Java-XML解析第一篇主流开源类库解析XML

1、流行的XML解析框架

1》底层解析方式：存在编码复杂性、难扩展、难复用....。想了解底层解析方式请参考：浅谈 Java XML 底层解析方式

2》Dom4j：基于 JAXP 解析方式，性能优异、功能强大、极易使用的优秀框架。

3》Jdom：本质也是基于 JAXP 但包结构被重新组织， API 大量使用了 Collections 类，在性能上被 dm4j 压了好几个档次。

4》XStream：基于 xmlpull 的 OXMapping 技术，更加倾向于将 XML 解析后映射为 Java 世界中的对象。

2、建立一个简单的demo.xml文件，用于提供给各种方式解析

<?xml version="1.0"?>
<classGrid>
    <classGridlb>
        <class_id>320170105000009363</class_id>
        <class_number>0301</class_number>
        <adviser>018574</adviser>
        <studentGrid>
            <studentGridlb>
                <stu_id>030101</stu_id>
                <stu_name>齐天</stu_name>
                <stu_age>9</stu_age>
                <stu_birthday>2008-11-07</stu_birthday>
            </studentGridlb>
            <studentGridlb>
                <stu_id>030102</stu_id>
                <stu_name>张惠</stu_name>
                <stu_age>10</stu_age>
                <stu_birthday>2009-04-08</stu_birthday>
            </studentGridlb>
            <studentGridlb>
                <stu_id>030103</stu_id>
                <stu_name>龙五</stu_name>
                <stu_age>9</stu_age>
                <stu_birthday>2008-11-01</stu_birthday>
            </studentGridlb>
        </studentGrid>
    </classGridlb>
    <classGridlb>
        <class_id>420170105000007363</class_id>
        <class_number>0302</class_number>
        <adviser>018577</adviser>
        <studentGrid>
            <studentGridlb>
                <stu_id>030201</stu_id>
                <stu_name>马宝</stu_name>
                <stu_age>10</stu_age>
                <stu_birthday>2009-09-02</stu_birthday>
            </studentGridlb>
        </studentGrid>
    </classGridlb>
</classGrid>

3、Dom4j、Jdom、Xstream不同的解析方式

1》Dom4j方式，性能好，API灵活，支持对 XML 文档的增删改查动作，毕竟是以树模型加载到内存中进行的操作。有可能成为将来的主流。项目结构如下：

pom.xml

<dependency>
   <groupId>dom4j</groupId>
   <artifactId>dom4j</artifactId>
   <version>1.6.1</version>
   <exclusions>
      <exclusion>
          <groupId>xml-apis</groupId>
          <artifactId>xml-apis</artifactId>
      </exclusion>
    </exclusions>
</dependency>

剔除 xml-apis 的用意 JDK 中已经有对应的类。

App.java

package com.lfy.cn.javaXmlPasareTest;

import java.io.File;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

/**
 * 
 *
 */
public class App 
{
    public static void main( String[] args ) throws DocumentException, ParseException{
        String path = System.getProperty("user.dir")+"\src\demo.xml";
        SAXReader reader = new SAXReader();
        Document document = reader.read(new File(path));

        List<StudentGridlb> studentGridlbList = new ArrayList<>();
        StudentGridlb studentGridlbVo;
        for (Object classGridlb : document.getRootElement().elements("classGridlb")) {
            Element classGridlbEle = (Element) classGridlb;
            DateFormat format = new SimpleDateFormat("yyyy-MM-dd");
            for (Object studentGridlb : classGridlbEle.element("studentGrid").elements("studentGridlb")) {
                Element studentGridlbEle = (Element) studentGridlb;

                studentGridlbVo = new StudentGridlb();
                studentGridlbVo.setStu_id(studentGridlbEle.elementTextTrim("stu_id"));
                studentGridlbVo.setStu_age(Integer.parseInt(studentGridlbEle.elementTextTrim("stu_age")));
                studentGridlbVo.setStu_name(studentGridlbEle.elementTextTrim("stu_name"));
                studentGridlbVo.setStu_birthday(format.parse(studentGridlbEle.elementTextTrim("stu_birthday")));
                studentGridlbList.add(studentGridlbVo);
            }
        }
        System.out.println(studentGridlbList);
    }
}

运行结果：

2》Jdom，基于树处理 XML，需要将树加载到内存中，所以解析大文件对内存的要求比较高。支持对 XML 文档的增删改查动作，毕竟是以树模型加载到内存中进行的操作。解析速度还可以。

pom.xml

<dependency>
      <groupId>jdom</groupId>
      <artifactId>jdom</artifactId>
      <version>1.1</version>
</dependency>

JdomTest.java

package com.lfy.cn.javaXmlPasareTest;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;

/**
 * 
 *
 */
public class JdomTest 
{
    public static void main( String[] args ) throws ParseException, FileNotFoundException, IOException, JDOMException{

        String path = System.getProperty("user.dir")+"\src\demo.xml";

        SAXBuilder jdomsaxBuilder = new SAXBuilder(false);
        Document doc = jdomsaxBuilder.build(path);
        Element rootElement = doc.getRootElement();

        List<StudentGridlb> studentGridlbList = new ArrayList<>();
        StudentGridlb studentGridlb;
        for (Object classGridlb : rootElement.getChildren("classGridlb")) {
            Element classGridlbEle = (Element) classGridlb;
            DateFormat format = new SimpleDateFormat("yyyy-MM-dd");
            for (Object studentGrid : classGridlbEle.getChild("studentGrid").getChildren("studentGridlb")) {
                Element studentGridEle = (Element) studentGrid;
                studentGridlb = new StudentGridlb();
                studentGridlb.setStu_id(studentGridEle.getChildTextTrim("stu_id"));
                studentGridlb.setStu_age(Integer.parseInt(studentGridEle.getChildTextTrim("stu_age")));
                studentGridlb.setStu_name(studentGridEle.getChildTextTrim("stu_name"));
                studentGridlb.setStu_birthday(format.parse(studentGridEle.getChildTextTrim("stu_birthday")));
                studentGridlbList.add(studentGridlb);
            }
        }
        XMLOutputter outputter = new XMLOutputter();
        outputter.output(doc, new FileOutputStream(path));
        System.out.println(studentGridlbList);
    }
}

3》Xstream：基于注解不需要其它辅助类或映射文件的OXMapping 技术。可以将 JavaBean 序列化为 XML，或将 XML 反序列化为 JavaBean，使得XML序列化不再繁琐。也可以将 JavaBean 序列化成 Json 或反序列化，使用非常方便。没有映射文件而且底层使用 xmlpull 推模型解析 XML，高性能、低内存占用，结合简洁明了的 API，上手基本是分分钟的事情。