Android中网络的判断

首先要在android中判断网络是否连接，首先得在AndroidManifest.xml配置文件加入网络权限

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /><uses-permission>

然后到程序的工具类中加入下面的方法来判断网络连接

// 网络连接判断
public static boolean netWorkCheck(Context context){
  ConnectivityManager cm =  (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
  NetworkInfo info = cm.getActiveNetworkInfo();
  if( info != null ){
    return info.isConnected();
  } else {
   return false;
 }
}

获取当前网络连接的类型信息

    public static int getConnectedType(Context context) {  
        if (context != null) {  
            ConnectivityManager mConnectivityManager = (ConnectivityManager) context  
                    .getSystemService(Context.CONNECTIVITY_SERVICE);  
            NetworkInfo mNetworkInfo = mConnectivityManager.getActiveNetworkInfo();  
            if (mNetworkInfo != null && mNetworkInfo.isAvailable()) {  
                return mNetworkInfo.getType();  
            }  
        }  
        return -1;  
    }

判断程序

//(activity)MainActivity
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import com.squareup.okhttp.Callback;
import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;
import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    private static final int NETWORKDISCONNECTED = 1;
    private static final int NETWORKCONNECTED = 2;
    private static final String TAG = "MainActivity";
    private ImageView mImageView;
    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case NETWORKDISCONNECTED:
                    mImageView.setVisibility(View.VISIBLE);
                    break;

                case NETWORKCONNECTED:
                    mImageView.setVisibility(View.INVISIBLE);
                    break;
            }
            super.handleMessage(msg);
        }
    };

    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            checkNetWork();
            //每隔五秒钟检查一下网络
            handler.postDelayed(runnable , 5000);
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        handler.post(runnable);
        checkNetWork();
        initView();
    }

    private void checkNetWork(){
        OkHttpClient client = new OkHttpClient();
        Request request = new  Request.Builder().url("http://www.baidu.com").build();
        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Request request, IOException e) {
                Log.i(TAG , "网络访问失败!");
                handler.sendEmptyMessage(NETWORKDISCONNECTED);
            }

            @Override
            public void onResponse(Response response) throws IOException {
                Log.i(TAG , "网络访问成功!");
                handler.sendEmptyMessage(NETWORKCONNECTED);
            }
        });
    }

    private void initView(){
        mImageView = (ImageView) findViewById(R.id.imageView);
    }
}

作者 王继辉