一、准备

1.检测当前版本的信息AndroidManifest.xml-->manifest-->android:versionName。

2.从服务器获取版本号（版本号存在于xml文件中）并与当前检测到的版本进行匹配，如果不匹配，提示用户进行升级，如果匹配则进入程序主界面。

3.当提示用户进行版本升级时，如果用户点击了确定，系统将自动从服务器上下载并进行自动升级，如果点击取消将进入程序主界面。

二、效果图

三、必要说明

服务器端存储apk文件，同时有version.xml文件便于比对更新。

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

<info>

 <version>2.0</version>

 <url>http://192.168.1.187:8080/mobilesafe.apk</url>

 <description>检测到最新版本，请及时更新！</description>

 <url_server>http://192.168.1.99/version.xml</url_server>

</info>

通过一个实体类获取上述信息。

package com.android;

public class UpdataInfo {

 private String version;

 private String url;

 private String description;

 private String url_server;

 public String getUrl_server() {

     return url_server;

 }

 public void setUrl_server(String url_server) {

     this.url_server = url_server;

 }

 public String getVersion() {

     return version;

 }

 public void setVersion(String version) {

     this.version = version;

 }

 public String getUrl() {

     return url;

 }

 public void setUrl(String url) {

     this.url = url;

 }

 public String getDescription() {

     return description;

 }

 public void setDescription(String description) {

     this.description = description;

 }

}

apk和版本信息地址都放在服务器端的version.xml里比较方便，当然如果服务器端不变动，apk地址可以放在strings.xml里，不过版本号信息是新的，必须放在服务器端，xml地址放在strings.xml。

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

<resources>

    <string name="hello">Hello World, VersionActivity!</string>

    <string name="app_name">Version</string>

    <string name="url_server">http://192.168.1.99/version.xml</string>

</resources>

不知道读者发现没有，笔者犯了个错误，那就是url_server地址必须放在本地，否则怎么读取version.xml，所以url_server不必在实体类和version里添加，毕竟是现需要version地址也就是url_server，才能够读取version。

三、代码实现

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

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent"

    android:orientation="vertical" >

 <Button

     android:id="@+id/btn_getVersion"

     android:text="检查更新"

     android:layout_width="wrap_content"

     android:layout_height="wrap_content"/>

</LinearLayout>

---

package com.android;

import java.io.InputStream;

import org.xmlpull.v1.XmlPullParser;

import android.util.Xml;

public class UpdataInfoParser {

  public static UpdataInfo getUpdataInfo(InputStream is) throws Exception{

     XmlPullParser  parser = Xml.newPullParser();

     parser.setInput(is, "utf-8");

     int type = parser.getEventType();

     UpdataInfo info = new UpdataInfo();

     while(type != XmlPullParser.END_DOCUMENT ){

         switch (type) {

         case XmlPullParser.START_TAG:

             if("version".equals(parser.getName())){

                 info.setVersion(parser.nextText());

             }else if ("url".equals(parser.getName())){

                 info.setUrl(parser.nextText());

             }else if ("description".equals(parser.getName())){

                 info.setDescription(parser.nextText());

             }

             break;

         }

         type = parser.next();

     }

     return info;

 }

}

---

package com.android;

import java.io.File;

import java.io.InputStream;

import java.net.HttpURLConnection;

import java.net.URL;

import android.app.Activity;

import android.app.AlertDialog;

import android.app.AlertDialog.Builder;

import android.app.ProgressDialog;

import android.content.DialogInterface;

import android.content.Intent;

import android.content.pm.PackageInfo;

import android.content.pm.PackageManager;

import android.net.Uri;

import android.os.Bundle;

import android.os.Environment;

import android.os.Handler;

import android.os.Message;

import android.util.Log;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.TextView;

import android.widget.Toast;

public class VersionActivity extends Activity {

 private final String TAG = this.getClass().getName();

    private final int UPDATA_NONEED = 0;

    private final int UPDATA_CLIENT = 1;

    private final int GET_UNDATAINFO_ERROR = 2;

 private final int SDCARD_NOMOUNTED = 3;

 private final int DOWN_ERROR = 4;

   private Button getVersion;

    private UpdataInfo info;

 private String localVersion;

  @Override

   public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

      setContentView(R.layout.main);

       getVersion = (Button) findViewById(R.id.btn_getVersion);

        getVersion.setOnClickListener(new OnClickListener() {

         @Override

           public void onClick(View v) {

                try {

                    localVersion = getVersionName();

                 CheckVersionTask cv = new CheckVersionTask();

                   new Thread(cv).start();

               } catch (Exception e) {

                  // TODO Auto-generated catch block

                   e.printStackTrace();

             }

            }

        });

  }

 private String getVersionName() throws Exception {

       //getPackageName()是你当前类的包名，0代表是获取版本信息  

       PackageManager packageManager = getPackageManager();

        PackageInfo packInfo = packageManager.getPackageInfo(getPackageName(),

              0);

      return packInfo.versionName;

 }

 public class CheckVersionTask implements Runnable {

      InputStream is;

      public void run() {

          try {

                String path = getResources().getString(R.string.url_server);

                URL url = new URL(path);

                HttpURLConnection conn = (HttpURLConnection) url

                        .openConnection();

               conn.setConnectTimeout(5000);

                conn.setRequestMethod("GET"); 

                int responseCode = conn.getResponseCode(); 

                if (responseCode == 200) { 

                    // 从服务器获得一个输入流 

                    is = conn.getInputStream(); 

                } 

               info = UpdataInfoParser.getUpdataInfo(is);

              if (info.getVersion().equals(localVersion)) {

                    Log.i(TAG, "版本号相同");

                   Message msg = new Message();

                    msg.what = UPDATA_NONEED;

                   handler.sendMessage(msg);

                    // LoginMain();

              } else {

                 Log.i(TAG, "版本号不相同 ");

                 Message msg = new Message();

                    msg.what = UPDATA_CLIENT;

                   handler.sendMessage(msg);

                }

            } catch (Exception e) {

              Message msg = new Message();

                msg.what = GET_UNDATAINFO_ERROR;

                handler.sendMessage(msg);

                e.printStackTrace();

         }

        }

    }

 Handler handler = new Handler() {

        @Override

       public void handleMessage(Message msg) {

         // TODO Auto-generated method stub

           super.handleMessage(msg);

            switch (msg.what) {

          case UPDATA_NONEED:

              Toast.makeText(getApplicationContext(), "不需要更新",

                       Toast.LENGTH_SHORT).show();

          case UPDATA_CLIENT:

               //对话框通知用户升级程序   

                showUpdataDialog();

              break;

           case GET_UNDATAINFO_ERROR:

               //服务器超时   

               Toast.makeText(getApplicationContext(), "获取服务器更新信息失败", 1).show(); 

             break;

           case DOWN_ERROR:

             //下载apk失败  

              Toast.makeText(getApplicationContext(), "下载新版本失败", 1).show(); 

             break;

           }

        }

    };

    /* 

   *  

  * 弹出对话框通知用户更新程序  

    *  

  * 弹出对话框的步骤： 

  *  1.创建alertDialog的builder.   

   *  2.要给builder设置属性, 对话框的内容,样式,按钮 

    *  3.通过builder 创建一个对话框 

  *  4.对话框show()出来   

  */  

    protected void showUpdataDialog() {

      AlertDialog.Builder builer = new Builder(this);

     builer.setTitle("版本升级");

       builer.setMessage(info.getDescription());

         //当点确定按钮时从服务器上下载 新的apk 然后安装   װ

     builer.setPositiveButton("确定", new DialogInterface.OnClickListener() {

         public void onClick(DialogInterface dialog, int which) {

             Log.i(TAG, "下载apk,更新");

                downLoadApk();

           }

        });

      builer.setNegativeButton("取消", new DialogInterface.OnClickListener() {

         public void onClick(DialogInterface dialog, int which) {

             // TODO Auto-generated method stub

               //do sth

         }

        });

      AlertDialog dialog = builer.create();

       dialog.show();

   }

 /* 

   * 从服务器中下载APK 

    */  

    protected void downLoadApk() {  

     final ProgressDialog pd;    //进度条对话框  

       pd = new  ProgressDialog(this);  

       pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);  

      pd.setMessage("正在下载更新");  

     pd.show();  

     new Thread(){  

          @Override  

         public void run() {  

                try {  

                  File file = DownLoadManager.getFileFromServer(info.getUrl(), pd);  

                 sleep(3000);  

                   installApk(file);  

                  pd.dismiss(); //结束掉进度条对话框  

              } catch (Exception e) {  

                    Message msg = new Message();  

                  msg.what = DOWN_ERROR;  

                    handler.sendMessage(msg);  

                  e.printStackTrace();  

               }  

          }}.start();  

    }  

   //安装apk   

   protected void installApk(File file) {  

     Intent intent = new Intent();  

     //执行动作  

     intent.setAction(Intent.ACTION_VIEW);  

      //执行的数据类型  

      intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");  

        startActivity(intent);  

 }  

}

---

package com.android;

import java.io.BufferedInputStream;

import java.io.File;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.net.HttpURLConnection;

import java.net.URL;

import android.app.ProgressDialog;

import android.os.Environment;

public class DownLoadManager {

 public static File getFileFromServer(String path, ProgressDialog pd) throws Exception{

     //如果相等的话表示当前的sdcard挂载在手机上并且是可用的

     if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){

         URL url = new URL(path);

         HttpURLConnection conn =  (HttpURLConnection) url.openConnection();

         conn.setConnectTimeout(5000);

         //获取到文件的大小

         pd.setMax(conn.getContentLength());

         InputStream is = conn.getInputStream();

         File file = new File(Environment.getExternalStorageDirectory(), "updata.apk");

         FileOutputStream fos = new FileOutputStream(file);

         BufferedInputStream bis = new BufferedInputStream(is);

         byte[] buffer = new byte[1024];

         int len ;

         int total=0;

         while((len =bis.read(buffer))!=-1){

             fos.write(buffer, 0, len);

             total+= len;

             //获取当前下载量

             pd.setProgress(total);

         }

         fos.close();

         bis.close();

         is.close();

         return file;

     }

     else{

         return null;

     }

 }

}

---

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

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

四、参考文献

http://blog.csdn.net/furongkang/article/details/6886526