Android 自动更新代码

import java.io.File;  

import java.io.FileOutputStream;

import java.io.IOException;  

import java.io.InputStream;  

import org.apache.http.HttpEntity;  
import org.apache.http.HttpResponse;  
import org.apache.http.client.ClientProtocolException;  
import org.apache.http.client.HttpClient;  
import org.apache.http.client.methods.HttpGet;  
import org.apache.http.impl.client.DefaultHttpClient;  
  
import android.app.AlertDialog;  
import android.app.Dialog;  
import android.app.ProgressDialog;  
import android.content.DialogInterface;  
import android.content.Intent;  
import android.net.Uri;  
import android.os.Bundle;  
import android.os.Environment;  
import android.os.Handler;  
  
public class Update extends BaseActivity {  
    public ProgressDialog pBar;  
    private Handler handler = new Handler();  
  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.update);  
        Dialog dialog = new AlertDialog.Builder(Update.this).setTitle("系统更新")  
                .setMessage("发现新版本，请更新！")// 设置内容  
                .setPositiveButton("确定",// 设置确定按钮  
                        new DialogInterface.OnClickListener() {  
  
                            @Override  
                            public void onClick(DialogInterface dialog,  
                                    int which) {  
                                pBar = new ProgressDialog(Update.this);  
                                pBar.setTitle("正在下载");  
                                pBar.setMessage("请稍候...");  
                                pBar  
                                        .setProgressStyle(ProgressDialog.STYLE_SPINNER);  
                                downFile("http://url:8765/OA.apk");   
                                   
                            }  
  
                        }).setNegativeButton("取消",    
                        new DialogInterface.OnClickListener() {  
                            public void onClick(DialogInterface dialog,  
                                    int whichButton) {  
                                // 点击"取消"按钮之后退出程序  
                                  
                            }  
                        }).create();// 创建  
        // 显示对话框  
        dialog.show();  
  
    }  
  
    void downFile(final String url) {  
        pBar.show();  
        new Thread() {  
            public void run() {  
                HttpClient client = new DefaultHttpClient();  
                // params[0]代表连接的url  
                HttpGet get = new HttpGet(url);  
                HttpResponse response;  
                try {  
                    response = client.execute(get);  
                    HttpEntity entity = response.getEntity();  
                    long length = entity.getContentLength();  
                    InputStream is = entity.getContent();  
                    FileOutputStream fileOutputStream = null;  
                    if (is != null) {  
  
                        File file = new File(Environment  
                                .getExternalStorageDirectory(), "OA.apk");  
                        fileOutputStream = new FileOutputStream(file);  
                          
                        byte[] buf = new byte[1024];  
                        int ch = -1;  
                        int count = 0;  
                        while ((ch = is.read(buf)) != -1) {  
                            // baos.write(buf, 0, ch);  
                            fileOutputStream.write(buf, 0, ch);  
                            count += ch;  
                            if (length > 0) {  
                              
                            }  
  
                        }  
  
                    }  
                    fileOutputStream.flush();  
                    if (fileOutputStream != null) {  
                        fileOutputStream.close();  
                    }  
                    down();  
                } catch (ClientProtocolException e) {  
                    // TODO Auto-generated catch block  
                    e.printStackTrace();  
                } catch (IOException e) {  
                    // TODO Auto-generated catch block  
                    e.printStackTrace();  
                }  
            }  
  
        }.start();  
  
    }  
  
    void down() {  
        handler.post(new Runnable() {  
            public void run() {  
                pBar.cancel();  
                update();  
            }  
        });  
  
    }  
  
    void update() {  
  
        Intent intent = new Intent(Intent.ACTION_VIEW);  
        intent.setDataAndType(Uri.fromFile(new File("/sdcard/OA.apk")),  
                "application/vnd.android.package-archive");  
        startActivity(intent);  
    }  
  
}