使用Handler机制建立图片加载框架(笔记)

最新推荐文章于 2020-08-10 11:14:00 发布
最新推荐文章于 2020-08-10 11:14:00 发布
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分类专栏： android框架
本文详细介绍了图片加载类ImageLoader的实现原理与优化策略，包括线程池管理、缓存机制、本地硬盘缓存及网络加载流程，旨在提高图片加载效率与用户体验。

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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.youkuaiyun.com/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.youkuaiyun.com/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[] {
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383299_1976.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383291_6518.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383291_8239.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383290_9329.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383290_1042.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383275_3977.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383265_8550.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383264_3954.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383264_4787.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383264_8243.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383248_3693.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383243_5120.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383242_3127.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383242_9576.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383242_1721.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383219_5806.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383214_7794.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383213_4418.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383213_3557.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383210_8779.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383172_4577.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383166_3407.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383166_2224.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383166_7301.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383165_7197.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383150_8410.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383131_3736.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383130_5094.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383130_7393.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383129_8813.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383100_3554.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383093_7894.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383092_2432.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383092_3071.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383091_3119.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383059_6589.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383059_8814.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383059_2237.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383058_4330.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406383038_3602.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382942_3079.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382942_8125.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382942_4881.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382941_4559.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382941_3845.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382924_8955.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382923_2141.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382923_8437.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382922_6166.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382922_4843.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382905_5804.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382904_3362.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382904_2312.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382904_4960.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382900_2418.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382881_4490.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382881_5935.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382880_3865.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382880_4662.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382879_2553.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382862_5375.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382862_1748.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382861_7618.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382861_8606.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382861_8949.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382841_9821.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382840_6603.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382840_2405.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382840_6354.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382839_5779.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382810_7578.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382810_2436.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382809_3883.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382809_6269.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382808_4179.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382790_8326.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382789_7174.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382789_5170.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382789_4118.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382788_9532.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382767_3184.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382767_4772.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382766_4924.jpg",
			"https://img-my.youkuaiyun.com/uploads/201407/26/1406382766_5762.jpg",
			"https://img-my.youkuaiyun.com/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.youkuaiyun.com/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;

	}

	
}

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