动态代理结合事物的应用

在jdk1.3中或更高版本中继承java.lang.reflect.InvocationHandler实现动态代理

package com.read.proxy;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Connection;
import com.read.util.ConnectionFactory;

/**
 * 动态代理处理类
 * @author 
 *
 */
public class TransactionWrapper {

	/**
	 * 装饰原始的业务代表对象，返回一个与业务代表对象有相同接口的代理对象
	 */
	public static Object decorate(Object delegate) {
		return Proxy.newProxyInstance(delegate.getClass().getClassLoader(),
				delegate.getClass().getInterfaces(), new XAWrapperHandler(
						delegate));
	}

	// 动态代理技术
	static final class XAWrapperHandler implements InvocationHandler {
		private final Object delegate;

		XAWrapperHandler(Object delegate) {
			this.delegate = delegate;
		}

		public Object invoke(Object proxy, Method method, Object[] args)
				throws Throwable {
			Connection conn = null;
			Object retValue = null;
			try {
				conn = JdbcQueryManager.getConnection();
				
				/** 如果方法名以‘add’,'delete','update'开头就启用事物 */
				if (method.getName().startsWith("add")
						|| method.getName().startsWith("delete")
						|| method.getName().startsWith("update")) {
					delegate.getClass().getMethod("setConn",Class.forName(Connection.class.getName())).invoke(delegate, new Object[]{conn});
					conn.setAutoCommit(false);
					System.out.println("开始事物.......");
				}else if(method.getName().startsWith("find")){
					//不启用事物
					conn.setAutoCommit(true);
				}else{
					//不启用事物
					conn.setAutoCommit(true);
				}

				// 调用目标对象上的业务逻辑方法
				retValue = method.invoke(delegate, args);

				if(!conn.getAutoCommit()){
					// 提交事务
					conn.commit();
					System.out.println("提交事物........");
				}
			
			} catch (Exception e) {
				e.printStackTrace();
				if(!conn.getAutoCommit()){
					conn.rollback();
					System.out.println("出错了，回滚数据........");
				}
				
				throw new Exception("操作错误！");
			} finally {
				//将连接放入连接池中
				ConnectionFactory.closeConnection(conn);
			}
			return retValue;
		}
	}

}

package com.read.proxy;

import java.sql.Connection;
import com.read.util.StrUtil;

/**
 * 测试，该类必须实现@see : com.read.proxy.TestProxyInter
 * @author 陈彪
 *
 */
public class TestProxy implements TestProxyInter {
	
	private ExecuteSQL exe = new ExecuteSQL();
	
	private Connection conn;

	public void setConn(Connection conn) {
		this.conn = conn;
	}
	
	public void addMat() throws Exception {
		
		try {
			exe.setConn(conn);
			exe.executeSql("insert into test(a) values(?)",new Object[]{StrUtil.replaceSql("1")});
			exe.executeSql("insert into test(a) values(?)",new Object[]{StrUtil.replaceSql("2")});
			exe.executeSql("insert into test(a) values(?)",new Object[]{StrUtil.replaceSql("3")});
			exe.executeSql("insert into test(a) values(?)",new Object[]{StrUtil.replaceSql("4")});
			//错误写法
			exe.executeSql("insert into test(af) values(?)",new Object[]{StrUtil.replaceSql("5")});
		} catch (Exception e) {
			e.printStackTrace();
			throw e;
		}

	}
	
	public static void main(String []args){
		TransactionWrapper in = new TransactionWrapper();
		TestProxyInter s = (TestProxyInter)in.decorate(new TestProxy());
		try {
			s.addMat();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	public Connection getConn() {
		return conn;
	}

}