RSS解析技术的应用

源码：

ActivityShowDescription.java

 

package cn.bzu.saxparseraccess_listshow.activity;import android.os.Bundle;import android.app.Activity;import android.content.Intent;import android.view.View;import android.widget.Button;import android.widget.TextView;public class ActivityShowDescription extends Activity {public void onCreate(Bundle icicle) {super.onCreate(icicle);setContentView(R.layout.activity_activity_show_description);String content = null;Intent startingIntent = getIntent();if (startingIntent != null) {Bundle bundle = startingIntent.getBundleExtra("android.intent.extra.rssItem");if (bundle == null) {content = "不好意思程序出错啦";} else {content = bundle.getString("title") + "\n\n"+ bundle.getString("pubDate") + "\n\n"+ bundle.getString("description")+ "\n\n详细信息请访问以下网址:\n" + bundle.getString("link");}} else {content = "不好意思程序出错啦";}TextView textView = (TextView) findViewById(R.id.content);textView.setText(content);Button backbutton = (Button) findViewById(R.id.back);backbutton.setOnClickListener(new Button.OnClickListener() {public void onClick(View v) {finish();}});}}

MainActivity.java

package cn.bzu.saxparseraccess_listshow.activity;import java.net.MalformedURLException;import org.xml.sax.SAXException;import cn.bzu.saxparseraccess_listshow.activity.R;import cn.bzu.saxparseraccess_listshow.entity.RssFeed;import cn.bzu.saxparseraccess_listshow.entity.RssItem;import cn.bzu.saxparseraccess_listshow.saxparser.RssFeed_SAXParser;import android.os.Bundle;import android.app.Activity;import android.content.Intent;import android.view.View;import android.widget.AdapterView;import android.widget.AdapterView.OnItemClickListener;import android.widget.ListView;import android.widget.SimpleAdapter;public class MainActivity extends Activity implements OnItemClickListener{// 从网络获取RSS地址public final String RSS_URL = "http://blog.sina.com.cn/rss/1267454277.xml";public final String tag = "RSSReader";private RssFeed feed = null;public void onCreate(Bundle icicle) {super.onCreate(icicle);setContentView(R.layout.activity_main);try {// 调用getFeed方法,从服务器取得rss提要feed = new RssFeed_SAXParser().getFeed(RSS_URL);} catch (MalformedURLException e) {e.printStackTrace();} catch (SAXException e) {e.printStackTrace();} catch (Exception e) {e.printStackTrace();}showListView(); // 把rss内容绑定到ui界面进行显示}private void showListView() {ListView itemlist = (ListView) findViewById(R.id.itemlist);if (feed == null) {setTitle("访问的RSS无效");return;}SimpleAdapter adapter = new SimpleAdapter(this,feed.getAllItemsForListView(),android.R.layout.simple_list_item_2, new String[] {RssItem.TITLE, RssItem.PUBDATE }, new int[] {android.R.id.text1, android.R.id.text2 });itemlist.setAdapter(adapter); // listview绑定适配器itemlist.setOnItemClickListener(this); // 设置itemclick事件代理itemlist.setSelection(0);}@SuppressWarnings("rawtypes")public void onItemClick(AdapterView parent, View v, int position, long id) // itemclick事件代理方法{Intent itemintent = new Intent(this, ActivityShowDescription.class);// 构建一个“意图”，用于指向activity// ：detailBundle b = new Bundle(); // 构建buddle，并将要传递参数都放入buddleb.putString("title", feed.getItem(position).getTitle());b.putString("description", feed.getItem(position).getDescription());b.putString("link", feed.getItem(position).getLink());b.putString("pubDate", feed.getItem(position).getPubDate());itemintent.putExtra("android.intent.extra.rssItem", b); // 用android.intent.extra.INTENT的名字来传递参数startActivityForResult(itemintent, 0);}}

RssFeed.java

package cn.bzu.saxparseraccess_listshow.entity;import java.util.ArrayList;import java.util.HashMap;import java.util.List;public class RssFeed {private String title;// 标题private String pubDate;// 发布日期  我的这错了，url的日期为pubDate而我定义的是pubdateprivate int itemCount;// 用于计算列表的数目private List<RssItem> rssItems;// 用于描述列表 itempublic RssFeed() {rssItems = new ArrayList<RssItem>();}// 返回列表的长度 添加RssItem条目public int addItem(RssItem item) {rssItems.add(item);//一开始这出空指针，原因 rssItem未初始化itemCount++;return itemCount;}// 根据下标获取RssItempublic RssItem getItem(int location) {return rssItems.get(location);}// 为ListView 设置HashMap<String,Object>public List<HashMap<String, Object>> getAllItemsForListView() {List<HashMap<String, Object>> data = new ArrayList<HashMap<String, Object>>();int size = rssItems.size();for (int i = 0; i < size; i++) {HashMap<String, Object> item = new HashMap<String, Object>();item.put(RssItem.TITLE, rssItems.get(i).getTitle());item.put(RssItem.PUBDATE, rssItems.get(i).getPubDate());  data.add(item);}return data;}public String getTitle() {return title;}public void setTitle(String title) {this.title = title;}public String getPubDate() {return pubDate;}public void setPubdate(String pubDate) {this.pubDate = pubDate;}public int getItemCount() {return rssItems.size();}public List<RssItem> getRssItems() {return rssItems;}}

RssItem,java

package cn.bzu.saxparseraccess_listshow.entity;public class RssItem {//为什幺定义这两个字符串呢，因为RssFeed的getAllItemsForListView() 会用到public static final String TITLE="title";public static final String PUBDATE="pubDate";private String title;private String description;private String link;private String category;private String pubDate;public RssItem() {}public String getTitle() {if(title.length()>42){//return title.substring(0, 42)+"...";//越界了return title.substring(0,42);}return title;}public void setTitle(String title) {this.title = title;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}public String getLink() {return link;}public void setLink(String link) {this.link = link;}public String getCategory() {return category;}public void setCategory(String category) {this.category = category;}public String getPubDate() {return pubDate;}public void setPubDate(String pubDate) {this.pubDate = pubDate;}@Overridepublic String toString() {return "RssItem [title=" + title + ", description=" + description+ ", link=" + link + ", category=" + category + ", pubDate="+ pubDate + "]";}}

RssFeed_SAXParser.java

package cn.bzu.saxparseraccess_listshow.saxparser;import java.net.MalformedURLException;import java.net.URL;import javax.xml.parsers.ParserConfigurationException;import javax.xml.parsers.SAXParser;import javax.xml.parsers.SAXParserFactory;import org.xml.sax.InputSource;import org.xml.sax.SAXException;import org.xml.sax.SAXNotRecognizedException;import org.xml.sax.SAXNotSupportedException;import org.xml.sax.XMLReader;import cn.bzu.saxparseraccess_listshow.entity.RssFeed;import cn.bzu.saxparseraccess_listshow.service.RssHandler;public class RssFeed_SAXParser {public RssFeed getFeed(String urlStr) throws MalformedURLException, Exception, SAXException{//需要穿一个URL地址    URL url=new URL(urlStr);    System.out.println("RssFeed_SAXParser-->url:"+url);    SAXParserFactory parserFactory=SAXParserFactory.newInstance();//构建sax解析工厂    SAXParser saxParser=parserFactory.newSAXParser();//解析工厂生产解析器    XMLReader xmlReader=saxParser.getXMLReader();//通过saxParser构建xmlReader阅读器    //构建自定义的xml解析器 作为 xmlReader的处理器（代理）    RssHandler rssHandler=new RssHandler();        xmlReader.setContentHandler(rssHandler);    //使用url打开流，并将流作为 xmlReader解析的输入源并解析    InputSource is=new InputSource(url.openStream());        xmlReader.parse(is);        return rssHandler.getRssFeed();}}

RssHandler.java

package cn.bzu.saxparseraccess_listshow.service;import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.helpers.DefaultHandler;import android.util.Log;import cn.bzu.saxparseraccess_listshow.entity.RssFeed;import cn.bzu.saxparseraccess_listshow.entity.RssItem;public class RssHandler extends DefaultHandler {RssFeed rssFeed;// 用于保存解析过程中的channelRssItem rssItem;// 用于保存解析过程中的itemString lastElementName = "";// 标记变量，用于标记在解析过程中我们关心的几个标签，若不是我们关心的标签记做0final int RSS_TITLE = 1;// 若是 title 标签，记做1，注意有两个title，但我们都保存在item的成员变量中final int RSS_LINK = 2;// 若是 link 标签，记做2final int RSS_DESCRIPTION = 3;// 若是 description 标签，记做3final int RSS_CATEGORY = 4;// 若是category标签,记做 4final int RSS_PUBDATE = 5; // 若是pubdate标签,记做// 5,注意有两个pubdate,但我们都保存在item的pubdate成员变量中int currentstate = 0;public RssHandler() {}// 下面通过重载 DefaultHandler 的 5 个方法来实现 sax 解析// 1. 这个方法在解析xml文档的一开始执行,一般我们需要在该方法中初始化解析过程中有可能用到的变量@Overridepublic void startDocument() throws SAXException {super.startDocument();rssFeed = new RssFeed();        rssItem = new RssItem();  }// 2. 当遇到文本结点时进行处理，空白符不用做处理，只需要对字符做处理@Overridepublic void characters(char[] ch, int start, int length)throws SAXException {super.characters(ch, start, length);// 获取字符串String text = new String(ch, start, length);Log.i("i", "要获取的内容："+text);// 判断当前标志位 与那一种标志相同，然后做相应处理switch (currentstate) {case RSS_TITLE:rssItem.setTitle(text);currentstate = 0;// 设置完后，重置为开始状态break;case RSS_PUBDATE:rssItem.setPubDate(text);System.out.println("RssHandler.pubDate:"+rssItem.getPubDate());currentstate = 0;// 设置完后，重置为开始状态break;case RSS_CATEGORY:rssItem.setCategory(text);currentstate = 0;// 设置完后，重置为开始状态break;case RSS_LINK:rssItem.setLink(text);currentstate = 0;// 设置完后，重置为开始状态break;case RSS_DESCRIPTION:System.out.println("RssHandler.characters:"+text);rssItem.setDescription(text);System.out.println("RssHandler.characters:Description="+rssItem.getDescription());currentstate = 0;// 设置完后，重置为开始状态break;default:break;}}/** * 3. 这个方法在解析标签开始标记时执行,一般我们需要在该方法取得标签属性值,但由于我们的rss文档 * 中并没有任何我们关心的标签属性,因此我们主要在这里进行的是设置标记变量currentstate, 以 标记我们处理到哪个标签 */@Overridepublic void startElement(String uri, String localName, String qName,Attributes attributes) throws SAXException {super.startElement(uri, localName, qName, attributes);// localName:不含命名空间前缀的标签名(建议使用)// qName:含有命名空间前缀的标签名// attributes:接收属性值if ("chanel".equals(localName)) {// 这个标签内没有我们关心的内容，所以不作处理，currentState=0currentstate = 0;return;}if ("item".equals(localName)) {/* * 若是item标签,则重新构造一个RSSItem,从而把已有(已经解析过的)item数据扔掉, 当 * 然事先是已经保存到rssFeed的itemlist集合中 */rssItem = new RssItem();return;}if ("title".equals(localName)) {// 若是title标签,置currentstate为1,表明这是我们关心的数据,// 这样在characters 方法中会把元素内容保存到rssItem变量中currentstate = RSS_TITLE;return;}if ("description".equals(localName)) {currentstate = RSS_DESCRIPTION;return;}if ("link".equals(localName)) {currentstate = RSS_LINK;return;}if ("pubDate".equals(localName)) {//忘了修改pubDate，所以最后结果老是nullcurrentstate = RSS_PUBDATE;return;}if ("category".equals(localName)) {currentstate = RSS_CATEGORY;return;}}// 4. 结束元素节点@Overridepublic void endElement(String uri, String localName, String qName)throws SAXException {super.endElement(uri, localName, qName);// 如果解析一个item节点结束，就将rssItem添加到rssFeed中。if ("item".equals(localName)) {rssFeed.addItem(rssItem);return;}}@Overridepublic void endDocument() throws SAXException {super.endDocument();// 这个方法在整个xml文档解析结束时执行,一般需要在该方法中返回或保存整个文档解析解析结果,// 但由于我们已经在解析过程中把结果保持在rssFeed中,所以这里什么也不做}public RssFeed getRssFeed() {return rssFeed;}}

布局文件：

activity_activity_show_description.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >    <TextView        android:id="@+id/content"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_weight="1.0"        android:autoLink="all"        android:text="" />    <Button        android:id="@+id/back"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="返回" /></LinearLayout>

activity_main.xml

<RelativeLayout 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" >    <ListView         android:id="@+id/itemlist"        android:layout_width="fill_parent"        android:layout_height="fill_parent"        /></RelativeLayout>

看一下运行图：