android中volley的应用
nwqw9564
8年前
来自： http://blog.csdn.net//chenguang79/article/details/44256981
Volley可说是把AsyncHttpClient和Universal-Image-Loader的优点集于了一身，既可以像AsyncHttpClient一样非常简单地进行HTTP通信，也可以像Universal-Image-Loader一样轻松加载网络上的图片。除了简单易用之外，Volley在性能方面也进行了大幅度的调整，它的设计目标就是非常适合去进行数据量不大，但通信频繁的网络操作，而对于大数据量的网络操作，比如说下载文件等，Volley的表现就会非常糟糕。
这里我用一个例子来演示一下，volley在ListView中的使用，并且listVIew中有图片加载。
主页面布局：activity_volley_json_image_test.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <ListView android:id="@+id/lv_volley" android:layout_width="fill_parent" android:layout_height="fill_parent"></ListView> <TextView android:id="@+id/txt_info" android:layout_width="fill_parent" android:layout_height="fill_parent" android:text="数据加载中......" android:textSize="18sp" android:gravity="center" android:visibility="gone"/> </LinearLayout> ListView中item的布局 <pre name="code" class="html"><?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"> <com.android.volley.toolbox.NetworkImageView android:id="@+id/img_pic" android:layout_width="100dp" android:layout_height="100dp" /> <LinearLayout android:layout_width="wrap_content" android:layout_height="100dp" android:orientation="vertical" android:layout_marginLeft="5dp"> <TextView android:id="@+id/txt_title" android:layout_width="wrap_content" android:layout_height="49dp" android:text="这是标题" android:gravity="center_vertical"/> <TextView android:id="@+id/txt_time" android:layout_width="wrap_content" android:layout_height="49dp" android:text="2015-03-12" android:gravity="center_vertical"/> </LinearLayout> </LinearLayout>
程序代码：Volley_Json_image_test
package com.example.cg.fangduo; import android.app.Activity; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.AbsListView; import android.widget.ListView; import android.widget.TextView; import com.android.volley.Request; import com.android.volley.RequestQueue; import com.android.volley.Response; import com.android.volley.VolleyError; import com.android.volley.toolbox.StringRequest; import com.android.volley.toolbox.Volley; import org.json.JSONArray; import org.json.JSONObject; import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map; public class Volley_Json_image_test extends Activity { //定义listview private ListView lv_volley; //定义提示暂无数据 private TextView txt_info; //定义volley请求 public RequestQueue mQueue; //定义数据 public List<Map<String, Object>> info; //定义列表的Adapter; public Volley_Json_image_Adapter volleyAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_volley__json_image_test); initView(); } /** * 初始化控件与信息 */ private void initView() { //初始化listview,初始时，因为数据从远程加载，所以在数据加载未完时，将listview设置为不可见 lv_volley = (ListView)this.findViewById(R.id.lv_volley); lv_volley.setOnScrollListener(new ScrollListener()); lv_volley.setVisibility(View.GONE); //初始化暂无数据,因为数据从远程加载，所以数据加载中的提示显示 txt_info = (TextView)this.findViewById(R.id.txt_info); txt_info.setVisibility(View.VISIBLE); //初始化volley请求 mQueue = Volley.newRequestQueue(this); //加载数据 // [{"notepic":"http://image.baidu.com/i?ct=503316480&tn=baiduimagedetail&statnum=girl&ipn=d&z=0&fr=ala&s=0&ic=0&lm=-1&itg=0&cg=girl&word=%E7%BE%8E%E5%A5%B3%E5%9B%BE%E7%89%87&ie=utf-8&in=3354&cl=2&st=&pn=6&rn=1&di=&ln=31000&&fmq=1378374347070_R&se=&sme=0&tab=&face=&&is=0,132526&cs=0,0&adpicid=0&pi=14147590090&os=0&istype=&ist=&jit=&objurl=http%3A%2F%2Fc.hiphotos.baidu.com%2Fimage%2Fpic%2Fitem%2F377adab44aed2e7341c3f0578401a18b87d6faa7.jpg","noteTypeid":1,"noteid":1,"noteFast":0,"noteTitle":"欢迎来到这个神奇的世界","noteDateTime":"2014-7-6"}, // {"notepic":"http://img3.imgtn.bdimg.com/it/u=2638575563,3145336706&fm=23&gp=0.jpg","noteTypeid":1,"noteid":2,"noteFast":0,"noteTitle":"今天好忙","noteDateTime":"2014-8-17"}, // {"notepic":"http://img1.imgtn.bdimg.com/it/u=2816850553,3679993090&fm=23&gp=0.jpg","noteTypeid":1,"noteid":3,"noteFast":0,"noteTitle":"不想加班","noteDateTime":"2014-8-17"}, // {"notepic":"http://img4.imgtn.bdimg.com/it/u=793795634,3401984036&fm=23&gp=0.jpg","noteTypeid":1,"noteid":4,"noteFast":0,"noteTitle":"美女图1","noteDateTime":"2014-8-29"}, // {"notepic":"http://img4.imgtn.bdimg.com/it/u=2978660446,2856475006&fm=23&gp=0.jpg","noteTypeid":1,"noteid":5,"noteFast":0,"noteTitle":"美女图2","noteDateTime":"2014-8-29"}, // {"notepic":"http://img5.imgtn.bdimg.com/it/u=1111035714,1878413225&fm=23&gp=0.jpg","noteTypeid":1,"noteid":5,"noteFast":0,"noteTitle":"美女图3","noteDateTime":"2014-8-29"}, // {"notepic":"http://img1.imgtn.bdimg.com/it/u=3981637234,1431600967&fm=23&gp=0.jpg","noteTypeid":1,"noteid":5,"noteFast":0,"noteTitle":"美女图4","noteDateTime":"2014-8-29"}, // {"notepic":"http://img3.imgtn.bdimg.com/it/u=1471976729,3245530376&fm=23&gp=0.jpg","noteTypeid":1,"noteid":5,"noteFast":0,"noteTitle":"美女图5","noteDateTime":"2014-8-29"}, // {"notepic":"http://img1.imgtn.bdimg.com/it/u=992411909,4001832108&fm=23&gp=0.jpg","noteTypeid":1,"noteid":5,"noteFast":0,"noteTitle":"美女图6","noteDateTime":"2014-8-29"}, // {"notepic":"http://img3.imgtn.bdimg.com/it/u=1438096542,2010064131&fm=23&gp=0.jpg","noteTypeid":1,"noteid":5,"noteFast":0,"noteTitle":"美女图7","noteDateTime":"2014-8-29"}, // {"notepic":"http://img1.imgtn.bdimg.com/it/u=2348235091,3744783718&fm=21&gp=0.jpg","noteTypeid":1,"noteid":5,"noteFast":0,"noteTitle":"美女图8","noteDateTime":"2014-8-29"}, // {"notepic":"http://img3.imgtn.bdimg.com/it/u=486736756,3902182809&fm=21&gp=0.jpg","noteTypeid":1,"noteid":5,"noteFast":0,"noteTitle":"美女图9","noteDateTime":"2014-8-29"}, // {"notepic":"http://img2.imgtn.bdimg.com/it/u=2671166332,507275986&fm=21&gp=0.jpg","noteTypeid":1,"noteid":5,"noteFast":0,"noteTitle":"美女图10","noteDateTime":"2014-8-29"}, // {"notepic":"http://img5.imgtn.bdimg.com/it/u=1857438318,1706082473&fm=21&gp=0.jpg","noteTypeid":1,"noteid":5,"noteFast":0,"noteTitle":"美女图11","noteDateTime":"2014-8-29"}, // {"notepic":"http://img0.imgtn.bdimg.com/it/u=547181070,2589863976&fm=21&gp=0.jpg","noteTypeid":1,"noteid":5,"noteFast":0,"noteTitle":"美女图12","noteDateTime":"2014-8-29"}, // {"notepic":"http://img4.imgtn.bdimg.com/it/u=1319733707,1742255567&fm=11&gp=0.jpg","noteTypeid":1,"noteid":6,"noteFast":0,"noteTitle":"美女图13","noteDateTime":"2014-8-29"}] StringRequest jsonRequest = new StringRequest(Request.Method.GET,"http://172.31.0.163:9090/VolleyData.ashx?flag=1", new Response.Listener<String>(){ @Override public void onResponse(String jsonObject) { txt_info.setVisibility(View.GONE); lv_volley.setVisibility(View.VISIBLE); Log.v("Volley_Json_image_test:",jsonObject.toString()); info = getlistForJson(jsonObject); volleyAdapter = new Volley_Json_image_Adapter(Volley_Json_image_test.this,info); lv_volley.setAdapter(volleyAdapter); } }, new Response.ErrorListener(){ @Override public void onErrorResponse(VolleyError volleyError) { Log.e("onErrorResponse:",volleyError.toString()); } }); mQueue.add(jsonRequest); //mQueue.start(); } /** * 定义当ListViwe滚动时触发的事件 */ class ScrollListener implements AbsListView.OnScrollListener { @Override public void onScrollStateChanged(AbsListView view, int scrollState) { } @Override public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { int lastItemid = lv_volley.getLastVisiblePosition(); if((lastItemid + 1) == totalItemCount) { //只有当列表数大于0（或是小于30时,加新数据。这个30是为了不让他重复加载） if(totalItemCount < 30 && totalItemCount > 0) { //加载数据 StringRequest jsonRequest2 = new StringRequest(Request.Method.GET, "http://172.31.0.163:9090/VolleyData.ashx?flag=2", new Response.Listener<String>() { @Override public void onResponse(String jsonObject) { info.addAll(getlistForJson(jsonObject)); volleyAdapter.notifyDataSetChanged(); } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError volleyError) { Log.e("onErrorResponse:", volleyError.toString()); } }); mQueue.add(jsonRequest2); } } } } /** * Json 转成 Map<> * @param jsonStr * @return */ public static Map<String, Object> getMapForJson(String jsonStr){ JSONObject jsonObject ; try { jsonObject = new JSONObject(jsonStr); Iterator<String> keyIter= jsonObject.keys(); String key; Object value ; Map<String, Object> valueMap = new HashMap<String, Object>(); while (keyIter.hasNext()) { key = keyIter.next(); value = jsonObject.get(key); valueMap.put(key, value); } return valueMap; } catch (Exception e) { // TODO: handle exception e.printStackTrace(); //Log.e(HttpClientUtils.TAG, e.toString()); } return null; } /** * Json 转成 List<Map<>> * @param jsonStr * @return */ public static List<Map<String, Object>> getlistForJson(String jsonStr){ List<Map<String, Object>> list = null; try { JSONArray jsonArray = new JSONArray(jsonStr); JSONObject jsonObj ; list = new ArrayList<Map<String,Object>>(); for(int i = 0 ; i < jsonArray.length() ; i ++){ jsonObj = (JSONObject)jsonArray.get(i); list.add(getMapForJson(jsonObj.toString())); } } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } return list; } } listView的Adapter的代码：Volley_Json_image_Adapter
package com.example.cg.fangduo; import android.content.Context; import android.graphics.Bitmap; import android.util.LruCache; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.TextView; import com.android.volley.RequestQueue; import com.android.volley.toolbox.ImageLoader; import com.android.volley.toolbox.NetworkImageView; import com.android.volley.toolbox.Volley; import java.util.List; import java.util.Map; /** * Created by cg on 2015/3/12. */ public class Volley_Json_image_Adapter extends BaseAdapter { private LayoutInflater inflater; //源数据 private List<Map<String, Object>> jsonInfo; //定义volley private RequestQueue mQueue; private ImageLoader imageLoader; public Volley_Json_image_Adapter(Context context, List<Map<String, Object>> jsonInfo) { this.jsonInfo = jsonInfo; this.inflater = LayoutInflater.from(context); mQueue = Volley.newRequestQueue(context); imageLoader = new ImageLoader(mQueue,new BitmapCache(){ @Override public Bitmap getBitmap(String s) { return null; } @Override public void putBitmap(String s, Bitmap bitmap) { } }); } @Override public int getCount() { return jsonInfo.size(); } @Override public Object getItem(int position) { return jsonInfo.get(position); } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { VolleyInfo volleyInfo; if(convertView==null) { volleyInfo = new VolleyInfo(); convertView = inflater.inflate(R.layout.lv_volley_item, null); volleyInfo.img_pic = (NetworkImageView)convertView.findViewById(R.id.img_pic); volleyInfo.txt_title = (TextView)convertView.findViewById(R.id.txt_title); volleyInfo.txt_time = (TextView)convertView.findViewById(R.id.txt_time); convertView.setTag(volleyInfo); }else { volleyInfo = (VolleyInfo)convertView.getTag(); } volleyInfo.txt_title.setText(jsonInfo.get(position).get("noteTitle").toString()); volleyInfo.txt_time.setText(jsonInfo.get(position).get("noteDateTime").toString()); //为图片控件加载图片，采用NetworkImageView控件。 //第一项是加载图片控件的默认图片，一般是图片加载中，这样的图片 //第二项是当发生错误的时候加载的图片，如网络图片路径不对或是加载失败的时候显示的图片 //第三项就是加载网络图片了 volleyInfo.img_pic.setDefaultImageResId(R.drawable.noimg); volleyInfo.img_pic.setErrorImageResId(R.drawable.a01); volleyInfo.img_pic.setImageUrl(jsonInfo.get(position).get("notepic").toString(),imageLoader); return convertView; } public class VolleyInfo { NetworkImageView img_pic; TextView txt_title; TextView txt_time; } /** * 对图片进行防OOM处理 */ public class BitmapCache implements ImageLoader.ImageCache{ private LruCache<String,Bitmap> mCache; public BitmapCache(){ int maxSize = 10*1024*1024; mCache = new LruCache<String, Bitmap>(maxSize){ protected int sizeOf(String key,Bitmap bitmap) { return bitmap.getRowBytes() * bitmap.getHeight(); } }; } @Override public Bitmap getBitmap(String url) { return mCache.get(url); } @Override public void putBitmap(String url, Bitmap bitmap) { mCache.put(url,bitmap); } } } 如果你想对Volley了解的更细一点，请参看：
http://blog.csdn.net/guolin_blog/article/details/17482095