Volley圖片加載並加入緩存處理(轉自http://blog.csdn.net/viewhandkownhealth/article/details/50957024)

直接上代碼  兩種方式 ImageView 和NetworkImageView

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先自定義全局Application 獲取

 

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;
      }
}

先上佈局文件

<?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加載

須要封裝一下自定義的BitmapCache類實現圖片緩存接口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()/1024;
}
};

}

@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記載

封裝一個VolleyUtils圖片加載並處理緩存的類，使用起來就比較方便了

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
//實例化二級緩存
softmap = new HashMap<String, SoftReference<Bitmap>>();
//實例化一級緩存  字節單位 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) {
//當oldValue被一級緩存逐出時，放入二級緩存中
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) {
// 存入一級緩存
lruCache.put(url, bitmap);
}

@Override
public Bitmap getBitmap(String url) {

//從一級緩存中獲取
Bitmap bitmap = lruCache.get(url);
//判斷一級緩存是否存在
if ( bitmap== null) {//一級緩存不存在
//從二級緩存中獲取
SoftReference<Bitmap> softRef = softmap.get(url);
if (softRef!=null) {
bitmap = softRef.get();
//獲取軟引用中圖片
//爲了便於使用將二級緩存中的圖片存放一級緩存中
     lruCache.put(url, bitmap);
     //將此圖片從二級緩存中移除
     softmap.remove(url);
}
}
return null;
}
});
}
return imageLoader;
}

}

在Activity或者Fragment或者適配中能夠直接調取用，下邊是以Activity爲實例的代碼

private ImageView test1;//用ImageView加載網略圖片

private NetworkImageView test2;//用NetworkImageView記載網略圖片

@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(){

//本人隨便找了一張美女的圖片

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

//方式一用ImageView加載
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加載
ImageLoader imageLoader = VolleyUtils.getImageLoader(this);
test2.setDefaultImageResId(R.drawable.ic_launcher);
test2.setErrorImageResId(R.drawable.ic_launcher);
test2.setImageUrl(url, imageLoader);

}