在sd卡中用程序创建目录

如果要想在sd卡中的一个子目录下创造文件FileOutputStream fos = new FileOutputStream("/sdcard/Wallpaper/"+fileName); 这是错误的，需要

// create a File object for the parent directory 
File wallpaperDirectory = new File("/sdcard/Wallpaper/"); 
// have the object build the directory structure, if needed. 
wallpaperDirectory.mkdirs(); 
// create a File object for the output file 
File outputFile = new File(wallpaperDirectory, filename); 
// now attach the OutputStream to the file object, instead of a String representation 
FileOutputStream fos = new FileOutputStream(outputFile); 

 

当然别忘了检查sd卡存在不Environment.getExternalStorageDirectory()