Android 网络请求框架Volley实例详解
首先上效果图
Logcat日志信息on Reponse
Volley特别适合数据量不大但是通信频繁的场景,像文件上传下载不适合!
首先第一步
用到的RequetQueue
RequestQueue.Java
RequestQueue请求队列首先得先说一下,ReuqestQueue是如何对请求进行管理的...RequestQueue是对所有的请求进行保存...然后通过自身的start()方法开启一个CacheDispatcher线程用于缓存调度,开启若干个NetWorkDispatcher线程用于网络调度...那么为什么要这样设计呢?
因为一个请求如果已经提交了一次,那么就只需要处理这一次结果就可以了,对于多次重复的请求,我们完全可以使用一个缓存来进行保存..从而减少一些不必要的网络请求,减小服务器的负担...如果一个请求在缓存中没存在过,那么我们再执行网络请求就可以了
总而言之,设计理念就是从RequestQueue取出请求,先判断缓存是否命中,如果缓存命中,则从缓存中取出数据,如果缓存没有命中,则提交网络请求,从服务器端获取数据
导入volley.jar 到您的Project libs里面,然后Add to Build path
然后创建NetCacheActivity类
package com.Android.xiong.gridlayoutTest; import android.app.Activity; import android.graphics.Bitmap; import android.graphics.Bitmap.Config; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.ImageView; import android.widget.Toast; import com.android.volley.Request.Method; import com.android.volley.RequestQueue; import com.android.volley.Response; import com.android.volley.VolleyError; import com.android.volley.toolbox.ImageRequest; import com.android.volley.toolbox.StringRequest; import com.android.volley.toolbox.Volley; public class NetCacheActivity extends Activity { private static final String URL = "http://sina.com";//请求的url private RequestQueue mRequestQueue; private Button btn_request; private ImageView iv_request; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.main); initView(); mRequestQueue = Volley.newRequestQueue(getApplicationContext()); } private void initView() { // TODO Auto-generated method stub btn_request = (Button) findViewById(R.id.btn_request); iv_request=(ImageView) findViewById(R.id.iv_request); } public void onClick(View v) { //volleyRequest();从网络上获取图片 imageRequest(); LoadImageView();//ImageLoader加载图片 } private void imageRequest() { // TODO Auto-generated method stub ImageRequest mImageRequest=new ImageRequest("http://www.bz55.com/uploads/allimg/130716/1-130G6111637.jpg", new Response.Listener() { //需要的注意的是导入Response.Listener 别导错包! @Override public void onResponse(Bitmap response) { // 将网络请求的图片返回并显示在ImageView中 try { Thread.sleep(3000);//休眠3秒 iv_request.setImageBitmap(response); Toast.makeText(getApplicationContext(), " onResponse", Toast.LENGTH_SHORT).show(); Log.d(" onResponse", response.toString()); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } },0, 0, Config.RGB_565, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { // 默认加载图片资源 iv_request.setImageResource(R.drawable.ic_launcher); Toast.makeText(getApplicationContext(), " onErrorResponse", Toast.LENGTH_SHORT).show(); Log.d(" onErrorResponse", error.toString()); } }); mRequestQueue.add(mImageRequest);//强图片请求添加到请求队列 } public void LoadImageView() { // 利用ImageLoader异步加载图片 final ImageLoader mImageLoader = new ImageLoader(mquest, new BitmapCache()); ImageListener listener = ImageLoader.getImageListener(iv_request, R.drawable.voice_to_short, R.drawable.ic_launcher); //get请求方式 mImageLoader .get("http://img.my.csdn.NET/uploads/201404/13/1397393290_5765.jpeg", listener); Log.d("ImageLoader", mImageLoader.toString()); } // import com.android.volley.Response.ErrorListener; private void volleyRequest() { StringRequest mRequest = new StringRequest(Method.GET, URL, new Response.Listener () { @Override public void onResponse(String response) { // TODO Auto-generated method stub Toast.makeText(getApplicationContext(), "onResponse ", Toast.LENGTH_LONG).show(); Log.d("on onResponse", response.toString());//请求成功 } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { // TODO Auto-generated method stub Toast.makeText(getApplicationContext(), "onErrorResponse", Toast.LENGTH_SHORT).show(); Log.d("on ErrorReponse", error.toString());//请求失败 } }); mRequestQueue.add(mRequest); } }
BitmapCache
package com.weixin.cache; import android.graphics.Bitmap; import android.support.v4.util.LruCache; import com.android.volley.toolbox.ImageLoader.ImageCache; public class BitmapCache implements ImageCache { private LruCachecache; public BitmapCache() { cache = new LruCache (8 * 1024 * 1024) { @Override protected int sizeOf(String key, Bitmap bitmap) { return bitmap.getRowBytes() * bitmap.getHeight(); } }; } @Override public Bitmap getBitmap(String url) { return cache.get(url); } @Override public void putBitmap(String url, Bitmap bitmap) { cache.put(url, bitmap); } }
布局文件activity_main.xml
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