Java数据解析---PULL

安卓和JAVA解析xml文件的三种方式:

1、PULL解析

2、SAX解析

3、DOM解析

三者各有所长，依情况选择解析方式

1、PULL和SAX均采用流式解析，意味着只能从头读到底，无法像DOM解析一样随机访问xml文件中的任意一个节点

2、PULL和SAX占用更少的内存解析，更适用于安卓上的解析xml文件

3、DOM解析时将文件全部解析完，最后让用户任意取特定的信息

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下面学习PULL解析方式。（PULL方法的简洁性是它最大的优势）

1、解析本地xml文件

  public class PullParser {

      public List<Worker> pullParsers() throws XmlPullParserException, IOException
      {
          List<Worker> list = null;
          Worker worker = null;
          //第一步：创建XML解析对象，需要通过工厂模式创建类的实例
          XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
          XmlPullParser parser = factory.newPullParser();
 //        第二步：设置待解析的xml数据源
         FileInputStream fis = new FileInputStream("worker.xml");
         parser.setInput(fis,"utf-8");
 //        第三步：获取当前xml标签的事件类型
         int event = parser.getEventType();
 //        第四步：通过分支语句处理不同的事件标签
         while(event!=XmlPullParser.END_DOCUMENT)
         {

             switch(event)
             {
 //            第五步：获取标签名称，处理标签信息
             case XmlPullParser.START_DOCUMENT://解析文件开始，创建列表集合对象
                 list = new ArrayList<Worker>();
                 break;
             case XmlPullParser.START_TAG:
                 String tagName = parser.getName();
                 if("worker".equals(tagName))
                 {
                     worker = new Worker();
                     int count = parser.getAttributeCount();//得到属性的个数
                     for(int i=;i<count;i++)
                     {
                         String attrName = parser.getAttributeName(i);
                         String attrValue = parser.getAttributeValue(i);
                         if("id".equals(attrName))
                             worker.setId(attrValue);
                     }
                 }
                 else if("name".equals(tagName))
                     worker.setName(parser.nextText());
                     worker.setMoney(Double.parseDouble(parser.nextText()));
                 break;

             case XmlPullParser.END_TAG://解析文件结束，
                  if("worker".equals(parser.getName()))
                  {
 //                第六步：将处理的数据保存到JavaBean或Map对象中
                      list.add(worker);
                      worker = null;
                  }
                  break;
             }
 //            第七步：获取下一个标签的事件类型，判断事件类型是否为文档结束事件，如果是则退出，反之重复第四、五、六步
             event = parser.next();
         }
         return list;
     }

     /**
60      * @param args
61      * @throws IOException
62      * @throws XmlPullParserException
63      */
     public static void main(String[] args) throws XmlPullParserException, IOException {
         PullParser  pullParser = new PullParser();
         List<Worker> list = pullParser.pullParsers();

         for(Worker w:list)
         {
             System.out.println(w);
         }
     }

 }

Demo

 <?xml version="1.0" encoding="UTF-8"?>
 <workers>
     <worker id="AQ01">
         <name>Mark</name>
     </worker>
     <worker id="AD02">
         <name>Luch</name>
     </worker>
     <worker id="AD03">
         <name>Lily</name>
     </worker>
     <worker id="AD04">
         <name>Lily</name>
     </worker>
 </workers>

xml文件

 package com.qianfeng.pullparser2;

 public class Worker {

     private String id;
     private String name;

     public Worker() {
         super();
         // TODO Auto-generated constructor stub
     }
     public Worker(String id, String name) {
         super();
         this.id = id;
         this.name = name;

     }
     public String getId() {
         return id;
     }
     public void setId(String id) {
         this.id = id;
     }
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }

     @Override
     public String toString() {
         return "Worker [id=" + id + ", name=" + name + "]";
     }
 }

Worker.class 对象类

解析效果：

 Worker [id=AQ01, name=Mark]
 Worker [id=AD02, name=Luch]
 Worker [id=AD03, name=Lily]
 Worker [id=AD04, name=Lily]

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2、解析服务器的xml文件

 package pull;

 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.List;

 import org.xmlpull.v1.XmlPullParser;
 import org.xmlpull.v1.XmlPullParserException;
 import org.xmlpull.v1.XmlPullParserFactory;

 public class Pull {

     /**
      * @param args
      * @throws XmlPullParserException
      * @throws IOException
      */
     public static void main(String[] args) throws XmlPullParserException, IOException {
         // TODO Auto-generated method stub
         List<Person> list = null;
         Person person=null;

         XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
         XmlPullParser parser =  factory.newPullParser();
         String path ="http://localhost:8080/aaa/person.xml";
         InputStream in = HttpUtil.getInputStream(path);
         parser.setInput(in, "utf-8");
         int event = parser.getEventType();
         while(event!=XmlPullParser.END_DOCUMENT)
         {
             switch(event)
             {
             case XmlPullParser.START_DOCUMENT:
                 System.out.println("文件解析开始");
                 list = new ArrayList<Person>();
                 break;
             case XmlPullParser.START_TAG:
                 String str = parser.getName();
                 if("person".equals(str))
                 {
                     person = new Person();
                     int count = parser.getAttributeCount();
                     for(int i=;i<count;i++)
                     {
                         String key = parser.getAttributeName(i);
                         String value = parser.getAttributeValue(i);
                         if("id".equals(key))
                         {
                             person.setName(value);
                         }
                     }
                 }
                 else if("name".equals(str))
                 {
                     person.setName(parser.nextText());
                 }
                 break;
             case XmlPullParser.END_TAG:
                 if("person".equals(parser.getName()))
                 {
                     list.add(person);
                     person=null;
                 }
                 break;
             }
             event = parser.next();

         }

         for(int i=;i<list.size();i++)
         {
             System.out.println(list);
         }

     }

 }

对应的HttpUtil自定义类getInpustStream方法

 package pull;

 import java.io.IOException;
 import java.io.InputStream;
 import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
 import java.net.URL;

 public class HttpUtil {
     public static InputStream getInputStream(String path) throws IOException{
         URL url = new URL(path);
         HttpURLConnection conn = (HttpURLConnection) url.openConnection();
         conn.setRequestMethod("GET");
         conn.setConnectTimeout();
         conn.setDoInput(true);
         if(conn.getResponseCode() ==)
         {
             InputStream in = conn.getInputStream();
             return in;
         }

         return null;

     }

 }

HttpHtil.java

解析效果：

 文件解析开始
 [Pserson [id=, name=张老师, age=], Pserson [id=, name=李老师, age=]]
 [Pserson [id=, name=张老师, age=], Pserson [id=, name=李老师, age=]]

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