JAVA執行緒池的簡單實現及優先順序設定
阿新 • • 發佈：2019-02-07
{
privatestatic ThreadPool instance =null;
// 優先順序低
publicstaticfinalint PRIORITY_LOW =0;
// 普通
publicstaticfinalint PRIORITY_NORMAL =1;
// 高
publicstaticfinalint PRIORITY_HIGH =2;
// 用以儲存空閒連線
private List[] _idxThreads;
// 關閉
privateboolean _shutdown =false;
// 執行緒數量
privateint _threadCount =0;
privateboolean _debug =false;
/**
* 返回ThreadPool例項
*
* @return
*/
publicstatic ThreadPool getInstance() {
if (instance ==null) {
instance =new ThreadPool();
}
return instance;
}
// 初始化執行緒list
private ThreadPool()
this._idxThreads =new List[] { new LinkedList(), new LinkedList(),
new LinkedList() };
this._threadCount=0;
}
/**
* 同步方法，完成任務後將資源放回執行緒池中
* @param repool
*/
protectedsynchronizedvoid repool(Pooled repool) {
if (this._shutdown) {
System.out.println("ThreadPool.repool():重設中……");
}
// 優先級別判定
switch (repool.getPriority()) {
case Thread.MIN_PRIORITY:
this._idxThreads[PRIORITY_LOW].add(repool);
break;
case Thread.NORM_PRIORITY:
this._idxThreads[PRIORITY_NORMAL].add(repool);
break;
case Thread.MAX_PRIORITY:
this._idxThreads[PRIORITY_HIGH].add(repool);
break;
default:
thrownew IllegalStateException("沒有此種級別");
}
// 通知所有執行緒
notifyAll();
}else{
if (this._debug) {
System.out.println("ThreadPool.repool():登出中……");
}
repool.shutDown();
}
if(this._debug){
System.out.println("ThreadPool.repool():完成");
}
}
publicvoid setDebug(boolean debug){
this._debug=debug;
}
publicsynchronizedvoid shutDown(){
this._shutdown=true;
if(this._debug){
System.out.println("ThreadPool.shutDown():關閉中……");
}
for(int index=0;index<=PRIORITY_NORMAL;index++){
List threads=this._idxThreads[index];
for(int threadIndex=0;threadIndex<threads.size();threadIndex++){
Pooled idleThread=(Pooled)threads.get(threadIndex);
idleThread.shutDown();
}
}
notifyAll();
}
/**
* 以指定的優先順序啟動執行緒
* @param target
* @param priority
*/
publicsynchronizedvoid start(Runnable target,int priority){
Pooled thread=null;
List idleList=this._idxThreads[priority];
int idleSize=idleList.size();
if(idleSize>0){
int lastIndex=idleSize-1;
thread=(Pooled)idleList.get(lastIndex);
idleList.remove(idleList);
thread.setTarget(target);
}else{
this._threadCount++;
thread=new Pooled(target,"Pooled->"+this._threadCount,this);
switch(priority){
case PRIORITY_LOW:
thread.setPriority(Thread.MIN_PRIORITY);
break;
case PRIORITY_NORMAL:
thread.setPriority(Thread.NORM_PRIORITY);
break;
case PRIORITY_HIGH:
thread.setPriority(Thread.MAX_PRIORITY);
break;
default:
thread.setPriority(Thread.NORM_PRIORITY);
}
//啟動
thread.start();
}
}
/**
* 返回執行緒數量
*
* @return
*/
publicint getThreadsCount() {
returnthis._threadCount;
}
}
privatestatic ThreadPool instance =null; // 優先順序低publicstaticfinalint PRIORITY_LOW =0; // 普通publicstaticfinalint PRIORITY_NORMAL =1; // 高publicstaticfinalint PRIORITY_HIGH =2; // 用以儲存空閒連線private List[] _idxThreads; // 關閉privateboolean _shutdown =false; // 執行緒數量privateint _threadCount =0; privateboolean _debug =false; /**
* 返回ThreadPool例項 * * @return */ publicstatic ThreadPool getInstance() { if (instance ==null) { instance =new ThreadPool(); } return instance; } // 初始化執行緒listprivate ThreadPool() this._idxThreads =new List[] { new LinkedList(), new LinkedList(), new LinkedList() }; this._threadCount=0; } /** * 同步方法，完成任務後將資源放回執行緒池中 * @param repool */ protectedsynchronizedvoid repool(Pooled repool) { if (this._shutdown) { System.out.println("ThreadPool.repool():重設中……"); } // 優先級別判定switch (repool.getPriority()) { case Thread.MIN_PRIORITY: this._idxThreads[PRIORITY_LOW].add(repool); break; case Thread.NORM_PRIORITY: this._idxThreads[PRIORITY_NORMAL].add(repool); break; case Thread.MAX_PRIORITY: this._idxThreads[PRIORITY_HIGH].add(repool); break; default: thrownew IllegalStateException("沒有此種級別"); } // 通知所有執行緒 notifyAll(); }else{ if (this._debug) { System.out.println("ThreadPool.repool():登出中……"); } repool.shutDown(); } if(this._debug){ System.out.println("ThreadPool.repool():完成"); } } publicvoid setDebug(boolean debug){ this._debug=debug; } publicsynchronizedvoid shutDown(){ this._shutdown=true; if(this._debug){ System.out.println("ThreadPool.shutDown():關閉中……"); } for(int index=0;index<=PRIORITY_NORMAL;index++){ List threads=this._idxThreads[index]; for(int threadIndex=0;threadIndex<threads.size();threadIndex++){ Pooled idleThread=(Pooled)threads.get(threadIndex); idleThread.shutDown(); } } notifyAll(); } /** * 以指定的優先順序啟動執行緒 * @param target * @param priority */ publicsynchronizedvoid start(Runnable target,int priority){ Pooled thread=null; List idleList=this._idxThreads[priority]; int idleSize=idleList.size(); if(idleSize>0){ int lastIndex=idleSize-1; thread=(Pooled)idleList.get(lastIndex); idleList.remove(idleList); thread.setTarget(target); }else{ this._threadCount++; thread=new Pooled(target,"Pooled->"+this._threadCount,this); switch(priority){ case PRIORITY_LOW: thread.setPriority(Thread.MIN_PRIORITY); break; case PRIORITY_NORMAL: thread.setPriority(Thread.NORM_PRIORITY); break; case PRIORITY_HIGH: thread.setPriority(Thread.MAX_PRIORITY); break; default: thread.setPriority(Thread.NORM_PRIORITY); } //啟動 thread.start(); } } /** * 返回執行緒數量 * * @return */ publicint getThreadsCount() { returnthis._threadCount; }}