ImageLoader简单使用
如图是效果图
我从接口拉出来的数据然后将它们展示在界面上
1 先定义布局 我定义了MyGridView来展示商品
2 导入jar包universal-image-loader-1.8.6-with-sources 用来展示商品使用 在使用 ImageLoader应加入
ImageLoader.getInstance().init(ImageLoaderConfiguration.createDefault(this));不然会报
java.lang.IllegalStateException: ImageLoader must be init with configuration before using字面意思是在使用前要初始化
3 定义适配器在getView中展示产品，不过我在展示的时候发现第一条数据总是在请求数据如下图，重复网址加载太慢也消耗服务器（也不知道是我哪里写错了第0条在重复请求 在网上我也没找到方法）
所以我定义了一个 View arrView[]有数据的时候就不许再请求了 这种解决的方法局限性很大 很不好
4 开启子线程 在子线程中加载数据，在handler中解析数据并将其展示在界面上
主要的代码如下
布局代码
package com.demo.content; import android.content.Context; import android.util.AttributeSet; import android.widget.GridView; public class MyGridView extends GridView { public MyGridView(Context context, AttributeSet attrs) { super(context, attrs); } public MyGridView(Context context) { super(context); } public MyGridView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } @Override public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int expandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2, MeasureSpec.AT_MOST); super.onMeasure(widthMeasureSpec, expandSpec); } }
<?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" > <ScrollView android:layout_width="match_parent" android:layout_height="match_parent" > <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:background="#eee" android:orientation="vertical" > <Button android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/app_name" android:textColor="#000" /> <View android:layout_width="match_parent" android:layout_height="5dp" android:background="@drawable/btn_normal" /> <com.demo.content.MyGridView android:id="@+id/gg_mygridview" android:layout_width="match_parent" android:layout_height="match_parent" android:horizontalSpacing="7dp" android:numColumns="2" android:verticalSpacing="7dp" /> </LinearLayout> </ScrollView> </LinearLayout>
1 package com.demo.activity; 2 3 import java.util.ArrayList; 4 import java.util.List; 5 import org.json.JSONArray; 6 import org.json.JSONObject; 7 import com.demo.content.MyGridView; 8 import com.demo.entity.Product; 9 import com.demo.pullrefresh.R; 10 import com.demo.util.GetThread; 11 import com.nostra13.universalimageloader.core.DisplayImageOptions; 12 import com.nostra13.universalimageloader.core.ImageLoader; 13 import com.nostra13.universalimageloader.core.ImageLoaderConfiguration; 14 import com.nostra13.universalimageloader.core.assist.ImageScaleType; 15 import com.nostra13.universalimageloader.core.display.FadeInBitmapDisplayer; 16 import android.annotation.SuppressLint; 17 import android.app.Activity; 18 import android.graphics.Bitmap; 19 import android.os.Bundle; 20 import android.os.Handler; 21 import android.util.Log; 22 import android.view.View; 23 import android.view.ViewGroup; 24 import android.widget.BaseAdapter; 25 import android.widget.ImageView; 26 import android.widget.TextView; 27 28 public class MyMainActivity extends Activity { 29 // 定义的布局 30 private MyGridView myGridView; 31 private DisplayImageOptions options; 32 // 产品 33 private List<Product> products; 34 // 地址 35 private String url = "" 36 + "Product/GetProductsByProType/12000000/20"; 37 38 @Override 39 protected void onCreate(Bundle arg0) { 40 // TODO Auto-generated method stub 41 super.onCreate(arg0); 42 setContentView(R.layout.mymainactivity); 43 options = new DisplayImageOptions.Builder() 44 .showImageForEmptyUri(R.drawable.ic_empty) 45 // image连接地址为空时 46 .showImageOnFail(R.drawable.ic_error) 47 // image加载失败 48 .resetViewBeforeLoading(true).cacheOnDisc(true) 49 .imageScaleType(ImageScaleType.EXACTLY) 50 .bitmapConfig(Bitmap.Config.RGB_565) 51 .displayer(new FadeInBitmapDisplayer(300))// 设置用户加载图片task（这里是渐现图片显示） 52 .build(); 53 // 创建默认的ImageLoader的参数 不加回报java.lang.IllegalStateException 54 // 但不是每次用到ImageLoader都要加 55 ImageLoader.getInstance().init( 56 ImageLoaderConfiguration.createDefault(this)); 57 myGridView = (MyGridView) findViewById(R.id.gg_mygridview); 58 // 开启线程 59 new GetThread(url, handler).start(); 60 } 61 62 @SuppressLint("HandlerLeak") 63 private Handler handler = new Handler() { 64 public void handleMessage(android.os.Message msg) { 65 switch (msg.what) { 66 case GetThread.SUCCESS: 67 String jsonString = (String) msg.obj; 68 // 用JSON来解析数据 69 products = getJsonProducts(jsonString); 70 Log.d("jiejie", "DDDDDDD" + products); 71 // 创建个适配器 72 Adapter adapter = new Adapter(); 73 myGridView.setAdapter(adapter); 74 break; 75 76 default: 77 break; 78 } 79 }; 80 }; 81 82 protected List<Product> getJsonProducts(String jsonString) { 83 List<Product> resultTempList = new ArrayList<Product>(); 84 try { 85 JSONArray array = new JSONArray(jsonString); 86 for (int i = 0; i < array.length(); i++) { 87 Product temProductSimple = new Product(); 88 JSONObject object = array.getJSONObject(i); 89 temProductSimple.setId(object.getInt("id")); 90 temProductSimple.setProType(object.getInt("ProType")); 91 temProductSimple.setProOrder(object.getInt("ProOrder")); 92 temProductSimple.setAddTime(object.getString("AddTime")); 93 temProductSimple.setTitle(object.getString("Title")); 94 temProductSimple.setSmallPic(object.getString("SmallPic")); 95 temProductSimple.setPrice(object.getDouble("Price")); 96 temProductSimple.setSalePrice(object.getDouble("SalePrice")); 97 temProductSimple.setZhishubi(object.getString("Zhishubi")); 98 temProductSimple.setProNo(object.getString("ProNo")); 99 temProductSimple.setContens(object.getString("Contens")); 100 temProductSimple.setBuyCount(object.getInt("BuyCount")); 101 temProductSimple.setReadCount(object.getInt("ReadCount")); 102 temProductSimple.setProImg(object.getString("ProImg")); 103 temProductSimple.setShopFlag(object.getString("ShopFlag")); 104 temProductSimple.setBrandId(object.getInt("BrandId")); 105 temProductSimple.setStartTime(object.getString("StartTime")); 106 if (object.get("Score") == null 107 || object.get("Score").toString() == "null") { 108 temProductSimple.setScore(0); 109 } else { 110 111 temProductSimple.setScore(object.getInt("Score")); 112 } 113 114 temProductSimple.setProductOrigin(object 115 .getString("ProductOrigin")); 116 if (object.get("kucun").toString() == "null") { 117 temProductSimple.setKucun(0); 118 119 } else { 120 temProductSimple.setKucun(object.getInt("kucun")); 121 } 122 123 resultTempList.add(temProductSimple); 124 } 125 } catch (Exception e) { 126 // TODO: handle exception 127 e.printStackTrace(); 128 System.out.println(e.toString()); 129 130 } 131 return resultTempList; 132 } 133 134 private View arrView[]; 135 136 private class Adapter extends BaseAdapter { 137 138 @Override 139 public int getCount() { 140 // TODO Auto-generated method stub 141 // return products.size(); 142 if (arrView == null) { 143 arrView = new View[products.size()]; 144 } 145 return products.size(); 146 } 147 148 @Override 149 public Object getItem(int arg0) { 150 // TODO Auto-generated method stub 151 return products.get(arg0); 152 } 153 154 @Override 155 public long getItemId(int arg0) { 156 // TODO Auto-generated method stub 157 return arg0; 158 } 159 160 @Override 161 public View getView(int arg0, View arg1, ViewGroup arg2) { 162 if (arrView[arg0] == null) { 163 Product info = products.get(arg0); 164 Holder holder = null; 165 if (null == arg1) { 166 holder = new Holder(); 167 168 arg1 = View.inflate(MyMainActivity.this, 169 R.layout.product_item, null); 170 holder.product_cost = (TextView) arg1 171 .findViewById(R.id.product_cost); 172 holder.product_title = (TextView) arg1 173 .findViewById(R.id.product_title); 174 holder.product_img = (ImageView) arg1 175 .findViewById(R.id.product_img); 176 holder.buy_count = (TextView) arg1 177 .findViewById(R.id.buy_count); 178 arg1.setTag(holder); 179 } else { 180 holder = (Holder) arg1.getTag(); 181 } 182 holder.product_cost.setText(products.get(arg0).getSalePrice() 183 + ""); 184 holder.product_title.setText(products.get(arg0).getTitle()); 185 holder.buy_count.setText(products.get(arg0).getBuyCount() + ""); 186 String urlString = "http://**/UploadImages/ProductImages/" 187 + products.get(arg0).getSmallPic(); 188 189 Log.d("jiejie", "dddddd___ " + arg0); 190 Log.d("jiejie", "_________" + info.getTitle()); 191 Log.d("jiejie", "ProducteGridAdapter--" + urlString); 192 ImageLoader.getInstance().displayImage(urlString, 193 holder.product_img, options); 194 195 arrView[arg0] = arg1; 196 } 197 return arrView[arg0]; 198 // return arg1; 199 200 } 201 202 } 203 204 static class Holder { 205 ImageView product_img; 206 TextView product_title; 207 TextView product_cost; 208 TextView buy_count; 209 } 210 }
package com.demo.util; import java.io.IOException; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.util.EntityUtils; import android.os.Handler; import android.os.Message; import android.util.Log; public class GetThread extends Thread { public static final int SUCCESS = 10, FAIL = -11; private String url; private Handler handler; public GetThread(String url, Handler handler) { this.url = url; this.handler = handler; } @Override public void run() { // TODO Auto-generated method stub super.run(); HttpClient httpClient = new DefaultHttpClient(); HttpGet httpGet = new HttpGet(url); try { HttpResponse httpResponse = httpClient.execute(httpGet); Message msg = Message.obtain(); Log.v("asdf", httpResponse.getStatusLine().getStatusCode() + "返回码 " + url); if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { String jsonString = EntityUtils.toString(httpResponse .getEntity()); msg.what = SUCCESS; msg.obj = jsonString; handler.sendMessage(msg); } else { msg.what = FAIL; handler.sendMessage(msg); } } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }
其中解析应该用JSON的jar包
String jsonString = (String) msg.obj; products = new Gson().fromJson(jsonString, new TypeToken<List<Product>>() { }.getType()); Log.d("jiejie", "解析的结果---"+products);
options = new DisplayImageOptions.Builder() // 设置图片URL为空或是错误的时候显示的图片 .showImageForEmptyUri(R.drawable.ic_empty) // image加载失败或解码过程中错误时候显示的图片 .showImageOnFail(R.drawable.ic_error) // 设置下载的图片是否缓存在内存中 .cacheInMemory(true) // 设置图片是否缓存在SD卡中 .cacheOnDisc(false) // 设置图片以如何的编码方式显示 .imageScaleType(ImageScaleType.EXACTLY) // 设置图片的解码类型 .bitmapConfig(Bitmap.Config.RGB_565) // 设置图片在下载前是否重置，复位 .resetViewBeforeLoading(true) // 设置图片加载好后渐入的动画事件 .displayer(new FadeInBitmapDisplayer(300))// 设置用户加载图片task（这里是渐现图片显示） .build();
/** * 清除内存缓存 */ public void clearMemoryCache() { imageLoader.clearMemoryCache(); } /** * 清除SD卡中的缓存 */ public void clearDiscCache() { imageLoader.clearDiscCache(); }