domain specific internal domain language (DSL) experience. 2. Dependency issue: Querydsl may require some additional dependency libraries to integrate with ORM, increasing the dependency complexity of the project. 3. Maintainability: Querydsl query statements exist in code form, and frequent changes in query logic may result in frequent code modifications. The following is a Java sample code that implements data addition, deletion, and modification using Querydsl: 1. Install dependency libraries Add the following dependencies to the 'pom. xml' file of the project: ```xml <dependency> <groupId>com.querydsl</groupId> <artifactId>querydsl-core</artifactId> <version>4.4.0</version> </dependency> <dependency> <groupId>com.querydsl</groupId> <artifactId>querydsl-sql</artifactId> <version>4.4.0</version> </dependency> ``` 2. Create database tables Suppose we have a simple student table that includes id, name, and age fields. 3. Create a Querydsl query class Firstly, we need to use the Querydsl plugin to generate the Querydsl query class, which is used to construct query statements. Add the following plugin code to the Maven plugin: ```xml <plugin> <groupId>com.mysema.maven</groupId> <artifactId>apt-maven-plugin</artifactId> <version>1.1.3</version> <executions> <execution> <goals> <goal>process</goal> </goals> <configuration> <outputDirectory>target/generated-sources</outputDirectory> <processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor> </configuration> </execution> </executions> </plugin> ``` 4. Create data access classes and entity classes We create a 'Student' entity class and a 'StudentRepository' interface: ```java import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; @Entity public class Student { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; private String name; private int age; //Omitting getter and setter methods } import org.springframework.data.jpa.repository.JpaRepository; import org.springframework.data.querydsl.QuerydslPredicateExecutor; public interface StudentRepository extends JpaRepository<Student, Long>, QuerydslPredicateExecutor<Student> { } ``` 5. Use Querydsl to query data Where you need to use Querydsl for queries, you can inject 'StudentRepository' and use the method provided by 'QuerydslPredicteExecutor' to construct query statements: ```java import com.querydsl.core.types.dsl.BooleanExpression; import com.querydsl.jpa.impl.JPAQueryFactory; import org.springframework.stereotype.Service; import javax.transaction.Transactional; import java.util.List; @Transactional @Service public class StudentService { private final StudentRepository repository; private final JPAQueryFactory queryFactory; public StudentService(StudentRepository repository, JPAQueryFactory queryFactory) { this.repository = repository; this.queryFactory = queryFactory; } public List<Student> findByAgeGreaterThan(int age) { QStudent student = QStudent.student; BooleanExpression greaterThan = student.age.gt(age); return queryFactory.selectFrom(student) .where(greaterThan) .fetch(); } } ``` In the above code, we use QStudent.student to represent the entity class Student, construct a query condition through 'age. createrThan (age)', and then use JPAQueryFactory to construct the query statement and execute the query. It should be noted that 'JPAQueryFactory' is automatically configured by Querydsl, and the following code needs to be added to the configuration class: ```java @Bean public JPAQueryFactory queryFactory(EntityManager entityManager) { return new JPAQueryFactory(entityManager); } ``` This way, you can use Querydsl to add, delete, modify, and query databases in Java. Querydsl official website link: https://www.querydsl.com/

ActiveJDBC is a lightweight Java ORM framework primarily used to simplify interaction with databases. It is based on the ActiveRecord mode and provides a concise and intuitive API, making it very convenient to use. The main advantages of ActiveJDBC include: 1. Easy to use: ActiveJDBC's API design is very concise, providing methods similar to database operations, allowing developers to easily perform database operations such as adding, deleting, modifying, and querying. 2. Lightweight: ActiveJDBC is a very lightweight framework without too many additional dependencies, making it very concise and efficient to use. 3. High performance: ActiveJDBC can provide high performance at the data access level by using dynamic proxy and cache technology. 4. Flexibility: ActiveJDBC supports the execution of custom SQL statements and provides rich query syntax to meet the needs of complex queries. 5. Support for multiple databases: ActiveJDBC supports various popular relational databases, including MySQL, Oracle, PostgreSQL, etc. Some drawbacks of ActiveJDBC include: 1. Relatively small community support: Compared to other mainstream Java ORM frameworks, ActiveJDBC has relatively small community support and relatively few related documents and resources. 2. Relatively incomplete documentation: There are relatively few official documents for ActiveJDBC, and many issues need to be resolved through source code or other channels. The following is the complete sample code for implementing database operations using ActiveJDBC: Firstly, we need to add the dependency of ActiveJDBC in the pom.xml file of the project: ```xml <dependency> <groupId>org.javalite</groupId> <artifactId>activejdbc</artifactId> <version>2.1</version> </dependency> ``` Then, create a data representation example, for example, create a data table named "users" with the following table structure: ```sql CREATE TABLE `users` ( `id` int(11) NOT NULL AUTO_INCREMENT, `username` varchar(255) NOT NULL, `password` varchar(255) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; ``` Next, create the User class, inherit the ActiveRecord class, and define the corresponding data table mapping relationship. The code is as follows: ```java import org.javalite.activejdbc.Model; public class User extends Model { static { validatePresenceOf("username", "password"); } } ``` Next, in Java code, the User class can be used for database operations, such as: ```java public class Main { public static void main(String[] args) { //Initialize database connection Base.open("com.mysql.jdbc.Driver", "jdbc:mysql://localhost/mydb", "root", "password"); //Create a new user User user = new User(); user.set("username", "admin"); user.set("password", "123456"); user.save(); //Query users based on criteria List<User> users = User.where("username = ?", "admin"); for (User u : users) { System.out.println("Username: " + u.get("username")); System.out.println("Password: " + u.get("password")); } //Update user information User user = User.findFirst("username = ?", "admin"); user.set("password", "newpassword"); user.save(); //Delete User User user = User.findFirst("username = ?", "admin"); user.delete(); //Close database connection Base.close(); } } ``` In the above code, we first initialize the database connection using the 'Base. open()' method, then use the User class to perform database operations, such as creating users, querying users, updating users, and deleting users. Finally, we close the database connection using the 'Base. close()' method. Reference link: ActiveJDBC official website: http://javalite.io/activejdbc

JOOQ (Java Object Oriented Querying) is a Java Domain Specific Language (DSL) used to write SQL queries in a type safe and object-oriented manner. It is a popular database access framework that can interact with mainstream relational databases such as MySQL, PostgreSQL, Oracle, SQL Server, etc. It provides rich and intuitive APIs, as well as powerful query building functions. The main advantages of jOOQ are as follows: 1. Type safety: jOOQ allows developers to write type safe queries in Java, reducing errors when writing SQL statements. 2. Powerful Query Builder: jOOQ provides a powerful query builder that can use natural Java language to chain call query methods, making query construction very intuitive and concise. 3. Support for multiple databases: jOOQ supports multiple mainstream relational databases without the need to learn specific syntax for each database. 4. Integrity: jOOQ provides comprehensive SQL syntax support, covering all SQL operations, allowing developers to use standard SQL to operate databases. 5. Scalability: jOOQ provides an API that is easy to extend, allowing developers to customize plugins and triggers to meet their own needs. JOOQ can introduce projects by adding the following Maven dependencies: ```xml <dependencies> <dependency> <groupId>org.jooq</groupId> <artifactId>jooq</artifactId> <version>3.15.0</version> </dependency> <dependency> <groupId>org.jooq</groupId> <artifactId>jooq-meta</artifactId> <version>3.15.0</version> </dependency> <dependency> <groupId>org.jooq</groupId> <artifactId>jooq-codegen</artifactId> <version>3.15.0</version> </dependency> <!-- Add your database driver here --> <!-- <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.26</version> </dependency> --> </dependencies> ``` The following is a Java sample code for implementing database addition, deletion, and modification using jOOQ: Firstly, it is necessary to use jOOQ's code generator to generate entity classes corresponding to database tables. Add the following configuration to the pom.xml file: ```xml <build> <plugins> <plugin> <groupId>org.jooq</groupId> <artifactId>jooq-codegen-maven</artifactId> <version>3.15.0</version> <executions> <execution> <id>generate-jooq-classes</id> <goals> <goal>generate</goal> </goals> </execution> </executions> <configuration> <jdbc> <driver>com.mysql.jdbc.Driver</driver> <url>jdbc:mysql://localhost:3306/db_example</url> <user>your_username</user> <password>your_password</password> </jdbc> <generator> <database> <name>org.jooq.meta.mysql.MySQLDatabase</name> <includes>.*</includes> <excludes></excludes> <inputSchema>public</inputSchema> </database> <target> <packageName>com.example.db.tables</packageName> <directory>src/main/java</directory> </target> </generator> </configuration> <dependencies> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.26</version> </dependency> </dependencies> </plugin> </plugins> </build> ``` In the above configuration, it is necessary to replace 'jdbc. url', 'jdbc. user', and 'jdbc. password' with the actual database connection information. The generated entity classes will be saved in the specified directory 'src/main/java/com/example/db/tables'. 2. Use the entity classes generated above for database operations, such as querying: ```java import static com.example.db.Tables.*; import org.jooq.*; import org.jooq.impl.*; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; public class DatabaseExample { public static void main(String[] args) { //Create database connection try (Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/db_example", "your_username", "your_password")) { //Create a configuration object for jOOQ Configuration configuration = new DefaultConfiguration().set(connection).set(SQLDialect.MYSQL); //Create a context object for jOOQ to execute SQL statements DSLContext dslContext = DSL.using(configuration); //Query data Result<Record> result = dslContext.select().from(EMPLOYEE).fetch(); for (Record record : result) { Integer id = record.getValue(EMPLOYEE.ID); String name = record.getValue(EMPLOYEE.NAME); System.out.println("ID: " + id + ", Name: " + name); } } catch (SQLException e) { e.printStackTrace(); } } } ``` In the above code, you need to add 'your'_ Username 'and' your '_ Replace 'password' with the actual database username and password. Please note that the above code is only a simple example, and in actual use, operations such as adding, deleting, modifying, and querying need to be carried out according to specific business needs. JOOQ's official website link: https://www.jooq.org/

To connect to the MongoDB database, you first need to install MongoDB and start the MongoDB service. You can install and start according to the guidelines provided on the official MongoDB website. The following is the complete sample code for connecting to the MongoDB database using Java: ```java import com.mongodb.MongoClient; import com.mongodb.MongoClientURI; import com.mongodb.client.MongoCollection; import com.mongodb.client.MongoDatabase; import org.bson.Document; public class MongoDBExample { public static void main(String[] args) { //MongoDB Connection URI String connectionString = "mongodb://localhost:27017"; //Connect to MongoDB database MongoClient mongoClient = new MongoClient(new MongoClientURI(connectionString)); //Select Database MongoDatabase database = mongoClient.getDatabase("mydb"); //Select Collection MongoCollection<Document> collection = database.getCollection("mycollection"); //Create Document Document document = new Document("name", "John") .append("age", 30) .append("city", "New York"); //Insert Document collection.insertOne(document); //Query Document Document query = new Document("name", "John"); Document result = collection.find(query).first(); System.out.println(result); //Close MongoDB connection mongoClient.close(); } } ``` In the above code, MongoDB's Java driver dependency library is used. You can add the following Maven dependencies in the 'pom. xml' file: ```xml <dependency> <groupId>org.mongodb</groupId> <artifactId>mongodb-driver-sync</artifactId> <version>4.4.4</version> </dependency> ``` In the code, the MongoDB connection URI was first created, specifying the host and port number of MongoDB. Then, the MongoClient object was created using this URI. Next, we selected the database and collection, and created a document. Finally, the document was inserted into the collection and queried. Please replace the URI, database name, and collection name according to the actual situation, and use the API provided by MongoDB for operations as needed. The following is a sample MongoDB document: ```json { "_id": ObjectId("605f8e5b8bddf835ea3e129c"), "name": "John", "age": 30, "city": "New York" } ``` This is a document that contains fields such as' name ',' age ', and' city '`_ The 'id' field is a unique identifier automatically generated by MongoDB. I hope this sample code can help you.