Android之异步任务AsyncTask解析XML数据

一、服务器端生成XML数据

①新建Web工程Web_AsyncTask_Xml

空白处右键->new->other->Web->Dynamic Web Project

②创建XML文件citys.xml

工程下面的WebContent右键->New ->other->XML->XMLFile->citys.xml，把新建的citys.xml文件拷贝一份放到包com.city.action下面，产生数据源，也就是说我在这个包里面把这个XML文件读出来，变成一个字符串而不是访问一个文件。（假设用手机访问天气预报，如果现在天气预报返回的格式是XML，当然这些数据是来自数据库，我们根本没有必要让这些数据生成一个文件，让用户再读这个文件。做练习是这样的，但是，实际开发开发并不是这样的，只需要在数据库中读取数据，直接把这些数据变成字符串，这样就少了一次Io读写。）

<?xml version="1.0" encoding="UTF-8"?>            Beijing                上海                广州                深圳

③在包com.city.action下面创建CityAction.java，接着创建CityDataSource.java（仿照上一篇Android之异步任务AsyncTask解析Json数据）

CityAction.java

package com.city.action;import java.io.IOException;import java.io.PrintWriter;import java.util.HashMap;import java.util.List;import java.util.Map;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import net.sf.json.JSONSerializer;/** * Servlet implementation class CityAction */@WebServlet("/CityAction")public class CityAction extends HttpServlet {private static final long serialVersionUID = 1L;    /**     * Default constructor.      */    public CityAction() {        // TODO Auto-generated constructor stub    }/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubthis.doPost(request, response);}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubresponse.setContentType("text/html;charset=utf-8");response.setCharacterEncoding("utf-8");request.setCharacterEncoding("utf-8");PrintWriter writer=response.getWriter();String type=request.getParameter("type");if(type.equals("xml")){String xmlString=CityDataSource.getCityListXML();//取出xmlwriter.println(xmlString);}writer.flush();writer.close();}}

CityDataSource.java

package com.city.action;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.Reader;import java.nio.charset.Charset;import java.util.ArrayList;import java.util.List;public class CityDataSource {public CityDataSource() {// TODO Auto-generated constructor stub}/** * 假设用手机访问天气预报，如果现在天气预报返回的格式是XML， 当然这些数据是来自数据库，我们根本没有必要让这些数据生成一个文件， * 让用户再读这个文件。做练习是这样的，但是，实际开发开发并不是这样的， 只需要在数据库中读取数据，直接把这些数据变成字符串，这样就少了一次Io读写。 *  * 使用InputStream去读，把XML变成一个字符串 *  *  * 服务器端的工作：把把字节流读取出来，放到StringBuilder中，并且什么都没解析，直接把结果通过一个字符串返回给客户端 * @return */public static String getCityListXML() {InputStream inputStream = CityDataSource.class.getClassLoader().getResourceAsStream("com/city/action/citys.xml");// 通过类的反射，得到一个类的加载器，然后用这个类的加载器去加载一个文件，这个文件就是一个流Reader reader=new InputStreamReader(inputStream,Charset.forName("utf-8"));//解决乱码BufferedReader bufferedReader=new BufferedReader(reader);//把一个流文件转换成字符串,把字节流转成字符流String value="";StringBuilder builder=new StringBuilder();try {while((value=bufferedReader.readLine())!=null){builder.append(value);}//System.out.println(builder.toString());//return new String(builder.toString().getBytes("iso8859-1"),"utf-8");//如果有乱码问题则加上这句话，在getCityListXML方法返回null} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{if(bufferedReader!=null){try {bufferedReader.close();} catch (Exception e2) {// TODO Auto-generated catch blocke2.printStackTrace();}}}//return list;return builder.toString();//return null;//如果有乱码，则加上getBytes("iso8859-1"),"utf-8")后再加上这句}public static void main(String[] args) {getCityListXML();}}

在地址栏输入http://192.168.1.100:8080/Web_AsyncTask_Xml/CityAction?type=xml显示如下

二、手机客户端

activity_main.xml

①添加访问网络权限

②新建包com.example.android_asynctask_xml.http，在包里面创建HttpUtils.java工具类

package com.example.android_asynctask_xml.http;import org.apache.http.HttpResponse;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 HttpUtils() {// TODO Auto-generated constructor stub}/** *  * @param path  获取指定路径的json信息 * @param encoding  指定编码格式 * @return */public static String sendPostMethod(String path,String encoding){String result="";HttpClient httpClient=new DefaultHttpClient();try {HttpPost post=new HttpPost(path);HttpResponse response=httpClient.execute(post);if(response.getStatusLine().getStatusCode()==200){result=EntityUtils.toString(response.getEntity(), encoding);}} catch (Exception e) {// TODO: handle exceptione.printStackTrace();}finally{httpClient.getConnectionManager().shutdown();//关闭连接}return result;}}

③新建包com.example.android_asynctask_xml.Entity，在包里面创建实体类City.java

package com.example.android_asynctask_xml.Entity;public class City {private String name;public String getName() {return name;}public void setName(String name) {this.name = name;}}

④新建包com.example.android_asynctask_xml.xml，在包里面创建工具类XMLTools.java

package com.example.android_asynctask_xml.xml;import java.io.StringReader;import java.util.ArrayList;import java.util.List;import org.xmlpull.v1.XmlPullParser;import org.xmlpull.v1.XmlPullParserFactory;import com.example.android_asynctask_xml.Entity.City;public class XMLTools {public XMLTools() {// TODO Auto-generated constructor stub}/** *  * 解析XML文件 * 利用XML解析工厂XmlPullParserFactory，通过工厂new一个解析器newPullParser *  * 在Mainactivity.java中调用 * @param xmlString * @return */public static List parseXML(String xmlString){List list=null;City city=null;try {XmlPullParserFactory factory=XmlPullParserFactory.newInstance();XmlPullParser parser=factory.newPullParser();parser.setInput(new StringReader(xmlString));int eventType=parser.getEventType();while(eventType!=XmlPullParser.END_DOCUMENT){switch (eventType) {case XmlPullParser.START_DOCUMENT:list=new ArrayList();break;case XmlPullParser.START_TAG:if("city".equals(parser.getName())){city=new City();}else if("name".equals(parser.getName())){String name=parser.nextText();city.setName(name);}break;case XmlPullParser.END_TAG:if("city".equals(parser.getName())){list.add(city);city=null;}break;}eventType=parser.next();}} catch (Exception e) {// TODO: handle exceptione.printStackTrace();}return list;}}

⑤在包com.example.android_asynctask_xml里面MainActivity.java

package com.example.android_asynctask_xml;import java.util.ArrayList;import java.util.List;import com.example.android_asynctask_xml.Entity.City;import com.example.android_asynctask_xml.http.HttpUtils;import com.example.android_asynctask_xml.xml.XMLTools;import android.support.v7.app.ActionBarActivity;import android.app.ProgressDialog;import android.os.AsyncTask;import android.os.Bundle;import android.util.Log;import android.view.Menu;import android.view.MenuItem;import android.widget.ArrayAdapter;import android.widget.Spinner;public class MainActivity extends ActionBarActivity {private final String TAG="MainActivity";private Spinner spinner1;private final String CITY_PATH="http://192.168.1.100:8080/Web_AsyncTask_Xml/CityAction?type=xml";private ArrayAdapter adapter;private ProgressDialog dialog;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);spinner1=(Spinner) this.findViewById(R.id.spinner1);//加载Spinner控件//adapter=new ArrayAdapter(context, resource, textViewResourceId);//spinner1.setAdapter(adapter);//这句话执行完之后，数据就已经有了，所以这行代码应该在另外一个线程中实现，然后再更新UIdialog=new ProgressDialog(MainActivity.this);dialog.setTitle("提示");dialog.setMessage("正在加载...");new MyTask().execute(CITY_PATH);//执行异步任务}class MyTask extends AsyncTask>{@Overrideprotected void onPreExecute() {// TODO Auto-generated method stubsuper.onPreExecute();dialog.show();}@Overrideprotected void onPostExecute(List result) {// TODO Auto-generated method stubsuper.onPostExecute(result);List list=new ArrayList();for(int i=0;i(MainActivity.this, android.R.layout.simple_spinner_dropdown_item, list);//构建适配器spinner1.setAdapter(adapter);dialog.dismiss();}/** * 注意：在做Android开发过程中HttpUtils和JsonTools工具类是必须要有的 * 在一个项目中json数据格式有可能有四到五种，所以工具类里的方法要有四到五个方法来解析 */@Overrideprotected List doInBackground(String... params) {// TODO Auto-generated method stubList list=null;String xmlString=HttpUtils.sendPostMethod(params[0], "utf-8");//Log.i(TAG, "--->>"+xmlString);//验证能否将xml数据取到本地list=XMLTools.parseXML(xmlString);//System.out.println("--list--"+list);return list;}//List这个结果表示json解析之后的结果，结果会很快塞到适配器当中}@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;}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {// Handle action bar item clicks here. The action bar will// automatically handle clicks on the Home/Up button, so long// as you specify a parent activity in AndroidManifest.xml.int id = item.getItemId();if (id == R.id.action_settings) {return true;}return super.onOptionsItemSelected(item);}}

具体步骤可以借鉴上一篇 Android之异步任务AsyncTask解析Json数据

运行效果图

更多相关文章

随机推荐