一天一点Android知识（实现强制下线功能）

强制下线功能：比如你的QQ号在别处登录了，就会将你强制挤下线。

ActivityCollector.java

package com.example.broadcastbestpractice;

import android.app.Activity;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by Codingbo on 2017/1/15.
 */

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 finishAll(){
        for(Activity activity :activities){
            if(!activity.isFinishing()){
                activity.finish();
            }
        }
    }
}
           

BaseActivity.java

package com.example.broadcastbestpractice;

import android.app.Activity;
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;

/**
 // Created by Codingbo on 2017/1/15.
*/

public class BaseActivity extends AppCompatActivity {
    private ForceOfflineReceiver receiver;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityCollector.addActivity(this);
    }
    @Override
    protected  void  onResume(){
        super.onResume();
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("com.example.broadcastbestpractice.FORCE_OFFLINE");
        receiver = new ForceOfflineReceiver();
        registerReceiver(receiver,intentFilter);
    }

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

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

    class ForceOfflineReceiver 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 forced to be offline. Please try to login again.");
            builder.setCancelable(false);
            builder.setPositiveButton("OK",new DialogInterface.OnClickListener(){
                public void onClick(DialogInterface dialog,int which){
                    ActivityCollector.finishAll();
                    Intent intent = new Intent(context,LoginActivity.class);
                    context.startActivity(intent);
                }
            });
            builder.show();
        }

    }
}
           

LoginActivity.java

package com.example.broadcastbestpractice;

import android.content.Intent;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

/*public class LoginActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
    }
} */

public class LoginActivity extends BaseActivity{
    private EditText accountEdit;
    private EditText passwordEdit;

    private Button login;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        accountEdit =(EditText)findViewById(R.id.account);
        passwordEdit=(EditText)findViewById(R.id.password);
        login=(Button)findViewById(R.id.login);
        login.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                String account = accountEdit.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 invalid",Toast.LENGTH_SHORT).show();
                }
            }

        });
    }
}
           

MainActivity.java

package com.example.broadcastbestpractice;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
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 = (Button)findViewById(R.id.force_offline);
        forceOffline.setOnClickListener(new View.OnClickListener(){
            @Override
            public  void onClick(View v){
                Intent intent = new Intent("com.example.broadcastbestpractice.FORCE_OFFLINE");
                sendBroadcast(intent);
            }
        });
    }
}
           

activity_login.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <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:text="Account:" />
        <EditText
            android:id="@+id/account"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_gravity="center_vertical"/>
    </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:id="@+id/password"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_gravity="center_vertical"
            android:inputType="textPassword"/>
    </LinearLayout>

    <Button
        android:id="@+id/login"
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:text="Login"/>
</LinearLayout>
           

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/force_offline"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Send force offline broadcast"/>
</LinearLayout>
           

AndroidManifest.xml

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        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>