ProgressDialog的hide()和dismiss()方法

在使用ProgressDialog作为网络加载数据的请求过程中，当数据加载完成，笔者很自然的将ProgressDialog调用了hide()方法，在当前activity退出时，遇到问题了android.view.WindowLeaked: Activity com.xxx.xxx.hangup.ProgressDialogActivity has leaked window com.android.internal.policy.PhoneWindow$DecorView{dd0bacf G.E...... R.....I. 0,0-684,0} that was originally added here
这个问题是说当前dialog所依附的activity被销毁，dialog依然存在，未被销毁。这真是平时使用api时，没怎么注意的结果呀。调用hide()方法是可以实现dialog的隐藏，但是dialog对象并未销毁。
下面是一个简单的测试这种异常代码

public class ProgressDialogActivity extends Activity {
    private ProgressDialog pd;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //创建一个ProgressDialog，并执行show()方法
        pd = new ProgressDialog(this);
        pd.setMessage("在activity中showdialog后，直接退出activity异常");
        pd.setTitle("dialog异常测试");
        pd.show();
    }
    @Override
    protected void onResume() {
        super.onResume();
        //暂时在onResume()中掉了dialog的hide()方法，然后我们执行手机back键，会发现异常log
        /**
         * 
        01-01 02:37:26.845: E/MultiWindowProxy(25617): getServiceInstance failed!
        01-01 02:37:30.569: E/WindowManager(25617): android.view.WindowLeaked: Activity com.xxx.xxx.hangup.ProgressDialogActivity has leaked window com.android.internal.policy.PhoneWindow$DecorView{dd0bacf G.E...... R.....I. 0,0-684,0} that was originally added here
        01-01 02:37:30.569: E/WindowManager(25617):     at android.view.ViewRootImpl.(ViewRootImpl.java:460)
        01-01 02:37:30.569: E/WindowManager(25617):     at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:306)
        01-01 02:37:30.569: E/WindowManager(25617):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:85)
        01-01 02:37:30.569: E/WindowManager(25617):     at android.app.Dialog.show(Dialog.java:326)
        01-01 02:37:30.569: E/WindowManager(25617):     at com.xxx.xxxx.hangup.ProgressDialogActivity.onCreate(ProgressDialogActivity.java:25)
        01-01 02:37:30.569: E/WindowManager(25617):     at android.app.Activity.performCreate(Activity.java:6301)
        01-01 02:37:30.569: E/WindowManager(25617):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1113)
        01-01 02:37:30.569: E/WindowManager(25617):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2523)
        01-01 02:37:30.569: E/WindowManager(25617):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2658)
        01-01 02:37:30.569: E/WindowManager(25617):     at android.app.ActivityThread.-wrap11(ActivityThread.java)
        01-01 02:37:30.569: E/WindowManager(25617):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1492)
        01-01 02:37:30.569: E/WindowManager(25617):     at android.os.Handler.dispatchMessage(Handler.java:111)
        01-01 02:37:30.569: E/WindowManager(25617):     at android.os.Looper.loop(Looper.java:207)
        01-01 02:37:30.569: E/WindowManager(25617):     at android.app.ActivityThread.main(ActivityThread.java:5741)
        01-01 02:37:30.569: E/WindowManager(25617):     at java.lang.reflect.Method.invoke(Native Method)
        01-01 02:37:30.569: E/WindowManager(25617):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
        01-01 02:37:30.569: E/WindowManager(25617):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:685)
         */
        if(pd != null){
            pd.hide();
        }   
    }
}

上面注释是异常log信息。

下面看下hide()和dismiss()方法的具体实现：
hide()源码实现如下：
/**
* Hide the dialog, but do not dismiss it.
*/
public void hide() {
if (mDecor != null) {
mDecor.setVisibility(View.GONE);
}
}

很明确的看到dialog是一个view视图，而hide()实现中只是将view设置为gone，并未移除。
dialog的dismiss()方法如下：

 /**
     * Dismiss this dialog, removing it from the screen. This method can be
     * invoked safely from any thread.  Note that you should not override this
     * method to do cleanup when the dialog is dismissed, instead implement
     * that in {@link #onStop}.
     */
    @Override
    public void dismiss() {
        if (Looper.myLooper() == mHandler.getLooper()) {
            dismissDialog();
        } else {
            mHandler.post(mDismissAction);
        }
    }

在看下dismissDialog内的实现：

 void dismissDialog() {
        if (mDecor == null || !mShowing) {
            return;
        }

        if (mWindow.isDestroyed()) {
            Log.e(TAG, "Tried to dismissDialog() but the Dialog's window was already destroyed!");
            return;
        }

        try {
            mWindowManager.removeViewImmediate(mDecor);
        } finally {
            if (mActionMode != null) {
                mActionMode.finish();
            }
            mDecor = null;
            mWindow.closeAllPanels();
            onStop();
            mShowing = false;

            sendDismissMessage();
        }
    }

看到了mWindowManager.removeViewImmediate(mDecor)的代码。
至此，dialog的view才被真正移除。
希望小伙伴们不要犯和我一样的low的错误。。。