android 删除文件以及递归删除文件夹

private void deleteDirectory(File file) { 
    if (file.isFile()) { 
        file.delete(); 
        return; 
    } 

    if(file.isDirectory()){ 
        File[] childFiles = file.listFiles(); 
        if (childFiles == null || childFiles.length == 0) { 
            file.delete(); 
            return; 
        } 

        for (int i = 0; i < childFiles.length; i++) { 
            deleteDirectory(childFiles[i]); 
        } 
        file.delete(); 
    } 
}