Android代碼實現APK文件的安裝與卸載

Android程序使用代碼的安裝和卸載！！！ 
安裝：
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);
卸載：
Uri packageURI = Uri.parse("package:com.demo.CanavaCancel");

Intent uninstallIntent = new Intent(Intent.ACTION_DELETE, packageURI);

startActivity(uninstallIntent);
Environment擁有一些可以獲取環境變量的方法 
package:com.demo.CanavaCancel 這個形式是 package:程序完整的路徑 (包名+程序名).
//下載apk程序代碼
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, "連接超時", 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;
    }

//打開APK程序代碼
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);
        }</pre>