如何检查Android网络连接状态

在发送任何HTTP请求前最好检查下网络连接状态,这样可以避免异常。这个教程将会介绍怎样在你的应用中检测网络连接状态。

 
创建新的项目
 
1.在Eclipse IDE中创建一个新的项目并把填入必须的信息。 File->New->Android Project
2.创建新项目后的第一步是要在AndroidManifest.xml文件中添加必要的权限。
  • 为了访问网络我们需要 INTERNET 权限
  • 为了检查网络状态我们需要 ACCESS_NETWORK_STATE 权限
AndroidManifest.xml
01 <?xml version="1.0" encoding="utf-8"?>
02 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
03     package="com.example.detectinternetconnection"
04     android:versionCode="1"
05     android:versionName="1.0" >
06   
07     <uses-sdk android:minSdkVersion="8" />
08   
09     <application
10         android:icon="@drawable/ic_launcher"
11         android:label="@string/app_name" >
12         <activity
13             android:name=".AndroidDetectInternetConnectionActivity"
14             android:label="@string/app_name" >
15             <intent-filter>
16                 <action android:name="android.intent.action.MAIN" />
17   
18                 <category android:name="android.intent.category.LAUNCHER" />
19             </intent-filter>
20         </activity>
21     </application>
22   
23     <!-- Internet Permissions -->
24     <uses-permission android:name="android.permission.INTERNET" />
25   
26     <!-- Network State Permissions -->
27     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
28   
29 </manifest>
3.创建一个新的类,名为ConnectionDetector.java,并输入以下代码。
ConnectionDetector.java 
01 package com.example.detectinternetconnection;
02   
03 import android.content.Context;
04 import android.net.ConnectivityManager;
05 import android.net.NetworkInfo;
06   
07 public class ConnectionDetector {
08   
09     private Context _context;
10   
11     public ConnectionDetector(Context context){
12         this._context = context;
13     }
14   
15     public boolean isConnectingToInternet(){
16         ConnectivityManager connectivity = (ConnectivityManager) _context.getSystemService(Context.CONNECTIVITY_SERVICE);
17           if (connectivity != null)
18           {
19               NetworkInfo[] info = connectivity.getAllNetworkInfo();
20               if (info != null)
21                   for (int i = 0; i < info.length; i++)
22                       if (info[i].getState() == NetworkInfo.State.CONNECTED)
23                       {
24                           return true;
25                       }
26   
27           }
28           return false;
29     }
30 }
4.当你需要在你的应用中检查网络状态时调用isConnectingToInternet()函数,它会返回true或false。
1 ConnectionDetector cd = new ConnectionDetector(getApplicationContext());
2   
3 Boolean isInternetPresent = cd.isConnectingToInternet(); // true or false
5.在这个教程中为了测试我仅仅简单的放置了一个按钮。只要按下这个按钮就会弹出一个 alert dialog 显示网络连接状态。
 
6.打开 res/layout 目录下的 main.xml 并创建一个按钮。
 
main.xml
01 <?xml version="1.0" encoding="utf-8"?>
02 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
03     android:layout_width="fill_parent"
04     android:layout_height="fill_parent"
05     android:orientation="vertical" >
06   
07     <TextView
08         android:layout_width="fill_parent"
09         android:layout_height="wrap_content"
10         android:text="Detect Internet Status" />
11   
12     <Button android:id="@+id/btn_check"
13         android:layout_height="wrap_content"
14         android:layout_width="wrap_content"
15         android:text="Check Internet Status"
16         android:layout_centerInParent="true"/>
17   
18 </RelativeLayout>
7.最后打开你的 MainActivity 文件并粘贴下面的代码。在下面的代码中我用一个 alert dialog 来显示预期的状态信息。
01 package com.example.detectinternetconnection;
02   
03 import android.app.Activity;
04 import android.app.AlertDialog;
05 import android.content.Context;
06 import android.content.DialogInterface;
07 import android.os.Bundle;
08 import android.view.View;
09 import android.widget.Button;
10   
11 public class AndroidDetectInternetConnectionActivity extends Activity {
12   
13     // flag for Internet connection status
14     Boolean isInternetPresent = false;
15   
16     // Connection detector class
17     ConnectionDetector cd;
18   
19     @Override
20     public void onCreate(Bundle savedInstanceState) {
21         super.onCreate(savedInstanceState);
22         setContentView(R.layout.main);
23   
24         Button btnStatus = (Button) findViewById(R.id.btn_check);
25   
26         // creating connection detector class instance
27         cd = new ConnectionDetector(getApplicationContext());
28   
29         /**
30          * Check Internet status button click event
31          * */
32         btnStatus.setOnClickListener(new View.OnClickListener() {
33   
34             @Override
35             public void onClick(View v) {
36   
37                 // get Internet status
38                 isInternetPresent = cd.isConnectingToInternet();
39   
40                 // check for Internet status
41                 if (isInternetPresent) {
42                     // Internet Connection is Present
43                     // make HTTP requests
44                     showAlertDialog(AndroidDetectInternetConnectionActivity.this,"Internet Connection",
45                             "You have internet connection", true);
46                 } else {
47                     // Internet connection is not present
48                     // Ask user to connect to Internet
49                     showAlertDialog(AndroidDetectInternetConnectionActivity.this, "No Internet Connection",
50                             "You don't have internet connection.", false);
51                 }
52             }
53   
54         });
55   
56     }
57   
58     /**
59      * Function to display simple Alert Dialog
60      * @param context - application context
61      * @param title - alert dialog title
62      * @param message - alert message
63      * @param status - success/failure (used to set icon)
64      * */
65     public void showAlertDialog(Context context, String title, String message, Boolean status) {
66         AlertDialog alertDialog = new AlertDialog.Builder(context).create();
67   
68         // Setting Dialog Title
69         alertDialog.setTitle(title);
70   
71         // Setting Dialog Message
72         alertDialog.setMessage(message);
73   
74         // Setting alert dialog icon
75         alertDialog.setIcon((status) ? R.drawable.success : R.drawable.fail);
76   
77         // Setting OK Button
78         alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
79             public void onClick(DialogInterface dialog, int which) {
80             }
81         });
82   
83         // Showing Alert Message
84         alertDialog.show();
85     }
86 }
运行并测试下你的程序吧!你将会得到类似下面的结果。
如何检查Android网络连接状态 
如何检查Android网络连接状态
posted @ 2012-09-03 10:50  吻上明天  阅读(372)  评论(0编辑  收藏  举报