java try后没有catch，只有finnally

今天看jdk1.6源码  ThreadPoolExecutor中Worker的runTask方法   

catch(RunTimeException ex) 中 tthrow ex，会把ex抛到上层，上层try没有catch异常，该异常还会往上层抛，

try后直接跟finnally,finnally中runLock.unlock(),会释放锁；

总结：try....finnally 的用法主要是为了释放资源，不进行异常捕获，将异常交由上层调用者处理；

1private void runTask(Runnable task) {
2            final ReentrantLock runLock = this.runLock;
3            runLock.lock();
4            try {
5                /*
6                 * If pool is stopping ensure thread is interrupted;
7                 * if not, ensure thread is not interrupted. This requires
8                 * a double-check of state in case the interrupt was
9                 * cleared concurrently with a shutdownNow -- if so,
10                 * the interrupt is re-enabled.
11                 */
12                if ((runState >= STOP ||
13                    (Thread.interrupted() && runState >= STOP)) &&
14                    hasRun)
15                    thread.interrupt();
16                /*
17                 * Track execution state to ensure that afterExecute
18                 * is called only if task completed or threw
19                 * exception. Otherwise, the caught runtime exception
20                 * will have been thrown by afterExecute itself, in
21                 * which case we don't want to call it again.
22                 */
23                boolean ran = false;
24                beforeExecute(thread, task);
25                try {
26                    task.run();
27                    ran = true;
28                    afterExecute(task, null);
29                    ++completedTasks;
30                } catch (RuntimeException ex) {
31                    if (!ran)
32                        afterExecute(task, ex);
33                    throw ex;
34                }
35            } finally {
36                runLock.unlock();
37            }
38        }