xml文件解析 document对象

一.Document对象相关                                                                      
                                                                                    
1.读取XML文件,获得document对象.                                                            
            SAXReader reader = new SAXReader();                                     
             Document  document = reader.read(new File("input.xml"));               
                                                                                    
                                                                                    
2.解析XML形式的文本,得到document对象.                                                         
             String text = "<members></members>";                                   
             Document document = DocumentHelper.parseText(text);                    
                                                                                    
3.主动创建document对象.                                                                  
             Document document = DocumentHelper.createDocument();                   
             Element root = document.addElement("members");// 创建根节点                 
                                                                                    
二. 节点相关                                                                            
                                                                                    
1. 获取文档的根节点.                                                                       
Element rootElm = document.getRootElement();                                       
                                                                                    
2.取得某节点的单个子节点.                                                                     
Element memberElm=root.element("member");// "member" 是节点名                          
                                                                                    
3.取得节点的文字                                                                          
String text=memberElm.getText();                                                   
也可以用:                                                                              
String text=root.elementText("name");                                              
这个是取得根节点下的name字节点的文字.                                                              
                                                                                    
4.取得某节点下名为"member"的所有字节点并进行遍历.                                                     
List nodes = rootElm.elements("member");                                           
                                                                                    
for (Iterator it = nodes.iterator(); it.hasNext();) {                              
    Element elm = (Element) it.next();                                              
    // do something                                                                 
}                                                                                  
                                                                                    
5.对某节点下的所有子节点进行遍历.                                                                 
             for(Iterator it=root.elementIterator();it.hasNext();){                 
                 Element element = (Element) it.next();                             
                 // do something                                                    
             }                                                                      
                                                                                    
6.在某节点下添加子节点.                                                                      
Element ageElm = newMemberElm.addElement("age");                                   
                                                                                    
7.设置节点文字.                                                                          
ageElm.setText("29");                                                              
                                                                                    
8.删除某节点.                                                                           
parentElm.remove(childElm);// childElm是待删除的节点,parentElm是其父节点                       
                                                                                    
三. 属性相关.                                                                           
1.取得某节点下的某属性                                                                       
             Element root=document.getRootElement();                                
             Attribute attribute=root.attribute("size");// 属性名 name                 
                                                                                    
2.取得属性的文字                                                                          
             String text=attribute.getText();                                       
也可以用:                                                                              
String text2=root.element("name").attributeValue("firstname");                     
这个是取得根节点下name字节点的属性firstname的值.                                                    
                                                                                    
3.遍历某节点的所有属性                                                                       
             Element root=document.getRootElement();                                
             for(Iterator it=root.attributeIterator();it.hasNext();){               
                 Attribute attribute = (Attribute) it.next();                       
                 String text=attribute.getText();                                   
                 System.out.println(text);                                          
             }                                                                      
                                                                                    
4.设置某节点的属性和文字.                                                                     
newMemberElm.addAttribute("name", "sitinspring");                                  
                                                                                    
5.设置属性的文字                                                                          
             Attribute attribute=root.attribute("name");                            
             attribute.setText("sitinspring");                                      
                                                                                    
6.删除某属性                                                                            
             Attribute attribute=root.attribute("size");// 属性名 name                 
             root.remove(attribute);                                                
                                                                                    
四. 将文档写入XML文件.                                                                     
1.文档中全为英文,不设置编码,直接写入的形式.                                                           
XMLWriter writer = new XMLWriter(new FileWriter("output.xml"));                    
writer.write(document);                                                            
writer.close();                                                                    
                                                                                    
2.文档中含有中文,设置编码格式写入的形式.                                                             
             OutputFormat format = OutputFormat.createPrettyPrint();                
             format.setEncoding("GBK");    // 指定XML编码                               
             XMLWriter writer = new XMLWriter(new FileWriter("output.xml"),format); 
                                                                                    
             writer.write(document);                                                
             writer.close();                                                        
                                                                                    
五. 字符串与XML的转换                                                                      
1.将字符串转化为XML                                                                       
String text = "<members> <member>sitinspring</member> </members>";                 
Document document = DocumentHelper.parseText(text);                                
                                                                                    
2.将文档或节点的XML转化为字符串.                                                                
             SAXReader reader = new SAXReader();                                    
             Document  document = reader.read(new File("input.xml"));               
             Element root=document.getRootElement();                                
             String docXmlText=document.asXML();                                    
             String rootXmlText=root.asXML();                                       
             Element memberElm=root.element("member");                              
             String memberXmlText=memberElm.asXML();                                
                                                                                    
六. 使用XPath快速找到节点.                                                                  
读取的XML文档示例                                                                         
<?xml version="1.0" encoding="UTF-8"?>                                             
<projectDescription>                                                               
   <name>MemberManagement</name>                                                    
   <comment></comment>                                                              
   <projects>                                                                       
     <project>PRJ1</project>                                                        
     <project>PRJ2</project>                                                        
     <project>PRJ3</project>                                                        
     <project>PRJ4</project>                                                        
   </projects>                                                                      
   <buildSpec>                                                                      
     <buildCommand>                                                                 
       <name>org.eclipse.jdt.core.javabuilder</name>                                
       <arguments>                                                                  
       </arguments>                                                                 
     </buildCommand>                                                                
   </buildSpec>                                                                     
   <natures>                                                                        
     <nature>org.eclipse.jdt.core.javanature</nature>                               
   </natures>                                                                       
</projectDescription>                                                              
                                                                                    
使用XPath快速找到节点project.                                                              
  public static void main(String[] args){                                           
     SAXReader reader = new SAXReader();                                            
                                                                                    
     try{                                                                           
       Document  doc = reader.read(new File("sample.xml"));                         
                                                                                    
       List projects=doc.selectNodes("/projectDescription/projects/project");       
                                                                                    
       Iterator it=projects.iterator();                                             
                                                                                    
       while(it.hasNext()){                                                         
         Element elm=(Element)it.next();                                            
         System.out.println(elm.getText());                                         
       }                                                                            
                                                                                    
     }                                                                              
     catch(Exception ex){                                                           
        ex.printStackTrace();                                                       
     }                                                                              
   }