JavaWeb之JDBC处理事务

【转账案例】

CREATE TABLE t_account(
	id INT PRIMARY KEY AUTO_INCREMENT,
	NAME VARCHAR(40),
	account DOUBLE
);

INSERT INTO t_account(NAME,account) VALUES('李星云',1000);
INSERT INTO t_account(NAME,account) VALUES('姬如雪',800);

SELECT * FROM t_account;

JDBCUtils.java

package zh.jdbc.demo;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class JDBCUtils {

	private JDBCUtils() {

	}

	// 获取数据库连接
	public static Connection getConnection(String driverClassName, String url,
			String username, String password) {

		try {
			Class.forName(driverClassName);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}

		Connection connection = null;
		try {
			connection = DriverManager.getConnection(url, username, password);
			return connection;
		} catch (SQLException cause) {
			throw new RuntimeException("获取数据库连接失败", cause);
		}

	}

	// 关闭资源
	public static void close(Statement statement, Connection connection) {

		if (statement != null) {
			try {
				statement.close();
			} catch (SQLException cause) {
				throw new RuntimeException("关闭Statement失败", cause);
			}
			statement = null;
		}

		if (connection != null) {
			try {
				connection.close();
			} catch (SQLException cause) {
				throw new RuntimeException("关闭数据库连接失败", cause);
			}
		}
		connection = null;

	}

	// 关闭资源
	public static void close(ResultSet resultSet, Statement statement,
			Connection connection) {

		if (resultSet != null) {
			try {
				resultSet.close();
			} catch (SQLException cause) {
				throw new RuntimeException("关闭ResultSet失败", cause);
			}
		}

		resultSet = null;

		close(statement, connection);

	}

}

AccountDao1.java

package zh.jdbc.demo;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class AccountDao1 {

	public AccountDao1() {

	}

	private String driverClassName = "com.mysql.jdbc.Driver";
	private String url = "jdbc:mysql://localhost:3306/day0528";
	private String username = "root";
	private String password = "zh1277718668";

	// 转账
	public boolean transfer(String from, String to, double account) {

		Connection connection = null;
		PreparedStatement pstatement = null;
		try {
			connection = JDBCUtils.getConnection(driverClassName, url,
					username, password);
			connection.setAutoCommit(false);// 开启事务

			String sql = "update t_account set account = account + ? where name = ?";
			pstatement = connection.prepareStatement(sql);

			pstatement.setDouble(1, 0 - account);
			pstatement.setString(2, from);
			pstatement.execute();
			
			pstatement.setDouble(1, account);
			pstatement.setString(2, to);			
			pstatement.executeUpdate();

			connection.commit();// 提交事务
			return true;
		} catch (Exception cause) {
			try {
				connection.rollback();// 回滚事务
				return false;
			} catch (SQLException e) {
				e.printStackTrace();
				throw new RuntimeException("转账失败", cause);
			}
		} finally {
			JDBCUtils.close(pstatement, connection);
		}

	}

}

或者，使用批处理

AccountDao2.java

package zh.jdbc.demo;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class AccountDao2 {

	public AccountDao2() {

	}

	private String driverClassName = "com.mysql.jdbc.Driver";
	private String url = "jdbc:mysql://localhost:3306/day0528";
	private String username = "root";
	private String password = "zh1277718668";

	// 转账
	public boolean transfer(String from, String to, double account) {

		Connection connection = null;
		PreparedStatement pstatement = null;
		try {
			connection = JDBCUtils.getConnection(driverClassName, url,
					username, password);
			connection.setAutoCommit(false);// 开启事务

			String sql = "update t_account set account = account + ? where name = ?";
			pstatement = connection.prepareStatement(sql);

			pstatement.setDouble(1, 0 - account);
			pstatement.setString(2, from);
			pstatement.addBatch();
			
			pstatement.setDouble(1, account);
			pstatement.setString(2, to);
			pstatement.addBatch();
			
			pstatement.executeBatch();// 批处理

			connection.commit();// 提交事务
			return true;
		} catch (Exception cause) {
			try {
				connection.rollback();// 回滚事务
				return false;
			} catch (SQLException e) {
				e.printStackTrace();
				throw new RuntimeException("转账失败", cause);
			}
		} finally {
			JDBCUtils.close(pstatement, connection);
		}

	}

}

AccountDaoDemo.java

package zh.jdbc.demo;

public class AccountDaoDemo {

	public static void main(String[] args) {

		//AccountDao1 accountDao = new AccountDao1();
		AccountDao2 accountDao = new AccountDao2();
		boolean transfer = accountDao.transfer("李星云", "姬如雪", 100);
		System.out.println(transfer);

	}

}

【结果】

先使用AccountDao1+AccountDaoDemo

再使用AccountDao2+AccountDaoDemo