Android中关于内部存储的一些重要函数

Returns the absolute path to the application specific cache directory on the filesystem. These files will be ones that get deleted first when the device runs low on storage. There is no guarantee when these files will be deleted. Note: you should not rely on the system deleting these files for you; you should always have a reasonable maximum, such as 1 MB, for the amount of space you consume with cache files, and prune those files when exceeding that space.

存储空间剩余多少的情况，没有严格的标准保障。

注意：你不应该依赖系统来清理这些缓存文件，你应该对这些缓存文件占用的最大存储空间设定个最大值，比如是1M，当实际占用空间超过这个值时，你应该对这些缓存文件做相应的清理工作（prune）。

Returns

• Returns the path of the directory holding application cache files.

See Also

• openFileOutput(String, int)
• getFileStreamPath(String)
• getDir(String, int)
• import android.app.Activity;
• import android.content.Context;
• import android.os.Bundle;
• import android.util.Log;
• public class MainActivity extends Activity {
• final static String TAG="robin";
•     /** Called when the activity is first created. */
•     @Override
•     public void onCreate(Bundle savedInstanceState) {
•         super.onCreate(savedInstanceState);
•         setContentView(R.layout.main);
•         Context context=this;
•         String path=context.getCacheDir().getAbsolutePath();
•         Log.i(TAG,"path:"+path);
•     }
• }
• path:/data/data/com.lenovo/cache

Retrieve, creating if needed, a new directory in which the application can place its own custom data files. You can use the returned File object to create and access files in this directory. Note that files created through a File object will only be accessible by your own application; you can only set the mode of the entire directory, not of individual files.

：参数是指文件夹的访问权限而并不包括其子文件夹和文件的访问权限

Parameters

Returns

• Returns a File object for the requested directory. The directory will have been created if it does not already exist.

See Also

• openFileOutput(String, int)
•         File file=context.getDir("download", Context.MODE_PRIVATE);
•         String path=file.getAbsolutePath();
•         Log.i(TAG,"path:"+path);

• public abstract File getFileStreamPath (String name)

  Since: API Level 1

  Returns the absolute path on the filesystem where a file created with openFileOutput(String, int) is stored.

  Parameters

  name

  The name of the file for which you would like to get its path.

  Returns

  • Returns an absolute path to the given file.

  See Also

  • openFileOutput(String, int)
  • getFilesDir()
  • getDir(String, int)
  •         File file=context.getFileStreamPath("download");
  •         String path=file.getAbsolutePath();
  •         Log.i(TAG,"path:"+path);

  • public abstract File getFilesDir ()

    Since: API Level 1

    Returns the absolute path to the directory on the filesystem where files created with openFileOutput(String, int) are stored.

    Returns

    • Returns the path of the directory holding application files.

    See Also

    • openFileOutput(String, int)
    • getFileStreamPath(String)
    • getDir(String, int)

  示例4

          File file=context.getFilesDir();

          String path=file.getAbsolutePath();

          Log.i(TAG,"path:"+path);

  运行结果

  10-02 09:15:11.102: I/robin(12359): path:/data/data/com.lenovo/files

  public abstract FileInputStream openFileInput (String name)

  Since: API Level 1

  Open a private file associated with this Context‘s application package for reading.

  Parameters

  name	The name of the file to open; can not contain path separators.

  Returns

  • FileInputStream Resulting input stream.

  Throws

  FileNotFoundException

  See Also

  • openFileOutput(String, int)
  • fileList()
  • deleteFile(String)
  • FileInputStream(String)

  public abstract FileOutputStream openFileOutput (String name, int mode)

  Since: API Level 1

  Open a private file associated with this Context‘s application package for writing. Creates the file if it doesn‘t already exist.

  Parameters

  name	The name of the file to open; can not contain path separators.
  mode	Operating mode. Use 0 or MODE_PRIVATE for the default operation, MODE_APPEND to append to an existing file, MODE_WORLD_READABLE and MODE_WORLD_WRITEABLE to control permissions.

  Returns

  • FileOutputStream Resulting output stream.

  Throws

  FileNotFoundException

  See Also

  • MODE_APPEND 表示写文件时是追加模式，即从文件末开始写数据
  • MODE_PRIVATE
  • MODE_WORLD_READABLE
  • MODE_WORLD_WRITEABLE
  • openFileInput(String)
  • fileList()
  • deleteFile(String)
  • FileOutputStream(String)

  示例5

Delete the given private file associated with this Context‘s application package.

Parameters

Returns

• True if the file was successfully deleted; else false.

See Also

• openFileInput(String)
• openFileOutput(String, int)
• fileList()
• delete()