【安卓笔记】硬盘缓存工具类的编写

package com.jakewharton.disklrucache;import java.io.BufferedInputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import android.content.Context;import android.content.pm.PackageManager;import android.content.pm.PackageManager.NameNotFoundException;import android.graphics.Bitmap;import android.graphics.Bitmap.CompressFormat;import android.graphics.BitmapFactory;import android.os.Environment;import android.text.TextUtils;/** * @author Rowandjj * *DiskLruCache的辅助工具类(DiskLruCache:) * 提供创建/读取/写入缓存的方法,并支持异步缓存写入. */public class DiskLruCacheHelper{private static final long DEFAULT_MAX_SIZE = 10*1024*1024;private static ExecutorService service = null;/** * * 创建DiskLruCache实例,默认版本号为当前应用版本号，缓存位置由getDiskCacheDir指定 * @param context 上下文 * @param cacheDirName 缓存文件夹名称 * @param maxSize 缓存最大值,单位是byte * @return 创建成功返回DiskLruCache实例否则返回null */public static DiskLruCache createCache(Context context,String cacheDirName,long maxSize){DiskLruCache cache = null;try{cache = DiskLruCache.open(getDiskCacheDir(cacheDirName, context), getAppVersion(context),1, maxSize);} catch (IOException e){e.printStackTrace();}return cache;}/** * 返回一个具有默认大小的DiskLruCache实例,默认大小为10Mb * @param context * @param cacheDirName * @return 创建成功返回DiskLruCache实例否则返回null */public static DiskLruCache createCache(Context context,String cacheDirName){return createCache(context, cacheDirName, DEFAULT_MAX_SIZE);}/** * 将图片写入缓存 */public static boolean writeBitmapToCache(DiskLruCache cache,Bitmap bitmap,String url){return writeBitmapToCache(cache, bitmap, url, CompressFormat.JPEG,100);}/** * 异步地将图片写入缓存。将不会不会写入结果。 * @param cache * @param bitmap * @param url */public static void asyncWriteBitmapToCache(final DiskLruCache cache,final Bitmap bitmap,final String url){if(service == null)service = Executors.newSingleThreadExecutor();service.execute(new Runnable(){@Overridepublic void run(){writeBitmapToCache(cache, bitmap, url);}});}/** * 将图片写入缓存 * @param cache 缓存对象 * @param bitmap 图片对象 * @param url 用于标识bitmap的唯一名称，通常为图片url * @return true表示写入缓存成功否则为false */public static boolean writeBitmapToCache(DiskLruCache cache,Bitmap bitmap,String url,CompressFormat format, int quality){if(cache == null || bitmap == null || url == null || TextUtils.isEmpty(url))return false;try{DiskLruCache.Editor editor = cache.edit(generateKey(url));if(editor != null){OutputStream out = editor.newOutputStream(0);if(bitmap.compress(format,quality, out)){editor.commit();return true;}else{editor.abort();}}} catch (IOException e){e.printStackTrace();}return false;}/** * 异步地将图片写入缓存。将不会不会写入结果。 */public static void asyncWriteBitmapToCache(final DiskLruCache cache,final Bitmap bitmap,final String url,final CompressFormat format, final int quality){if(service == null)service = Executors.newSingleThreadExecutor();service.execute(new Runnable(){@Overridepublic void run(){writeBitmapToCache(cache, bitmap, url,format,quality);}});}/** * 异步地将inputStram流写入缓存，将不会返回写入结果。 */public static void asyncWriteStreamToCache(final DiskLruCache cache,final InputStream in,final String url){if(service == null)service = Executors.newSingleThreadExecutor();service.execute(new Runnable(){@Overridepublic void run(){asyncWriteStreamToCache(cache, in, url);}});}/** * 将inputStram流写入缓存 * @param cache * @param in * @param url * @return */public static boolean writeStreamToCache(DiskLruCache cache,InputStream in,String url){if(cache == null || in == null || url == null|| TextUtils.isEmpty(url))return false;DiskLruCache.Editor editor = null;try{editor = cache.edit(generateKey(url));if(editor != null){OutputStream out = editor.newOutputStream(0);BufferedInputStream bin = new BufferedInputStream(in);byte[] buffer = new byte[1024];int len = 0;while((len = bin.read(buffer)) != -1){out.write(buffer, 0, len);out.flush();}editor.commit();return true;}} catch (IOException e){e.printStackTrace();}return false;}/** * 异步地将文件写入缓存，将不会返回写入结果。 */public static void asyncWriteFileToCache(final DiskLruCache cache,final File file,final String url){if(service == null)service = Executors.newSingleThreadExecutor();service.execute(new Runnable(){@Overridepublic void run(){writeFileToCache(cache, file, url);}});}/** * 将文件写入缓存 * @return true表示写入成功否则写入失败 */public static boolean writeFileToCache(DiskLruCache cache,File file,String url){if(cache == null || file == null || url == null || !file.exists() || TextUtils.isEmpty(url)){return false;}FileInputStream fin = null;try{fin = new FileInputStream(file);} catch (FileNotFoundException e){e.printStackTrace();}return writeStreamToCache(cache, fin, url);}/** * 异步地将字符串写入缓存,将不会返回写入结果 */public static void asyncWriteStringToCache(final DiskLruCache cache,final String str,final String url){if(service == null)service = Executors.newSingleThreadExecutor();service.execute(new Runnable(){@Overridepublic void run(){writeStringToCache(cache, str, url);}});}/** * 将字符串写入缓存 * @param cache * @param str * @param url * @return */public static boolean writeStringToCache(DiskLruCache cache,String str,String url){if(cache == null || str == null || url == null || TextUtils.isEmpty(url) || TextUtils.isEmpty(str)){return false;}DiskLruCache.Editor editor = null;try{editor = cache.edit(generateKey(url));if(editor != null){OutputStream out = editor.newOutputStream(0);out.write(str.getBytes());out.flush();}editor.commit();return true;} catch (IOException e){e.printStackTrace();}return false;}/** * 停止内部正在写缓存的线程， * 这将导致部分写缓存任务不能进行。 */public static void stop(){if(service != null)service.shutdownNow();}/** * * 根据url获取缓存，并将结果以String形式返回 * @param cache * @param url * @return 成功则返回String否则返回null */public static String readCacheToString(DiskLruCache cache,String url){if(cache == null || url == null || TextUtils.isEmpty(url))return null;String key = generateKey(url);DiskLruCache.Snapshot snapshot = null;try{snapshot = cache.get(key);if(snapshot != null){InputStream in = snapshot.getInputStream(0);StringBuilder builder = new StringBuilder(1024*2);int len = 0;byte[] buffer = new byte[1024];while((len = in.read(buffer)) != -1){builder.append(new String(buffer,0,len));}return builder.toString();}} catch (Exception e){e.printStackTrace();}return null;}/** * 根据url获取缓存，并将缓存以InputStream形式返回 * * @param cache DiskLruCache实例 * @param url 缓存名 * @return 命中则返回InputStream流否则返回null */public static InputStream readCacheToInputStream(DiskLruCache cache,String url){if(cache == null || url == null || TextUtils.isEmpty(url))return null;String key = generateKey(url);DiskLruCache.Snapshot snapshot = null;try{snapshot = cache.get(key);} catch (IOException e){e.printStackTrace();}if(snapshot != null)return snapshot.getInputStream(0);return null;}/** * 根据url获取缓存，并将缓存以Bitmap形式返回 * @param cache * @param url * @return 成功返回bitmap，否则返回null */public static Bitmap readCacheToBitmap(DiskLruCache cache,String url){InputStream in = readCacheToInputStream(cache, url);if(in != null)return BitmapFactory.decodeStream(in);return null;}/** * 获取缓存文件路径(优先选择sd卡) * @param cacheDirName 缓存文件夹名称 * @param context 上下文 * @return */public static File getDiskCacheDir(String cacheDirName,Context context){String cacheDir;if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)&&!Environment.isExternalStorageRemovable()){cacheDir = getExternalCacheDir(context);if(cacheDir == null)//部分机型返回了nullcacheDir = getInternalCacheDir(context);}else{cacheDir = getInternalCacheDir(context);}File dir = new File(cacheDir,cacheDirName);if(!dir.exists())dir.mkdirs();return dir;}/** * 获取当前app版本号 * @param context 上下文 * @return 当前app版本号 */public static int getAppVersion(Context context){PackageManager manager = context.getPackageManager();int code = 1;try{code = manager.getPackageInfo(context.getPackageName(),0).versionCode;} catch (NameNotFoundException e){e.printStackTrace();}return code;}/** * 根据指定的url移除指定缓存 * Note:请不要是使用DiskLruCache.remove() * * @param cache * @param url * @return */public static boolean remove(DiskLruCache cache,String url){if(cache == null || url == null || TextUtils.isEmpty(url)){return false;}try{return cache.remove(generateKey(url));} catch (IOException e){e.printStackTrace();}return false;}/** * 根据原始键生成新键，以保证键的名称的合法性 * @param key 原始键，通常是url * @return */public static String generateKey(String key){String cacheKey;try{MessageDigest digest = MessageDigest.getInstance("md5");digest.update(key.getBytes());cacheKey = bytesToHexString(digest.digest());} catch (NoSuchAlgorithmException e){e.printStackTrace();cacheKey = String.valueOf(key.hashCode());}return cacheKey;}private static String bytesToHexString(byte[] bytes){StringBuilder builder = new StringBuilder();for(int i = 0; i < bytes.length; i++){String hex = Integer.toHexString(0xff&bytes[i]);if(hex.length() == 1)builder.append('0');builder.append(hex);}return builder.toString();}private static String getExternalCacheDir(Context context){File dir = context.getExternalCacheDir();if(dir == null)return null;if(!dir.exists())dir.mkdirs();return dir.getPath();}private static String getInternalCacheDir(Context context){File dir = context.getCacheDir();if(!dir.exists())dir.mkdirs();return dir.getPath();}}

代码比较简单，而且都有注释，我就不过多解释了。

以后在开发中，，如果需要构建DiskLruCache，调用DiskLruCacheHelper.createCache，取缓存调用

github地址:https://github.com/Rowandjj/DiskLruCacheHelper

快乐不是因为得到的多而是因为计较的少！