广播及广播接收器

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静态注册广播接收器

<receiver android:name=".MainActivity$MyGPSReceiver"
            android:exported="true"
            android:enabled="true">
     <intent-filter>
           <action android:name="android.location.PROVIDERS_CHANGED"/>
      </intent-filter>
 </receiver>

动态注册广播接收器

• onResume()中注册【注册完成后会首先收到一条广播】
• onPause()中取消注册

package com.example.wifidemo;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.support.v4.content.LocalBroadcastManager;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";
    private MyReceiver mMyReceiver;

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

    @Override
    protected void onPause() {
        super.onPause();
        // 取消注册广播接收器
        unregisterMyReceiver();

    }

    @Override
    protected void onResume() {
        super.onResume();
        // 注册广播接收器
        registerMyReceiver();
    }

    private void registerMyReceiver() {
        mMyReceiver = new MyReceiver();
        IntentFilter filter = new IntentFilter();
        // 接收wifi状态改变的广播
        filter.addAction(WifiManager.WIFI_STATE_CHANGED_ACTION);
        Log.e(TAG, "在onResume（）方法中注册接收器");
        // 注册
        registerReceiver(mMyReceiver, filter);
    }

    private void unregisterMyReceiver() {
        if (mMyReceiver != null) {
            unregisterReceiver(mMyReceiver);
            mMyReceiver = null;
        }

    }

    class MyReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            Log.e(TAG, "收到广播");
            String action = intent.getAction();
            if (WifiManager.WIFI_STATE_CHANGED_ACTION.equals(action)) {
                int wifiState = intent.getIntExtra(WifiManager.EXTRA_WIFI_STATE, 0);
                Log.e("H3c", "wifiState" + wifiState);
                switch (wifiState) {
                    case WifiManager.WIFI_STATE_DISABLED:
                    case WifiManager.WIFI_STATE_DISABLING:
                    case WifiManager.WIFI_STATE_UNKNOWN:
                        break;
                    case WifiManager.WIFI_STATE_ENABLING:
                    case WifiManager.WIFI_STATE_ENABLED:
                        break;
                    //
                }
            }
        }
    }

}

发送本地广播，注册、取消注册本地广播接收器

package com.example.wifidemo;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.support.v4.content.LocalBroadcastManager;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import butterknife.BindView;
import butterknife.ButterKnife;
import butterknife.OnClick;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";
    private static final String MY_BROADCAST_ACTION = "my_broadcast";
    @BindView(R.id.btn_localbroadcast)
    Button btn_localbroadcast;
    private MyReceiver mMyReceiver;
    private LocalBroadcastManager mLocalBroadcastManager;
    private Context mContext;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);
        mContext = this;
    }

    @OnClick(R.id.btn_localbroadcast)
    public void sendLocalBoradcast(){
        Toast.makeText(this, "btn被点击", Toast.LENGTH_SHORT).show();
        Log.e(TAG,"btn被点击");
        // 发送本地广播
        mLocalBroadcastManager = LocalBroadcastManager.getInstance(mContext);
        Intent intent = new Intent();
        intent.setAction(MY_BROADCAST_ACTION);
        mLocalBroadcastManager.sendBroadcast(intent);
    }

    @Override
    protected void onPause() {
        super.onPause();
        // 取消注册广播接收器
        unregisterMyReceiver();

    }

    @Override
    protected void onResume() {
        super.onResume();
        // 注册广播接收器
        registerMyReceiver();
    }

    private void registerMyReceiver() {
        Log.e(TAG, "在onResume（）方法中注册接收器");
        mMyReceiver = new MyReceiver();
        IntentFilter filter = new IntentFilter();
        // 接收wifi状态改变的广播
        filter.addAction(MY_BROADCAST_ACTION);
        // 注册
        mLocalBroadcastManager = LocalBroadcastManager.getInstance(mContext);
        mLocalBroadcastManager.registerReceiver(mMyReceiver, filter);
    }

    private void unregisterMyReceiver() {
        if (mMyReceiver != null) {
            mLocalBroadcastManager = LocalBroadcastManager.getInstance(mContext);
            mLocalBroadcastManager.unregisterReceiver(mMyReceiver);
            mMyReceiver = null;
        }

    }

    class MyReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (MY_BROADCAST_ACTION.equals(action)) {
                Log.e(TAG, "接收到了广播");
            }


        }
    }


}