Android平台下的一些常用知识

安装某个应用      

Intent intent = new Intent(Intent.ACTION_VIEW); 

intent.setDataAndType(Uri.fromFile(new File("/sdcard/XXX.apk")), "application/vnd.android.package-archive");

把一个字符串写进文件

String str = "goodgoodstudy,daydayup";    

 File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath(),"字符串.txt");

 FileOutputStream out=new FileOutputStream(file,true);

byte[] bytes = str.getBytes() ;

 out.write(bytes);

  out.close() ;

把文件内容读出到一个字符串

File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath(),"字符串.txt");

                    FileInputStream in = new FileInputStream(file);

                    int length = (int) file.length();

                    byte[] tmp = new byte[length];

                    in.read(tmp, 0, length);

                    String str = new String(tmp);

                    Toast.makeText(act, str, 0).show();

模拟HOME按键

Intent intent = new Intent(Intent.ACTION_MAIN);

                intent.addCategory(Intent.CATEGORY_HOME);

                intent.addFlags
4000
(Intent.FLAG_ACTIVITY_NEW_TASK);

                startActivity(intent);