项目开发使用模板：Android代码实现APK下载安装（代码依赖包afinal_0.5_bin.jar,可资源下载）
<span style="white-space:pre"> </span>protected void showUpdateDialog() {
<span style="white-space:pre"> </span>//this = Activity.this
<span style="white-space:pre"> </span>AlertDialog.Builder builder = new Builder(SplashActivity.this);
<span style="white-space:pre"> </span>builder.setTitle("提示升级");
//<span style="white-space:pre"> </span>builder.setCancelable(false);//强制升级
<span style="white-space:pre"> </span>builder.setOnCancelListener(new OnCancelListener() {
<span style="white-space:pre"> </span>
<span style="white-space:pre"> </span>@Override
<span style="white-space:pre"> </span>public void onCancel(DialogInterface dialog) {
<span style="white-space:pre"> </span>// TODO Auto-generated method stub
<span style="white-space:pre"> </span>//无操作或者返回就代替用户做选择，进入主页面
<span style="white-space:pre"> </span>enterHome();
<span style="white-space:pre"> </span>dialog.dismiss();
<span style="white-space:pre"> </span>
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>});
<span style="white-space:pre"> </span>builder.setMessage(description);
<span style="white-space:pre"> </span>builder.setPositiveButton("立刻升级", new OnClickListener() {
<span style="white-space:pre"> </span>@Override
<span style="white-space:pre"> </span>public void onClick(DialogInterface dialog, int which) {
<span style="white-space:pre"> </span>// 下载APK，并且替换安装
<span style="white-space:pre"> </span>if (Environment.getExternalStorageState().equals(
<span style="white-space:pre"> </span>Environment.MEDIA_MOUNTED)) {
<span style="white-space:pre"> </span>// sdcard存在
<span style="white-space:pre"> </span>// afnal
<span style="white-space:pre"> </span>FinalHttp finalhttp = new FinalHttp();
<span style="white-space:pre"> </span>finalhttp.download(apkurl, Environment
<span style="white-space:pre"> </span>.getExternalStorageDirectory().getAbsolutePath()+"/mobilesafe2.0.apk",
<span style="white-space:pre"> </span>new AjaxCallBack<File>() {
<span style="white-space:pre"> </span>@Override
<span style="white-space:pre"> </span>public void onFailure(Throwable t, int errorNo,
<span style="white-space:pre"> </span>String strMsg) {
<span style="white-space:pre"> </span>t.printStackTrace();
<span style="white-space:pre"> </span>Toast.makeText(getApplicationContext(), "下载失败", 1).show();
<span style="white-space:pre"> </span>super.onFailure(t, errorNo, strMsg);
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>@Override
<span style="white-space:pre"> </span>public void onLoading(long count, long current) {
<span style="white-space:pre"> </span>// TODO Auto-generated method stub
<span style="white-space:pre"> </span>super.onLoading(count, current);
<span style="white-space:pre"> </span>tv_update_info.setVisibility(View.VISIBLE);
<span style="white-space:pre"> </span>//当前下载百分比
<span style="white-space:pre"> </span>int progress = (int) (current * 100 / count);
<span style="white-space:pre"> </span>tv_update_info.setText("下载进度："+progress+"%");
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>@Override
<span style="white-space:pre"> </span>public void onSuccess(File t) {
<span style="white-space:pre"> </span>// TODO Auto-generated method stub
<span style="white-space:pre"> </span>super.onSuccess(t);
<span style="white-space:pre"> </span>installAPK(t);
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>/**
<span style="white-space:pre"> </span> * 安装APK
<span style="white-space:pre"> </span> * @param t
<span style="white-space:pre"> </span> */
<span style="white-space:pre"> </span>private void installAPK(File t) {
<span style="white-space:pre"> </span> Intent intent = new Intent();
<span style="white-space:pre"> </span> intent.setAction("android.intent.action.VIEW");
<span style="white-space:pre"> </span> intent.addCategory("android.intent.category.DEFAULT");
<span style="white-space:pre"> </span> intent.setDataAndType(Uri.fromFile(t), "application/vnd.android.package-archive");
<span style="white-space:pre"> </span>
<span style="white-space:pre"> </span> startActivity(intent);
<span style="white-space:pre"> </span>
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>
<span style="white-space:pre"> </span>
<span style="white-space:pre"> </span>});
<span style="white-space:pre"> </span>} else {
<span style="white-space:pre"> </span>Toast.makeText(getApplicationContext(), "没有sdcard，请安装上在试",
<span style="white-space:pre"> </span>0).show();
<span style="white-space:pre"> </span>return;
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>});
<span style="white-space:pre"> </span>builder.setNegativeButton("下次再说", new OnClickListener() {
<span style="white-space:pre"> </span>@Override
<span style="white-space:pre"> </span>public void onClick(DialogInterface dialog, int which) {
<span style="white-space:pre"> </span>// TODO Auto-generated method stub
<span style="white-space:pre"> </span>dialog.dismiss();
<span style="white-space:pre"> </span>enterHome();// 进入主页面
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>});
<span style="white-space:pre"> </span>builder.show();
<span style="white-space:pre"> </span>}原文：http://blog.csdn.net/zeb_perfect/article/details/44622521