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news 2025/8/17 23:03:26

建筑网站、,如何进行网络营销,wordpress <>,专业做网站平台上一张图爽一下先，哈哈上主题三级缓存，关于数据缓存问题经常用到，尤其是加载网络图片仅仅是线程池网络框架有时候并不能满足我们的需求，这时候我们考虑三级缓存，即从磁盘中读写数据， 访问网络图片的框架有…

上一张图爽一下先，哈哈

上主题三级缓存，关于数据缓存问题经常用到，尤其是加载网络图片仅仅是线程池+网络框架有时候并不能满足我们的需求，这时候我们考虑三级缓存，即从磁盘中读写数据，访问网络图片的框架有很多，个人喜好觉得volley非常的好用可能是自己在这个上面研究过一段时间吧，

废话不多说了直接上demo，明天签到项目中吧，

先

DiskLruCache不了解的先查一下

/**
* 图片缓存管理类获取ImageLoader对象
*/
public class ImageCacheManager {

public static String TAG = ImageCacheManager.class.getSimpleName();

// 获取图片缓存类对象
public static ImageCache mImageCache = new ImageCacheUtil();
// 获取ImageLoader对象
public static ImageLoader mImageLoader = new ImageLoader(VolleyRequestQueueManager.mRequestQueue, mImageCache);

/**
* 获取ImageListener
*
* @param view
* @param defaultImage
* @param errorImage
* @return
*/
public static ImageListener getImageListener(final ImageView view, final Bitmap defaultImage, final Bitmap errorImage) {

return new ImageListener() {

@Override
public void onErrorResponse(VolleyError error) {
// 回调失败
if (errorImage != null) {
view.setImageBitmap(errorImage);
}
}

@Override
public void onResponse(ImageContainer response, boolean isImmediate) {
// 回调成功
if (response.getBitmap() != null) {
view.setImageBitmap(response.getBitmap());
} else if (defaultImage != null) {
view.setImageBitmap(defaultImage);
}
}
};

}

/**
* 提供给外部调用方法
*
* @param url
* @param view
* @param defaultImage
* @param errorImage
*/
public static void loadImage(String url, ImageView view, Bitmap defaultImage, Bitmap errorImage) {
mImageLoader.get(url, ImageCacheManager.getImageListener(view, defaultImage, errorImage), 0, 0);
}

/**
* 提供给外部调用方法
*
* @param url
* @param view
* @param defaultImage
* @param errorImage
*/
public static void loadImage(String url, ImageView view, Bitmap defaultImage, Bitmap errorImage, int maxWidth, int maxHeight) {
mImageLoader.get(url, ImageCacheManager.getImageListener(view, defaultImage, errorImage), maxWidth, maxHeight);
}
}

----------------------------------------------

package com.example.mydemo;

import java.io.File;
import java.io.IOException;
import java.io.OutputStream;

import libcore.io.DiskLruCache;
import libcore.io.DiskLruCache.Snapshot;
import android.content.Context;
import android.content.pm.PackageInfo;
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.support.v4.util.LruCache;
import android.util.Log;

import com.android.volley.toolbox.ImageLoader.ImageCache;
import com.example.mydemo.utils.MD5Utils;

/**
* 图片缓存帮助类
* 包含内存缓存LruCache和磁盘缓存DiskLruCache
* 即二级缓存
*/
public class ImageCacheUtil implements ImageCache {

public String TAG=ImageCacheUtil.this.getClass().getSimpleName();

//缓存类
public static LruCache<String, Bitmap> mLruCache;
public static DiskLruCache mDiskLruCache;

//磁盘缓存大小
public static final int DISKMAXSIZE = 10 * 1024 * 1024;

public ImageCacheUtil() {
// 获取应用可占内存的1/8作为缓存
int maxSize = (int) (Runtime.getRuntime().maxMemory() / 8);
// 实例化LruCaceh对象
mLruCache = new LruCache<String, Bitmap>(maxSize) {
@Override
protected int sizeOf(String key, Bitmap bitmap) {
return bitmap.getRowBytes() * bitmap.getHeight();
}
};
try {
// 获取DiskLruCahce对象
mDiskLruCache = DiskLruCache.open(getDiskCacheDir(MyApplication.newInstance(), "Rabbit"), getAppVersion(MyApplication.newInstance()), 1, DISKMAXSIZE);
} catch (IOException e) {
e.printStackTrace();
}
}

/**
* 从缓存（内存缓存，磁盘缓存）中获取Bitmap
*/
@Override
public Bitmap getBitmap(String url) {
if (mLruCache.get(url) != null) {
// 从LruCache缓存中取
Log.i(TAG,"从LruCahce获取");
return mLruCache.get(url);
} else {
String key = MD5Utils.md5(url);
try {
if (mDiskLruCache.get(key) != null) {
// 从DiskLruCahce取
Snapshot snapshot = mDiskLruCache.get(key);
Bitmap bitmap = null;
if (snapshot != null) {
bitmap = BitmapFactory.decodeStream(snapshot.getInputStream(0));
// 存入LruCache缓存
mLruCache.put(url, bitmap);
Log.i(TAG,"从DiskLruCahce获取");
}
return bitmap;
}
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}

/**
* 存入缓存（内存缓存，磁盘缓存）
*/
@Override
public void putBitmap(String url, Bitmap bitmap) {
// 存入LruCache缓存
mLruCache.put(url, bitmap);
// 判断是否存在DiskLruCache缓存，若没有存入
String key = MD5Utils.md5(url);
try {
if (mDiskLruCache.get(key) == null) {
DiskLruCache.Editor editor = mDiskLruCache.edit(key);
if (editor != null) {
OutputStream outputStream = editor.newOutputStream(0);
if (bitmap.compress(CompressFormat.JPEG, 100, outputStream)) {
editor.commit();
} else {
editor.abort();
}
}
mDiskLruCache.flush();
}
} catch (IOException e) {
e.printStackTrace();
}

}

/**
* 该方法会判断当前sd卡是否存在，然后选择缓存地址
*
* @param context
* @param uniqueName
* @return
*/
public static File getDiskCacheDir(Context context, String uniqueName) {
String cachePath=null;
if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState()) || !Environment.isExternalStorageRemovable()) {

cachePath = context.getExternalCacheDir().getPath();
} else {
cachePath = context.getCacheDir().getPath();
}
return new File(cachePath + File.separator + uniqueName);
}

/**
* 获取应用版本号
*
* @param context
* @return
*/
public int getAppVersion(Context context) {
try {
PackageInfo info = context.getPackageManager().getPackageInfo(context.getPackageName(), 0);
return info.versionCode;
} catch (NameNotFoundException e) {
e.printStackTrace();
}
return 1;
}

}

--------------------------------------------------------------

import android.app.Activity;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;

public class MainActivity extends Activity implements OnClickListener {

private ImageView image;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

image = (ImageView) findViewById(R.id.image);
image.setOnClickListener(this);
}

String url = "http://img5.duitang.com/uploads/item/201404/13/20140413232106_tGXkT.jpeg";

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.image:

ImageCacheManager.loadImage(url, image,
getBitmapFromRes(R.drawable.ic_launcher),
getBitmapFromRes(R.drawable.ic_launcher));
break;

default:
break;
}
}

public Bitmap getBitmapFromRes(int resId) {
Resources res = this.getResources();
return BitmapFactory.decodeResource(res, resId);

}
}

-----------------------------------------------------------------

package com.example.mydemo;

import android.app.Application;

public class MyApplication extends Application {

public static String TAG;
private static MyApplication myApplication;
public static MyApplication newInstance(){
return myApplication;
}

@Override
public void onCreate() {
// TODO Auto-generated method stub
super.onCreate();

TAG=this.getClass().getSimpleName();
myApplication = this;
}

------------------------------------------------------

package com.example.mydemo;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolbox.Volley;

public class VolleyRequestQueueManager {

// 获取请求队列类
public static RequestQueue mRequestQueue = Volley.newRequestQueue(MyApplication.newInstance());

//添加任务进任务队列
public static void addRequest(Request<?> request, Object tag) {
if (tag != null) {
request.setTag(tag);
}
mRequestQueue.add(request);
}

//取消任务
public static void cancelRequest(Object tag){
mRequestQueue.cancelAll(tag);
}

}

-----------------------------------------------------------

送个MD5工具类

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Utils {
/**
* 使用md5的算法进行加密
*/
public static String md5(String plainText) {
byte[] secretBytes = null;
try {
secretBytes = MessageDigest.getInstance("md5").digest(
plainText.getBytes());
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException("没有md5这个算法！");
}
String md5code = new BigInteger(1, secretBytes).toString(16);// 16进制数字
// 如果生成数字未满32位，需要前面补0
for (int i = 0; i < 32 - md5code.length(); i++) {
md5code = "0" + md5code;
}
return md5code;
}
}