dom4j的读写xml文件，读写xml字符串

百度了一些博客，大同小异，在选取jar包工具的时候大概看了下，大抵是jdom原始，dom4j优秀。于是做了些练习。

参考：http://www.cnblogs.com/mengdd/archive/2013/06/05/3119927.html

package com.test.xml;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;
import java.util.Random;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

/**
* @ClassName: TestDom4j 
* @Description:dom4j练习xml的读写 
* @author mrf
* @date 2015-11-11 下午02:25:20 
*
 */
public class TestDom4j {
    
    /**
    * @Title: read 
    * @Description:读取xml文件 
    * @param @param path    参数
    * @return void    返回类型
     * @throws DocumentException 
     */
    public static void read(String path) throws DocumentException{
        SAXReader saxReader = new SAXReader();
        Document doc = saxReader.read(new File(path));
        //获取根元素
        Element root = doc.getRootElement();
        System.out.println(root.getName()+root.attributeValue("name"));
        //获取子元素
        @SuppressWarnings("unchecked")
        List<Element> grades = root.elements();
        if(!grades.isEmpty()){
            for (int i = 0; i < grades.size(); i++) {
                Element element = grades.get(i);
                System.out.println(element.getName()+element.attributeValue("name"));
                @SuppressWarnings("unchecked")
                List<Element> classes = element.elements();
                if(classes.size()>0){
                    for (int j = 0; j < classes.size(); j++) {
                        Element cls = classes.get(j);
                        @SuppressWarnings("unchecked")
                        List<Element> stus = cls.elements();
                        if(!stus.isEmpty()){
                            for (int k = 0; k < stus.size(); k++) {
                                Element stu = stus.get(k);
                                System.out.println(stu.getName()+stu.attributeValue("name"));
                                
                                //以下证明elements方法返回值不会为null,另查看源码发现也是直接创建list
//                                List list = stu.elements();
//                                System.out.println(list==null);
//                                System.out.println(list.size());
//                                System.out.println(list);
                            }
                        }
                        
                    }
                }
            }
        }
    }
    
    /**
    * @Title: getRandoStr 
    * @Description:获取一个随机字符串 
    * @param @param len
    * @param @return    参数
    * @return String    返回类型
     */
    public static String getRandoStr(int len){
        String base = "abcdefghijklmnopqrstuvwxyz1234567890";
        Random random = new Random();
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < len; i++) {
            sb.append(base.charAt(random.nextInt(base.length())));
        }
        
        return sb.toString();
    }
    
    /**
    * @Title: write 
    * @Description: 测试写一个school文件
    * @param @throws IOException    参数
    * @return void    返回类型
     */
    public static void write(String path) throws IOException{
        //创建doc文档
        Document doc = DocumentHelper.createDocument();
        Element root = DocumentHelper.createElement("school");
        //设置根元素
        doc.setRootElement(root);
        //添加属性
        root.addAttribute("name","实验中学");
        root.addAttribute("position","河北石家庄");
        
        Element grade = root.addElement("grade");
        grade.addAttribute("name", "年级");
        grade.addAttribute("size", "1");
        Element cls = grade.addElement("class");
        cls.addAttribute("name", "班级");
        cls.addAttribute("size", "70");
        Element stu = cls.addElement("student");
        stu.addAttribute("name", getRandoStr(4));
        stu.addAttribute("age", 13+"");
        stu.addAttribute("sex", new Random().nextInt(2)+"");
        stu.setText("学生");
        
//        //添加三个子节点初一初二初三
//        for (int i = 1; i < 4; i++) {
//            Element grade = root.addElement("grade");
//            grade.addAttribute("name", "grade_"+i);
//            grade.addAttribute("size", "20");
//            //添加20个班级
//            for (int j = 1; j < 21; j++) {
//                Element cls = grade.addElement("class");
//                cls.addAttribute("name", "grade_"+i+"_class_"+j);
//                cls.addAttribute("size", "70");
//                //添加70个学生
//                for (int k = 1; k < 71; k++) {
//                    Element stu = cls.addElement("student");
//                    stu.addAttribute("name", getRandoStr(4));
//                    stu.addAttribute("age", 12+i+"");
//                    stu.addAttribute("sex", new Random().nextInt(2)+"");
//                    stu.setText("学生");
//                }
//            }
//        }
        
        
        //输出
        //控制台
        new XMLWriter().write(doc);
        
        //文件
        //格式 -缩进	 true表示换行
        OutputFormat format = new OutputFormat("	",true);
        XMLWriter writer = new XMLWriter(new FileOutputStream(path),format);
        writer.write(doc);
        writer.flush();
        writer.close();
        
    }
    
    //解析xml字符串
    public static Document parseStr(String xmlStr) throws DocumentException{
        Document doc = DocumentHelper.parseText(xmlStr);
        return doc;
    }
    
    public static void main(String[] args) throws IOException, DocumentException {
//        write("src/main/java/com/test/xml/school.xml");
        
        read("src/main/java/com/test/xml/school.xml");
        
    }

}