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

 1 public class PullParser {
 2     
 3     public List<Worker> pullParsers() throws XmlPullParserException, IOException
 4     {
 5         List<Worker> list = null;
 6         Worker worker = null;
 7         //第一步：创建XML解析对象，需要通过工厂模式创建类的实例
 8         XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
 9         XmlPullParser parser = factory.newPullParser();
10 //        第二步：设置待解析的xml数据源
11         FileInputStream fis = new FileInputStream("worker.xml");
12         parser.setInput(fis,"utf-8");
13 //        第三步：获取当前xml标签的事件类型
14         int event = parser.getEventType();
15 //        第四步：通过分支语句处理不同的事件标签
16         while(event!=XmlPullParser.END_DOCUMENT)
17         {
18             
19             switch(event)
20             {
21 //            第五步：获取标签名称，处理标签信息
22             case XmlPullParser.START_DOCUMENT://解析文件开始，创建列表集合对象
23                 list = new ArrayList<Worker>();
24                 break;
25             case XmlPullParser.START_TAG:
26                 String tagName = parser.getName();
27                 if("worker".equals(tagName))
28                 {
29                     worker = new Worker();
30                     int count = parser.getAttributeCount();//得到属性的个数
31                     for(int i=0;i<count;i++)
32                     {
33                         String attrName = parser.getAttributeName(i);
34                         String attrValue = parser.getAttributeValue(i);
35                         if("id".equals(attrName))
36                             worker.setId(attrValue);
37                     }
38                 }
39                 else if("name".equals(tagName))
40                     worker.setName(parser.nextText());
41                     worker.setMoney(Double.parseDouble(parser.nextText()));
42                 break;
43                 
44             case XmlPullParser.END_TAG://解析文件结束，
45                  if("worker".equals(parser.getName()))
46                  {
47 //                第六步：将处理的数据保存到JavaBean或Map对象中
48                      list.add(worker);
49                      worker = null;
50                  }
51                  break;
52             }
53 //            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
54             event = parser.next();
55         }
56         return list;
57     }
58 
59     /**
60      * @param args
61      * @throws IOException 
62      * @throws XmlPullParserException 
63      */
64     public static void main(String[] args) throws XmlPullParserException, IOException {
65         PullParser  pullParser = new PullParser();
66         List<Worker> list = pullParser.pullParsers();
67         
68         for(Worker w:list)
69         {
70             System.out.println(w);
71         }
72     }
73 
74 }

<?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>

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 + "]";
    }
}

解析效果：

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

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=0;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=0;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(5000);
        conn.setDoInput(true);
        if(conn.getResponseCode() ==200)
        {
            InputStream in = conn.getInputStream();
            return in;
        }
        
        
        return null;
        
    }

}

解析效果：

文件解析开始
[Pserson [id=0, name=张老师, age=0], Pserson [id=0, name=李老师, age=0]]
[Pserson [id=0, name=张老师, age=0], Pserson [id=0, name=李老师, age=0]]