Broadcast的实例

ActivityCollector用于管理所有的活动

baseActivity是所有活动继承的基类

MainActivity是实现登陆判断功能的

SecondActivity是实现发送广播实现强制下线功能的

 ActivityCollector类

package com.example.forced_offline;

import android.app.Activity;

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


public class ActivityCollector {
    public static List activityList = new ArrayList<>();//存储所有活动的数列

    public static void addActivity(Activity activity) {
        activityList.add(activity);
    }//向数列中添加活动的方法

    public static void removeActivity(Activity activity) {
        activityList.remove(activity);
    }//从数列中移除活动的方法


    //删除数列中所有活动的方法
    public static void finishAllActivity() {
        for (Activity activity : activityList) {
            if (!activity.isFinishing()) {
                activity.finish();
            }
        }
        activityList.clear();
    }
}

baseActivity类

package com.example.forced_offline;

import android.os.Bundle;
import android.util.Log;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;


public class baseActivity extends AppCompatActivity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //当活动被创建时向活动管理类中添加
        ActivityCollector.addActivity(this);
        Log.d("baseActivity",getClass().getSimpleName());
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        //当活动被销毁时将其从活动管理类中移除
        ActivityCollector.removeActivity(this);
    }
}

MainActivity活动

package com.example.forced_offline;

import androidx.appcompat.app.alertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.text.TextWatcher;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends baseActivity implements View.onClickListener {
    //输入框和按钮
    EditText id, password;
    Button login;
//存储正确账号密码的常量
    private static final String CORRECT_ID = "admin";
    private static final String CORRECT_PASSWORD = "123456";
    //存储被输入的账号密码
    String idText, passwordText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //控件绑定
        initUI();
        //按钮点击事件
        login.setonClickListener(this);
    }
//控件初始化函数
    public void initUI() {
        id = findViewById(R.id.id);
        password = findViewById(R.id.password);
        login = findViewById(R.id.login);
    }
//按钮点击函数
    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.login:
                //获取输入的账号密码
                idText = id.getText().toString();
                passwordText = password.getText().toString();
                //判断输入的账号密码与正确的是否一致
                if ((idText.equals(CORRECT_ID)) && (passwordText.equals(CORRECT_PASSWORD))) {
                    //如果一致跳转到下一个活动
                    Intent intent = new Intent(MainActivity.this, SecondActivity.class);
                    startActivity(intent);
                } else {
                    //如果不一致，跳出一个对话框，使其退出活动
                    alertDialog.Builder dialog = new alertDialog.Builder(MainActivity.this);
                    dialog.setTitle("密码错误");
                    dialog.setMessage("请退出重新登陆！！！");
                    dialog.setCancelable(false);
                    dialog.setPositiveButton("OK", new DialogInterface.onClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
                            ActivityCollector.finishAllActivity();
                        }
                    });
                    dialog.show();
                }

                break;
        }
    }
}

SecondActivity活动

package com.example.forced_offline;

import androidx.appcompat.app.AppCompatActivity;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import java.util.zip.Inflater;

public class SecondActivity extends baseActivity {
    //按钮
    Button offLine;
    //自定义的接收广播
    MyBroadcastReceiver broadcastReceiver;
    //自定义action
    final String ACTION_OF_MY_OFFLINE = "ACTION_OF_MY_OFFLINE";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        //初始化控件
        initUI();
        //初始化广播
        broadcastReceiver = new MyBroadcastReceiver();
        //初始化和添加广播的intentFilter，添加需要监听的action
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(ACTION_OF_MY_OFFLINE);
        registerReceiver(broadcastReceiver, intentFilter);

        offLine.setonClickListener(new View.onClickListener() {
            @Override
            public void onClick(View view) {
                //发送自定义广播即通过intent发送自定义action
                Intent intent = new Intent(ACTION_OF_MY_OFFLINE);
                sendBroadcast(intent);
            }
        });
    }

    //接收广播类
    class MyBroadcastReceiver extends BroadcastReceiver {
        //接收到响应广播所做出的动作
        @Override
        public void onReceive(Context context, Intent intent) {
            switch (intent.getAction()) {
                case ACTION_OF_MY_OFFLINE:
                    //关闭所有活动
                    ActivityCollector.finishAllActivity();
                    break;
            }
        }
    }

    //初始化控件
    private void initUI() {
        offLine = findViewById(R.id.offLine);
    }

    //释放广播资源
    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(broadcastReceiver);
    }
}

mainactivity的布局代码

secondactivity的布局代码