Affairs control and error treatment in the ORMLITE CORE framework
Affairs control and error treatment in the ORMLITE CORE framework
1. Introduction
ORMLITE CORE is a powerful Java object relationship mapping (ORM) library, which provides a simple and flexible way to operate the database.During the development process, transaction control and error treatment are very important aspects. This article will introduce the best practice of how to achieve transaction control and error treatment in the ORMLITE CORE framework.
2. Affairs control
Affairs is a mechanism for database operations to ensure the consistency and integrity of a series of operations.In ORMLITE CORE, we can use the `TransactionManager` class to control the beginning, submission and rollback of the transaction.
1. Starting affairs:
try {
TransactionManager.callInTransaction(database, new Callable<Void>() {
public Void call() throws Exception {
// Perform the database operation here
return null;
}
});
} catch (SQLException e) {
// Treatment abnormalities
}
We use the method to start a new transaction block with the method of `TransactionManager.Callintransaction (), and accept an object of a` Callace "as a parameter.In the `Call ()` method, we can perform the database operation that needs to be performed in transactions.If any abnormalities occur, transactions will be rolled back.
2. Submit transaction:
database.commit(transaction);
If no abnormalities occur at the end of the transaction, we can use the method of `database.commit () to submit transactions.
3. Roll back transactions:
database.rollback(transaction);
If you need to roll back the transaction manually, you can use the method of `database.rollback ().
3. Error treatment
In ORMLITE CORE, error treatment is very important, it can help us identify and solve potential problems.
1. Capture SQL exception:
SQL abnormalities may occur during the database operation.To capture and deal with these abnormalities, we can use the `sqlexception` to capture abnormal information for further processing.
try {
// Execute the database operation
} catch (SQLException e) {
// Process SQL abnormalities
}
2. Handle the abnormalities in transactions:
When performing database operations in transactions, abnormal conditions may be encountered, which may cause transaction failure.In order to deal with these abnormalities, we can use the `Throw` keywords to throw an exception in the method of the` call () `method, and then use the` catch` block of the transaction to process it.
try {
TransactionManager.callInTransaction(database, new Callable<Void>() {
public Void call() throws Exception {
// Perform the database operation here and may throw an abnormality
if (error) {
Throw New Sqlexception ("Error!");
}
return null;
}
});
} catch (SQLException e) {
// Treatment of transaction abnormalities
}
4. Example application
Below is a simple example application, showing how to use ORMLITE CORE for transaction control and error treatment.
public class Main {
public static void main(String[] args) {
// Initialize database connection
DatabaseConnectionSource connectionSource = null;
try {
connectionSource = new JdbcConnectionSource(DatabaseConfig.URL);
// Starting transaction
TransactionManager.callInTransaction(connectionSource, new Callable<Void>() {
public Void call() throws Exception {
// Create a new user
User user = new user ("Zhang San", "zhangsan@example.com");
userDao.create(user);
// Try to create repeated users, it will throw out SQL abnormalities, causing transactions to roll back
userDao.create(user);
return null;
}
});
} catch (SQLException e) {
// Process SQL abnormalities
e.printStackTrace();
} finally {
if (connectionSource != null) {
try {
connectionSource.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
In the above example, we used a `UserDao` object to perform the database operation.In affairs, we first create a new user, and then try to create a repeated user.Due to the repeated insertion operation, the transaction will be rolled back.
5. Conclusion
It is very important to implement transaction control and error treatment in the ORMLITE CORE framework.By using the `TransactionManager` and processing SQL abnormalities, the consistency and integrity of the database operation can be ensured.This article provides a simple example application to help you understand how to apply these best practices in the Oremlite Core.
references:
-Omlite official website: https://ormlite.com/
-Omlite core document: https://ormlite.com/javadoc/ormlite-core/
