android - 任务进入后台或进入前台时回调？

Question

我有一个 Activity A，它启动自定义选项卡。我需要知道自定义选项卡打开时，任务( Activity 所属的)是进入后台还是进入前台。
我知道这个问题 How to detect when an Android app goes to the background and come back to the foreground .这个问题提到的解决方案对我不起作用，因为一旦启动自定义选项卡，就会收到 onbackground 回调，这不是我想要的。当包含 Activity A 的任务进入后台时，我想要 onbackground 回调。

Answer 1

使用 CustomTabsCallback您可以使用 TAB_HIDDEN 收听选项卡何时隐藏(进入后台)回调或 TAB_SHOWN callback when the Tab becomes visible (goes into foreground).
从文档:
TAB_HIDDEN

Sent when the tab becomes hidden.

TAB_SHOWN

Sent when the tab becomes visible.

下面是一个完整的工作示例，说明如何使用上述回调:

public class CustomTabsActivity extends AppCompatActivity {

    private CustomTabsServiceConnection mCustomTabsServiceConnection;
    private CustomTabsClient mCustomTabsClient;
    private CustomTabsSession mCustomTabsSession;
    private CustomTabsIntent.Builder builder = new CustomTabsIntent.Builder();

    @Override
    protected void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.customTabsButton).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                showCustomTabs();
            }
        });
        initCustomTabs();
    }

    @Override
    protected void onStart() {
        super.onStart();
        CustomTabsClient.bindCustomTabsService(this, "com.android.chrome", mCustomTabsServiceConnection);
    }

    @Override
    protected void onResume() {
        super.onResume();
    }

    @Override
    protected void onStop() {
        super.onStop();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
    }

    private void initCustomTabs() {
        mCustomTabsServiceConnection = new CustomTabsServiceConnection()
        {
            @Override
            public void onCustomTabsServiceConnected(@NotNull ComponentName componentName, @NotNull CustomTabsClient customTabsClient)
            {
                mCustomTabsClient = customTabsClient;
                mCustomTabsClient.warmup(0L);
                mCustomTabsSession = mCustomTabsClient.newSession(new CustomTabsCallback()
                {
                    @Override
                    public void onNavigationEvent(int navigationEvent, Bundle extras) {
                        switch (navigationEvent)
                        {
                            case CustomTabsCallback.TAB_SHOWN:
                                //Sent when the tab becomes visible (goes into foreground)
                                break;
                            case CustomTabsCallback.TAB_HIDDEN:
                                //Sent when the tab becomes hidden (goes into background)
                                break;
                        }
                    }
                });
                builder.setSession(mCustomTabsSession);
            }
            @Override
            public void onServiceDisconnected(ComponentName name) {
                mCustomTabsClient = null;
            }
        };
        CustomTabsClient.bindCustomTabsService(this, "com.android.chrome", mCustomTabsServiceConnection);
    }

    private void showCustomTabs(){
        builder.setShowTitle(true);
        CustomTabsIntent customTabsIntent = builder.build();
        customTabsIntent.launchUrl(this, Uri.parse("https://stackoverflow.com/"));
    }
}