Android(安卓)强制下线功能第一行代码

强制下线功能：先关闭掉所有的活动，然后回到登陆界面

相应工程：http://download.csdn.net/detail/u012005313/9004889

先创建一个ActivityCollector类用于管理所有的活动

package com.example.zj.broadcastbestpractice;import android.app.Activity;import java.util.ArrayList;import java.util.List;/** * Created by zj on 15-8-14. */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();            }        }    }}

创建BaseActivity类作为所有活动的父类

package com.example.zj.broadcastbestpractice;import android.app.Activity;import android.os.Bundle;/** * Created by zj on 15-8-14. */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);    }}

创建一个登陆界面的布局

<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:stretchColumns="1">    <TableRow>        <TextView            android:layout_height="wrap_content"            android:text="Account:"            />        <EditText            android:id="@+id/account"            android:layout_height="wrap_content"            android:hint="Input your account"            />    </TableRow>    <TableRow>        <TextView            android:layout_height="wrap_content"            android:text="Password:"            />        <EditText            android:id="@+id/password"            android:layout_height="wrap_content"            android:inputType="textPassword"            />    </TableRow>    <TableRow>        <Button            android:id="@+id/login"            android:layout_height="wrap_content"            android:layout_span="2"            android:text="Login"            />    </TableRow></TableLayout>

新建LoginActivity继承自BaseActivity

package com.example.zj.broadcastbestpractice;import android.app.Activity;import android.content.Intent;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;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.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);                    Log.i("this", "------------------------intent to MainActivity");                    startActivity(intent);                    finish();                } else {                    Toast.makeText(LoginActivity.this, "account or password error", Toast.LENGTH_SHORT).show();                }            }        });    }}

从上面代码可知，我们模拟了一个非常简单的登陆功能

用户名：admin

密码：123456

MainActivity可理解为登录成功后的程序主界面，在主界面设置一个按钮，增加强制下线的功能

修改activity_main.xml代码

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <Button        android:id="@+id/force_offline"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="Send force offline broadcast"        /></LinearLayout>

修改MainActivity代码

package com.example.zj.broadcastbestpractice;import android.app.Activity;import android.content.Intent;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.widget.Button;public class MainActivity extends Activity {    @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.zj.broadcastbestpractice.FORCE_OFFLINE");                sendBroadcast(intent);            }        });    }}

重点：我们在按钮的点击事件里发送一条广播，广播值为

com.zj.broadcastbestpractice.FORCE_OFFLINE

这条广播就是用于通知程序强制用户下线的，也就是说强制用户下线的逻辑并不是写在MainActivity里面，而是应该写在接受这条广播的广播接收器里面，这样强制下线的功能就不会依附于任何的界面，不管是在程序的任何地方，只需要发出这样一条广播，就可以完成强制下线的操作

创建一个广播接收器，新建ForceOfflineReceiver继承自BroadcastReceiver

package com.example.zj.broadcastbestpractice;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 root on 15-8-14. */public class ForceOfflineReceiver extends BroadcastReceiver {    @Override    public void onReceive(final Context context, Intent intent) {        AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(context);        dialogBuilder.setTitle("Warning");        dialogBuilder.setMessage("You are forced to be offline.  Please try to login again.");        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();    }}

要点：

首先使用AlertDialog.Builder来构建一个对话框（调用setCancelable()方法将对话框设为不可取消，否则用户按一下Back键就可以关闭对话框继续使用程序）

然后使用setPositiveButton()方法给对话框注册确定按钮，当用户点击了确定按钮时，就调用ActivityCollector的finishAll()方法来销毁所有的活动，并重新启动LoginActivity

note：由于我们是在广播接收器里启动活动，因此一定要给Intent加入FLAG_ACTIVITY_NEW_TASK这个标志，最后，还需要把对话框的类型设为TYPE_SYSTEM_ALERT，不然无法在广播接收器中弹出

配置AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.zj.broadcastbestpractice" >    <application        android:allowBackup="true"        android:icon="@mipmap/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity            android:name=".MainActivity"            android:label="@string/app_name" >        </activity>        <activity            android:name=".LoginActivity"            android:label="@string/title_activity_login" >            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>        <receiver android:name=".ForceOfflineReceiver" >            <intent-filter>                <action android:name="com.zj.broadcastbestpractice.FORCE_OFFLINE" />            </intent-filter>        </receiver>    </application></manifest>

完成，启动项目

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