几个常用的工具类-异步下载、handler下载工具类、图片缓存等

2019-11-09 14:13:40

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-工具类目录： —1、异步任务工具类 —2、Handler 下载工具类 —3、图片缓存到内存工具类 —4、缓存工具类，缓存到一级缓存中

这几个是适合初学者使用的下载缓存工具类

——————异步任务下载的工具类 /** * 异步任务的封装 * @author Ken * */

public class AbsAsyncTask extends AsyncTask<String, Void, Object> { //任务处理类型 PRivate DownType downType; private ImageView iv; private OnDownListener onDownListener; public AbsAsyncTask(DownType downType){ this.downType = downType; } @Override protected Object doInBackground(String... params) { byte[] bs = getByteArray(params[0]); if (bs != null) { switch (downType) { case JSON: //表示下载的是JSON String json = new String(bs); if(onDownListener != null){ Object datas = onDownListener.downJSON(json); return datas; } break; case IMAGE: //表示下载的Image Bitmap bitmap = BitmapFactory.decodeByteArray(bs, 0, bs.length); return bitmap; } } return null; } @Override protected void onPostExecute(Object result) { if(result != null){ switch (downType) { case JSON: if(onDownListener != null){ onDownListener.paresJSON(result); } break; case IMAGE: Bitmap bitmap = (Bitmap) result; if(iv != null){ iv.setImageBitmap(bitmap); } break; } } } public AbsAsyncTask with(ImageView iv){ this.iv = iv; return this; } //任务处理类型的枚举 public static enum DownType{ JSON, IMAGE } /** * 根据URL下载的到byte数组 * @param url * @return */ private byte[] getByteArray(String urlStr){ InputStream in = null; ByteArrayOutputStream out = null; try { URL url = new URL(urlStr); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("GET"); conn.setReadTimeout(3000); conn.connect(); if(conn.getResponseCode() == 200){ in = conn.getInputStream(); out = new ByteArrayOutputStream(); byte[] buffer = new byte[1024 * 8]; int len = 0; while((len = in.read(buffer)) != -1){ out.write(buffer, 0, len); } //得到下载好的json字符串 return out.toByteArray(); } } catch (Exception e) { e.printStackTrace(); } finally { try { if(in != null){ in.close(); } if(out != null){ out.close(); } } catch (IOException e) { e.printStackTrace(); } } return null; } /** * List<News> * * List<House> * @author Ken * */ public interface OnDownListener{ Object downJSON(String json); void paresJSON(Object datas); } /** * 设置json下载功能以后的回调方法 * @param onDownListener */ public AbsAsyncTask setOnDownListener(OnDownListener onDownListener) { this.onDownListener = onDownListener; return this; }}

———-Handler 下载工具类

import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Handler;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.URL;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;/** * Created by Ken on 2016/9/9.17:09 */public class DownUtil { /* 创建一个拥有5个线程的线程池 */ private static ExecutorService executor = Executors.newFixedThreadPool(5); private OnDownListener onDownListener; private Handler handler = new Handler(); //设置解析JSON的接口回调 public DownUtil setOnDownListener(OnDownListener onDownListener) { this.onDownListener = onDownListener; return this; } private OnDownImageListener onDownImageListener; //设置图片下载的接口 public DownUtil setOnDownImageListener(OnDownImageListener onDownImageListener) { this.onDownImageListener = onDownImageListener; return this; } /** * 下载JSON数据 */ public void downJSON(final String url){ executor.submit(new Runnable() { @Override public void run() { //在子线程中执行 byte[] bytes = requestURL(url); if(bytes != null){ String json = new String(bytes); //解析JSON if(onDownListener != null){ final Object object = onDownListener.paresJson(json); //将解析的结果回传给主线程 handler.post(new Runnable() { @Override public void run() { //在主线程中执行 onDownListener.downSucc(object); } }); } } } }); } /** * 下载图片 * @param url */ public void downBitmap(final String url){ executor.submit(new Runnable() { @Override public void run() { //在子线程中执行 byte[] bytes = requestURL(url); if(bytes != null) { final Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length); if(onDownImageListener != null){ handler.post(new Runnable() { @Override public void run() { onDownImageListener.downSuccImg(bitmap); } }); } } } }); } /** * 下载资源 * @return */ private byte[] requestURL(String urlStr){ InputStream in = null; ByteArrayOutputStream out = null; try { URL url = new URL(urlStr); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("GET"); conn.setReadTimeout(3000); conn.connect(); if(conn.getResponseCode() == 200){ in = conn.getInputStream(); out = new ByteArrayOutputStream(); byte[] buffer = new byte[1024 * 8]; int len; while((len = in.read(buffer)) != -1){ out.write(buffer, 0, len); } //得到下载好的json字符串 return out.toByteArray(); } } catch (Exception e) { e.printStackTrace(); } finally { try { if(in != null){ in.close(); } if(out != null){ out.close(); } } catch (IOException e) { e.printStackTrace(); } } return null; } /** * 接口回调 */ public interface OnDownListener{ //解析JSON时回调 Object paresJson(String json); //解析完成后回调 void downSucc(Object object); } /** * 下载图片的接口回调 */ public interface OnDownImageListener{ void downSuccImg(Bitmap bitmap); }}

————-图片缓存工具类——–缓存到硬盘—————–

import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Bitmap.CompressFormat;import android.os.Environment;import android.util.Log;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;/** * 图片缓存工具类 * * Created by Administrator on 2016/9/11 0011. */public class ImageUtil {//public static String path = Environment.getExternalStorageDirectory() +"/imageCache"; public static boolean isMounted(){return Environment.getExternalStorageState().equals (Environment.MEDIA_MOUNTED);}//public static void saveImage(Bitmap bitmap, String url){//if (!isMounted()){return ;}//File file = new File(path); if (!file.exists()){ file.mkdirs();} File urlFile = new File(url);file = new File(file,urlFile.getName()); try { bitmap.compress(CompressFormat.PNG, 100,new FileOutputStream (file));} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} }//public static Bitmap getIamge(String url){ File file = new File(url);String name = file.getName();File imageFile = new File(path,name); if(imageFile.exists()){return BitmapFactory.decodeFile(imageFile.getAbsolutePath());} Log.d("print",imageFile.getAbsolutePath()); return null;}}

——————–图片缓存工具类-缓存到一级缓存———————————————- package com.qf.util;

import android.graphics.Bitmap;import android.util.LruCache;/** * Created by Ken on 2016/9/19.9:45 * 图片缓存的工具类 */public class LruCacheUtil {/** * 内存缓存的对象 * 参数：内存缓存最大值 -- 通常设置为可使用的内存的1/8 * * lrucache如果缓存的大小已经达到了最大值，采用的移除策略：最近时间最少使用的缓存数据被移除 * * bitmap.getByteCount() * bitmap.getRowBytes() * bitmap.getHeight() * : 一个bitmap所占的内存大小（字节） */private static LruCache<String, Bitmap> lruCache = new LruCache<String, Bitmap>((int) (Runtime.getRuntime().maxMemory() / 8)){/** * 该方法用于计算缓存数据的大小 * @param key* @return*/@Overrideprotected int sizeOf(String key, Bitmap bitmap) {return bitmap.getRowBytes() * bitmap.getHeight();} };/** * 添加缓存 */public static void putCache(String url, Bitmap bitmap){ String key = md5Util.MD5(url);lruCache.put(key, bitmap);}/** * 获得缓存 * @param url* @return*/public static Bitmap getCache(String url){ String key = MD5Util.MD5(url); return lruCache.get(key);}}

————————MD5Util加密工具类—————————

/** * Created by Ken on 2016/9/19.10:13 */public class MD5Util {public final static String MD5(String s) {char hexDigits[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'}; try {byte[] btInput = s.getBytes();// 获得MD5摘要算法的 MessageDigest 对象MessageDigest mdInst = MessageDigest.getInstance("MD5");// 使用指定的字节更新摘要mdInst.update(btInput);// 获得密文byte[] md = mdInst.digest();// 把密文转换成十六进制的字符串形式int j = md.length; char str[] = new char[j * 2]; int k = 0; for (int i = 0; i < j; i++) {byte byte0 = md[i];str[k++] = hexDigits[byte0 >>> 4 & 0xf];str[k++] = hexDigits[byte0 & 0xf];}return new String(str);} catch (Exception e) { e.printStackTrace(); return null;} }}

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