Android 网络应用重点———使用HttpGet 下载apk文件并安装

本例使用HttpGet 从服务器端下载一个apk文件,然后自动将apk安装到手机上
下载文件原理： 先获得一个InputStream,读取到数据，再写入到目的地(通常写到SD卡)， 概括起来也就是先读再写
主要代码如下:

public class Main extends Activity implements OnClickListener
{
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button btnDownloadInstallApk = (Button) findViewById(R.id.btnDownloadInstallApk);
btnDownloadInstallApk.setOnClickListener(this);
}
//安装apk文件
private void installApk(String filename)
{
File file = new File(filename);
Intent intent = new Intent();
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.setAction(Intent.ACTION_VIEW);     //浏览网页的Action(动作)
String type = "application/vnd.android.package-archive";
intent.setDataAndType(Uri.fromFile(file), type);  //设置数据类型
startActivity(intent);
}
@Override
public void onClick(View view)
{
//下载文件  存放目的地
String downloadPath = Environment.getExternalStorageDirectory().getPath() + "/download_cache";
String url = "http://192.168.1.123/oa/apk/action.apk";
File file = new File(downloadPath);
if(!file.exists())
file.mkdir();
HttpGet httpGet = new HttpGet(url);
try
{
HttpResponse httpResponse = new DefaultHttpClient().execute(httpGet);
if (httpResponse.getStatusLine().getStatusCode() == 200)
{
InputStream is = httpResponse.getEntity().getContent();
// 开始下载apk文件
FileOutputStream fos = new FileOutputStream(downloadPath + "/action.apk");
byte[] buffer = new byte[8192];
int count = 0;
while ((count = is.read(buffer)) != -1)
{
fos.write(buffer, 0, count);
}
fos.close();
is.close();
//安装  apk 文件
installApk(downloadPath+ "/action.apk");
}
} catch (Exception e){}
}
}