android - SingleInstance Activity 让我感到困惑

Question

一个 Activity 是一个单一的实例 Activity 。

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;

public class A extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setTitle("A");
        startActivity(new Intent(this, B.class));
    }

    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);
        testLog("new Intent A");
    }

    private void testLog(String string) {
        Log.d("test", string);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        testLog("destroy A");
    }
}

B Activity 是标准 Activity 。

在正常情况下A->B。用户action返回操作，B销毁。用户再次按下，A 销毁。没错。

但在另一种情况下:A->B。用户操作主页按钮。当用户重启任务时，android框架调用A的onNewIntent()。

为什么？我的意思是 Activity 堆栈应该是这样的:

-B
-A

为什么android框架将 Intent 路由到A？

Answer 1

singleTop、singleTask 和singleInstance 之间存在差异。阅读the documentation了解更多信息，但您确实要注意 singleInstance 的描述。

Only allow one instance of this activity to ever be running. This activity gets a unique task with only itself running in it; if it is ever launched again with the same Intent, then that task will be brought forward and its Activity.onNewIntent() method called. If this activity tries to start a new activity, that new activity will be launched in a separate task. See the Tasks and Back Stack document for more details about tasks.

这正是您所看到的并且应该是预期的行为。