android文件缓存管理

缓存类  :

public class ConfigCache {

    private static final String TAG = ConfigCache.class.getName();

    public static final int CONFIG_CACHE_MOBILE_TIMEOUT  = 3600000;  //1 hour
    public static final int CONFIG_CACHE_WIFI_TIMEOUT    = 300000;   //5 minute

    public static String getUrlCache(String url) {
        if (url == null) {
            return null;

        }
        String result = null;
        File file = new File(AppApplication.mSdcardDataDir + "/" + getCacheDecodeString(url));
        if (file.exists() && file.isFile()) {
            long expiredTime = System.currentTimeMillis() - file.lastModified();

            Log.d(TAG, file.getAbsolutePath() + " expiredTime:" + expiredTime/60000 + "min");

            //1. in case the system time is incorrect (the time is turn back long ago)

            //2. when the network is invalid, you can only read the cache

            if (AppApplication.mNetWorkState != NetworkUtils.NETWORN_NONE && expiredTime < 0) {

                return null;

            }
            if(AppApplication.mNetWorkState == NetworkUtils.NETWORN_WIFI

                   && expiredTime > CONFIG_CACHE_WIFI_TIMEOUT) {

                return null;

            } else if (AppApplication.mNetWorkState == NetworkUtils.NETWORN_MOBILE

                   && expiredTime > CONFIG_CACHE_MOBILE_TIMEOUT) {
                return null;
            }
            try {

                result = FileUtils.readTextFile(file);

            } catch (IOException e) {

                e.printStackTrace();
            }

        }

        return result;
    }

    public static void setUrlCache(String data, String url) {

        File file = new File(AppApplication.mSdcardDataDir + "/" + getCacheDecodeString(url));

        try {

            //创建缓存数据到磁盘，就是创建文件

            FileUtils.writeTextFile(file, data);

        } catch (IOException e) {

            Log.d(TAG, "write " + file.getAbsolutePath() + " data failed!");

            e.printStackTrace();

        }

    }
    public static String getCacheDecodeString(String url) {

        //1. 处理特殊字符

        //2. 去除后缀名带来的文件浏览器的视图凌乱(特别是图片更需要如此类似处理，否则有的手机打开图库，全是我们的缓存图片)

        if (url != null) {

            return url.replaceAll("[.:/,%?&=]", "+").replaceAll("[+]+", "+");

        }

        return null;

    }
}

用法  :

void getConfig(){

        //首先尝试读取缓存

        String cacheConfigString = ConfigCache.getUrlCache(CONFIG_URL);

        //根据结果判定是读取缓存，还是重新读取

        if (cacheConfigString != null) {

       //     showConfig(cacheConfigString);   //后面可以是UI更新，仅供参考

        } else {

            //如果缓存结果是空，说明需要重新加载

            //缓存为空的原因可能是1.无缓存;2. 缓存过期;3.读取缓存出错

            AsyncHttpClient client = new AsyncHttpClient();

            client.get(CONFIG_URL, new AsyncHttpResponseHandler(){

                @Override

                public void onSuccess(String result){

                    //成功下载，则保存到本地作为后面缓存文件

                    ConfigCache.setUrlCache(result,  CONFIG_URL);

                    //后面可以是UI更新，仅供参考
              //      showConfig(result);

                }
                @Override

                public void onFailure(Throwable arg0) {

                    //根据失败原因，考虑是显示加载失败，还是再读取缓存
                }

            });
        }
}

相关的工具类 :

/**
* 文件处理工具类
*
* @author naibo-liao
* @时间： 2013-1-4下午03:13:08
*/
public class FileUtils {  

    public static final long B = 1;
    public static final long KB = B * 1024;
    public static final long MB = KB * 1024;
    public static final long GB = MB * 1024;
    private static final int BUFFER = 8192;
    /**
     * 格式化文件大小<b> 带有单位
     *
     * @param size
     * @return
     */
    public static String formatFileSize(long size) {
        StringBuilder sb = new StringBuilder();
        String u = null;
        double tmpSize = 0;
        if (size < KB) {
            sb.append(size).append("B");
            return sb.toString();
        } else if (size < MB) {
            tmpSize = getSize(size, KB);
            u = "KB";
        } else if (size < GB) {
            tmpSize = getSize(size, MB);
            u = "MB";
        } else {
            tmpSize = getSize(size, GB);
            u = "GB";
        }
        return sb.append(twodot(tmpSize)).append(u).toString();
    }  

    /**
     * 保留两位小数
     *
     * @param d
     * @return
     */
    public static String twodot(double d) {
        return String.format("%.2f", d);
    }  

    public static double getSize(long size, long u) {
        return (double) size / (double) u;
    }  

    /**
     * sd卡挂载且可用
     *
     * @return
     */
    public static boolean isSdCardMounted() {
        return android.os.Environment.getExternalStorageState().equals(
                android.os.Environment.MEDIA_MOUNTED);
    }  

    /**
     * 递归创建文件目录
     *
     * @param path
     * */
    public static void CreateDir(String path) {
        if (!isSdCardMounted())
            return;
        File file = new File(path);
        if (!file.exists()) {
            try {
                file.mkdirs();
            } catch (Exception e) {
                Log.e("hulutan", "error on creat dirs:" + e.getStackTrace());
            }
        }
    }  

    /**
     * 读取文件
     *
     * @param file
     * @return
     * @throws IOException
     */
    public static String readTextFile(File file) throws IOException {
        String text = null;
        InputStream is = null;
        try {
            is = new FileInputStream(file);
            text = readTextInputStream(is);;
        } finally {
            if (is != null) {
                is.close();
            }
        }
        return text;
    }  

    /**
     * 从流中读取文件
     *
     * @param is
     * @return
     * @throws IOException
     */
    public static String readTextInputStream(InputStream is) throws IOException {
        StringBuffer strbuffer = new StringBuffer();
        String line;
        BufferedReader reader = null;
        try {
            reader = new BufferedReader(new InputStreamReader(is));
            while ((line = reader.readLine()) != null) {
                strbuffer.append(line).append("\r\n");
            }
        } finally {
            if (reader != null) {
                reader.close();
            }
        }
        return strbuffer.toString();
    }  

    /**
     * 将文本内容写入文件
     *
     * @param file
     * @param str
     * @throws IOException
     */
    public static void writeTextFile(File file, String str) throws IOException {
        DataOutputStream out = null;
        try {
            out = new DataOutputStream(new FileOutputStream(file));
            out.write(str.getBytes());
        } finally {
            if (out != null) {
                out.close();
            }
        }
    }  

    /**
     * 将Bitmap保存本地JPG图片
     * @param url
     * @return
     * @throws IOException
     */
    public static String saveBitmap2File(String url) throws IOException {  

        BufferedInputStream inBuff = null;
        BufferedOutputStream outBuff = null;  

        SimpleDateFormat sf = new SimpleDateFormat("yyyy_MM_dd_HH_mm_ss");
        String timeStamp = sf.format(new Date());
        File targetFile = new File(Constants.ENVIROMENT_DIR_SAVE, timeStamp
                + ".jpg");
        File oldfile = ImageLoader.getInstance().getDiscCache().get(url);
        try {  

            inBuff = new BufferedInputStream(new FileInputStream(oldfile));
            outBuff = new BufferedOutputStream(new FileOutputStream(targetFile));
            byte[] buffer = new byte[BUFFER];
            int length;
            while ((length = inBuff.read(buffer)) != -1) {
                outBuff.write(buffer, 0, length);
            }
            outBuff.flush();
            return targetFile.getPath();
        } catch (Exception e) {  

        } finally {
            if (inBuff != null) {
                inBuff.close();
            }
            if (outBuff != null) {
                outBuff.close();
            }
        }
        return targetFile.getPath();
    }  

    /**
     * 读取表情配置文件
     *
     * @param context
     * @return
     */
    public static List<String> getEmojiFile(Context context) {
        try {
            List<String> list = new ArrayList<String>();
            InputStream in = context.getResources().getAssets().open("emoji");// 文件名字为rose.txt
            BufferedReader br = new BufferedReader(new InputStreamReader(in,
                    "UTF-8"));
            String str = null;
            while ((str = br.readLine()) != null) {
                list.add(str);
            }  

            return list;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }  

    /**
     * 获取一个文件夹大小
     *
     * @param f
     * @return
     * @throws Exception
     */
    public static long getFileSize(File f) {
        long size = 0;
        File flist[] = f.listFiles();
        for (int i = 0; i < flist.length; i++) {
            if (flist.isDirectory()) {
                size = size + getFileSize(flist);
            } else {
                size = size + flist.length();
            }
        }
        return size;
    }  

    /**
     * 删除文件
     *
     * @param file
     */
    public static void deleteFile(File file) {  

        if (file.exists()) { // 判断文件是否存在
            if (file.isFile()) { // 判断是否是文件
                file.delete(); // delete()方法 你应该知道 是删除的意思;
            } else if (file.isDirectory()) { // 否则如果它是一个目录
                File files[] = file.listFiles(); // 声明目录下所有的文件 files[];
                for (int i = 0; i < files.length; i++) { // 遍历目录下所有的文件
                    deleteFile(files); // 把每个文件 用这个方法进行迭代
                }
            }
            file.delete();
        }
    }
}