package cn.itcast.transaction;import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;import cn.itcast.utils.JdbcUtils;
//代码加上事务了加上回滚了加上提交了//jdbc中事务操作
public class TransactionTest1 {public static void main(String[] args) throws SQLException {//修改id=2这个人的money=500;
String sql = "update account set money=500 where id=2";
Connection con = JdbcUtils.getConnection();con.setAutoCommit(false);//开启事务,相当于start transaction;

Statement st = con.createStatement();
st.executeUpdate(sql);//事务回滚
//con.rollback();

con.commit();//事务提交
st.close();
con.close();
}
}

package cn.itcast.transaction;import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;import cn.itcast.utils.JdbcUtils;
//代码加上事务了加上回滚了加上提交了//jdbc中事务操作
public class TransactionTest2 {public static void main(String[] args) {//修改id=2这个人的money=500;
String sql = "update account set money=500 where id=2";//事务操作的异常不能说想抛就抛
Connection con = null;
Statement st  = null;try {//如果数据库操作过程中捕获异常了,con = JdbcUtils.getConnection();con.setAutoCommit(false);//开启事务,相当于start transaction;st = con.createStatement();st.executeUpdate(sql);
} catch (SQLException e) {e.printStackTrace();//事务回滚 有异常就把事务回滚,有异常就说明出问题了//出问题就把数据恢复到原始,那就回滚吧try {con.rollback();} catch (SQLException e1) {e1.printStackTrace();}
}finally{//finally里面的内容肯定是能执行到的try {con.commit();//事务提交st.close();//资源关闭  释放资源操作  con.close();//资源关闭 } catch (SQLException e) {e.printStackTrace();}}}
}

package cn.itcast.utils;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ResourceBundle;public class JdbcUtils {private static final String DRIVERCLASS;private static final String URL;private static final String USERNAME;private static final String PASSWORD;private static final ThreadLocal<Connection> tl = new ThreadLocal<Connection>();static {DRIVERCLASS = ResourceBundle.getBundle("jdbc").getString("driverClass");URL = ResourceBundle.getBundle("jdbc").getString("url");USERNAME = ResourceBundle.getBundle("jdbc").getString("username");PASSWORD = ResourceBundle.getBundle("jdbc").getString("password");}static {try {// 将加载驱动操作，放置在静态代码块中.这样就保证了只加载一次.
            Class.forName(DRIVERCLASS);} catch (ClassNotFoundException e) {e.printStackTrace();}}public static Connection getConnection() throws SQLException {Connection con = tl.get();// 从ThreadLocal中获取Connection。第一次获取得到的是null.if (con == null) {// 2.获取连接con = DriverManager.getConnection(URL, USERNAME, PASSWORD);tl.set(con); // 将con装入到ThreadLocal中。
        }// tl.remove(); //解除return con;}// 关闭操作public static void closeConnection(Connection con) throws SQLException {if (con != null) {con.close();}}public static void closeStatement(Statement st) throws SQLException {if (st != null) {st.close();}}public static void closeResultSet(ResultSet rs) throws SQLException {if (rs != null) {rs.close();}}
}