Android应用自动更新功能的实现！！！

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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);
}
}