Volley图片加载并加入缓存处理

直接上代码 两种方式 ImageView 和NetworkImageView

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先自定义全局Application 获取

public classMyApplication extends Application {

private static RequestQueuerequestQueue;

private static MyApplicationapplication;

@Override

public void onCreate() {

// TODO Auto-generated methodstub

super.onCreate();

application = this;

requestQueue =Volley.newRequestQueue(this);

}

public static MyApplicationgetInstance() {

// TODO Auto-generated methodstub

return application;

}

public static RequestQueuegetRequestQueue(){

return requestQueue;

}

}
先上布局文件
<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical" >

<ImageView

android:id="@+id/iv_test1"

android:layout_width="match_parent"

android:layout_height="300dp"

android:layout_marginTop="10dp"/>

<com.android.volley.toolbox.NetworkImageView

android:id="@+id/iv_test2"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center"

android:layout_marginTop="10dp" >

</com.android.volley.toolbox.NetworkImageView>

</LinearLayout>

方式一用ImageView加载

需要封装一下自定义的BitmapCache类实现图片缓存接口ImageCache

public class BitmapCache implements ImageCache{

public LruCache<String, Bitmap> cache;

public BitmapCache(){

int maxMermorySize = (int)(Runtime.getRuntime().maxMemory()/1024);

cache = new LruCache<String, Bitmap>(maxMermorySize/8){

@Override

protected int sizeOf(String key, Bitmap value) {

// TODO Auto-generated method stub

return value.getRowBytes()*value.getHeight();

}

};

}

@Override

public Bitmap getBitmap(String key) {

// TODO Auto-generated method stub

return cache.get(key);

}

@Override

public void putBitmap(String key, Bitmap value) {

// TODO Auto-generated method stub

cache.put(key, value);

}

}

方式二 用NetworkImageView记载

封装一个VolleyUtils图片加载并处理缓存的类，使用起来就比较方便了

public class VolleyUtils {

private static ImageLoader imageLoader;

private static LruCache<String,Bitmap> lruCache;

private static HashMap<String,SoftReference<Bitmap>> softmap;

private static void initCache() {

// TODO Auto-generated method stub

//实例化二级缓存

softmap = new HashMap<String, SoftReference<Bitmap>>();

//实例化一级缓存 字节单位 KB

int maxMermorySize = (int)(Runtime.getRuntime().maxMemory()/1024);

lruCache = new LruCache<String, Bitmap>(maxMermorySize/8){

@Override

protected int sizeOf(String key, Bitmap value) {

// TODO Auto-generated method stub

//return lruCache.size()

return value.getRowBytes()*value.getHeight()/1024;//返回KB的大小

}

@Override

protected void entryRemoved(boolean evicted, String key,

Bitmap oldValue, Bitmap newValue) {

//当oldValue被一级缓存逐出时，放入二级缓存中

if (evicted) {

softmap.put(key, new SoftReference<Bitmap>(oldValue));

}

}

};

}

public static ImageLoader getImageLoader(Context context){

if (imageLoader==null) {

initCache();

imageLoader = new ImageLoader(MyApplication.getRequestQueue(), new ImageCache() {

@Override

public void putBitmap(String url, Bitmap bitmap) {

// 存入一级缓存

lruCache.put(url, bitmap);

}

@Override

public Bitmap getBitmap(String url) {

//从一级缓存中获取

Bitmap bitmap = lruCache.get(url);

//判断一级缓存是否存在

if ( bitmap== null) {//一级缓存不存在

//从二级缓存中获取

SoftReference<Bitmap> softRef = softmap.get(url);

if (softRef!=null) {

bitmap = softRef.get();

//获取软引用中图片

//为了便于使用将二级缓存中的图片存放一级缓存中

lruCache.put(url, bitmap);

//将此图片从二级缓存中移除

softmap.remove(url);

}

}

return null;

}

});

}

return imageLoader;

}

}

在Activity或者Fragment或者适配中可以直接调取用，下边是以Activity为实例的代码

private ImageView test1;//用ImageView加载网略图片

private NetworkImageView test2;//用NetworkImageView记载网略图片

@Override

protected void onCreate(Bundle arg0) {

// TODO Auto-generated method stub

super.onCreate(arg0);

test1 = (ImageView)findViewById(R.id.iv_test1);

test2 = (NetworkImageView) findViewById(R.id.iv_test2);

initImage();

}

private void initImage(){

//本人随便找了一张美女的图片

String url = "http://img.pconline.com.cn/images/upload/upc/tx/wallpaper/1205/25/c2/11755122_1337938898582.jpg";

//方式一用ImageView加载

ImageLoader loader = new ImageLoader(MyApplication.getRequestQueue(), new BitmapCache());

ImageListener listener = ImageLoader.getImageListener(test1,

R.drawable.ic_launcher, R.drawable.ic_launcher);

loader.get(url, listener);

//方式二用NetworkImageView加载

ImageLoader imageLoader = VolleyUtils.getImageLoader(this);

test2.setDefaultImageResId(R.drawable.ic_launcher);

test2.setErrorImageResId(R.drawable.ic_launcher);

test2.setImageUrl(url, imageLoader);

}