android应用客户端自动升级（转）

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);
	}

}