Principles of transaction management in Javaee API framework
The transaction management in the Javaee API is one of the key components to achieve distributed transactions.Affairs management can ensure the consistency and integrity of data between multiple operations or requests.The Javaee API provides some interfaces and classes to implement transaction management. The most commonly used is the Java Transaction API (JTA) and Java Persistence API (JPA).
In Javaee, transaction management is responsible for the transaction manager.The transaction manager is part of the Javaee container, which is responsible for the beginning, submission and rollback operation of coordination and control.
The implementation principle of transaction management is as follows:
1. At the beginning of transaction: When the application calls a method with a transaction annotation (such as `@transactions), the transaction manager starts a new transaction.The transaction manager will allocate a unique transaction ID for the transaction and bind the ID with the current thread.
2. Database connection acquisition: The transaction manager will get a database connection from the connection pool.This connection will be reused during the entire transaction to ensure the consistency of the affairs.
3. The boundary of transaction: The transaction manager starts the transaction before the method is executed and the transaction is over after the method execution is completed.If an exception is thrown during the method execution process, the transaction manager will mark the transaction as a failure and perform the rollback operation.
4. Submission and rollback of transaction: If the method is successfully executed without abnormalities, the transaction manager will mark the transaction as success and perform the submission operation.This will cause all database operations to submit within the boundary of the transaction, thereby ensuring the consistency and integrity of the data.If an exception is thrown during the method execution process, the transaction manager will mark the transaction as a failure and perform the rollback operation.Rolling operations will revoke all database operations that occur within the border of affairs, so that the data is back to the state before the start of the transaction.
5. The isolation level of transaction: The transaction manager can also configure the isolation level of the transaction to control the read and write operations between different transactions.Common isolation levels include Read_committed, Read_unCommitted, Repectable_read, and Serializable.
Below is an example code that uses Javaee API to implement transaction management:
import javax.annotation.Resource;
import javax.enterprise.context.RequestScoped;
import javax.inject.Inject;
import javax.transaction.Transactional;
@RequestScoped
public class TransactionalExample {
@Inject
private DatabaseService databaseService;
@Resource
private javax.transaction.UserTransaction userTransaction;
@Transactional
public void performTransaction() {
try {
userTransaction.begin();
// Perform the database operation
databaseService.insertData();
userTransaction.commit();
} catch (Exception e) {
e.printStackTrace();
try {
userTransaction.rollback();
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
}
In the above code, the annotation of `@transactional` is used to identify that the method is a transaction.In the `Performtransaction` method, use the` userTransAction` interface to start, submit and roll back transactions.When capturing abnormalities, execute the rolling operation to ensure the consistency of the data.
In summary, transaction management in the Javaee API through transaction manager coordination and control of transactions, submission, and rollback operations.It uses a connection pool to obtain the database connection and use the transaction boundary to ensure the consistency and integrity of the database operation.The isolation level of transactions can be configured according to needs to control read and write operations between different transactions.
