此篇博客通过模拟连接MyEclipse搭建的服务器下载图片,实现在实际开发中的场景运用。

MainActivity的代码

package com.example.e13_listview3;import java.util.HashMap;import java.util.List;import android.os.AsyncTask;import android.os.Bundle;import android.app.Activity;import android.app.ProgressDialog;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.util.Log;import android.view.LayoutInflater;import android.view.Menu;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.ListView;import android.widget.TextView;public class MainActivity extends Activity {private ListView listView;private MyAdapter adapter;private ProgressDialog dialog; //创建一个进度条private byte[] data;private final static String PATH = "http://111.0.166.84:8080/http/";@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);listView = (ListView) this.findViewById(R.id.listView1);adapter = new MyAdapter();dialog = new ProgressDialog(MainActivity.this);dialog.setTitle("正在下载");dialog.setMessage("客官,请稍后.....");new MyTask().execute(PATH);}class MyTask extends AsyncTask>> {private List> list;@Overrideprotected void onPreExecute() {// TODO Auto-generated method stubdialog.show();super.onPreExecute();}@Overrideprotected List> doInBackground(String... params) {// TODO Auto-generated method stub//通过异步任务下载图片list = CitySource.getList();String name = (String) list.get(0).get("view");data = HttpUtils.sendPostMethod(params[0] + name + ".jpg");Log.i("info", "--------->" + PATH + name + ".jpg");return list;}@Overrideprotected void onPostExecute(List> result) {// TODO Auto-generated method stubadapter.setList(result);//如果数据有更新,该方法会自动更新listviewadapter.notifyDataSetChanged();listView.setAdapter(adapter);dialog.dismiss();super.onPostExecute(result);}}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}public class MyAdapter extends BaseAdapter {private List> list;public List> getList() {return list;}public void setList(List> list) {this.list = list;}@Overridepublic int getCount() {// TODO Auto-generated method stubreturn list.size();}@Overridepublic Object getItem(int arg0) {// TODO Auto-generated method stubreturn list.get(arg0);}@Overridepublic long getItemId(int arg0) {// TODO Auto-generated method stubreturn arg0;}@Overridepublic View getView(int position, View convertView, ViewGroup viewGroup) {// TODO Auto-generated method stubView view = null;if (convertView == null) {               //填充布局文件,仅在第一次启动的时候系统会调用该方法view = LayoutInflater.from(MainActivity.this).inflate(R.layout.item_list, null);} else {view = convertView;}Log.i("info", "-------->"+view);TextView text = (TextView) view.findViewById(R.id.textView1);ImageView imageView = (ImageView) view.findViewById(R.id.imageView1);text.setText((CharSequence) list.get(position).get("name"));Bitmap bm = BitmapFactory.decodeByteArray(data, 0, data.length);imageView.setImageBitmap(bm);return view;}}}

HttpUtiles获得网络连接

package com.example.e13_listview3;import java.io.IOException;import org.apache.http.HttpResponse;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.HttpClient;import org.apache.http.client.methods.HttpPost;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.util.EntityUtils;public class HttpUtils {    public static byte[] sendPostMethod(String url){byte[] result=null;HttpPost httpPost=new HttpPost(url);HttpClient client=new DefaultHttpClient();try {HttpResponse httpResponse=client.execute(httpPost);result=EntityUtils.toByteArray(httpResponse.getEntity());} catch (ClientProtocolException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}            return result;        }}

CitySource模拟远程服务器的列表数据

package com.example.e13_listview3;import java.util.ArrayList;import java.util.HashMap;import java.util.List;public class CitySource {public static List> getList(){List> list=new ArrayList>();HashMap map=new HashMap();map.put("name", "杭州");map.put("view", "hangzhou");HashMap map1=new HashMap();map1.put("name", "杭州");map1.put("view", "hangzhou");list.add(map);list.add(map1);return list;}}


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