強制下線是一種很常見的場面，比如我們的qq被別人登陸了，那麼你就會強制下線。

它的思路是什麼樣的呢。

其實也並不難，我們只需要在介面上彈出一個對話方塊，讓使用者無法進行其他操作，必須點選對話方塊的確定按鈕，然後返回登入介面。

但存在一個問題，我們被強制下線時，我們可能正在打遊戲，咔擦，完了，一個對話方塊彈出來，你遊戲就gg了。

強制下線需要關閉所有的活動，然後回到登入介面。

配置檔案mainifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.sunshunli.broadcastbestpractice">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
        </activity>
        <activity android:name=".LoginActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>
 

mainactivity：

package com.example.sunshunli.broadcastbestpractice;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends BaseActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button forceoffline = findViewById(R.id.fore_offlinen);
        forceoffline.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent("com.example.broadcastpractice.FORCE_OFFLINE");
                sendBroadcast(intent);
            }
        });
    }
}
 

Baseactivivty

package com.example.sunshunli.broadcastbestpractice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;

public class BaseActivity extends AppCompatActivity{
    private ForceOfflineReceive receiver;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityCollector.addActivity(this);
    }


    @Override
    protected void onPostResume() {
        super.onPostResume();
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("com.example.broadcastpractice.FORCE_OFFLINE");
        receiver = new ForceOfflineReceive();
        registerReceiver(receiver,intentFilter);
    }

    @Override
    protected void onPause() {
        super.onPause();
        if(receiver!=null){
            unregisterReceiver(receiver);
            receiver=null;
        }
    }

    protected void onDestory(){
        super.onDestroy();
        ActivityCollector.removeActivity(this);
    }
    class ForceOfflineReceive extends BroadcastReceiver{
        @Override
        public void onReceive(final Context context, Intent intent) {
            AlertDialog.Builder builder = new AlertDialog.Builder(context);
            builder.setTitle("Warning");
            builder.setMessage("You are force to be offline ,please try to login again");
            builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    ActivityCollector.finshall();
                    Intent intent =new Intent(context,LoginActivity.class);
                    context.startActivity(intent);
                }
            });
            builder.show();
        }
    }
}
 

loginactivity:

package com.example.sunshunli.broadcastbestpractice;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class LoginActivity extends BaseActivity{
    private EditText accoutEdit;
    private EditText passwordEdit;
    private Button login;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        accoutEdit=findViewById(R.id.account);
        passwordEdit=findViewById(R.id.password);
        login=findViewById(R.id.login);
        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String account = accoutEdit.getText().toString();
                String password = passwordEdit.getText().toString();
                if (account.equals("admin")&&password.equals("123456")){
                    Intent intent = new Intent(LoginActivity.this,MainActivity.class);
                    startActivity(intent);
                    finish();
                }else{
                    Toast.makeText(LoginActivity.this, "account or password is error", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

activitycollector:

package com.example.sunshunli.broadcastbestpractice;
import android.app.Activity;
import java.util.ArrayList;
import java.util.List;

public class ActivityCollector {
    public static List<Activity>  activities = new ArrayList<>();
    public static void addActivity(Activity activity){
        activities.add(activity);
    }
    public static void removeActivity(Activity activity){
        activities.remove(activity);
    }
    public static void finshall(){
        for (Activity activity :activities){
            if (!activity.isFinishing()){
                activity.finish();
            }
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".LoginActivity">
<LinearLayout
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="60dp">
    <TextView
        android:layout_width="90dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:textSize="18sp"
        android:text="Account:"
        />
    <EditText
        android:layout_width="0dp"
        android:layout_weight="1"
        android:id="@+id/account"
        android:layout_gravity="center_vertical"
        android:layout_height="wrap_content" />
</LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="60dp">
        <TextView
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:textSize="18sp"
            android:text="Password:"
            />
        <EditText
            android:layout_width="0dp"
            android:layout_weight="1"
            android:id="@+id/password"
            android:layout_gravity="center_vertical"
            android:layout_height="wrap_content"
            android:inputType="textPassword"/>
    </LinearLayout>
    <Button
        android:id="@+id/login"
        android:text="login"
        android:layout_width="match_parent"
        android:layout_height="60dp" />
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/fore_offlinen"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="send force offioce broadcast"/>

</LinearLayout>