5大參數
a.核心線程數
b 最大線程數
c 線程空閑時間
d 阻塞隊列大小：queueCapacity
e 任務拒絕處理器 ：rejectedExceptionHandler
根據jdk 1.7,他又四類構造函數：
1. ThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue)
2. ThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, RejectedExecutionHandler handler)
3. ThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory)
4. ThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory, RejectedExecutionHandler handler)
實現線程池，有四種策略：
1.newCachedThreadPool
jdk 1.6源碼：
public
static
ExecutorService newCachedThreadPool() {
return
new
ThreadPoolExecutor(0, Integer.
MAX_VALUE
,
60L, TimeUnit.
SECONDS
,
new
SynchronousQueue<Runnable>());
}
2 newFixedThreadPool
jdk 1.6源碼：
public
static
ExecutorService newFixedThreadPool(
int
nThreads) {
return
new
ThreadPoolExecutor(nThreads, nThreads,
0L, TimeUnit.
MILLISECONDS
,
new
LinkedBlockingQueue<Runnable>());
}
3 newSingleThreadExecutor
jdk 1.6源碼：
public
static
ExecutorService newSingleThreadExecutor() {
return
new
FinalizableDelegatedExecutorService
(
new
ThreadPoolExecutor(1, 1,
0L, TimeUnit.
MILLISECONDS
,
new
LinkedBlockingQueue<Runnable>()));
}
4 newScheduledThreadPool
jdk 1.6源碼：
public
static
ScheduledExecutorService newScheduledThreadPool (
int
corePoolSize) {
return
new
ScheduledThreadPoolExecutor(corePoolSize);
}
public
ScheduledThreadPoolExecutor(
int
corePoolSize) {
super
(corePoolSize, Integer.
MAX_VALUE
, 0, TimeUnit.
NANOSECONDS
,
new
DelayedWorkQueue());
}