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  • JDBC | 第四章: JDBC之Transaction事务提交与回滚

    默认情况下,当我们创建一个数据库连接时,会运行在自动提交模式(Auto-commit)下。这意味着,任何时候我们执行一条SQL完成之后,事务都会自动提交。所以我们执行的每一条SQL都是一个事务,并且如果正在运行DML或者DDL语句,这些改变会在每一条SQL语句结束的时存入数据库。有时候我们想让一组SQL语句成为事务的一部分,那样我们就可以在所有语句运行成功的时候提交,并且如果出现任何异常,这些语句作为事务的一部分,我们可以选择将其全部回滚。

    让我们通过一个简单的示例理解一下,这里使用JDBC的事务管理来支持数据的完整性

     /*
         * 发生异常回滚所有执行更新的sql
         * */
        public void insrolledAll() {
            Connection connection = null;
            PreparedStatement preparedStatement = null;
            PreparedStatement preparedStatement1 = null;
            //这里参数用?占位符表示
            String sqlTeacher = "insert into teacher ( name, age, hobby, addr) values (?,?,?,?)";
            String sqlStudent = "insert into student (name, age, addr, hobby) values (?,?,?,?)";
            try {
                //获取数据连接
                connection = basicUse.getConnection();
                //设置事务自动提交为手动提交
                connection.setAutoCommit(false);
    
                //获取发送sql指令执行sql进行预编译
                preparedStatement = connection.prepareStatement(sqlStudent);
    
                //设置sql语句参数索引从1开始
                preparedStatement.setObject(1, "Tom");
                preparedStatement.setObject(2, 24);
                preparedStatement.setObject(3, "上海");
                preparedStatement.setObject(4, "篮球");
                preparedStatement.executeUpdate();
                System.out.println("执行sqlStudent" + sqlStudent);
    
                //手动制造异常
                int i = 10 / 0;
    
                preparedStatement1 = connection.prepareStatement(sqlTeacher);
                preparedStatement1.setObject(1, "kenx");
                preparedStatement1.setObject(2, 24);
                preparedStatement1.setObject(3, "足球");
                preparedStatement1.setObject(4, "北京");
                preparedStatement1.executeUpdate();
                System.out.println("执行sqlTeacher" + sqlTeacher);
    
                //提交事务
                connection.commit();
    
            } catch (Exception e) {
                //回滚事务
                try {
                    connection.rollback();
                    System.out.println("JDBC Transaction rolled back successfully");
                } catch (SQLException e1) {
                    System.out.println("SQLException in rollback" + e1.getMessage());
                    e1.printStackTrace();
                }
                e.printStackTrace();
            } finally {
                //执行完数据库操作后记得关闭数据库连接资源
                try {
                    preparedStatement.close();
                    preparedStatement1.close();
                    connection.close();
    
                } catch (SQLException e) {
                    e.printStackTrace();
                }
    
            }
    
        }
    

    JDBC Savepoint示例

    有时候一个事务可能是一组复杂的语句,因此可能想要回滚到事务中某个特殊的点。JDBC Savepoint帮我们在事务中创建检查点(checkpoint),这样就可以回滚到指定点。当事务提交或者整个事务回滚后,为事务产生的任何保存点都会自动释放并变为无效。把事务回滚到一个保存点

     /*
         * 发生异常回滚到指定的位置
         * */
        public void insrolledSavepoint() {
            Savepoint savepoint = null;
            Connection connection = null;
            PreparedStatement preparedStatement = null;
            PreparedStatement preparedStatement1 = null;
            //这里参数用?占位符表示
            String sqlTeacher = "insert into teacher ( name, age, hobby, addr) values (?,?,?,?)";
            String sqlStudent = "insert into student (name, age, addr, hobby) values (?,?,?,?)";
            try {
                //获取数据连接
                connection = basicUse.getConnection();
                //设置事务自动提交为手动提交
                connection.setAutoCommit(false);
    
                //获取发送sql指令执行sql进行预编译
                preparedStatement = connection.prepareStatement(sqlStudent);
    
                //设置sql语句参数索引从1开始
                preparedStatement.setObject(1, "JDBC");
                preparedStatement.setObject(2, 24);
                preparedStatement.setObject(3, "上海");
                preparedStatement.setObject(4, "篮球");
                preparedStatement.executeUpdate();
                System.out.println("执行sqlStudent" + sqlStudent);
    
    
                //设置回滚的点  失败只会回滚老师信息
                savepoint = connection.setSavepoint("teacher");
    
                preparedStatement1 = connection.prepareStatement(sqlTeacher);
                preparedStatement1.setObject(1, "kenx");
                preparedStatement1.setObject(2, 24);
                preparedStatement1.setObject(3, "足球");
                preparedStatement1.setObject(4, "北京");
                preparedStatement1.executeUpdate();
                System.out.println("执行sqlTeacher" + sqlTeacher);
    
                   //手动制造异常
                   int i = 10 / 0;
                //提交事务
                connection.commit();
    
    
            } catch (Exception e) {
                //回滚事务
                try {
                    if (StrUtil.isEmptyIfStr(savepoint)) {
                        //回滚所有更新sql
                        connection.rollback();
                        System.out
                                .println("JDBC Transaction rolled back successfully");
                    } else {
                        connection.rollback(savepoint);
                        System.out.println("JDBC Transaction rolled back successfully");
                        connection.commit();
                    }
    
                } catch (SQLException e1) {
                    System.out.println("SQLException in rollback" + e1.getMessage());
                    e1.printStackTrace();
                }
                e.printStackTrace();
            } finally {
                //执行完数据库操作后记得关闭数据库连接资源
                try {
                    preparedStatement.close();
                    preparedStatement1.close();
                    connection.close();
    
                } catch (SQLException e) {
                    e.printStackTrace();
                }
    
            }
    
        }
    

    完整项目案例
    点击这里 github

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  • 原文地址:https://www.cnblogs.com/kenx/p/13553145.html
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