运用ThreadLocal解决jdbc事务管理

JdbcUtils.java

public class JdbcUtils {

    private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();

    private static DataSource ds;

    

    static {

        ds = new ComboPooledDataSource();

    }

    

    public static DataSource getDataSource() {

        return ds;

    }

    

    // 当前线程绑定一个开启事务的连接

    // ThreadLocal是一个map集合 具有get() set() remove()方法 key是线程名称

    public static Connection getConnection() throws SQLException {

        Connection conn = tl.get();

        if (conn == null) {

            conn = ds.getConnection();

            tl.set(conn);            

        }

        return conn;

    }

    

    public static void startTransaction() {

        try {

            Connection conn = getConnection(); //调用

            if(conn != null) {

                conn.setAutoCommit(false);

            }

        } catch (Exception e) {

            throw new RuntimeException();

        }

    }

    

    public static void rollback() {

        try {

            Connection conn = getConnection(); //调用

            if(conn != null) {

                conn.rollback();

                conn.commit();

            }

        } catch (Exception e) {

            throw new RuntimeException();

        }

    }

    

    public static void commit() {

        try {

            Connection conn = getConnection(); //调用

            if(conn != null) {

                conn.commit();

            }

        } catch (Exception e) {

            throw new RuntimeException();

        }

    }

    

    public static void close() {

        try {

            Connection conn = getConnection(); //调用

            if(conn != null) {

                try {

                    conn.close();

                } finally {

                    tl.remove();

                }                

            }

        } catch (Exception e) {

            throw new RuntimeException();

        }

    }

}

AccountService.java

public class AccountService {

    

    // ThreadLocal 解决方案

    public void transfer(int sourceid,int destid,double money) throws SQLException {

        

        try {

            JdbcUtils.startTransaction();

            AccountDao dao = new AccountDao();

            

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

            Account b = dao.find(destid); //select

            

            a.setMoney(a.getMoney()-100);

            b.setMoney(b.getMoney()+100);

            

            dao.update(a); //update

            dao.update(b); //update

　　　　　　　JdbcUtils.commit();            

        } catch (Exception e) {

            JdbcUtils.rollback();
　　　　　　　throw new RuntimeException();

        } finally {

            JdbcUtils.close();

        }

        

}