/**
 *
 * 本應用資料清除管理器
 */
public class DataClearManager {


    /**
     * 獲取本應用快取大小
     * @param context
     * @return
     */
    public static String getTotalCacheSize(Context context) throws Exception {
        long cacheSize = getFolderSize(context.getCacheDir());//快取路徑---/data/data/com.xxx.xxx/cache - 應用內快取（注：對應方法getCacheDir()）
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {//判斷sd卡有沒有正常掛載
            cacheSize += getFolderSize(context.getExternalCacheDir());//sd卡外部的快取路徑
        }
        return getFormatSize(cacheSize);
    }

    /**
     * * 清除本應用所有的資料 * *
     * @param context 上下文物件
     * @param filepath  自定義的快取路徑（清除自定義路徑下的檔案）
     */
    public static void cleanApplicationData(Context context, String... filepath) {
        cleanInternalCache(context);
        cleanExternalCache(context);
        cleanDatabases(context);
        cleanSharedPreference(context);
        cleanFiles(context);
        if (filepath == null) {
            return;
        }
        for (String filePath : filepath) {
            cleanCustomCache(filePath);
        }
    }



    /**
     * * 清除本應用內部快取(/data/data/com.xxx.xxx/cache) * *
     *
     * @param context
     */
    public static void cleanInternalCache(Context context) {
        deleteFilesByDirectory(context.getCacheDir());
    }

    /**
     * * 清除本應用所有資料庫(/data/data/com.xxx.xxx/databases) * *
     *
     * @param context
     */
    public static void cleanDatabases(Context context) {
        deleteFilesByDirectory(new File("/data/data/"
                + context.getPackageName() + "/databases"));
    }

    /**
     * * 清除本應用SharedPreference(/data/data/com.xxx.xxx/shared_prefs) *
     *
     * @param context
     */
    public static void cleanSharedPreference(Context context) {
        deleteFilesByDirectory(new File("/data/data/"
                + context.getPackageName() + "/shared_prefs"));
    }

    /**
     * * 按名字清除本應用資料庫 * *
     *
     * @param context
     * @param dbName
     */
    public static void cleanDatabaseByName(Context context, String dbName) {
        context.deleteDatabase(dbName);
    }

    /**
     * * 清除/data/data/com.xxx.xxx/files下的內容 * *
     *
     * @param context
     */
    public static void cleanFiles(Context context) {
        deleteFilesByDirectory(context.getFilesDir());
    }

    /**
     * * 清除外部cache下的內容(/mnt/sdcard/android/data/com.xxx.xxx/cache)
     *
     * @param context
     */
    public static void cleanExternalCache(Context context) {
        if (Environment.getExternalStorageState().equals(
                Environment.MEDIA_MOUNTED)) {
            deleteFilesByDirectory(context.getExternalCacheDir());
        }
    }

    /**
     * * 清除自定義路徑下的檔案，使用需小心，請不要誤刪。而且只支援目錄下的檔案刪除 * *
     *
     * @param filePath
     */
    public static void cleanCustomCache(String filePath) {
        deleteFilesByDirectory(new File(filePath));
    }



    /**
     * * 刪除方法 這裡只會刪除某個資料夾下的檔案，如果傳入的directory是個檔案，將不做處理 * *
     *
     * @param directory
     */
    private static void deleteFilesByDirectory(File directory) {
        if (directory != null && directory.exists() && directory.isDirectory()) {
            for (File item : directory.listFiles()) {
                item.delete();
            }
        }
    }

    // 獲取檔案
    //Context.getExternalFilesDir() --> SDCard/Android/data/你的應用的包名/files/ 目錄，一般放一些長時間儲存的資料
    //Context.getExternalCacheDir() --> SDCard/Android/data/你的應用包名/cache/目錄，一般存放臨時快取資料
    public static long getFolderSize(File file) throws Exception {
        long size = 0;
        try {
            File[] fileList = file.listFiles();
            for (File aFileList : fileList) {
                // 如果下面還有檔案
                if (aFileList.isDirectory()) {
                    size = size + getFolderSize(aFileList);
                } else {
                    size = size + aFileList.length();
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return size;
    }

    /**
     * 刪除指定目錄下檔案及目錄
     *
     * @param deleteThisPath

     * @return
     */
    public static void deleteFolderFile(String filePath, boolean deleteThisPath) {
        if (!TextUtils.isEmpty(filePath)) {
            try {
                File file = new File(filePath);
                if (file.isDirectory()) {// 如果下面還有檔案
                    File files[] = file.listFiles();
                    for (File file1 : files) {
                        deleteFolderFile(file1.getAbsolutePath(), true);
                    }
                }
                if (deleteThisPath) {
                    if (!file.isDirectory()) {// 如果是檔案，刪除
                        file.delete();
                    } else {// 目錄
                        if (file.listFiles().length == 0) {// 目錄下沒有檔案或者目錄，刪除
                            file.delete();
                        }
                    }
                }
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

    /**
     * 格式化單位
     *
     * @param size
     * @return
     */
    public static String getFormatSize(double size) {
        double kiloByte = size / 1024;
        if (kiloByte < 1) {
            return size + "Byte";
        }

        double megaByte = kiloByte / 1024;
        if (megaByte < 1) {
            BigDecimal result1 = new BigDecimal(Double.toString(kiloByte));
            return result1.setScale(2, BigDecimal.ROUND_HALF_UP)
                    .toPlainString() + "KB";
        }

        double gigaByte = megaByte / 1024;
        if (gigaByte < 1) {
            BigDecimal result2 = new BigDecimal(Double.toString(megaByte));
            return result2.setScale(2, BigDecimal.ROUND_HALF_UP)
                    .toPlainString() + "MB";
        }

        double teraBytes = gigaByte / 1024;
        if (teraBytes < 1) {
            BigDecimal result3 = new BigDecimal(Double.toString(gigaByte));
            return result3.setScale(2, BigDecimal.ROUND_HALF_UP)
                    .toPlainString() + "GB";
        }
        BigDecimal result4 = new BigDecimal(teraBytes);
        return result4.setScale(2, BigDecimal.ROUND_HALF_UP).toPlainString()
                + "TB";
    }

    public static String getCacheSize(File file) throws Exception {
        return getFormatSize(getFolderSize(file));
    }

}

/**
 * Created by jane on 2017/12/20.
 *
 * LruCache  LinkedHashMap
 * lru演算法 最近最少使用演算法
 */

public class LruCacheUtils {
    //申明記憶體快取
    private LruCache<String,Bitmap> mLruCache;


    //在構造方法中進行初使化
    public LruCacheUtils(Context context) {
        //得到當前應用程式的記憶體
        int maxMemory=(int)Runtime.getRuntime().maxMemory();
        //記憶體快取為當前應用程式的8分之1
        int cacheMemory=maxMemory/8;

        //進行初使化-指定快取空間的大小
        mLruCache=new LruCache<String, Bitmap>(cacheMemory){
            @Override
            protected int sizeOf(String key, Bitmap value) {
                return value.getByteCount();//自定義bitmap資料大小的計算方式
            }
        };
    }

    /**
     * 儲存圖片到記憶體快取
     * @param key 圖片的url
     * @param bitmap 圖片
     */
    public void savePicToMemory(String key,Bitmap bitmap){
        try {
            mLruCache.put(key,bitmap);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 通過key值得到快取的圖片
     * @param key 圖片的url地址
     * @return Bitmap 或 null
     */
    public  Bitmap getPicFromMemory(String key){

        Bitmap bitmap=null;
        try {
            //通過key獲取圖片
            bitmap= mLruCache.get(key);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return bitmap;
    }

    /**
     * 清除快取
     * evict:驅逐 逐出
     */
    public void clearCache() {
        if (mLruCache != null) {
            if (mLruCache.size() > 0) {
                Log.d("CacheUtils",
                        "mMemoryCache.size() " + mLruCache.size());
                mLruCache.evictAll();

                Log.d("CacheUtils", "mMemoryCache.size()" + mLruCache.size());
            }
            mLruCache = null;
        }
    }

}

//呼叫工具類-初使化
        LruCacheUtils lruCacheUtils = new LruCacheUtils(getActivity());

        btnAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //首先判斷記憶體中圖片有沒有快取
                Bitmap bitmap=lruCacheUtils.getPicFromMemory(picurl);

                if(bitmap!=null){
                    Toast.makeText(getActivity(),"從記憶體快取中獲取！",Toast.LENGTH_SHORT).show();
                    imageView.setImageBitmap(bitmap);
                }else {
                    //從網路獲取
                    new MyPicTask().execute(picurl);
                }
            }

        });

  class MyPicTask extends AsyncTask<String,Void,Bitmap> {

        @Override
        protected Bitmap doInBackground(String... strings) {

            try {
                //使用HttpUrlConnection
                URL url=new URL(strings[0]);
                HttpURLConnection connection=(HttpURLConnection) url.openConnection();
                connection.setRequestMethod("GET");
                connection.setReadTimeout(5000);
                connection.setConnectTimeout(5000);

                if(connection.getResponseCode()==200){
                    InputStream inputStream=connection.getInputStream();
                    return BitmapFactory.decodeStream(inputStream);
                }

            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(Bitmap bitmap) {
            super.onPostExecute(bitmap);
            //顯示圖片
            imageView.setImageBitmap(bitmap);
            //儲存在記憶體快取中
            lruCacheUtils.savePicToMemory(picurl,bitmap);
        }
    }

  try {
            //獲取本應用的快取大小
           String cacheSize= DataClearManager.getTotalCacheSize(getActivity());
           textView.setText(cacheSize);


        } catch (Exception e) {
            e.printStackTrace();
        }

        btnClear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //清空快取
                DataClearManager.cleanApplicationData(getActivity());
            }
        });