一个简易的账号登录/广播的使用

先把所有的代码贴出来然后一个一个复习

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.admin.broadcastbestpracticw">
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".LoginActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".MainActivity">

        </activity>
        <receiver android:name=".ForceOfflineReceiver">
            <intent-filter>
                <action android:name="com.example.broadcastbewspractice.FORCE_OFFLINE"/>
            </intent-filter>
        </receiver>
    </application>

</manifest>

然后是第一个  Activity 管理器类

package com.example.admin.broadcastbestpracticw;

import android.app.Activity;

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

/**
 * Created by admin on 2016/3/18.
 */
public class ActivityCollector {
    public  static List<Activity> activities=new ArrayList<Activity>();
    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();
            }
        }
    }


}

第二个 所有活动的父类

package com.example.admin.broadcastbestpracticw;

import android.app.Activity;
import android.os.Bundle;

/**
 * Created by admin on 2016/3/18.
 */


    public class BaseActivity extends Activity {
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            ActivityCollector.addActivity(this);
        }

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

第三个 登录界面 设计

package com.example.admin.broadcastbestpracticw;

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

/**
 * Created by admin on 2016/3/18.
 */
public class LoginActivity extends BaseActivity{
    private EditText accountEdit;
    private EditText passwordEdit;
    private Button login;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.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();
                //如果账号是admin密码是123456 就认为登陆成功
                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();;

                }
            }
        });
    }
}

第四个 主界面 设置

package com.example.admin.broadcastbestpracticw;

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 AppCompatActivity {

    @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.broadcastbewspractice.FORCE_OFFLINE");
                sendBroadcast(intent);
            }
        });
    }
}

然后是广播接收器

package com.example.admin.broadcastbestpracticw;

import android.app.AlertDialog;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.view.WindowManager;

/**
 * Created by admin on 2016/3/18.
 */
public class ForceOfflineReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(final Context context, final Intent intent) {
        //用AlertDialog来创建一个对话框
        AlertDialog.Builder dialogBuilder=new AlertDialog.Builder(context);
        dialogBuilder.setTitle("Warning!!!!");
        dialogBuilder.setMessage("你已被强制下线，请再次登录");
        dialogBuilder.setCancelable(false);
        dialogBuilder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                ActivityCollector.finishAll();
                Intent intent = new Intent(context, LoginActivity.class);
                intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                context.startActivity(intent);
            }
        });
        AlertDialog alertDialog=dialogBuilder.create();
        alertDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
        alertDialog.show();
    }
}