Android如何实现文件下载并自动安装apk包

安装：
String str = "/CanavaCancel.apk";
String fileName = Environment.getExternalStorageDirectory() + str;
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(new File(fileName)), "application/vnd.android.package-archive");
startActivity(intent);
卸载：
Uri packageURI = Uri.parse("package:com.demo.CanavaCancel");
Intent uninstallIntent = new Intent(Intent.ACTION_DELETE, packageURI);
startActivity(uninstallIntent);


Environment拥有一些可以获取环境变量的方法
package:com.demo.CanavaCancel 这个形式是 package:程序完整的路径 (包名+程序名).
//下载apk程序代码
protected File downLoadFile(String httpUrl) {
// TODO Auto-generated method stub
final String fileName = "updata.apk";
File tmpFile = new File("/sdcard/update");
if (!tmpFile.exists()) {
tmpFile.mkdir();
}
final File file = new File("/sdcard/update/" + fileName);

try {
URL url = new URL(httpUrl);
try {
HttpURLConnection conn = (HttpURLConnection) url
.openConnection();
InputStream is = conn.getInputStream();
FileOutputStream fos = new FileOutputStream(file);
byte[] buf = new byte[256];
conn.connect();
double count = 0;
if (conn.getResponseCode() >= 400) {
Toast.makeText(Main.this, "连接超时", Toast.LENGTH_SHORT)
.show();
} else {
while (count <= 100) {
if (is != null) {
int numRead = is.read(buf);
if (numRead <= 0) {
break;
} else {
fos.write(buf, 0, numRead);
}

} else {
break;
}

}
}

conn.disconnect();
fos.close();
is.close();
} catch (IOException e) {
// TODO Auto-generated catch block

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

e.printStackTrace();
}

return file;
}
//打开APK程序代码

private void openFile(File file) {
// TODO Auto-generated method stub
Log.e("OpenFile", file.getName());
Intent intent = new Intent();
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.setAction(android.content.Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(file),
"application/vnd.android.package-archive");
startActivity(intent);
}