java try后沒有catch，只有finnally

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

catch(RunTimeException ex) 中 tthrow ex，會把ex拋到上層，上層try沒有catch異常，該異常還會往上層拋，

try后直接跟finnally,finnally中runLock.unlock(),會釋放鎖；

總結：try....finnally 的用法主要是為了釋放資源，不進行異常捕獲，將異常交由上層調用者處理；

 

        private void runTask(Runnable task) {
            final ReentrantLock runLock = this.runLock;
            runLock.lock();
            try {
                /*
                 * If pool is stopping ensure thread is interrupted;
                 * if not, ensure thread is not interrupted. This requires
                 * a double-check of state in case the interrupt was
                 * cleared concurrently with a shutdownNow -- if so,
                 * the interrupt is re-enabled.
                 */
                if ((runState >= STOP ||
                    (Thread.interrupted() && runState >= STOP)) &&
                    hasRun)
                    thread.interrupt();
                /*
                 * Track execution state to ensure that afterExecute
                 * is called only if task completed or threw
                 * exception. Otherwise, the caught runtime exception
                 * will have been thrown by afterExecute itself, in
                 * which case we don't want to call it again.
                 */
                boolean ran = false;
                beforeExecute(thread, task);
                try {
                    task.run();
                    ran = true;
                    afterExecute(task, null);
                    ++completedTasks;
                } catch (RuntimeException ex) {
                    if (!ran)
                        afterExecute(task, ex);
                    throw ex;
                }
            } finally {
                runLock.unlock();
            }
        }