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();