Android应用自动更新功能的实现！！！

自动更新功能的实现原理，就是我们事先和后台协商好一个接口，我们在应用的主Activity里，去访问这个接口，如果需要更新，后台会返回一些数据(比如，提示语；最新版本的url等)。然后我们给出提示框，用户点击开始下载，下载完成开始覆盖安装程序，这样用户的应用就保持最新的拉。

为了让大家容易理解，我像往常一样准备一个小例子，这里为了方便我就省去了和后台交互部分了。步骤分别如下：

第一步：新建一个Android工程命名为:UpdateDemo.代码结构如下图所示：

第二步：新建一个UpdateManager.java类，负责软件更新功能模块，代码如下：

package com.tutor.update;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;


import android.app.AlertDialog;
import android.app.Dialog;
import android.app.AlertDialog.Builder;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.DialogInterface.OnClickListener;
import android.net.Uri;
import android.os.Handler;
import android.os.Message;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ProgressBar;

public class UpdateManager {

    private Context mContext;

    //提示语
    private String updateMsg = "有最新的软件包哦，亲快下载吧~";

    //返回的安装包url
    private String apkUrl = "http://softfile.3g.qq.com:8080/msoft/179/24659/43549/qq_hd_mini_1.4.apk";


    private Dialog noticeDialog;

    private Dialog downloadDialog;
     /* 下载包安装路径 */
    private static final String savePath = "/sdcard/updatedemo/";

    private static final String saveFileName = savePath + "UpdateDemoRelease.apk";

    /* 进度条与通知ui刷新的handler和msg常量 */
    private ProgressBar mProgress;


    private static final int DOWN_UPDATE = 1;

    private static final int DOWN_OVER = 2;

    private int progress;

    private Thread downLoadThread;

    private boolean interceptFlag = false;

    private Handler mHandler = new Handler(){
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case DOWN_UPDATE:
                mProgress.setProgress(progress);
                break;
            case DOWN_OVER:

                installApk();
                break;
            default:
                break;
            }
        };
    };

    public UpdateManager(Context context) {
        this.mContext = context;
    }

    //外部接口让主Activity调用
    public void checkUpdateInfo(){
        showNoticeDialog();
    }


    private void showNoticeDialog(){
        AlertDialog.Builder builder = new Builder(mContext);
        builder.setTitle("软件版本更新");
        builder.setMessage(updateMsg);
        builder.setPositiveButton("下载", new OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
                showDownloadDialog();
            }
        });
        builder.setNegativeButton("以后再说", new OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });
        noticeDialog = builder.create();
        noticeDialog.show();
    }

    private void showDownloadDialog(){
        AlertDialog.Builder builder = new Builder(mContext);
        builder.setTitle("软件版本更新");

        final LayoutInflater inflater = LayoutInflater.from(mContext);
        View v = inflater.inflate(R.layout.progress, null);
        mProgress = (ProgressBar)v.findViewById(R.id.progress);

        builder.setView(v);
        builder.setNegativeButton("取消", new OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
                interceptFlag = true;
            }
        });
        downloadDialog = builder.create();
        downloadDialog.show();

        downloadApk();
    }

    private Runnable mdownApkRunnable = new Runnable() {
        @Override
        public void run() {
            try {
                URL url = new URL(apkUrl);

                HttpURLConnection conn = (HttpURLConnection)url.openConnection();
                conn.connect();
                int length = conn.getContentLength();
                InputStream is = conn.getInputStream();

                File file = new File(savePath);
                if(!file.exists()){
                    file.mkdir();
                }
                String apkFile = saveFileName;
                File ApkFile = new File(apkFile);
                FileOutputStream fos = new FileOutputStream(ApkFile);

                int count = 0;
                byte buf[] = new byte[1024];

                do{
                    int numread = is.read(buf);
                    count += numread;
                    progress =(int)(((float)count / length) * 100);
                    //更新进度
                    mHandler.sendEmptyMessage(DOWN_UPDATE);
                    if(numread <= 0){
                        //下载完成通知安装
                        mHandler.sendEmptyMessage(DOWN_OVER);
                        break;
                    }
                    fos.write(buf,0,numread);
                }while(!interceptFlag);//点击取消就停止下载.

                fos.close();
                is.close();
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch(IOException e){
                e.printStackTrace();
            }

        }
    };

     /**
     * 下载apk
     * @param url
     */

    private void downloadApk(){
        downLoadThread = new Thread(mdownApkRunnable);
        downLoadThread.start();
    }
     /**
     * 安装apk
     * @param url
     */
    private void installApk(){
        File apkfile = new File(saveFileName);
        if (!apkfile.exists()) {
            return;
        }
        Intent i = new Intent(Intent.ACTION_VIEW);
        i.setDataAndType(Uri.parse("file://" + apkfile.toString()), "application/vnd.android.package-archive");
        mContext.startActivity(i);

    }
}

第三步：在MainActivity.java也就是主Activity调用,代码如下:

package com.tutor.update;

import android.app.Activity;
import android.os.Bundle;

public class MainAcitivity extends Activity {


    private UpdateManager mUpdateManager;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        //这里来检测版本是否需要更新
        mUpdateManager = new UpdateManager(this);
        mUpdateManager.checkUpdateInfo();
    }
}

第四步：添加程序所用的资源与权限：

下载的时候用到了ProgressBar,所以事先写了一个progress.xml布局文件，代码如下:

<?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="wrap_content">

  <ProgressBar
    android:id="@+id/progress"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    style="?android:attr/progressBarStyleHorizontal"
  />
</LinearLayout>

下载的时候用到了网络部分，所以要在AndroidManifest.xml中添加网络权限，代码如下:

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

第五步:运行查看效果如下:

     

 图一:提示有最新包                                                                                   图二：点击开始下载

图三：下载完开始安装，我这里模拟器空间不足了。

OK~大功告成了，继续看球，阿森纳已经0:1了，希望范大将军救驾！大家晚安~稍后将会为大家分享更多内容，尽请期待！