try {
    // 获取应用的缓存目录
    File dir = getApplicationContext().getCacheDir();
    // 删除缓存目录中的所有文件
    deleteDir(dir);
} catch (Exception e) {
    e.printStackTrace();
}

private boolean deleteDir(File dir) {
    if (dir != null && dir.isDirectory()) {
        String[] children = dir.list();
        for (int i = 0; i < children.length; i++) {
            boolean success = deleteDir(new File(dir, children[i]));
            if (!success) {
                return false;
            }
        }
        return dir.delete();
    } else if(dir!= null){
        return dir.delete();
    } else {
        return false;
    }
}