JDBC---使用Connection连接对象来管理事务

JDBC 使用Connection连接对象来管理事务管理事务:

• 事务：一个包含多个步骤的业务操作。如果这个业务操作被事务管理，则这多个步骤要么同时成功，要么同时失败。

• 操作：

  1. 开启事务
  2. 提交事务
  3. 回滚事务

• 使用Connection对象来管理事务

  • 开启事务：setAutoCommit(boolean autoCommit) ：调用该方法设置参数为false，即开启事务
    • 在执行sql之前开启事务
  • 提交事务：commit()
    • 当所有sql都执行完提交事务
  • 回滚事务：rollback()
    • 在catch中回滚事务

package thinking_in_java.jdbc;

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

/**
 * @PackageName: thinking_in_java.jdbc
 * @ClassName: Transactional
 * @Author: 
 * @Date: 2020/9/28 10:41
 * @Description: //TODO
 */
public class Transactional {
	/**
	 * 事务操作
	 */
	public static void main(String[] args) {
		Connection conn = null;
		PreparedStatement pstmt1 = null;
		PreparedStatement pstmt2 = null;

		try {
			//1.获取连接
			conn = JDBCUtils.getConnection();
			//开启事务
			conn.setAutoCommit(false);
			//2.定义sql
			//2.1 张三 - 500
			String sql1 = "update account set balance = balance - ? where id = ?";
			//2.2 李四 + 500
			String sql2 = "update account set balance = balance + ? where id = ?";
			//3.获取执行sql对象
			pstmt1 = conn.prepareStatement(sql1);
			pstmt2 = conn.prepareStatement(sql2);
			//4. 设置参数
			pstmt1.setDouble(1, 500);
			pstmt1.setInt(2, 2);

			pstmt2.setDouble(1, 500);
			pstmt2.setInt(2, 3);
			//5.执行sql
			pstmt1.executeUpdate();
			// 手动制造异常
			//int i = 3/0;
			pstmt2.executeUpdate();
			//提交事务
			conn.commit();
		} catch (Exception e) {
			//事务回滚
			try {
				if (conn != null) {
					conn.rollback();
				}
			} catch (SQLException e1) {
				e1.printStackTrace();
			}
			e.printStackTrace();
		} finally {
			JDBCUtils.close(pstmt1, conn);
			JDBCUtils.close(pstmt2, null);
		}
	}
}

package thinking_in_java.jdbc;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

/**
 * @PackageName: thinking_in_java.jdbc
 * @ClassName: JDBCUtils
 * @Author: 
 * @Date: 2020/9/28 10:43
 * @Description: //TODO
 */
public class JDBCUtils {

	private static String url;
	private static String user;
	private static String password;
	private static String driver;

	static {
		Properties properties = new Properties();
		ClassLoader classLoader = JDBCUtils.class.getClassLoader();
		InputStream resourceAsStream = classLoader.getResourceAsStream("jdbc.properties");
		try {
			properties.load(resourceAsStream);
			url = properties.getProperty("url");
			user = properties.getProperty("user");
			password = properties.getProperty("password");
			driver = properties.getProperty("driver");
			Class.forName(driver);
		} catch (IOException | ClassNotFoundException e) {
			e.printStackTrace();
		}
	}

	public JDBCUtils() {
	}

	public static Connection getConnection() throws SQLException {
		return DriverManager.getConnection(url, user, password);
	}

	public static void close(Statement statement,Connection connection){
		close(null,statement,connection);
	}

	public static void close(ResultSet rs, Statement stmt, Connection conn) {
		if (rs != null) {
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}

		if (stmt != null) {
			try {
				stmt.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}

		if (conn != null) {
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
}