浅谈java.util.concurrent包的并发处理(转)

我们都知道，在JDK1.5之前，Java中要进行业务并发时，通常需要有程序员独立完成代码实现，而当针对高质量Java多线程并发程序设计时,为防止死蹦等现象的出现，比如使用java之前的wait()、notify()和synchronized等，每每需要考虑性能、死锁、公平性、资源管理以及如何避免线程安全性方面带来的危害等诸多因素，往往会采用一些较为复杂的安全策略，加重了程序员的开发负担.万幸的是，在JDK1.5出现之后，Sun大神终于为我们这些可怜的小程序员推出了java.util.concurrent工具包以简化并发完成。开发者们借助于此，将有效的减少竞争条件（race conditions）和死锁线程。concurrent包很好的解决了这些问题，为我们提供了更实用的并发程序模型。

java.util.concurrent下主要的接口和类：

Executor：具体Runnable任务的执行者。

ExecutorService:一个线程池管理者，其实现类有多种，比如普通线程池，定时调度线程池ScheduledExecutorService等，我们能把一个

Runnable,Callable提交到池中让其调度。

Future：是与Runnable,Callable进行交互的接口，比如一个线程执行结束后取返回的结果等等，还提供了cancel终止线程。

BlockingQueue：阻塞队列。

下面我写一个简单的事例程序：

FutureProxy.java

查看复制到剪切板打印

package org.test.concurrent;
/** *//**
* Title: LoonFramework
* Description:利用Future模式进行处理
* Copyright: Copyright (c) 2007
* Company: LoonFramework
* @author chenpeng
* @email：ceponline@yahoo.com.cn
* @version 0.1
*/
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadFactory;
public abstract class FutureProxy<T> {
private final class CallableImpl implements Callable<T> {
public T call() throws Exception {
return FutureProxy.this.createInstance();
}
}
private static class InvocationHandlerImpl<T> implements InvocationHandler {
private Future<T> future;
private volatile T instance;
InvocationHandlerImpl(Future<T> future){
this.future = future;
}
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
synchronized(this){
if(this.future.isDone()){
this.instance = this.future.get();
}else{
while(!this.future.isDone()){
try{
this.instance = this.future.get();
}catch(InterruptedException e){
Thread.currentThread().interrupt();
}
}
}
return method.invoke(this.instance, args);
}
}
}
/** *//**
* 实现java.util.concurrent.ThreadFactory接口
* @author chenpeng
*
*/
private static final class ThreadFactoryImpl implements ThreadFactory {
public Thread newThread(Runnable r) {
Thread thread = new Thread(r);
thread.setDaemon(true);
return thread;
}
}
private static ExecutorService service = Executors.newCachedThreadPool(new ThreadFactoryImpl());
protected abstract T createInstance();
protected abstract Class<? extends T> getInterface();
/** *//**
* 返回代理的实例
* @return
*/
@SuppressWarnings("unchecked")
public final T getProxyInstance() {
Class<? extends T> interfaceClass = this.getInterface();
if (interfaceClass == null || !interfaceClass.isInterface()) {
throw new IllegalStateException();
}
Callable<T> task = new CallableImpl();
Future<T> future = FutureProxy.service.submit(task);
return (T) Proxy.newProxyInstance(interfaceClass.getClassLoader(),
new Class<?>[] { interfaceClass }, new InvocationHandlerImpl(future));
}
}

package org.test.concurrent;
/** *//**
* <p>Title: LoonFramework</p>
* <p>Description:利用Future模式进行处理</p>
* <p>Copyright: Copyright (c) 2007</p>
* <p>Company: LoonFramework</p>
* @author chenpeng  
* @email：ceponline@yahoo.com.cn 
* @version 0.1
*/
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadFactory;

public abstract class FutureProxy<T> {

    private final class CallableImpl implements Callable<T> {

        public T call() throws Exception {
            return FutureProxy.this.createInstance();
        }
    }

    private static class InvocationHandlerImpl<T> implements InvocationHandler {

        private Future<T> future;
        
        private volatile T instance;
        
        InvocationHandlerImpl(Future<T> future){
            this.future = future;
        }
        
        public Object invoke(Object proxy, Method method, Object[] args)
                throws Throwable {
            synchronized(this){
                if(this.future.isDone()){
                    this.instance = this.future.get();
                }else{
                    while(!this.future.isDone()){
                        try{
                            this.instance = this.future.get();
                        }catch(InterruptedException e){
                            Thread.currentThread().interrupt();
                        }
                    }
                }
                
                return method.invoke(this.instance, args);
            }
        }
    }

    /** *//**
     * 实现java.util.concurrent.ThreadFactory接口
     * @author chenpeng
     *
     */
    private static final class ThreadFactoryImpl implements ThreadFactory {

        public Thread newThread(Runnable r) {
            Thread thread = new Thread(r);
            thread.setDaemon(true);
            return thread;
        }
    }

    private static ExecutorService service = Executors.newCachedThreadPool(new ThreadFactoryImpl());

    protected abstract T createInstance();

    protected abstract Class<? extends T> getInterface();
    
    /** *//**
     * 返回代理的实例
     * @return
     */
    @SuppressWarnings("unchecked")
    public final T getProxyInstance() {
        Class<? extends T> interfaceClass = this.getInterface();
        if (interfaceClass == null || !interfaceClass.isInterface()) {
            throw new IllegalStateException();
        }

        Callable<T> task = new CallableImpl();

        Future<T> future = FutureProxy.service.submit(task);

        return (T) Proxy.newProxyInstance(interfaceClass.getClassLoader(),
                new Class<?>[] { interfaceClass }, new InvocationHandlerImpl(future));
    }
}

Test.java

查看复制到剪切板打印

package org.test.concurrent;
import java.util.Calendar;
/** *//**
* Title: LoonFramework
* Description:
* Copyright: Copyright (c) 2007
* Company: LoonFramework
* @author chenpeng
* @email：ceponline@yahoo.com.cn
* @version 0.1
*/
interface DateTest{
String getDate();
}
class DateTestImpl implements DateTest{
private String _date=null;
public DateTestImpl(){
try{
_date+=Calendar.getInstance().getTime();
//设定五秒延迟
Thread.sleep(5000);
}catch(InterruptedException e){
}
}
public String getDate() {
return "date "+_date;
}
}
class DateTestFactory extends FutureProxy<DateTest>{
@Override
protected DateTest createInstance() {
return new DateTestImpl();
}
@Override
protected Class<? extends DateTest> getInterface() {
return DateTest.class;
}
}
public class Test{
public static void main(String[] args) {
DateTestFactory factory = new DateTestFactory();
DateTest[] dts = new DateTest[100];
for(int i=0;i<dts.length;i++){
dts[i]=factory.getProxyInstance();
}
//遍历执行
for(DateTest dt : dts){
System.out.println(dt.getDate());
}
}
}

posted @ 2009-07-17 20:06 tmrp 阅读(1268) 评论(0) 编辑收藏举报

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浅谈java.util.concurrent包的并发处理(转)

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