用ThreadLocal管理事务

1、适用场景

一个service，操作两个dao，要求两个dao为同一个事务，要么全成功，要么全失败。

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" alt="" />

DBUtils，使用ThreadLocal

 public class DbUtils {
     //线程局部数据容器
     private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();
     private static DataSource ds;
     private static Connection conn;
     static{
         ds=new ComboPooledDataSource();
     }

     public static DataSource getdDataSource()
     {
         return ds;
     }
     public static Connection getcConnection()
     {

         try {
             conn=tl.get();//是否已经有值
             if(conn==null)//没有值就添加
             {
                 conn=ds.getConnection();
                 tl.set(conn);
             }

         } catch (SQLException e) {
             e.printStackTrace();
         }
         return conn;
     }

     public static void remove()
     {
         tl.remove();//实现一个删除thredlocal中与线程相关的对象
     }
 }

过滤器中管理事务

 public void doFilter(ServletRequest request, ServletResponse response,
             FilterChain chain) throws IOException, ServletException {
         Connection conn = null;
         try {
             conn = DbUtils.getcConnection();
             conn.setAutoCommit(false);
             chain.doFilter(request, response);//放行
             conn.commit();//如果没有出错，提交事务，所以需要在dao中抛出异常，不能try-catch，否则无法捕捉到错误
             System.err.println("成功.......................");
         } catch (Exception e) {
             System.err.println("出错了......................");
             try {
                 //判断是否是数据库错误，如果不是还是提交
                 if (e instanceof SQLException) {
                     conn.rollback();
                 } else {
                     conn.commit();
                 }
             } catch (SQLException e1) {
                 e1.printStackTrace();
             }
         } finally {
             try {
                 conn.close();//关闭连接
                 DbUtils.remove();//实现一个删除thredlocal中与线程相关的对象
             } catch (SQLException e) {
                 e.printStackTrace();
             }
         }
     }

注意：必须在dao中抛出异常，否则无法捕捉到，永远是提交事务。

dao层：

try {
                DataSource ds=DbUtils.getdDataSource();
                Connection conn=ds.getConnection();
                QueryRunner run =new QueryRunner(ds);
                String sql="INSERT INTO users VALUES (?,?,? ";
                run.update(conn, sql,"U005","Tom","456");
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }

如果需要进行事务的管理，添加到过滤器url中即可