1、boolean java.io.File.mkdir()
public boolean mkdir ()
Since: API Level 1
Creates the directory named by the trailing filename of this file. Does not create the complete path required to create this directory.
创建一个目录根据指定的文件名。
Note that this method does not throw IOException on failure. Callers must check the return value.
Returns
true if the directory has been created, false otherwise.
See Also
mkdirs()
例如：
File dir = new File(SDPATH + dirName);
dir.mkdir();
2、boolean java.io.File.exists()
public boolean exists ()
Since: API Level 1
Returns a boolean indicating whether this file can be found on the underlying file system.
Returns
true if this file exists, false otherwise.
判断文件是否存在。
例如：
File file = new File(SDPATH + fileName);
return file.exists();