使用Handler机制建立图片加载框架(笔记)
package com.zhy.utils;
import java.io.File;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.LinkedList;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Environment;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.support.v4.util.LruCache;
import android.util.Log;
import android.widget.ImageView;
import com.zhy.utils.ImageSizeUtil.ImageSize;
/**
* 图片加载类
* http://blog.csdn.net/lmj623565791/article/details/41874561
* @author zhy
*
*/
public class ImageLoader
{
private static ImageLoader mInstance;
/**
* 图片缓存的核心对象
*/
private LruCache<String, Bitmap> mLruCache;
/**
* 线程池
*/
private ExecutorService mThreadPool;
private static final int DEAFULT_THREAD_COUNT = 1; //默认线程数 1 个
/**
* 队列的调度方式
*/
private Type mType = Type.LIFO;
/**
* 任务队列
*/
private LinkedList<Runnable> mTaskQueue;
/**
* 后台轮询线程
*/
private Thread mPoolThread;
private Handler mPoolThreadHandler;
/**
* UI线程中的Handler
*/
private Handler mUIHandler;
/**
* mSemaphorePoolThreadHandler = new Semaphore(0);
* 用于控制我们的mPoolThreadHandler的初始化完成，我们在使用
* mPoolThreadHandler会进行判空，如果为null，会通过mSemaphorePoolThreadHandler.acquire()进行阻塞；
* 当mPoolThreadHandler初始化结束，我们会调用.release();解除阻塞。
*/
private Semaphore mSemaphorePoolThreadHandler = new Semaphore(0);
private Semaphore mSemaphoreThreadPool;
private boolean isDiskCacheEnable = true; //是否进行本地硬盘缓存
private static final String TAG = "ImageLoader";
public enum Type
{
FIFO, LIFO; // LAST IN FAST OUT
}
private ImageLoader(int threadCount, Type type)
{
init(threadCount, type);
}
/**
* 初始化
*
* @param threadCount
* @param type
*/
private void init(int threadCount, Type type)
{
initBackThread();
// 获取我们应用的最大可用内存
int maxMemory = (int) Runtime.getRuntime().maxMemory();
int cacheMemory = maxMemory / 8; // 内存缓存的最大容量为: 程序最大容量的八分之一
mLruCache = new LruCache<String, Bitmap>(cacheMemory)
{
@Override
protected int sizeOf(String key, Bitmap value)
{
return value.getRowBytes() * value.getHeight(); // 图片的大小
}
};
// 创建线程池
mThreadPool = Executors.newFixedThreadPool(threadCount); // 数量确定的线程池
mTaskQueue = new LinkedList<Runnable>();
mType = type;
mSemaphoreThreadPool = new Semaphore(threadCount); // 信号量的个数(threadCount)
}
/**
* 初始化后台轮询线程
*/
private void initBackThread()
{
// 后台轮询线程
mPoolThread = new Thread()
{
@Override
public void run()
{
Looper.prepare();
mPoolThreadHandler = new Handler() //子线程中的轮询handler
{
@Override
public void handleMessage(Message msg)
{
// 线程池去取出一个任务进行执行
mThreadPool.execute(getTask());
try
{
mSemaphoreThreadPool.acquire();
} catch (InterruptedException e)
{
}
}
};
// 释放一个信号量
mSemaphorePoolThreadHandler.release();
Looper.loop(); //
};
};
mPoolThread.start();
}
public static ImageLoader getInstance()
{
if (mInstance == null)
{
synchronized (ImageLoader.class)
{
if (mInstance == null)
{
mInstance = new ImageLoader(DEAFULT_THREAD_COUNT, Type.LIFO);
}
}
}
return mInstance;
}
public static ImageLoader getInstance(int threadCount, Type type)
{
if (mInstance == null)
{
synchronized (ImageLoader.class)
{
if (mInstance == null)
{
mInstance = new ImageLoader(threadCount, type);
}
}
}
return mInstance;
}
/**
* 根据path为imageview设置图片
*
* @param path
* @param imageView
*/
public void loadImage(final String path, final ImageView imageView,
final boolean isFromNet)
{
imageView.setTag(path);
if (mUIHandler == null)
{
mUIHandler = new Handler()
{
public void handleMessage(Message msg)
{
// 获取得到图片，为imageview回调设置图片
ImgBeanHolder holder = (ImgBeanHolder) msg.obj;
Bitmap bm = holder.bitmap;
ImageView imageview = holder.imageView;
String path = holder.path;
// 将path与getTag存储路径进行比较
if (imageview.getTag().toString().equals(path))
{
imageview.setImageBitmap(bm);
}
};
};
}
// 根据path在缓存中获取bitmap
Bitmap bm = getBitmapFromLruCache(path);
if (bm != null)
{
refreashBitmap(path, imageView, bm);
} else
{
addTask(buildTask(path, imageView, isFromNet));
}
}
/**
* 根据传入的参数，新建一个任务
*
* @param path
* @param imageView
* @param isFromNet
* @return
*/
private Runnable buildTask(final String path, final ImageView imageView,
final boolean isFromNet)
{
return new Runnable()
{
@Override
public void run()
{
Bitmap bm = null;
if (isFromNet)
{
File file = getDiskCacheDir(imageView.getContext(),
md5(path));
if (file.exists())// 如果在缓存文件中发现
{
Log.e(TAG, "find image :" + path + " in disk cache .");
bm = loadImageFromLocal(file.getAbsolutePath(),
imageView);
} else
{
if (isDiskCacheEnable)// 检测是否开启硬盘缓存
{
boolean downloadState = DownloadImgUtils
.downloadImgByUrl(path, file);
if (downloadState)// 如果下载成功 ,就从本地进行下载
{
Log.e(TAG,
"download image :" + path
+ " to disk cache . path is "
+ file.getAbsolutePath());
bm = loadImageFromLocal(file.getAbsolutePath(),
imageView);
}
} else
// 直接从网络加载
{
Log.e(TAG, "load image :" + path + " to memory.");
bm = DownloadImgUtils.downloadImgByUrl(path,
imageView);
}
}
} else
{
bm = loadImageFromLocal(path, imageView);
}
// 3、把图片加入到缓存
addBitmapToLruCache(path, bm);
refreashBitmap(path, imageView, bm);
mSemaphoreThreadPool.release();
}
};
}
private Bitmap loadImageFromLocal(final String path,
final ImageView imageView)
{
Bitmap bm;
// 加载图片
// 图片的压缩
// 1、获得图片需要显示的大小
ImageSize imageSize = ImageSizeUtil.getImageViewSize(imageView);
// 2、压缩图片
bm = decodeSampledBitmapFromPath(path, imageSize.width,
imageSize.height);
return bm;
}
/**
* 从任务队列取出一个方法
*
* @return
*/
private Runnable getTask()
{
if (mType == Type.FIFO)
{
return mTaskQueue.removeFirst();
} else if (mType == Type.LIFO)
{
return mTaskQueue.removeLast();
}
return null;
}
/**
* 利用签名辅助类，将字符串字节数组
*
* @param str
* @return
*/
public String md5(String str)
{
byte[] digest = null;
try
{
MessageDigest md = MessageDigest.getInstance("md5");
digest = md.digest(str.getBytes());
return bytes2hex02(digest);
} catch (NoSuchAlgorithmException e)
{
e.printStackTrace();
}
return null;
}
/**
* 方式二
*
* @param bytes
* @return
*/
public String bytes2hex02(byte[] bytes)
{
StringBuilder sb = new StringBuilder();
String tmp = null;
for (byte b : bytes)
{
// 将每个字节与0xFF进行与运算，然后转化为10进制，然后借助于Integer再转化为16进制
tmp = Integer.toHexString(0xFF & b);
if (tmp.length() == 1)// 每个字节8为，转为16进制标志，2个16进制位
{
tmp = "0" + tmp;
}
sb.append(tmp);
}
return sb.toString();
}
private void refreashBitmap(final String path, final ImageView imageView,
Bitmap bm)
{
Message message = Message.obtain();
ImgBeanHolder holder = new ImgBeanHolder();
holder.bitmap = bm;
holder.path = path;
holder.imageView = imageView;
message.obj = holder;
mUIHandler.sendMessage(message);
}
/**
* 将图片加入LruCache
*
* @param path
* @param bm
*/
protected void addBitmapToLruCache(String path, Bitmap bm)
{
if (getBitmapFromLruCache(path) == null)
{
if (bm != null)
mLruCache.put(path, bm);
}
}
/**
* 根据图片需要显示的宽和高对图片进行压缩
*
* @param path
* @param width
* @param height
* @return
*/
protected Bitmap decodeSampledBitmapFromPath(String path, int width,
int height)
{
// 获得图片的宽和高，并不把图片加载到内存中
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(path, options);
options.inSampleSize = ImageSizeUtil.caculateInSampleSize(options,
width, height);
// 使用获得到的InSampleSize再次解析图片
options.inJustDecodeBounds = false;
Bitmap bitmap = BitmapFactory.decodeFile(path, options);
return bitmap;
}
private synchronized void addTask(Runnable runnable)
{
mTaskQueue.add(runnable);
// if(mPoolThreadHandler==null)wait();
try
{
if (mPoolThreadHandler == null)
mSemaphorePoolThreadHandler.acquire(); // 他的作用是什么呢??? 看灰机
} catch (Exception e)
{
}
mPoolThreadHandler.sendEmptyMessage(0x110);
}
/**
* 获得缓存图片的地址
*
* @param context
* @param uniqueName 使用md5 作为其文件名
* @return
*/
public File getDiskCacheDir(Context context, String uniqueName)
{
String cachePath;
if (Environment.MEDIA_MOUNTED.equals(Environment
.getExternalStorageState()))
{
cachePath = context.getExternalCacheDir().getPath();
} else
{
cachePath = context.getCacheDir().getPath();
}
return new File(cachePath + File.separator + uniqueName);
}
/**
* 根据path在缓存中获取bitmap
*
* @param key
* @return
*/
private Bitmap getBitmapFromLruCache(String key)
{
return mLruCache.get(key);
}
private class ImgBeanHolder
{
Bitmap bitmap;
ImageView imageView;
String path;
}
}
其他的一些类
package com.zhy.utils;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.BitmapFactory.Options;
import android.util.Log;
import android.widget.ImageView;
import com.zhy.utils.ImageSizeUtil.ImageSize;
/**
* http://blog.csdn.net/lmj623565791/article/details/41874561
* @author zhy
*
*/
public class DownloadImgUtils
{
/**
* 根据url下载图片在指定的文件
*
* @param urlStr
* @param file
* @return
*/
public static boolean downloadImgByUrl(String urlStr, File file)
{
FileOutputStream fos = null;
InputStream is = null;
try
{
URL url = new URL(urlStr);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
is = conn.getInputStream();
fos = new FileOutputStream(file);
byte[] buf = new byte[512];
int len = 0;
while ((len = is.read(buf)) != -1)
{
fos.write(buf, 0, len);
}
fos.flush();
return true;
} catch (Exception e)
{
e.printStackTrace();
} finally
{
try
{
if (is != null)
is.close();
} catch (IOException e)
{
}
try
{
if (fos != null)
fos.close();
} catch (IOException e)
{
}
}
return false;
}
/**
* 根据url下载图片在指定的文件
*
* @param urlStr
* @param file
* @return
*/
public static Bitmap downloadImgByUrl(String urlStr, ImageView imageview)
{
FileOutputStream fos = null;
InputStream is = null;
try
{
URL url = new URL(urlStr);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
is = new BufferedInputStream(conn.getInputStream());
is.mark(is.available()); // 最为一个标记来表示位置
Options opts = new Options();
opts.inJustDecodeBounds = true;
Bitmap bitmap = BitmapFactory.decodeStream(is, null, opts);
//获取imageview想要显示的宽和高
ImageSize imageViewSize = ImageSizeUtil.getImageViewSize(imageview);
opts.inSampleSize = ImageSizeUtil.caculateInSampleSize(opts,
imageViewSize.width, imageViewSize.height);
opts.inJustDecodeBounds = false;
is.reset(); // 重新设置其其实位置, 达到该流能够重复使用的效果
bitmap = BitmapFactory.decodeStream(is, null, opts);
conn.disconnect();
return bitmap;
} catch (Exception e)
{
e.printStackTrace();
} finally
{
try
{
if (is != null)
is.close();
} catch (IOException e)
{
}
try
{
if (fos != null)
fos.close();
} catch (IOException e)
{
}
}
return null;
}
}
package com.zhy.utils;
public class Images
{
public final static String[] imageThumbUrls = new String[] {
"http://img.my.csdn.net/uploads/201407/26/1406383299_1976.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383291_6518.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383291_8239.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383290_9329.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383290_1042.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383275_3977.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383265_8550.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383264_3954.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383264_4787.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383264_8243.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383248_3693.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383243_5120.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383242_3127.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383242_9576.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383242_1721.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383219_5806.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383214_7794.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383213_4418.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383213_3557.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383210_8779.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383172_4577.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383166_3407.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383166_2224.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383166_7301.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383165_7197.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383150_8410.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383131_3736.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383130_5094.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383130_7393.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383129_8813.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383100_3554.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383093_7894.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383092_2432.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383092_3071.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383091_3119.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383059_6589.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383059_8814.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383059_2237.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383058_4330.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406383038_3602.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382942_3079.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382942_8125.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382942_4881.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382941_4559.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382941_3845.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382924_8955.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382923_2141.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382923_8437.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382922_6166.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382922_4843.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382905_5804.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382904_3362.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382904_2312.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382904_4960.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382900_2418.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382881_4490.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382881_5935.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382880_3865.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382880_4662.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382879_2553.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382862_5375.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382862_1748.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382861_7618.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382861_8606.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382861_8949.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382841_9821.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382840_6603.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382840_2405.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382840_6354.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382839_5779.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382810_7578.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382810_2436.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382809_3883.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382809_6269.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382808_4179.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382790_8326.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382789_7174.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382789_5170.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382789_4118.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382788_9532.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382767_3184.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382767_4772.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382766_4924.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382766_5762.jpg",
"http://img.my.csdn.net/uploads/201407/26/1406382765_7341.jpg" };
}
package com.zhy.utils;
import java.lang.reflect.Field;
import android.annotation.TargetApi;
import android.graphics.BitmapFactory.Options;
import android.os.Build;
import android.util.DisplayMetrics;
import android.view.ViewGroup.LayoutParams;
import android.widget.ImageView;
/**
* http://blog.csdn.net/lmj623565791/article/details/41874561
* @author zhy
*
*/
public class ImageSizeUtil
{
/**
* 根据需求的宽和高以及图片实际的宽和高计算SampleSize
*
* @param options
* @param width
* @param height
* @return
*/
public static int caculateInSampleSize(Options options, int reqWidth,
int reqHeight)
{
int width = options.outWidth;
int height = options.outHeight;
int inSampleSize = 1;
if (width > reqWidth || height > reqHeight)
{
int widthRadio = Math.round(width * 1.0f / reqWidth);
int heightRadio = Math.round(height * 1.0f / reqHeight);
inSampleSize = Math.max(widthRadio, heightRadio);
}
return inSampleSize;
}
/**
* 根据ImageView获适当的压缩的宽和高
*
* @param imageView
* @return
*/
public static ImageSize getImageViewSize(ImageView imageView)
{
ImageSize imageSize = new ImageSize();
DisplayMetrics displayMetrics = imageView.getContext().getResources()
.getDisplayMetrics();
LayoutParams lp = imageView.getLayoutParams();
int width = imageView.getWidth();// 获取imageview的实际宽度
if (width <= 0)
{
width = lp.width;// 获取imageview在layout中声明的宽度
}
if (width <= 0)
{
//width = imageView.getMaxWidth();// 检查最大值
width = getImageViewFieldValue(imageView, "mMaxWidth");
/*
* 可以看到这里或者最大宽度，我们用的反射，而不是getMaxWidth()；维萨呢，
* 因为getMaxWidth竟然要API 16，我也是醉了；为了兼容性，我们采用反射的方
* 案。
* */
}
if (width <= 0)
{
width = displayMetrics.widthPixels;
}
int height = imageView.getHeight();// 获取imageview的实际高度
if (height <= 0)
{
height = lp.height;// 获取imageview在layout中声明的宽度
}
if (height <= 0)
{
height = getImageViewFieldValue(imageView, "mMaxHeight");// 检查最大值
}
if (height <= 0)
{
height = displayMetrics.heightPixels;
}
imageSize.width = width;
imageSize.height = height;
return imageSize;
}
public static class ImageSize
{
int width;
int height;
}
/**
* 通过反射获取imageview的某个属性值
*
* @param object
* @param fieldName
* @return
*/
private static int getImageViewFieldValue(Object object, String fieldName)
{
int value = 0;
try
{
Field field = ImageView.class.getDeclaredField(fieldName);
field.setAccessible(true);
int fieldValue = field.getInt(object);
if (fieldValue > 0 && fieldValue < Integer.MAX_VALUE)
{
value = fieldValue;
}
} catch (Exception e)
{
}
return value;
}
}