android 软件在线版本更新功能的实现

首先需要建立几个辅助类：

一、ConnectUtil类，判断时候具有可用网络，需要借助系统的ConnectivityManager

public class ConnectUtil {
public static boolean isConnect(Context context){
ConnectivityManager manager=(ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
if(manager!=null){
NetworkInfo info=manager.getActiveNetworkInfo();
if(info!=null&&info.isConnected()){
if(info.getState()==NetworkInfo.State.CONNECTED){
return true;
}
}
}
return false;
}
}

二、检查已有的版本信息，借助系统的packagerManager类

PackageManager manager = getPackageManager();
PackageInfo info;
try {
info = manager.getPackageInfo(getPackageName(), 0);
} catch (NameNotFoundException e) {
e.printStackTrace();
}
String versionName = info.versionName;
// 下载时刻出现一个进度条
pd = new ProgressDialog(this);

三、从服务器上下载apk文件

这里有两个问题尚未彻底弄明白：URLencoding进行URL编码的意义何在

封装后的HttpGet、HttpPost仅仅适用于请求返回为字符串的情况吗？如果请求返回二进制的apk，或者图片，就必须借助原始的HttpURLConnection？

package com.example.util;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
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 java.net.URLEncoder;
import java.util.List;
import java.util.Map;

import org.apache.http.HttpConnection;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
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 org.apache.http.util.EncodingUtils;
import org.apache.http.util.EntityUtils;

import android.app.ProgressDialog;
import android.content.SharedPreferences;
import android.os.Environment;

public class DownLoadUtil {
// 下载apk并将其保存在sd卡的路径中
public void downloadApk(String urlPath, ProgressDialog pd) {
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED)) {
BufferedInputStream bis = null;
BufferedOutputStream bos = null;
FileOutputStream fos = null;

try {
// url中带有中文，之前首先需要编码
// 应当仅仅编码其中的中文部分
/*
* System.out.println("编码前"+urlPath);
* System.out.println("编码后"+URLEncoder.encode(urlPath));
*/
urlPath = URLEncoder.encode(urlPath).replaceAll("%3A", ":")
.replaceAll("%2F", "/");
System.out.println(urlPath);
URL url = new URL(urlPath);
HttpURLConnection connection = (HttpURLConnection) url
.openConnection();
connection.setConnectTimeout(5000);
bis = new BufferedInputStream(connection.getInputStream());
File file = new File(Environment.getExternalStorageDirectory()
+ "/update/");
if (!file.exists()) {
file.mkdirs();
}
// 如果下载的时候需要出现进度条

// 如果实现文件不存在的话，outputstream构造函数调用时候会自动创建新文件
//但是前提是目录需要存在
fos = new FileOutputStream(file.getAbsolutePath() + "/绿萝空气.apk");
bos = new BufferedOutputStream(fos);
byte[] buffer = new byte[1024];
int len = 0;
int total = 0;
pd.setMax(connection.getContentLength());
while ((len = bis.read(buffer)) > 0) {
bos.write(buffer);
total += len;
pd.setProgress(total);
if (total == pd.getMax()) {
pd.dismiss();
}
}

} catch (Exception e) {
e.printStackTrace();

} finally {
try {
bis.close();
fos.close();
bos.close();
} catch (IOException e) {
e.printStackTrace();
}

}

}

}

/*// 如果发送的是get请求,使用这种方法可以下载apk么？
public String sendGetRequest(String url) {
HttpGet get = new HttpGet(url);
HttpClient client = new DefaultHttpClient();
try {
HttpResponse result = client.execute(get);

if (result != null
&& result.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {

* BufferedInputStream bis=new
* BufferedInputStream(result.getEntity().getContent()) ; byte[]
* buffer=new byte[bis.available()]; bis.read(buffer);
* System.out.println(new String(buffer));

String resultString = EntityUtils.toString(result.getEntity());
// System.out.println(resultString);
return resultString;
}

} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();

}
return null;

}
*/
}

apk的安装，借助系统的intent

protected void installApk(File file) {
Intent intent = new Intent();
// 执行动作
// 这里是系统配置的intent，因此不需要在配置文件中进行过多的更改
intent.setAction(Intent.ACTION_VIEW);
// 执行的数据类型
intent.setDataAndType(Uri.fromFile(file),
"application/vnd.android.package-archive");
startActivity(intent);
}

这时候发现了一个问题，apk安装时候提示“解析包时出现问题”；是由于签名的原因吗？不很确定