学步园

最近在研究项目更新下载的方法，通过启动Service进行后台下载，并通过Notification做实时显示，分析如下：

关联文件结构图：

act.xml布局：

<FrameLayout 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"
    tools:context=".MainActivity" >
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical" >
        <ImageView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1000" />
        <Button
            android:id="@+id/but_down"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="下载" />
    </LinearLayout>
</FrameLayout>

MainActivity：

package com.example.test20150104;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity implements
		android.view.View.OnClickListener {

	private Button but_down = null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);
		setContentView(R.layout.act);
		but_down = (Button) findViewById(R.id.but_down);
		but_down.setOnClickListener(this);
	}

	@Override
	public void onClick(View v) {
		if (R.id.but_down == v.getId()) {
			Downloader loader = new Downloader(this);
			if (!loader.isLoading())
				loader.load();
			else
				Toast.makeText(this, "正在后台下载中...", Toast.LENGTH_SHORT).show();
		}
	}

}

Downloader.java

package com.example.test20150104;

import android.content.Context;
import android.content.Intent;
import android.os.Handler;


/**
 * 可拓展断点续传
 * 
 * @author yayalvtu 2014-12-30 上午11:02:09
 */
public class Downloader {

	private Context context;
	/**
	 * 判断是否还在下载
	 */
	private static boolean loading;
	
	public static Handler handler=new Handler(){
		public void handleMessage(android.os.Message msg) {
			loading=false;
		};
	};
	public Downloader(Context context) {
		this.context = context;
	}

	public void load() {
		loading=true;
		Intent intent = new Intent(context, DownLoadService.class);
		context.startService(intent);
	}

	public boolean isLoading() {

		return loading;
	}

}

DownLoadService.java

package com.example.test20150104;

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.text.SimpleDateFormat;
import java.util.Date;

import android.annotation.SuppressLint;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.IBinder;
import android.support.v4.app.NotificationCompat;

public class DownLoadService extends Service {
	private NotificationManager manager = null;
	private NotificationCompat.Builder builder;
	/**
	 * 下载路径
	 */
	private String path;

	@Override
	public IBinder onBind(Intent intent) {
		return null;
	}

	@SuppressLint("SimpleDateFormat")
	@Override
	public void onCreate() {
		super.onCreate();
		manager = (NotificationManager) this
				.getSystemService(NOTIFICATION_SERVICE);
		SimpleDateFormat df = new SimpleDateFormat("yyyyMMddHHmmss");
		path = "http://www.yylvtu.com/app/YaYaLvTu01.apk?ver="
				+ df.format(new Date());//下载地址
	}

	@Override
	public int onStartCommand(Intent intent, int flags, int startId) {

		new DownloadImageTask().execute(path);

		return super.onStartCommand(intent, flags, startId);
	}

	private class DownloadImageTask extends AsyncTask<String, Integer, Bitmap> {
		@Override
		protected void onPostExecute(Bitmap result) {//下载后
			if (result != null) {
				builder.setProgress(0, 0, true);
				builder.setContentText("下载完成");
				Notification no = builder.build();
				no.flags = Notification.FLAG_AUTO_CANCEL;
				no.defaults = Notification.DEFAULT_SOUND;
				manager.notify(1, no);
			} else {
				builder.setProgress(0, 0, true);
				builder.setContentText("下载失败..");
				manager.notify(1, builder.build());
			}
			Downloader.handler.sendEmptyMessage(0);//通知下载已经停止
			stopSelf();//关闭Service
		}
//文件存放位置
		private String filePath = "/storage/emulated/0/yylt/downloads/yylvtu.apk";
		

		@Override
		protected Bitmap doInBackground(String... params) {
			String path = params[0];
			try {

				URL u = new URL(path);
				URLConnection conn = u.openConnection();
				InputStream is = conn.getInputStream();
				long total_length = conn.getContentLength();
				FileOutputStream fos = new FileOutputStream(filePath);
				int len = 0;
				byte[] buf = new byte[1024];
				int current_len = 0;
				int progress = 0;// 当前下载进度
				int temp = 0;

				while ((len = is.read(buf)) != -1) {
					current_len += len;
					fos.write(buf, 0, len);
					if ((current_len - temp) > 204800) {//间断性的更新进度条，否则会因更新过于频繁而导致进度条不刷新
						temp = current_len;
						progress = (int) ((current_len / (float) total_length) * 100);
						this.publishProgress(progress);
					}
				}
				is.close();

				Resources res = getResources();
				Bitmap bmp = BitmapFactory.decodeResource(res,
						R.drawable.ic_launcher);//这里只是一个标志，实际意义为下载完成  中间无故障
				return bmp;
			} catch (Exception e) {
				e.printStackTrace();
			}
			return null;
		}

		@Override
		protected void onProgressUpdate(Integer... values) {//更新进度条
			builder.setContentText("下载进度：" + values[0] + "%");
			builder.setProgress(100, values[0], false);
			Notification no = builder.build();
			no.flags = Notification.FLAG_NO_CLEAR;
			manager.notify(1, no);
			no = null;
		}

		@Override
		protected void onPreExecute() {//现在前的准备

			builder = new NotificationCompat.Builder(DownLoadService.this);
			builder.setSmallIcon(R.drawable.ic_launcher);
			builder.setLargeIcon(BitmapFactory.decodeResource(getResources(),
					R.drawable.ic_launcher));
			builder.setContentTitle("apk文件");

			Intent notificationIntent1 = new Intent(Intent.ACTION_VIEW);
			notificationIntent1.setDataAndType(
					Uri.fromFile(new File(filePath)),
					"application/vnd.android.package-archive");
			PendingIntent pi = PendingIntent.getActivity(DownLoadService.this,
					0, notificationIntent1, PendingIntent.FLAG_ONE_SHOT);
			builder.setContentIntent(pi);

			builder.setProgress(100, 0, false);
			builder.setTicker("文件开始下载...");
			Notification no = builder.build();
			no.flags |= Notification.FLAG_AUTO_CANCEL;
			manager.notify(1, no);
		}
	}

}

权限配置：

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

    <!-- 版本更新 -->
     <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
    <uses-permission android:name="android.permission.INSTALL_PACKAGES" />

资源链接：http://download.csdn.net/detail/atsince/8324281