dom4j读写xml文件

首先我们给出一段示例程序：

import
  java.io.File;
import
  java.io.FileWriter;
import
  java.util.Iterator;

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

 
public
   
class
  DOM4JTest   {

      
/** */
 
/**   */
      
/** */
 
/**   */
      
/** */
 
/**   */
      
/** */
 
/**
     * DOM4J读写XML示例
     *
     *  @param  args
     *  @throws  Exception
      */
      
public
   
static
   
void
  main(String[] args)   {
          
try
    {
            XMLWriter writer  =   
null
 ; 
//  声明写XML的对象
            SAXReader reader  =   
new
  SAXReader();

            OutputFormat format  =  OutputFormat.createPrettyPrint();
            format.setEncoding( 
" GBK "
 ); 
//  设置XML文件的编码格式

            String filePath  =   
" d:\\student.xml "
 ;
            File file  =   
new
  File(filePath);
              
if
  (file.exists())   {
                Document document  =  reader.read(file); 
//  读取XML文件
                Element root  =  document.getRootElement(); 
//  得到根节点
                 
boolean
  bl  =   
false
 ;
                  
for
  (Iterator i  =  root.elementIterator( 
" 学生 "
 ); i.hasNext();)   {
                    Element student  =  (Element) i.next();
                      
if
  (student.attributeValue( 
" sid "
 ).equals( 
" 001 "
 ))   {
                         
//  修改学生sid=001的学生信息
                        student.selectSingleNode( 
" 姓名 "
 ).setText( 
" 王五 "
 );
                        student.selectSingleNode( 
" 年龄 "
 ).setText( 
" 25 "
 );

                        writer  =   
new
  XMLWriter( 
new
  FileWriter(filePath), format);
                        writer.write(document);
                        writer.close();
                        bl  =   
true
 ;
                         
break
 ;
                    }
                }
                  
if
  (bl)   {
                     
//  添加一个学生信息
                    Element student  =  root.addElement( 
" 学生 "
 );
                    student.addAttribute( 
" sid "
 ,  
" 100 "
 );
                    Element sid  =  student.addElement( 
" 编号 "
 );
                    sid.setText( 
" 100 "
 );
                    Element name  =  student.addElement( 
" 姓名 "
 );
                    name.setText( 
" 嘎嘎 "
 );
                    Element sex  =  student.addElement( 
" 性别 "
 );
                    sex.setText( 
" 男 "
 );
                    Element age  =  student.addElement( 
" 年龄 "
 );
                    age.setText( 
" 21 "
 );

                    writer  =   
new
  XMLWriter( 
new
  FileWriter(filePath), format);
                    writer.write(document);
                    writer.close();
                }
             }   
else
    {
                 
//  新建student.xml文件并新增内容
                Document _document  =  DocumentHelper.createDocument();
                Element _root  =  _document.addElement( 
" 学生信息 "
 );
                Element _student  =  _root.addElement( 
" 学生 "
 );
                _student.addAttribute( 
" sid "
 ,  
" 001 "
 );
                Element _id  =  _student.addElement( 
" 编号 "
 );
                _id.setText( 
" 001 "
 );
                Element _name  =  _student.addElement( 
" 姓名 "
 );
                _name.setText( 
" 灰机 "
 );
                Element _age  =  _student.addElement( 
" 年龄 "
 );
                _age.setText( 
" 18 "
 );

                writer  =   
new
  XMLWriter( 
new
  FileWriter(file), format);
                writer.write(_document);
                writer.close();
            }
            System.out.println( 
" 操作结束!  "
 );
         }   
catch
  (Exception e)   {
            e.printStackTrace();
        }

    }
}

执行结果应该是这样：

 

循环解析节点：

private
   
void
  getAllNodes(String xml)   {
         
try
    {
           Document authtmp  =  DocumentHelper.parseText(xml);
           List < Element >  list  =  authtmp.selectNodes( 
" //sms/node "
 );
             
for
  ( 
int
  j  =   
0
 ; j  <  list.size(); j ++ )   {
               Element node  =  (Element) list.get(j);
               nodeByNodes(node);
           }
        }   
catch
  (Exception e)   {
           e.printStackTrace();
       }
   }

     
private
   
void
  nodeByNodes(Element node)   {
         
if
  (node.element( 
" node "
 )  !=   
null
 )   {
           String id  =  node.attributeValue( 
" id "
 );
           String name  =  node.attributeValue( 
" name "
 );
           System.out.print(id  +   
" ------- "
 );
           System.out.println(name);
             
for
  (Iterator i  =  node.elementIterator( 
" node "
 ); i.hasNext();)   {
               Element newNode  =  (Element) i.next();
               nodeByNodes(newNode);
           }
        }   
else
    {
           String id  =  node.attributeValue( 
" id "
 );
           String name  =  node.attributeValue( 
" name "
 );
           System.out.print(id  +   
" ------- "
 );
           System.out.println(name);
       }
   }

其次DOM4J的解释

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

9.添加一个CDATA节点.

Element contentElm = infoElm.addElement( 
" content "
 );
contentElm.addCDATA(diary.getContent());

  contentElm.getText(); 
// 特别说明：获取节点的CDATA值与获取节点的值是一个方法
  contentElm.clearContent(); 
//清除节点中的内容，CDATA亦可

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(); 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();
   }
 }