Java Affairs API: Complete Guidance Manual

Java Affairs API: Complete Guidance Manual preface: In modern software development, transaction management is a vital part.One transaction is the logical unit of the data operation of the data. It can contain multiple operations to ensure that these operations are either successfully executed or all fails.Java provides a powerful and flexible transaction API for managing the operation of databases.This article will introduce the Java transaction API in detail, including the concept of transactions, the characteristics of transaction, the level of transaction isolation, and how to use transactions in Java. 1. The concept of transaction Affairs is an orderly collection of a set of database operations. They are regarded as a logical unit, and they are all successfully executed or all fails.The four key attributes of transactions (ACID) are as follows: -ATOMICITY: All operations in a transaction are either successful or all failed. -Consistency: The execution of transactions does not cause the database to be invalid, and it must follow the predefined rules and constraints. -ISOLATION: The execution of transactions should be independent of other concurrent transactions, and each transaction should feel that it is working independently. -Durability: Once the transaction is successfully submitted, the change it does should be permanent, and even if the system fails, it cannot be lost. 2. The characteristics of transaction In the Java Affairs API, the transaction manager is responsible for the life cycle of managing affairs.The following are some important features provided by the transaction manager: -The start and submission of transactions: Use the method to start a new transaction with the method of `BegintransAction (), and use the` Commit () "method to submit transactions.Before submitting transactions, multiple database operations can be performed. -The rollback: If abnormalities occur during the execution of the transaction, you can use the `Rollback () method to roll back the transaction and revoke the changes to the database. -State status: Affairs can be in a state of activity, submitted state, or rolling status.You can use the `GetStatus ()" method to obtain the current state of transaction. 3. Affairs isolation level The level of transaction isolation refers to the degree of interaction between multiple concurrent transactions.Java Affairs API supports the following four isolation levels: -TRANSACTION_NONE: No transaction support. -TRANSACTION_READ_UNCOMMITTED: A transaction can read data that other transactions have not yet been submitted, which may cause problems that are dirty, fantasy, and non -repeated reading. -Transaction_read_committed -TRANSACTION_REPEATABLE_READ: A transaction can read the same data multiple times during the entire transaction, and ensure that other transactions cannot be modified, avoiding phantom reading and non -repeated problems. -TRANSACTION_SERIALIZABLE: All transactions are implemented one by one in order to avoid dirty reading, illusion, and unspeakable reading problems, but sacrificing concurrency performance. 4. Equity management in Java The general steps of using transactions in Java are as follows: -Stop the transaction manager with `javax.transaction.usertransaction` interface. -Call the method to start a new transaction. -Express the database operation. -Coles the `Commit ()" method to submit transactions, or call the `rollback () method when the abnormality occurs. The following is a simple Java transaction example code: import javax.transaction.UserTransaction; import javax.naming.InitialContext; import javax.transaction.Status; // Get the transaction manager UserTransaction utx = (UserTransaction) new InitialContext().lookup("java:comp/UserTransaction"); try { // Starting transaction utx.begin(); // Execute the database operation // ... // Submit a transaction utx.commit(); } catch (Exception e) { // Abnormal treatment if (utx.getStatus() == Status.STATUS_ACTIVE) { utx.rollback(); } } in conclusion: The Java transaction API provides a powerful and flexible transaction management function, which can ensure that the operation of the database is consistent, atomic and durable.By understanding the concept, characteristics, and isolation level of transactions, and how to use transactions in Java, you can better design and manage transaction operations in the application.