android 读写文件(包括从sdcard中)

超、凢脫俗 2021-06-24 13:59 439阅读 0赞

1、从应用程序目录中读取文件：(不需要特殊权限)

文件被保存到了/data/data/报名/files/ 下。

public static void rememberInfo(Context context,String userName,String passwd) \{  
try \{  
FileOutputStream fos =context.openFileOutput("abc.txt",Context.MODE\_PRIVATE);  
BufferedOutputStream fs = new BufferedOutputStream(fos);  
  
fs.write((userName+";"+passwd).getBytes());  
fs.close();  
fos.close();  
\} catch (IOException e) \{  
e.printStackTrace();  
\}  
\}  
  
public static String getUserInfo (Context context) \{  
String res = "";  
try \{  
FileInputStream  fis = context.openFileInput("abc.txt");  
InputStreamReader isr = new InputStreamReader (fis);  
BufferedReader br = new BufferedReader(isr);  
  
res=br.readLine();  
br.close();  
isr.close();  
fis.close();  
\} catch (IOException e) \{  
e.printStackTrace();  
\}  
return res;  
\}

2、从sdcard中读取文件：

1)写文件时需要有android.permission.WRITE\_EXTERNAL\_STORAGE 权限；android4以后，从sdcard卡中读取文件也需要有权限；

2)从sdcard存取时，一般都需要判断sdcard的状态；

public static void rememberInfo4Sd(Context context,String userName,String passwd) \{  
if (Environment.MEDIA\_MOUNTED.equals(Environment.getExternalStorageState())) \{//判断sdcard是否挂载  
File file = new File(Environment.getExternalStorageDirectory(),"abc.txt");  
try \{  
FileOutputStream fo = new FileOutputStream(file);  
BufferedOutputStream bo = new BufferedOutputStream(fo);  
bo.write((userName+";"+passwd).getBytes());  
  
bo.close();  
fo.close();  
\} catch (IOException e) \{  
e.printStackTrace();  
\}  
  
\} else \{  
Toast.makeText(context, "请检查sd卡是否安装好", Toast.LENGTH\_SHORT).show();  
\}  
\}  
  
public static String getUserInfo4sd(Context context) \{  
String res = "";  
if (Environment.MEDIA\_MOUNTED.equals(Environment.getExternalStorageState())) \{//判断sdcard是否挂载  
File file = new File(Environment.getExternalStorageDirectory(),"abc.txt");  
try \{  
FileInputStream fi = new FileInputStream(file);  
InputStreamReader isr = new InputStreamReader (fi);  
BufferedReader br = new BufferedReader(isr);  
  
res=br.readLine();  
br.close();  
isr.close();  
fi.close();  
\} catch (IOException e) \{  
e.printStackTrace();  
\}  
\}  
return res;  
\}