dbutis事务管理

1、在dao层用dbutils实现事务管理

     //从a--->b帐户转100元
     public void transfer() throws SQLException{
         Connection conn = null;
         try{
             conn = JdbcUtils.getConnection();
             conn.setAutoCommit(false);

             QueryRunner runner = new QueryRunner();  //不能给数据源，给数据源的话runner执行完一条sql会自动关闭连接，无法实现事务
             String sql1 = "update account set money=money-100 where name='aaa'";
             runner.update(conn,sql1);

             String sql2 = "update account set money=money+100 where name='bbb'";
             runner.update(conn,sql2);

             conn.commit();
         }finally{
             if(conn!=null){
                 conn.close();
             }
         }
     }

2、service层和dao层分离实现事务管理

dao层

 public class AccountDao {

     public AccountDao() {
         super();
         // TODO Auto-generated constructor stub
     }

12     private Connection conn;
13     public AccountDao(Connection conn){
14         this.conn = conn;
15     }

     public void update(Account a){
         try{
             QueryRunner runner = new QueryRunner();
             String sql = "update account set money=? where id=?";
             Object params[] = {a.getMoney(),a.getId()};
             runner.update(con,sql, params);
         }catch (Exception e) {
             throw new RuntimeException(e);
         }
     }

     public Account find(int id){
         try{
             QueryRunner runner = new QueryRunner();
             String sql = "select * from account where id=?";
             return (Account) runner.query(con,sql, id, new BeanHandler(Account.class));
         }catch (Exception e) {
             throw new RuntimeException(e);
         }
     }

service层

 public void transfer1(int sourceid,int targetid,double money) throws SQLException{

         Connection conn = null;
         try{
             conn = JdbcUtils.getConnection();
             conn.setAutoCommit(false); //开始事务

             AccountDao dao = new AccountDao(conn);

             Account a = dao.find(sourceid);   //select
             Account b = dao.find(targetid);   //select

             a.setMoney(a.getMoney()-money);
             b.setMoney(b.getMoney()+money);   

             dao.update(a); //update

             dao.update(b);//update

             conn.commit(); //提交事务
         }finally{
             if(conn!=null) conn.close();
         }
     }

3、使用ThreadLocal实现事务管理

dao层

     public void update(Account a){
         try{
             QueryRunner runner = new QueryRunner();
             String sql = "update account set money=? where id=?";
             Object params[] = {a.getMoney(),a.getId()};
             runner.update(JdbcUtils.getConnection(),sql, params);
         }catch (Exception e) {
             throw new RuntimeException(e);
         }
     }

     public Account find(int id){
         try{
             QueryRunner runner = new QueryRunner();
             String sql = "select * from account where id=?";
             return (Account) runner.query(JdbcUtils.getConnection(),sql, id, new BeanHandler(Account.class));
         }catch (Exception e) {
             throw new RuntimeException(e);
         }
     }

service层

     //用上ThreadLocal的事务管理
     public void transfer2(int sourceid,int targetid,double money) throws SQLException{

 4         try{
 5             JdbcUtils.startTransaction();
 6             AccountDao dao = new AccountDao();
 7             Account a = dao.find(sourceid);   //select
 8             Account b = dao.find(targetid);   //select
 9             a.setMoney(a.getMoney()-money);
10             b.setMoney(b.getMoney()+money);
11             dao.update(a); //update
12             dao.update(b);//update
13             JdbcUtils.commitTransaction();
14         }finally{
15             JdbcUtils.closeConnection();
         }
     }

JDBC工具类

 public class JdbcUtils {
     private static DataSource ds;

 4     private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();  //map
     static{
         try{
             Properties prop = new Properties();
             InputStream in = JdbcUtils.class.getClassLoader().getResourceAsStream("dbcpconfig.properties");
             prop.load(in);
             BasicDataSourceFactory factory = new BasicDataSourceFactory();
             ds = factory.createDataSource(prop);
         }catch (Exception e) {
             throw new ExceptionInInitializerError(e);
         }
     }

     public static DataSource getDataSource(){
         return ds;
     }

21     public static Connection getConnection() throws SQLException{
22         try{
23             //得到当前线程上绑定的连接
24             Connection conn = tl.get();
25             if(conn==null){  //代表线程上没有绑定连接
26                 conn = ds.getConnection();
27                 tl.set(conn);
28             }
29             return conn;
30         }catch (Exception e) {
31             throw new RuntimeException(e);
32         }
33     }

36     public static void startTransaction(){
37         try{
38             //得到当前线程上绑定连接开启事务
39             Connection conn = tl.get();
40             if(conn==null){  //代表线程上没有绑定连接
41                 conn = ds.getConnection();
42                 tl.set(conn);
43             }
44             conn.setAutoCommit(false);
45         }catch (Exception e) {
46             throw new RuntimeException(e);
47         }
48     }

51     public static void commitTransaction(){
52         try{
53             Connection conn = tl.get();
54             if(conn!=null){
55                 conn.commit();
56             }
57         }catch (Exception e) {
58             throw new RuntimeException(e);
59         }
60     }

62     public static void closeConnection(){
63         try{
64             Connection conn = tl.get();
65             if(conn!=null){
66                 conn.close();
67             }
68         }catch (Exception e) {
69             throw new RuntimeException(e);
70         }finally{
71             tl.remove();   //千万注意，解除当前线程上绑定的链接（从threadlocal容器中移除对应当前线程的链接）
72         }
73     }
 }