How to use the transaction API in the Java class library for data operation
How to use the transaction API in the Java class library for data operation
introduction:
Affairs is an important concept in the database management system, which is used to ensure the consistency and persistence of data operation.In the Java class library, we can use the transaction API to manage the transactions in the data operation process.
overview:
This article will introduce how to use the transaction API in the Java library for data operation.First of all, we will discuss the basic concepts and characteristics of transactions, and then introduce the transaction API provided in the Java class library.Finally, we will use some example code to demonstrate how to use the transaction API for data operation.
1. The concept and characteristics of transactions:
Affairs is a mechanism used to manage data operation in the database management system.It has the following characteristics:
1. Atomicity: Either the transaction is either successfully implemented or rolled back.If errors occur during transaction execution, all execution operations will be revoked, and the status of the database will return to the state before the start of the transaction.
2. consistency (consistency): Before and after the execution of transactions, the integrity constraints of the database should be maintained.That is, the status of the database should meet the pre -defined integrity constraints.
3. Isolation: During the execution of the transaction, other transactions are isolated, and each transaction cannot perceive the existence of other transactions.This ensures the correct implementation of the parallel transaction.
4. Durability: Once the transaction is submitted successfully, the result should be kept in the database, and it will not be lost even if the system failure occurs.
Second, the transaction API in the Java class library:
The Java class library provides some standardized APIs for transaction management, including the Java transaction API (JTA) and Java persistent API (JPA).Among them, JTA is used to manage distributed transactions, and JPA is used for data object mapping between Java applications and databases.
1. JTA transaction API:
JTA provides some interfaces and classes for managing transactions in distributed environments.Some of these important interfaces and classes include:
-javax.transaction.usertransaction: interfaces used to start, submit and roll back transactions.
-javax.transactions.transactionManager: Interfaces used to manage transactions provide methods such as opening, submission and rollback transactions.
2. JPA transaction API:
JPA expands JTA, providing transaction management for data operations between Java applications and databases.By using the EntityManager object, we can perform transactional data operations.Here are some commonly used JPA transaction API methods:
-EntityManager.Gettransaction (): Get the current transaction.
-Entitytransaction.begin (): Starting transaction.
-Entitytransaction.commit (): Submit transaction.
-Entitytransactions.rollback (): Roll back transactions.
Third, use the transaction API for the example code of data operation:
The following is an example code that uses JTA and JPA transaction APIs:
// Import the required class
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.transaction.UserTransaction;
public class TransactionExample {
public static void main(String[] args) {
// Create EntityManagerFactory objects
EntityManagerFactory emf = Persistence.createEntityManagerFactory("persistenceUnitName");
// Create EntityManager object
EntityManager em = emf.createEntityManager();
// Get the usertransaction object
UserTransaction utx = com.arjuna.ats.jta.UserTransaction.userTransaction();
try {
// Starting transaction
utx.begin();
// Get EntityTransactions object
EntityTransaction tx = em.getTransaction();
// Execute data operation
// ...
// Submit a transaction
tx.commit();
} catch (Exception e) {
// Roll back transactions
utx.rollback();
e.printStackTrace();
} finally {
// Close entityManager
em.close();
}
// Close EntityManagerFactory
emf.close();
}
}
In the above sample code, we first created EntityManagerFactory and EntityManager objects, and then obtained the UserTransaction object.In the TRY-Catch-Finally code block, we start transactions, perform data operations, and submit transactions.If abnormalities occur during transaction processing, rollback transactions and print abnormal information.Finally, we close the EntityManager and EntityManagerFactory objects.
in conclusion:
This article introduces how to use the transaction API in the Java library for data operation.By understanding the basic concepts and characteristics of transactions, and the API provided by the Java class library, we can effectively manage data operations in Java applications.At the same time, we demonstrated how to use the JTA and JPA transaction APIs to perform data operation through sample code.In actual projects, rational use of transaction APIs can ensure the consistency and reliability of data operation.
