DBUtils应用事务

迷南。 2022-05-16 12:44 163阅读 0赞

### 1. DBUtils应用事务方式一 ###

public void transfer1(int sourceid,int targetid,double money) throws SQLException{
    
            Connection conn = null;
            try{
                conn = JdbcUtils.getConnection();
                conn.setAutoCommit(false);
    
                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();
            }finally{
                if(conn!=null) conn.close();
            }
        }

### 2. DBUtils应用事务方式二——ThreadLocal ###

public class JdbcUtils {
        private static DataSource ds;
    
        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;
        }
    
        public static Connection getConnection() throws SQLException{
            try{
                //得到当前线程上绑定的连接
                Connection conn = tl.get();
                if(conn==null){  //代表线程上没有绑定连接
                    conn = ds.getConnection();
                    tl.set(conn);
                }
                return conn;
            }catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
    
    
        public static void startTransaction(){
            try{
                //得到当前线程上绑定连接开启事务
                Connection conn = tl.get();
                if(conn==null){  //代表线程上没有绑定连接
                    conn = ds.getConnection();
                    tl.set(conn);
                }
                conn.setAutoCommit(false);
            }catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
    
    
        public static void commitTransaction(){
            try{
                Connection conn = tl.get();
                if(conn!=null){
                    conn.commit();
                }
            }catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
    
        public static void closeConnection(){
            try{
                Connection conn = tl.get();
                if(conn!=null){
                    conn.close();
                }
            }catch (Exception e) {
                throw new RuntimeException(e);
            }finally{
                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）
            }
        }
    }

//用上ThreadLocal的事务管理
        public void transfer2(int sourceid,int targetid,double money) throws SQLException{
    
            try{
                JdbcUtils.startTransaction();
                AccountDao dao = new AccountDao();
                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
                JdbcUtils.commitTransaction();
            }finally{
                JdbcUtils.closeConnection();
            }
        }