android-smart-image-view源码分析

public class BitmapImage implements SmartImage {

//定义Bitmap对象

private Bitmap bitmap;

//构造方法

public BitmapImage(Bitmap bitmap) {

this.bitmap = bitmap;

}

//实现getBitmap方法

public Bitmap getBitmap(Context context) {

return bitmap;

}

}

• 【WebImage（根据Url获取图片资源，需要注意的是这里用到了缓存，注意代码注释）】---->

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package com.loopj.android.image;

import java.io.InputStream;

import java.net.URL;

import java.net.URLConnection;

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

public class WebImage implements SmartImage {

//超时设置

private static final int CONNECT_TIMEOUT = 5000;

private static final int READ_TIMEOUT = 10000;

//缓存对象

private static WebImageCache webImageCache;

//WebImage的构造方法，获取URL

private String url;

public WebImage(String url) {

this.url = url;

}

//实现方法，处理相应的业务逻辑

public Bitmap getBitmap(Context context) {

// Don’t leak context

if(webImageCache == null) {

webImageCache = new WebImageCache(context);

}

// Try getting bitmap from cache first

//此处做了简单的二级缓存（内存缓存和磁盘缓存）

Bitmap bitmap = null;

if(url != null) {

//先从缓存获取bitmap对象

bitmap = webImageCache.get(url);

if(bitmap == null) {

//未找到则从网络加载

bitmap = getBitmapFromUrl(url);

if(bitmap != null){

//加载后将bitmap对象put到缓存中

webImageCache.put(url, bitmap);

}

}

}

return bitmap;

}

/**

• 根据Url获取网络图片资源

• @param url

• @return

*/

private Bitmap getBitmapFromUrl(String url) {

Bitmap bitmap = null;

try {

URLConnection conn = new URL(url).openConnection();

conn.setConnectTimeout(CONNECT_TIMEOUT);

conn.setReadTimeout(READ_TIMEOUT);

bitmap = BitmapFactory.decodeStream((InputStream) conn.getContent());

} catch(Exception e) {

e.printStackTrace();

}

return bitmap;

}

/**

• 提供移除缓存的方法

• @param url

*/

public static void removeFromCache(String url) {

if(webImageCache != null) {

webImageCache.remove(url);

}

}

}