判断网络连接情况案例

一、打开Eclipse并新建一个Android app项目

　　如图：

在布局文件中添加一个Button控件

并配置ID和I18N

如图：

布局文件代码如下：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.networktest.MainActivity" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/tv1" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/textView1"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="133dp"
        android:text="@string/but1" />

</RelativeLayout>

I18N资源文件代码如下：

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">NetworkTest</string>
    <string name="tv1"></string>
    <string name="action_settings">Settings</string>
    <string name="text1">网络异常</string>
    <string name="text2">网络正常</string> 
    <string name="but1">重新测试</string>
    <string name="toast1">获取权限失败,请查看权限分配情况!</string>
    <string name="toast2">网络连接异常,请检查网络连接情况!</string>
</resources>

新建一个Test类

如图：

在Test类中编写代码

代码如下：

package com.example.networktest;

import android.app.Activity;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;
import android.widget.Toast;

public class Test implements OnClickListener {
    private TextView tv;
    private ConnectivityManager cm;
    private Context context;
    private NetworkInfo netInfo;
    
    public Test(Context context){
        this.context=context;
    }
    @Override
    public void onClick(View v) {
         String text ;
         int color;
         Activity c = (Activity)context;
         tv = (TextView)c.findViewById(R.id.textView1); 
         
         try {
             cm = (ConnectivityManager) c.getSystemService(Context.CONNECTIVITY_SERVICE);
             netInfo = cm.getActiveNetworkInfo();
        } catch (Exception e) {
            Toast.makeText(
                    context,c.getResources().getString(R.string.toast1),Toast.LENGTH_LONG
            ).show();
        }
         if(netInfo==null){
             //网络异常
             text = c.getResources().getString(R.string.text1);
             color = c.getResources().getColor(R.color.red);
             Toast.makeText(
                    context,c.getResources().getString(R.string.toast2),Toast.LENGTH_LONG
            ).show();
         }else{
             //网络正常
             text = c.getResources().getString(R.string.text2);
             color = c.getResources().getColor(R.color.green);
         }
         tv.setText(text);
         tv.setBackgroundColor(color);
    }
}

然后在MainActivity.java类中写入调用代码

代码如下：

package com.example.networktest;

import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;



public class MainActivity extends Activity {
private Button but;
    
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //程序运行自动检查网络
        setContentView(R.layout.activity_main);
        new Test(this).onClick(null);
        //手动刷新
        but = (Button)findViewById(R.id.button1);
        but.setOnClickListener(new Test(this)); 
    }
}

然后在Android配置文件AndroidManifest.xml中配置相关权限

代码如图：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.networktest"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="17"
        android:targetSdkVersion="19" />
    <!-- 判断网络连接状态权限 -->
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <!-- 访问Internet权限 -->
    <uses-permission android:name="android.permission.INTERNET"/>
    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

运行结果如图：