今天有了一个这样的需求 ：下载一个apk文件，然后当你下载完成后，按钮的文字发生改变，变成点击安装，然后安装完成之后，变成打开。

这是下载apk的方法：

/** * 后台在下面一个Apk 下载完成后返回下载好的文件 * * @param httpUrl * @return */ private File downFile(final String httpUrl) {
new Thread(new Runnable() {
@Override public void run() {
try {
URL url = new URL(httpUrl);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setConnectTimeout(5000);
FileOutputStream fileOutputStream = null;
InputStream inputStream;
if (connection.getResponseCode() == 200) {
inputStream = connection.getInputStream();
if (inputStream != null) {
file = getFile(httpUrl);
fileOutputStream = new FileOutputStream(file);
byte[] buffer = new byte[1024];
int length = 0;
while ((length = inputStream.read(buffer)) != -1) {
fileOutputStream.write(buffer, 0, length);
}
fileOutputStream.close();
fileOutputStream.flush();
}
inputStream.close();
}
System.out.println("已经下载完成");
// 往handler发送一条消息 更改button的text属性 Message message = handler.obtainMessage();
message.what = 1;
handler.sendMessage(message);
}
catch (MalformedURLException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
}
}
).start();
return file;
}

这是安装APK的方法：

/** * 安装APK */ private void installApk() {
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");
startActivity(intent);
}

这是打开APK的方法：

/** * 打开已经安装好的apk */ private void openApk(Context context, String url) {
PackageManager manager = context.getPackageManager();
// 这里的是你下载好的文件路径 PackageInfo info = manager.getPackageArchiveInfo(Environment.getExternalStorageDirectory().getAbsolutePath() + getFilePath(url), PackageManager.GET_ACTIVITIES);
if (info != null) {
Intent intent = manager.getLaunchIntentForPackage(info.applicationInfo.packageName);
startActivity(intent);
}
}

打开APK 这里弄了好久，之前不知道有个getLaunchIntentForPackage方法 这个方法只要你能得到这个apk的报名，然后将包名加到后面，startActivity 它就会自动自动你的APK的主界面了。相信得到一个APK的的信息这个大家都会了，这里就不说了。

下面是我的所有代码：

/** * 下载Apk 安装Apk 打开APK * * @author Administrator * */public class MainActivity extends Activity {
private Button button1;
private static final String URL_STRING = "http://gdown.baidu.com/data/wisegame/b7d7e4efd8199dea/tianyiyuedu_310.apk";
private static int down = 0;
File file;
private Handler handler = new Handler() {
@Override public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case 1: button1.setText("点击安装");
down = 1;
break;
case 2: down = 2;
button1.setText("打开");
break;
}
}
}
;
@Override protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button1 = (Button) findViewById(R.id.button1);
button1.setOnClickListener(new OnClickListener() {
@Override public void onClick(View v) {
// 下载apk if (down == 0) {
downFile(URL_STRING);
button1.setText("正在下载");
// 安装APK }
else if (down == 1) {
installApk();
// 打开apk }
else if (down == 2) {
openApk(MainActivity.this, URL_STRING);
}
}
}
);
}
// 接收到安装完成apk的广播 BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
@Override public void onReceive(Context context, Intent intent) {
System.out.println("接收到安装完成apk的广播");
Message message = handler.obtainMessage();
message.what = 2;
handler.sendMessage(message);
}
}
;
/** * 后台在下面一个Apk 下载完成后返回下载好的文件 * * @param httpUrl * @return */ private File downFile(final String httpUrl) {
new Thread(new Runnable() {
@Override public void run() {
try {
URL url = new URL(httpUrl);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setConnectTimeout(5000);
FileOutputStream fileOutputStream = null;
InputStream inputStream;
if (connection.getResponseCode() == 200) {
inputStream = connection.getInputStream();
if (inputStream != null) {
file = getFile(httpUrl);
fileOutputStream = new FileOutputStream(file);
byte[] buffer = new byte[1024];
int length = 0;
while ((length = inputStream.read(buffer)) != -1) {
fileOutputStream.write(buffer, 0, length);
}
fileOutputStream.close();
fileOutputStream.flush();
}
inputStream.close();
}
System.out.println("已经下载完成");
// 往handler发送一条消息 更改button的text属性 Message message = handler.obtainMessage();
message.what = 1;
handler.sendMessage(message);
}
catch (MalformedURLException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
}
}
).start();
return file;
}
/** * 安装APK */ private void installApk() {
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");
startActivity(intent);
}
@Override protected void onStart() {
super.onStart();
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(Intent.ACTION_PACKAGE_ADDED);
intentFilter.addDataScheme("package");
// 注册一个广播 registerReceiver(broadcastReceiver, intentFilter);
}
@Override protected void onDestroy() {
super.onDestroy();
// 解除广播 unregisterReceiver(broadcastReceiver);
}
/** * 打开已经安装好的apk */ private void openApk(Context context, String url) {
PackageManager manager = context.getPackageManager();
// 这里的是你下载好的文件路径 PackageInfo info = manager.getPackageArchiveInfo(Environment.getExternalStorageDirectory().getAbsolutePath() + getFilePath(url), PackageManager.GET_ACTIVITIES);
if (info != null) {
Intent intent = manager.getLaunchIntentForPackage(info.applicationInfo.packageName);
startActivity(intent);
}
}
/** * 根据传过来url创建文件 * */ private File getFile(String url) {
File files = new File(Environment.getExternalStorageDirectory().getAbsoluteFile(), getFilePath(url));
return files;
}
/** * 截取出url后面的apk的文件名 * * @param url * @return */ private String getFilePath(String url) {
return url.substring(url.lastIndexOf("/"), url.length());
}
}

布局文件就只要一个按钮，就不贴出来了。还有一个东西，就是监听一个应用安装完成的广播，我这里是直接在代码中注册：

IntentFilter filter = new IntentFilter();
filter.addAction("android.intent.action.PACKAGE_ADDED");
filter.addAction("android.intent.action.PACKAGE_REMOVED");
filter.addDataScheme("package");

监听安装apk和卸载apk的广播，其它的相信大家看代码也能看懂了，代码有点粗糙（菜鸟一枚），有哪里写的不好的地方，欢迎大家指正。

这个程序我没有考虑其他的情况，比如apk安装出错了，要怎么处理，等等。。

忘记说了，还需要在配置文件中添加访问网络和往sd卡写文件的权限：

源代码的下载地址