android调用系统相机拍照并将照片储存在缓存中，并以列表展示照片

package com.paizhao.test; /** * 通过拍照加载图片 * @author yeyun * */ import java.io.IOException; import java.io.InputStream; import java.lang.ref.SoftReference; import java.util.HashMap; import java.util.LinkedHashMap; import java.util.List; import java.util.concurrent.ConcurrentHashMap; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.params.HttpConnectionParams; import org.apache.http.params.HttpParams; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.media.ThumbnailUtils; import android.net.http.AndroidHttpClient; import android.os.AsyncTask; import android.os.Handler; import android.util.Log; import android.view.View; import android.widget.BaseAdapter; import android.widget.ImageView; import android.widget.TextView; public class ImageLoaderFromPZ { private static final String TAG = "ImageLoader"; private static final int MAX_CAPACITY = 10;// 一级缓存的最大空间 private static final long DELAY_BEFORE_PURGE = 100* 1000;// 定时清理缓存 // 0.75是加载因子为经验值，true则表示按照最近访问量的高低排序，false则表示按照插入顺序排序 private HashMap<String, Bitmap> mFirstLevelCache = new LinkedHashMap<String, Bitmap>( MAX_CAPACITY / 2, 0.75f, true) { private static final long serialVersionUID = 1L; protected boolean removeEldestEntry(Entry<String, Bitmap> eldest) { if (size() > MAX_CAPACITY) {// 当超过一级缓存阈值的时候，将老的值从一级缓存搬到二级缓存 mSecondLevelCache.put(eldest.getKey(), new SoftReference<Bitmap>(eldest.getValue())); return true; } return false; }; }; // 二级缓存，采用的是软应用，只有在内存吃紧的时候软应用才会被回收，有效的避免了oom private ConcurrentHashMap<String, SoftReference<Bitmap>> mSecondLevelCache = new ConcurrentHashMap<String, SoftReference<Bitmap>>( MAX_CAPACITY / 2); // 定时清理缓存 private Runnable mClearCache = new Runnable() { @Override public void run() { clear(); } }; private Handler mPurgeHandler = new Handler(); // 重置缓存清理的timer private void resetPurgeTimer() { mPurgeHandler.removeCallbacks(mClearCache); mPurgeHandler.postDelayed(mClearCache, DELAY_BEFORE_PURGE); } /** * 清理缓存 */ private void clear() { mFirstLevelCache.clear(); mSecondLevelCache.clear(); } /** * 返回缓存，如果没有则返回null * * @param url * @return */ public Bitmap getBitmapFromCache(String url) { Bitmap bitmap = null; bitmap = getFromFirstLevelCache(url);// 从一级缓存中拿 if (bitmap != null) { return bitmap; } bitmap = getFromSecondLevelCache(url);// 从二级缓存中拿 return bitmap; } /** * 从二级缓存中拿 * * @param url * @return */ private Bitmap getFromSecondLevelCache(String url) { Bitmap bitmap = null; SoftReference<Bitmap> softReference = mSecondLevelCache.get(url); if (softReference != null) { bitmap = softReference.get(); if (bitmap == null) {// 由于内存吃紧，软引用已经被gc回收了 mSecondLevelCache.remove(url); } } return bitmap; } /** * 从一级缓存中拿 * * @param url * @return */ private Bitmap getFromFirstLevelCache(String url) { Bitmap bitmap = null; synchronized (mFirstLevelCache) { bitmap = mFirstLevelCache.get(url); if (bitmap != null) {// 将最近访问的元素放到链的头部，提高下一次访问该元素的检索速度（LRU算法） mFirstLevelCache.remove(url); mFirstLevelCache.put(url, bitmap); } } return bitmap; } /** * 加载图片，如果缓存中有就直接从缓存中拿，缓存中没有就从sd卡中取 * @param url * @param adapter * @param holder */ public void loadImageFormSD(String url, List<View> views,List fileS) { resetPurgeTimer(); for(int i=0;i<views.size();i++){ ImageView img=(ImageView)views.get(i); Bitmap bit=getBitmapFromCache((String)fileS.get(i)); if(bit!=null){ img.setImageBitmap(bit); } } } /** * 放入缓存 * * @param url * @param value */ public void addImage2Cache(String url, Bitmap value) { if (value == null || url == null) { return; } synchronized (mFirstLevelCache) { mFirstLevelCache.put(url, value); } } class ImageLoadTask1 extends AsyncTask<Object, Void, Bitmap> { String url; List<View> views; List fileS; @Override protected Bitmap doInBackground(Object... params) { url = (String) params[0]; views=(List<View>)params[1]; fileS=(List)params[2]; BitmapFactory.Options opt = new BitmapFactory.Options(); opt.inSampleSize = 1; opt.inJustDecodeBounds = true; BitmapFactory.decodeFile(url, opt); int bitmapSize = opt.outHeight * opt.outWidth * 4; opt.inSampleSize = bitmapSize / (1000 * 2000); opt.inJustDecodeBounds = false; Bitmap drawable = BitmapFactory.decodeFile(url, opt); drawable = ThumbnailUtils.extractThumbnail(drawable, 100,100, ThumbnailUtils.OPTIONS_RECYCLE_INPUT); return drawable; } @Override protected void onPostExecute(Bitmap result) { if (result == null) { return; } addImage2Cache(url, result);// 放入缓存 //adapter.notifyDataSetChanged();// 触发getView方法执行，这个时候getView实际上会拿到刚刚缓存好的图片 } } }