android文件读取

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1.手机flash读写这个属于app的独立权限，即每个app默认只能读写自己文件夹下的文件.默认路径为/data/data/your_project/files/

2.sdcard读写默认android系统对每个app都开放读写功能。默认路径为/mnt/sdcard/ 或者/sdcard/
写外部存储即sdcard的权限<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>

存储文件：
FileOutputStream outStream=this.openFileOutput("sqc.txt",Context.MODE_PRIVATE);
outStream.write("文件的读写",getBytes());
outStream.close();

读取文件：
FileInputStream inStream=this.getContext().openFileInput("sqc.txt");

使用绝对路径打开文件：
File file = new File("/data/data/com.sqc/files/sqc.txt");
FileInputStream inStream = new FileInputStream(file);
Log.i("FileTest", readInStream(inStream));

读取文件的方法：

public static String readInStream(FileInputStream inStream){
  try {
   ByteArrayOutputStream outStream = new ByteArrayOutputStream();
   byte[] buffer = new byte[1024];
   int length = -1;
   while((length = inStream.read(buffer)) != -1 ){
    outStream.write(buffer, 0, length);
   }
   outStream.close();
   inStream.close();
   return outStream.toString();
  } catch (IOException e){
   Log.i("FileTest", e.getMessage());
  }
  return null;
}Activity还提供了getCacheDir()和getFilesDir()方法：
getCacheDir()方法用于获取/data/data/<package name>/cache目录
getFilesDir()方法用于获取/data/data/<package name>/files目录

2.sdcard读写相关API

获取SDCard的状态：Environment.getExtemalStorageState()
  EnvironmentMEDIA_MOUNTED手机装有SDCard，并且可以进行读写
获取SDCard的目录：Environment.getExtemalStorageDirectory()
     File saveFile=new File("/sdcard/zhzhg.txt");
        或：File sdCardDir=new File("/sdcard");//获取SD卡目录
     File saveFile-new File(sdCardDir,"zhzhg.txt");
        FileOutputStream outStream = new FileOutputStream(saveFile);
outStream.write("文件的读写".getBytes());
outStream.close();

一般你的程序要写sd的话需要申请如下权限
    <permission name="android.permission.WRITE_EXTERNAL_STORAGE" >
        <group gid="sdcard_rw" />
    </permission>

在sdcard中创建/删除文件的权限用android.permission.MOUNT_UNMOUNT_FILESYSTEMS
往sdcard中写入数据权限为android.permission.WRITE_EXTERNAL_STORAGE