android image cache 图片缓存 异步 下载
16lz
2022-06-13
自动判断从内存还是网络获取图片,缓存自动回收
import java.io.InputStream;import java.lang.ref.SoftReference;import java.net.HttpURLConnection;import java.net.URL;import java.util.Date;import java.util.HashMap;import android.graphics.Bitmap;import android.graphics.BitmapFactory;/** * * @author yizhe * @date 2012-6-13 */public class BitmapLoader {// 内存缓存,SoftReference实现自动回收private static HashMap<String, SoftReference<Bitmap>> imageCache = new HashMap<String, SoftReference<Bitmap>>();/** * 自动判断从内存还是从网络获取图片 * * @param imageURL * @return */public static Bitmap loadBitmap(String imageURL) {long time = new Date().getTime();Comm.print(time + "--loadBitmap--" + imageURL);Bitmap bm = null;if (imageCache.containsKey(imageURL)) {// 从内存中获取Comm.print(time + "--loadBitmap--from Cache");SoftReference<Bitmap> reference = imageCache.get(imageURL);bm = reference.get();}if (null == bm) {// 到网络下载Comm.print(time + "--loadBitmap--from Net");bm = getNetBitmap2(imageURL);if (null != bm) {imageCache.put(imageURL, new SoftReference<Bitmap>(bm)); // 保存到内存}}if (null == bm) {Comm.print(time + "--loadBitmap--false");} else {Comm.print(time + "--loadBitmap--true");}return bm;}// 从网络下载图片,方法2,本方法下载图片可能出现返回200状态但得到的bitmap为null的情况private static Bitmap getNetBitmap(String imageURL) {Bitmap bitmap = null;try {// 要下载的图片的地址，URL url = new URL(imageURL);// 获取到路径HttpURLConnection conn = (HttpURLConnection) url.openConnection();// http协议连接对象conn.setRequestMethod("GET");// 这里是不能乱写的，详看API方法conn.setConnectTimeout(9000);// 别超过10秒。int state = conn.getResponseCode();if (state == 200) {Comm.print("--loadNetBitmap--" + state);InputStream inputStream = conn.getInputStream();bitmap = BitmapFactory.decodeStream(inputStream);}} catch (Exception e) {Comm.print("--loadNetBitmap--e--" + e.toString());}return bitmap;}// 从网络下载图片,方法2,请使用本方法下载图片,public static Bitmap getNetBitmap2(String imageURL) {Bitmap bitmap = null;try {URL url = new URL(imageURL);// 获取到路径HttpURLConnection conn = (HttpURLConnection) url.openConnection();// http协议连接对象conn.setRequestMethod("GET");// 这里是不能乱写的，详看API方法conn.setConnectTimeout(9000);// 别超过10秒。int state = conn.getResponseCode();if (state == 200) {Comm.print("--loadNetBitmap--" + state);int length = (int) conn.getContentLength();// 获取长度InputStream is = conn.getInputStream();if (length != -1) {byte[] imgData = new byte[length];byte[] temp = new byte[512];int readLen = 0;int destPos = 0;while ((readLen = is.read(temp)) > 0) {System.arraycopy(temp, 0, imgData, destPos, readLen);destPos += readLen;}bitmap = BitmapFactory.decodeByteArray(imgData, 0,imgData.length);}}} catch (Exception e) {Comm.print("--loadNetBitmap--e--" + e.toString());}return bitmap;}}
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