Android 实时监听网络状态

在开发android应用时，涉及到要进行网络访问，时常需要进行网络状态的检查，以提供给用户必要的提醒。一般可以通过ConnectivityManager来完成该工作。

ConnectivityManager有四个主要任务：

1、监听手机网络状态（包括GPRS，WIFI， UMTS等)

2、手机状态发生改变时，发送广播

3、当一个网络连接失败时进行故障切换

4、为应用程序提供可以获取可用网络的高精度和粗糙的状态

当我们要在程序中监听网络状态时，只要一下几个步骤即可：

1、定义一个Receiver重载其中的onReceive函数，在其中完成所需要的功能，如根据WIFI和GPRS是否断开来改变空间的外观或者提示是否能访问网络

[code]package com.bsharksdk.receiver;

import com.bsharksdk.main.BSharkApi;
import com.bsharksdk.ui.BSToast;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

/**
 * @author Javen
 * 
 */
public class ConnectionChangeReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        ConnectivityManager connectivityManager=(ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo  mobNetInfo=connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
        NetworkInfo  wifiNetInfo=connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);

        if (!mobNetInfo.isConnected() && !wifiNetInfo.isConnected()) {
            BSToast.showLong(context, "网络不可以用");//BSToast为显示提示的类
            //改变背景或者 处理网络的全局变量
        }else {
            //改变背景或者 处理网络的全局变量
        }
    }
}

[code]package com.boens.service;

import android.content.Context;
import android.widget.Toast;

public class BSToast {
    public static void showLong(Context context, String infostr) {
        Toast.makeText(context, infostr, Toast.LENGTH_LONG).show();
    }

    public static void showShort(Context context, String infostr) {
        Toast.makeText(context, infostr, Toast.LENGTH_SHORT).show();
    }
}

[code]//在AndroidManifest.xml中注册广播
<service android:enabled="true" android:name="com.boens.service.ConnectionChangeReceiver" ></service>

2、在适当的地方注册Receiver，可以在程序中注册，在onCreate中调用如下函数即可：

[code]private  void registerReceiver(){
        IntentFilter filter=new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
        myReceiver=new ConnectionChangeReceiver();
        this.registerReceiver(myReceiver, filter);
    }

3、在适当时取消注册Receiver，可以在程序中取消，在onDestroye中调用如下函数即可：

[code]private  void unregisterReceiver(){
        this.unregisterReceiver(myReceiver);
    }

4、Activity中注册广播

[code]package com.boens.login;

import android.app.Activity;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.RelativeLayout;

import com.boens.homepage.R;
import com.boens.service.ConnectionChangeReceiver;
import com.boens.tools.DecodeSampledBitmapFromResource;
/*
 * 欢迎动画加载
 */
public class FirstActivity extends Activity {

    private Button registerButton;
    private Button loginButton;
    private ImageView imageView_icon;
    private static FirstActivity first_Activity;
     private ConnectionChangeReceiver myReceiver;
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
            setContentView(R.layout.firstpage_login);
            first_Activity = this;
            **registerReceiver();**
            registerButton = (Button) findViewById(R.id.register_btn_first);
            loginButton = (Button) findViewById(R.id.login_btn_first);
            //background_first = (RelativeLayout) findViewById(R.id.background_first);
            imageView_icon = (ImageView) findViewById(R.id.icon_imageview_first);
            //加载位图像素为200*200
            imageView_icon.setImageBitmap(DecodeSampledBitmapFromResource.decodeSampledBitmapFromResource(getResources(), R.drawable.logohuban, 200, 200));
            loginButton.setOnClickListener(new Button.OnClickListener() {

                @Override
                public void onClick(View arg0) {

                    Intent intent = new Intent();
                    intent.setClass(FirstActivity.this, com.boens.login.MainActivity.class);
                    startActivity(intent);
                }

            });

            registerButton.setOnClickListener(new Button.OnClickListener() {

                @Override
                public void onClick(View arg0) {

                    Intent intent = new Intent();
                    intent.setClass(FirstActivity.this, com.boens.login.RegisterActivity.class);
                    startActivity(intent);

                }

            });
        }
    /*注册网络状态监听*/
    **private  void registerReceiver(){
        IntentFilter filter=new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
        myReceiver=new ConnectionChangeReceiver();
        this.registerReceiver(myReceiver, filter);
    }**

    /*取消网络状态监听*/
    **public  void unregisterReceiver(){
        this.unregisterReceiver(myReceiver);
    }**
    //程序退出时可获取实例来调用unregisterReceiver()方法取消广播
    public static FirstActivity getInstance() {
         if (first_Activity != null) {
               return first_Activity;
           }
           return null;
    }

}

记得在 Activity中 设置变量 private ConnectionChangeReceiver myReceiver;

记得添加访问网络需要的权限

[code]<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <uses-permission android:name="android.permission.INTERNET" />