Android广播:实现强制下线功能(第一行代码Android学习)

首先是要创建一个类用来管理所有活动的启动销毁等，把它命名为AcitivityCollector

代码:

public class ActivityCollector {
    public static List<Activity> activities = new ArrayList<>();

    public static void addAcitivity(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();
            }
        }
    }
}

然后创建一个所有类的父类BaseActivity

代码:

public class BaseActivity extends AppCompatActivity {

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityCollector.addAcitivity(this);
    }

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

先创建一个登录界面的Activity,布局就用简单的两个TextView和两个EditText加上一个Button

然后是这个Login的后端代码:

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.button1);
        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String account = accountEdit.getText().toString();
                String password = passwordEdit.getText().toString();
                if(account.equals("yozora")&&password.equals("19970914")){
                    finish();//结束当前活动

                    //启动MainActivity
                    Intent intent = new Intent(LoginActivity.this,MainActivity.class);
                    startActivity(intent);
                }else{
                    Toast.makeText(LoginActivity.this,"用户名或密码错误",Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

之后在MainActivity的布局中加一个Button，这个用来发送广播

MainActivity的代码:

public class MainActivity extends BaseActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = (Button) findViewById(R.id.button2);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent("com.example.broadcastbestpractice.FORCE_OFFLINE");
                sendBroadcast(intent);
            }
        });
    }
}

现在就需要注册广播了，

修改BaseActivity代码:

public class BaseActivity extends AppCompatActivity {

    class ForceOfflineReceiver extends BroadcastReceiver{

        @Override
        public void onReceive(final Context context, Intent intent) {
            AlertDialog.Builder builder = new AlertDialog.Builder(context);
            builder.setTitle("警告");
            builder.setMessage("你已经被强制下线，请重新登录");
            builder.setCancelable(false);
            builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    ActivityCollector.finishAll();//销毁所有的活动

                    //回到登录界面(LoginActivity)
                    Intent intent = new Intent(context,LoginActivity.class);
                    context.startActivity(intent);
                }
            });
            builder.show();
        }
    }

    private ForceOfflineReceiver receiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityCollector.addAcitivity(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);
    }
}