Java地带 Java使用java.util.concurrent实现的线程池、消息队列功能
ThreadPoolManager类：负责管理线程池，调用轮询的线程来访问字符串缓冲区的内容，维护缓冲区，当线程池溢出时抛出的Runnable任务被加入到字符缓冲区。
public class ThreadPoolManager
{
private static ThreadPoolManager tpm = new ThreadPoolManager();
// 线程池维护线程的最少数量
private final static int CORE_POOL_SIZE = 4;
// 线程池维护线程的最大数量
private final static int MAX_POOL_SIZE = 10;
// 线程池维护线程所允许的空闲时间
private final static int KEEP_ALIVE_TIME = 0;
// 线程池所使用的缓冲队列大小
private final static int WORK_QUEUE_SIZE = 10;
// 消息缓冲队列
Queue msgQueue = new LinkedList();
// 访问消息缓存的调度线程
final Runnable accessBufferThread = new Runnable()
{
public void run()
{
// 查看是否有待定请求，如果有，则创建一个新的AccessDBThread，并添加到线程池中
if( hasMoreAcquire() )
{
String msg = ( String ) msgQueue.poll();
Runnable task = new AccessDBThread( msg );
threadPool.execute( task );
}
}
};
final RejectedExecutionHandler handler = new RejectedExecutionHandler()
{
public void rejectedExecution( Runnable r, ThreadPoolExecutor executor )
{
System.out.println(((AccessDBThread )r).getMsg()+"消息放入队列中重新等待执行");
msgQueue.offer((( AccessDBThread ) r ).getMsg() );
}
};
// 管理数据库访问的线程池
final ThreadPoolExecutor threadPool = new ThreadPoolExecutor(
CORE_POOL_SIZE, MAX_POOL_SIZE, KEEP_ALIVE_TIME, TimeUnit.SECONDS,
new ArrayBlockingQueue( WORK_QUEUE_SIZE ), this.handler );
// 调度线程池
final ScheduledExecutorService scheduler = Executors
.newScheduledThreadPool( 1 );
final ScheduledFuture taskHandler = scheduler.scheduleAtFixedRate(
accessBufferThread, 0, 1, TimeUnit.SECONDS );
public static ThreadPoolManager newInstance()
{
return tpm;
}
private ThreadPoolManager(){}
private boolean hasMoreAcquire()
{
return !msgQueue.isEmpty();
}
public void addLogMsg( String msg )
{
Runnable task = new AccessDBThread( msg );
threadPool.execute( task );
}
}
public class AccessDBThread implements Runnable
{
private String msg;
public String getMsg()
{
return msg;
}
public void setMsg( String msg )
{
this.msg = msg;
}
public AccessDBThread(){
super();
}
public AccessDBThread(String msg){
this.msg = msg;
}
public void run()
{
// 向数据库中添加Msg变量值
System.out.println("Added the message: "+msg+" into the Database");
}
}
public class TestDriver
{
ThreadPoolManager tpm = ThreadPoolManager.newInstance();
public void sendMsg( String msg )
{
tpm.addLogMsg( msg + "记录一条日志 " );
}
public static void main( String[] args )
{
for( int i = 0; i < 100; i++ )
{
new TestDriver().sendMsg( Integer.toString( i ) );
}
}
}
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