图片三级缓存工具类

效果图

功能代码

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.Message;
import android.support.v4.util.LruCache;
import android.util.Log;

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
* Created by Administrator on 2016/5/16.
* /article/7632922.html
* 图片获取工具，三级缓存
*/
public class ImageCacheUitl {
public static final int SUCCESS = 1;
public static final int FAIL = 0;
private Context context;
private LruCache<String, Bitmap> cache;
private File cacheDir;
private Handler handler;
private ExecutorService executorService;

public ImageCacheUitl(Context context, Handler handler) {
this.context = context;
this.handler = handler;
cacheDir = context.getCacheDir();//获得cache文件夹
executorService = Executors.newFixedThreadPool(5);//维护几个网络线程下载图片
int maxSize = (int) (Runtime.getRuntime().maxMemory() / 8);//获得运行环境的内存大小的1/8
cache = new LruCache<String, Bitmap>(maxSize) {
@Override
protected int sizeOf(String key, Bitmap value) {
return value.getRowBytes() * value.getHeight(); //返回当前一行所占的字节数*高度，就是图片的大小
}
};
}

//通过url获取图片
public Bitmap getBitmapFromUrl(String url, int position) {
Bitmap bitmap = cache.get(url);
if (bitmap != null) {
Log.v("-->", "从内存中获得图片" + url);
return bitmap;
}

bitmap = getBitmapFromFile(url);
if (bitmap != null) {
Log.v("-->", "从文件中获得图片" + url);
return bitmap;
}

Log.i("-->", "从网络中获得图片" + url);
getBitmapFromNet(url, position);
return null;
}

//从文件中获取图片
private Bitmap getBitmapFromFile(String url) {
try {
String[] strings = url.split("/");
String bitmapFileName = strings[strings.length - 1];
File file = new File(cacheDir, bitmapFileName);
Bitmap bitmap = BitmapFactory.decodeFile(file.getPath());
if (bitmap == null)
return null;
cache.put(url, bitmap);
return bitmap;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}

//从网络中获取图片
private void getBitmapFromNet(String url, int position) {
executorService.execute(new RunnableTask(url, position));
}

//图片下载线程
private class RunnableTask implements Runnable {
private String imageUrl;
private int position;
private HttpURLConnection httpURLConnection;

public RunnableTask(String imageUrl, int position) {
this.imageUrl = imageUrl;
this.position = position;
}

@Override
public void run() {
try {
URL url = new URL(imageUrl);
httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("GET");
httpURLConnection.setReadTimeout(5000);
httpURLConnection.setConnectTimeout(5000);
if (httpURLConnection.getResponseCode() == 200) {
InputStream inputStream = httpURLConnection.getInputStream();
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
Message msg = Message.obtain();
msg.obj = bitmap;
msg.arg1 = position;
msg.what = SUCCESS;
handler.sendMessage(msg);
cache.put(imageUrl, bitmap);
writeToLoc(imageUrl, bitmap);
return;
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (httpURLConnection != null)
httpURLConnection.disconnect();
}
handler.obtainMessage(FAIL).sendToTarget();
}
}

//图片存储到本地
private void writeToLoc(String imageUrl, Bitmap bitmap) {
try {
String[] strings = imageUrl.split("/");
String bitmapFileName = strings[strings.length - 1];
Log.v("-->", "bitmapFileName" + bitmapFileName);
File file = new File(cacheDir, bitmapFileName);
FileOutputStream fileOutputStream = new FileOutputStream(file);
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fileOutputStream);
} catch (Exception e) {
e.printStackTrace();
}
}

}