DiskLrucCache使用Demo(强烈推荐，很好用)

来源：互联网发布：旅游教学软件编辑：程序博客网时间：2024/06/10 07:28

DiskLrucCache使用的Demo，这个demo是从网络获取一张图片，保存到本地缓存中(sdcard和内存)，当下载成功后，再打开不会重新向网络请求图片，而是世界使用本地资源。

要使用DiskLrucCache需要先下载此类. 下载地址点这里

主类：

/** * DiskLrucCache使用Demo *  * @author pangzf * @date 2014年8月12日 下午2:13:26 */public class DemoActivity extends Activity {    private DiskLruCache mDiskLrucache;    private ImageView mIvShow;    private String mBitMapUrl;    private String mKey;    private ProgressDialog mPd;    private Handler mHandler = new Handler() {        @Override        public void dispatchMessage(Message msg) {            super.dispatchMessage(msg);            // 10.下载图片之后展示            boolean isSuccess = (boolean) msg.obj;            if (isSuccess) {                Snapshot snapshot;                try {                    snapshot = mDiskLrucache.get(mKey);                    InputStream is = snapshot.getInputStream(0);                    mIvShow.setImageBitmap(BitmapFactory.decodeStream(is));                } catch (IOException e) {                    e.printStackTrace();                }            }            if (mPd != null && mPd.isShowing()) {                mPd.dismiss();            }        }    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_demo);        mIvShow = (ImageView) findViewById(R.id.iv_show);        mPd = new ProgressDialog(DemoActivity.this);        try {            // 1.存放缓存的目录            File directory = DiskLrucacheUtils.getDiskCache(DemoActivity.this,                    "bitmap");            // 2.版本号            int appVersion = DiskLrucacheUtils.getAppVersion(DemoActivity.this);            int valueCount = 1;            // 3.缓存的最大值，这里设置10m            long maxSize = 10 * 1024 * 1024;            // 4.打开disklrucache            mDiskLrucache = DiskLruCache.open(directory, appVersion,                    valueCount, maxSize);            mBitMapUrl = "https://raw.githubusercontent.com/pangzaifei/LineChartView/master/LineChartView/effice_picture/a.jpg";            if (mDiskLrucache != null) {                // 5.如果在缓存中存在就用缓存中的bitmap，如果不存在上网上下载                mKey = DiskLrucacheUtils.getKey(mBitMapUrl);                Snapshot snapshot = mDiskLrucache.get(mKey);                if (snapshot != null) {                    InputStream is = snapshot.getInputStream(0);                    Bitmap bitmap = BitmapFactory.decodeStream(is);                    if (bitmap != null) {                        mIvShow.setImageBitmap(bitmap);                    }                } else {                    mPd.show();                    new Thread() {                        public void run() {                            // 6.下载图片                            mPd.setMessage("正在加载数据....");                            userDiskLrucache();                        };                    }.start();                }            }        } catch (Exception e) {            e.printStackTrace();        }    }    private void userDiskLrucache() {        try {            String bitMapUrl = "https://raw.githubusercontent.com/pangzaifei/LineChartView/master/LineChartView/effice_picture/a.jpg";            String key = DiskLrucacheUtils.getKey(bitMapUrl);            Editor edit = mDiskLrucache.edit(key);            // 7.从服务器下载图片            boolean isSuccess = DiskLrucacheUtils.downloadBitmap(bitMapUrl,                    edit.newOutputStream(0));            if (isSuccess) {                // 8.提交到缓存                edit.commit();                // 9.下载成功去展示图片                Message msg = mHandler.obtainMessage();                msg.obj = true;                mHandler.sendMessage(msg);            } else {                edit.abort();            }        } catch (Exception e) {            e.printStackTrace();        }    }    @Override    protected void onPause() {        try {            if (mDiskLrucache != null) {                mDiskLrucache.flush();            }        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        super.onPause();    }    @Override    protected void onDestroy() {        try {            if (mDiskLrucache != null) {                mDiskLrucache.close();            }        } catch (IOException e) {            e.printStackTrace();        }        super.onDestroy();    }}

使用DiskLrucache自己写的工具类.

package com.pangzaifei.disklrucachedemo.libcore;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.File;import java.io.IOException;import java.io.OutputStream;import java.net.HttpURLConnection;import java.net.URL;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import android.content.Context;import android.content.pm.PackageInfo;import android.content.pm.PackageManager.NameNotFoundException;import android.os.Environment;/** * diskLrucache的工具类 *  * @author pangzf * @date 2014年8月12日 上午10:58:50 */public class DiskLrucacheUtils {    /**     * 获得缓存目录，当sdcard存在的时候使用，sdcard图片缓存，如果sdcard不存在使用data/data下的图片缓存     *      * @param context     * @param uniqueName     * @return     */    public static File getDiskCache(Context context, String uniqueName) {        String path;        if (Environment.getExternalStorageDirectory().equals(                Environment.MEDIA_MOUNTED)) {            // 存在sdcard            path = Environment.getExternalStorageDirectory().getPath();        } else {            // 不存在sdcard使用手机内存            path = context.getCacheDir().getPath();        }        return new File(path + File.separator + uniqueName);    }    /**     * 获得app版本号     *      * @param context     * @return     * @throws NameNotFoundException     */    public static int getAppVersion(Context context)            throws NameNotFoundException {        PackageInfo packageInfo = context.getPackageManager().getPackageInfo(                context.getPackageName(), 0);        return packageInfo.versionCode;    }    /**     * 将图片url进行md5加密生成一个字符串，因为有的url地址里面存在特殊字符     *      * @param urlStr     * @return     * @throws NoSuchAlgorithmException     */    public static String getKey(String urlStr) throws NoSuchAlgorithmException {        MessageDigest messageDigest = MessageDigest.getInstance("md5");        messageDigest.update(urlStr.getBytes());        return bytesToString(messageDigest.digest());    }    /**     * byte转string     *      * @param bytes     */    private static String bytesToString(byte[] bytes) {        StringBuilder sb = new StringBuilder();        for (int i = 0; i < bytes.length; i++) {            String hex = Integer.toHexString(0xFF & bytes[i]);            if (hex.length() == 1) {                sb.append(0);            }            sb.append(hex);        }        return sb.toString();    }    /**     * 下载图片到cache     *      * @param imageString     * @param ops     * @return     */    public static boolean downloadBitmap(String imageString, OutputStream ops) {        URL url;        HttpURLConnection conn = null;        BufferedInputStream bis = null;        BufferedOutputStream bos = null;        try {            url = new URL(imageString);            conn = (HttpURLConnection) url.openConnection();            bis = new BufferedInputStream(conn.getInputStream());            bos = new BufferedOutputStream(ops);            int b;            while ((b = bis.read()) != -1) {                bos.write(b);            }            return true;        } catch (IOException e) {            e.printStackTrace();        } finally {            try {                if (conn != null) {                    conn.disconnect();                }                if (bos != null) {                    bos.close();                }                if (bis != null) {                    bis.close();                }            } catch (IOException e) {                e.printStackTrace();            }        }        return false;    }}

源码下载地址

感谢guolin的博客对我的帮助。

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