Volley简单学习使用一

• JSON对象
• 图片加载

    <uses-permissionandroid:name="android.permission.INTERNET"/>

    private RequestQueue mRequestQueue;
    //创建一个RequestQueue
    mRequestQueue = Volley.newRequestQueue(this);
       
    //创建一个StringRequest---GET请求
    String url = "http://www.baidu.com";
    StringRequest stringRequest = new StringRequest(url,
    new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            Log.d(TAG, response);
        }
    },
    new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.e(TAG, error.getMessage());
        }
    });
       
    //将StringRequest对象添加到RequestQueue
    mRequestQueue.add(stringRequest);

    String jsonurl = "http://pipes.yahooapis.com/pipes/pipe.run?_id=giWz8Vc33BG6rQEQo_NLYQ&_render=json";
    Response.Listener<JSONObject> listener = new Response.Listener<JSONObject>() {
        @Override
        public void onResponse(JSONObject response) {
            Log.i(TAG, response.toString());
        }
    };
   
    Response.ErrorListener errorListener = new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.i(TAG, error.getMessage());
        }
    };
 
    JsonObjectRequest jr = new JsonObjectRequest(Request.Method.GET, jsonurl, null, listener, errorListener);
    mRequestQueue.add(jr);

    JsonObjectRequest postRequest = new JsonObjectRequest(Request.Method.POST, jsonurl,  null, listener, errorListener) { 
       
        //将Post的参数写入到map中
        @Override 
        protected Map<String, String> getParams() throws AuthFailureError { 
            Map<String, String> map = new HashMap<String, String>(); 
            map.put("params1", "value1"); 
            map.put("params2", "value2"); 
            return map; 
        } 
    }; 
    mRequestQueue.add(postRequest);

    String imageUrl = "http://a.hiphotos.baidu.com/image/pic/item/3801213fb80e7bec5cfb43e02d2eb9389b506b89.jpg";
    int max_width  = 300;
    int max_height = 300;
    Response.Listener<Bitmap> listener = new Response.Listener<Bitmap>() {
        @Override
        public void onResponse(Bitmap response) {
            myImageView.setImageBitmap(response);
        }
    };
   
    Response.ErrorListener errorListener = new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            myImageView.setImageResource(R.drawable.default_pg);
        }
    };
   
    ImageRequest imageRequest = new ImageRequest(imageUrl, listener, max_width, max_height, Config.RGB_565, errorListener);
    mRequestQueue.add(imageRequest);

    * @param url URL of the image
    * @param listener Listener to receive the decoded bitmap
    * @param maxWidth Maximum width to decode this bitmap to, or zero for none
    * @param maxHeight Maximum height to decode this bitmap to, or zero for
    *            none
    * @param decodeConfig Format to decode the bitmap to
    * @param errorListener Error listener, or null to ignore errors

    //第一步创建RequestQueue,前面已经创建，这里不再重复创建
    String imageUrl = "http://a.hiphotos.baidu.com/image/pic/item/3801213fb80e7bec5cfb43e02d2eb9389b506b89.jpg";
   
    //创建LruCache保存下载过的图片
    final LruCache<String, Bitmap> mImageLruCache = new LruCache<String, Bitmap>(20);
   
    //创建ImageCache，供后面使用
    ImageCache imageCache = new ImageCache() {
        @Override
        public void putBitmap(String url, Bitmap bitmap) {
            mImageLruCache.put(url, bitmap);
        }
       
        @Override
        public Bitmap getBitmap(String url) {
            return mImageLruCache.get(url);
        }
    };
   
    //创建ImageLoader
    ImageLoader imageLoader = new ImageLoader(mRequestQueue, imageCache);
   
    /**
     * @param imageView The imageView that the listener is associated with.
     * @param defaultImageResId Default image resource ID to use, or 0 if it doesn't exist.
     * @param errorImageResId Error image resource ID to use, or 0 if it doesn't exist.
     */
    //获取一个ImageListener对象
    ImageListener imageListener = ImageLoader.getImageListener(myImageView, R.drawable.default_pg, R.drawable.failed_pg);
   
    //调用ImageLoader的get()方法加载网络上的图片
    imageLoader.get(imageUrl, imageListener);
   
    //如果想对加载图片大小进行限定，使用get()的另一个重载方式
    imageLoader.get(imageUrl, imageListener, 300, 300);

    final LruCache<String, Bitmap> mImageLruCache = new LruCache<String, Bitmap>(maxSize){
        @Override
        protected int sizeOf(String url, Bitmap bitmap){
            return bitmap.getRowBytes() * bitmap.getHeight();
        }
    };
   
    ImageCache imageCache = new ImageCache() {
        @Override
        public void putBitmap(String url, Bitmap bitmap) {
            mImageLruCache.put(url, bitmap);
        }
       
        @Override
        public Bitmap getBitmap(String url) {
            return mImageLruCache.get(url);
        }
    };

    <com.android.volley.toolbox.NetworkImageView
        android:id="@+id/myNetworkImageView"
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:contentDescription="@string/hello_world"
        />

    //前面创建ImageLoader与前面相同，不再重复创建
    //使用NetworkImageView
    NetworkImageView imageView = (NetworkImageView) findViewById(R.id.myNetworkImageView);
    imageView.setDefaultImageResId(R.drawable.default_pg);
    imageView.setErrorImageResId(R.drawable.failed_pg);
    imageView.setImageUrl(imageUrl, imageLoader);