限制后从外部存储中删除旧图像

Question

我已经在我的应用程序中实现了离线缓存，为此我将图像存储在外部 storage.I 希望一旦我的缓存图像文件夹限制达到 30 然后它开始用新图像替换旧图像 ones.For 我实现了以下删除算法-

 public static boolean deleteDir(File dir)
   {
        if (dir != null && dir.isDirectory())
        {
            String[] children = dir.list();

            if(children.length>30)
            {
                int exceed=children.length-30;

                for (int i = 0; i <exceed; i++)
                {

                    boolean success = deleteDir(new File(dir, children[i]));
                    if (!success)
                    {
                        return false;
                    }
                    else
                    {
                        Log.e("deleted","file deleted");
                    }

                }
            }

        }
        return dir.delete();
    }

但是上面的算法不起作用，因为 expected.It 可能会删除新添加的 images.I 也尝试在 algorithm.But 下面实现它也不起作用，因为 expected.I 失败了明白我哪里错了。

public static boolean deleteDir(File dir)
       {
            if (dir != null && dir.isDirectory())
            {
                String[] children = dir.list();

                if(children.length>30)
                {
                    int exceed=children.length-30;
                    int destroy=(children.length-exceed)-1;
                    for (int i = children.length; i >destroy; i--)
                    {

                        boolean success = deleteDir(new File(dir, children[i]));
                        if (!success)
                        {
                            return false;
                        }
                        else
                        {
                            Log.e("deleted","file deleted");
                        }

                    }
                }

            }
            return dir.delete();
        }

Answer 1

试试这个

public static void deleteDir(File dir) {
        if (dir != null && dir.isDirectory()) {
            File[] files = dir.listFiles();
            if (files.length > 30) {
                Arrays.sort(files, new Comparator<File>() {
                    @Override
                    public int compare(File o1, File o2) {
                        if (o1.lastModified() > o2.lastModified()) {
                            return 1;
                        } else if (o1.lastModified() < o2.lastModified()) {
                            return -1;
                        }
                        return 0;
                    }
                });
                for (int i = 0; i < files.length - 30; i++) {
                    files[i].delete();
                }
            }
        }

    }

限制后从外部存储中删除旧图像

Deleting older images from external storage after a limit

android

caching

android-external-storage