三级缓存
本文章可以学到：
1、图片压缩
2、图片异步加载
3、内存缓存
4、本地缓存
5、网络缓存
6、MD5加密
代码下载：http://download.csdn.net/detail/runingling/9674550
MyBitmapUtils //工具集package com.example.liangshaoteng.mycache.Utils;
import android.graphics.Bitmap;
import android.util.Log;
import android.widget.ImageView;
import com.example.liangshaoteng.mycache.R;
/**
* Created by LiangShaoTeng on 2016/10/26.
*/
public class MyBitmapUtils {
private final MemoryCacheUtils memoryCacheUtils;
private final LocalCacheUtils localCacheUtils;
private final NetCacheUtils netCacheUtils;
private Bitmap bitmap;
public MyBitmapUtils() {
//内存
memoryCacheUtils = new MemoryCacheUtils();
//本地
localCacheUtils = new LocalCacheUtils();
//网络
netCacheUtils = new NetCacheUtils(memoryCacheUtils,localCacheUtils);
}
public void disPlay(ImageView imageView,String url){
imageView.setImageResource(R.mipmap.ic_launcher);
//内存缓存
bitmap = memoryCacheUtils.getImageBitmapMemory(url);
if(bitmap !=null){
imageView.setImageBitmap(bitmap);
System.out.println("从内存获取图片");
return;
}
//本地缓存
bitmap = localCacheUtils.getImageBitmapLocal(url);
if(bitmap !=null){
imageView.setImageBitmap(bitmap);
//从本地获取图片存入内存
memoryCacheUtils.setBitmapToMemory(url, bitmap);
System.out.println("从本地获取图片");
return;
}
//网络存储
netCacheUtils.getBitmapRequest(imageView,url);
}
}
MemoryCacheUtils //内存缓存package com.example.liangshaoteng.mycache.Utils;
import android.graphics.Bitmap;
import android.os.Environment;
import android.util.LruCache;
/**
* Created by LiangShaoTeng on 2016/10/26.
*/
public class MemoryCacheUtils {
private final LruCache mMemoryCache;
public MemoryCacheUtils() {
//获取手机允许最大内存的1/8，如果超过指定内存，就开始回收
long maxMemory = Runtime.getRuntime().maxMemory() / 8;
//需要传入允许的内存最大值,虚拟机默认内存16M,真机不一定相同
mMemoryCache = new LruCache((int) maxMemory) {
@Override
protected int sizeOf(String key, Bitmap value) {
//获取对象的大小
int byteCount = value.getByteCount();
return byteCount;
}
};
}
public Bitmap getImageBitmapMemory(String url) {
//通过url的key值查找图片
try {
String encode = MD5Encoder.encode(url);
Bitmap bitmap = mMemoryCache.get(encode);
return bitmap;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public void setBitmapToMemory(String url, Bitmap bitmap) {
try {
String encode = MD5Encoder.encode(url);
mMemoryCache.put(encode, bitmap);
} catch (Exception e) {
e.printStackTrace();
}
}
}
LocalCacheUtils //本地缓存package com.example.liangshaoteng.mycache.Utils;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Environment;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FilterInputStream;
/**
* Created by LiangShaoTeng on 2016/10/26.
*/
public class LocalCacheUtils {
private static final String CACHE_PATH=Environment.getExternalStorageDirectory().getAbsolutePath()+"/cache";
public Bitmap getImageBitmapLocal(String url) {
try {
String encode = MD5Encoder.encode(url);
File file=new File(CACHE_PATH,encode);
//decodeStream 解码输入流的位图
//FileInputStream 用于读取本地文件中的字节数据，继承自InputStream类
Bitmap bitmap= BitmapFactory.decodeStream(new FileInputStream(file));
return bitmap;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public void setBitmapToLocal(String url,Bitmap bitmap){
try {
String encode = MD5Encoder.encode(url);
File file=new File(CACHE_PATH,encode);
File parentFile = file.getParentFile();
if(!parentFile.exists()){
parentFile.mkdir();
}
//bitmap.compress(CompressFormat,quality,)
//CompressFormat 压缩格式
bitmap.compress(Bitmap.CompressFormat.JPEG,100,new FileOutputStream(file));
} catch (Exception e) {
e.printStackTrace();
}
}
}
NetCacheUtils //网络缓存package com.example.liangshaoteng.mycache.Utils;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Rect;
import android.os.AsyncTask;
import android.widget.ImageView;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
/**
* Created by LiangShaoTeng on 2016/10/26.
*/
public class NetCacheUtils {
MemoryCacheUtils memoryCacheUtils;
LocalCacheUtils localCacheUtils;
private HttpURLConnection urlConnection;
public NetCacheUtils(MemoryCacheUtils memoryCacheUtils, LocalCacheUtils localCacheUtils) {
this.localCacheUtils=localCacheUtils;
this.memoryCacheUtils=memoryCacheUtils;
}
public void getBitmapRequest(ImageView imageView, String url) {
new BitmapTask().execute(imageView,url);
}
class BitmapTask extends AsyncTask{
private ImageView imageView;
private String url;
@Override
protected Bitmap doInBackground(Object... objects) {
imageView = (ImageView) objects[0];
url = (String) objects[1];
return downLoadBitmap(url);
}
@Override
protected void onPostExecute(Bitmap bitmap) {
if(bitmap!=null){
imageView.setImageBitmap(bitmap);
System.out.println("从網絡获取图片");
//存入内存
memoryCacheUtils.setBitmapToMemory(url,bitmap);
//存入本地
localCacheUtils.setBitmapToLocal(url,bitmap);
}
super.onPostExecute(bitmap);
}
}
private Bitmap downLoadBitmap(String url) {
try {
urlConnection = (HttpURLConnection) new URL(url).openConnection();
urlConnection.setRequestMethod("GET");
if(urlConnection.getResponseCode()== HttpURLConnection.HTTP_OK){
BitmapFactory.Options bitmapFactory=new BitmapFactory.Options();
bitmapFactory.inSampleSize = 2;//宽高压缩为原来的1/2
bitmapFactory.inPreferredConfig= Bitmap.Config.ARGB_4444;
/*Rect rect=new Rect();
rect.contains(5,500,5,5);*/
Bitmap bimap=BitmapFactory.decodeStream(urlConnection.getInputStream(),null ,bitmapFactory);
return bimap;
}
} catch (IOException e) {
e.printStackTrace();
}finally {
urlConnection.disconnect();
}
return null;
}
}
MD5Encoder //MD5package com.example.liangshaoteng.mycache.Utils;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
/**
* Created by LiangShaoTeng on 2016/10/26.
*/
public class MD5Encoder {
public static String encode(String string) throws Exception {
byte[] hash = MessageDigest.getInstance("MD5").digest(string.getBytes("UTF-8"));
StringBuilder hex = new StringBuilder(hash.length * 2);
for (byte b : hash) {
if ((b & 0xFF) < 0x10) {
hex.append("0");
}
hex.append(Integer.toHexString(b & 0xFF));
}
return hex.toString();
}
}