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\t true表示换行
         OutputFormat format = new OutputFormat("\t",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");

     }

 }