Dom4j 学习笔记

dom4j 是一种解析 XML 文档的开放源代码 XML 框架。dom4j下载地址

本文主要记载了一些简单的使用方法。

一、xml文件的解析

dom4j既可以解析普通的xml文件，也可以解析一个InputStream，先看看xml文件长什么样子：

<books>
<book>
<id>1</id>
<name>Java编程思想</name>
<price>80</price>
<author>张三</author>
</book>
<book>
<id>2</id>
<name>三国演义</name>
<price>30</price>
<author>罗贯中</author>
</book>
<book>
<id>3</id>
<name>红楼梦</name>
<price>35</price>
<author>曹雪芹</author>
</book>
<book>
<id>4</id>
<name>西游记</name>
<price>25</price>
<author>吴承恩</author>
</book><book>
<id>5</id>
<name>水浒传</name>
<price>30</price>
<author>施耐庵</author>
</book>
</books>

通过读取这一段xml文件并解析，将xml文件中的内容存储到javabean中。

private List<Book> bs;
private Book b;

//读取xml文件获得Document对象
@Test
public void test1(){
try {
//1.读取xml文件，获取document对象
SAXReader reader = new SAXReader();
Document document = reader.read(new File("F:\\test\\books.xml"));
//2.获取根节点<books>
Element root = document.getRootElement();
bs = new ArrayList<Book>();
//3.迭代，获取根节点的所有子节点<book>
for (Iterator<Element> es = root.elementIterator(); es.hasNext();) {
Element e = es.next();
b = new Book();
//4.再次迭代，获取子节点的子节点<id><name><price><author>
for (Iterator<Element> e_son = e.elementIterator();e_son.hasNext();) {
Element ee = e_son.next();
if(ee.getName().equals("id")){
b.setId(Integer.parseInt(ee.getText().toString()));
}else if(ee.getName().equals("name")){
b.setName(ee.getText());
}else if(ee.getName().equals("price")){
b.setPrice(Integer.parseInt(ee.getText()));
}else if(ee.getName().equals("auhtor")){
b.setAuthor(ee.getText());
}
}
bs.add(b);
}
} catch (DocumentException e) {
e.printStackTrace();
}

for (Book bk : bs) {
System.out.println(bk.getName());
}
}

Book.java

public class Book {

private int id;
private String name;
private int price;
private String author;
private Detail detail;
private Attribute attribute;

public Attribute getAttribute() {
return attribute;
}
public void setAttribute(Attribute attribute) {
this.attribute = attribute;
}
public Detail getDetail() {
return detail;
}
public void setDetail(Detail detail) {
this.detail = detail;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getPrice() {
return price;
}
public void setPrice(int price) {
this.price = price;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
}

Attribute.java

public class Attribute {

private String category;
private String edition;
public String getCategory() {
return category;
}
public void setCategory(String category) {
this.category = category;
}
public String getEdition() {
return edition;
}
public void setEdition(String edition) {
this.edition = edition;
}

}

Detail.java

public class Detail {

private String pressTime;
private String storyTime;
public String getPressTime() {
return pressTime;
}
public void setPressTime(String pressTime) {
this.pressTime = pressTime;
}
public String getStoryTime() {
return storyTime;
}
public void setStoryTime(String storyTime) {
this.storyTime = storyTime;
}
}

好，我们稍微修改一下xml文件，再看看个该如何解析：

<books>
<book>
<id>1</id>
<name>Java编程思想</name>
<price>80</price>
<author>张三</author>
<detail>
<pressTime>天朝</pressTime>
<storyTime>21世纪</storyTime>
</detail>
</book>
<book>
<id>2</id>
<name>三国演义</name>
<price>30</price>
<author>罗贯中</author>
<detail>
<pressTime>明朝</pressTime>
<storyTime>汉末</storyTime>
</detail>
</book>
<book>
<id>3</id>
<name>红楼梦</name>
<price>35</price>
<author>曹雪芹</author>
<detail>
<pressTime>清朝</pressTime>
<storyTime>不详</storyTime>
</detail>
</book>
<book>
<id>4</id>
<name>西游记</name>
<price>25</price>
<author>吴承恩</author>
<detail>
<pressTime>明朝</pressTime>
<storyTime>大唐</storyTime>
</detail>
</book><book>
<id>5</id>
<name>水浒传</name>
<price>30</price>
<author>施耐庵</author>
<detail>
<pressTime>明朝</pressTime>
<storyTime>大宋</storyTime>
</detail>
</book>
</books>

又多了一层嵌套，看解析方式：

private List<Book> bs;
private Book b;
private Detail detail;

// 读取xml文件获得Document对象
@Test
public void test1() {
try {
// 1.读取xml文件，获取document对象
SAXReader reader = new SAXReader();
Document document = reader.read(new File("F:\\test\\books.xml"));
// 2.获取根节点<books>
Element root = document.getRootElement();
bs = new ArrayList<Book>();
// 3.迭代，获取根节点的所有子节点<book>
for (Iterator<Element> es = root.elementIterator(); es.hasNext();) {
Element e = es.next();
b = new Book();
// 4.再次迭代，获取子节点的子节点<id><name><price><author>
for (Iterator<Element> e_son = e.elementIterator(); e_son
.hasNext();) {
Element ee = e_son.next();
if (ee.getName().equals("id")) {
b.setId(Integer.parseInt(ee.getText().toString()));
} else if (ee.getName().equals("name")) {
b.setName(ee.getText());
} else if (ee.getName().equals("price")) {
b.setPrice(Integer.parseInt(ee.getText()));
} else if (ee.getName().equals("auhtor")) {
b.setAuthor(ee.getText());
} else if (ee.getName().equals("detail")) {
detail = new Detail();
for (Iterator<Element> ds = ee.elementIterator(); ds
.hasNext();) {
Element d = ds.next();
if (d.getName().equals("pressTime")) {
detail.setPressTime(d.getText());
} else if (d.getName().equals("storyTime")) {
detail.setStoryTime(d.getText());
}
}
b.setDetail(detail);
}
}
bs.add(b);
}
} catch (DocumentException e) {
e.printStackTrace();
}

for (Book bk : bs) {
System.out.println(bk.getName()+","+bk.getDetail().getPressTime());
}
}

继续修改xml文件，为之添加属性：

<books>
<book category="编程技术" edition="8">
<id>1</id>
<name>Java编程思想</name>
<price>80</price>
<author>张三</author>
<detail>
<pressTime>天朝</pressTime>
<storyTime>21世纪</storyTime>
</detail>
</book>
<book category="历史小说" edition="1">
<id>2</id>
<name>三国演义</name>
<price>30</price>
<author>罗贯中</author>
<detail>
<pressTime>明朝</pressTime>
<storyTime>汉末</storyTime>
</detail>
</book>
<book category="小说" edition="2">
<id>3</id>
<name>红楼梦</name>
<price>35</price>
<author>曹雪芹</author>
<detail>
<pressTime>清朝</pressTime>
<storyTime>不详</storyTime>
</detail>
</book>
<book category="神话小说" edition="4">
<id>4</id>
<name>西游记</name>
<price>25</price>
<author>吴承恩</author>
<detail>
<pressTime>明朝</pressTime>
<storyTime>大唐</storyTime>
</detail>
</book>
<book category="小说" edition="5">
<id>5</id>
<name>水浒传</name>
<price>30</price>
<author>施耐庵</author>
<detail>
<pressTime>明朝</pressTime>
<storyTime>大宋</storyTime>
</detail>
</book>
</books>

给每一个book都添加了属性，又该怎么遍历呢？attribute的遍历和element的遍历非常类似，看代码：

// 读取xml文件获得Document对象
@Test
public void test1() {
try {
// 1.读取xml文件，获取document对象
SAXReader reader = new SAXReader();
Document document = reader.read(new File("F:\\test\\books.xml"));
// 2.获取根节点<books>
Element root = document.getRootElement();
bs = new ArrayList<Book>();
// 3.迭代，获取根节点的所有子节点<book>
for (Iterator<Element> es = root.elementIterator(); es.hasNext();) {
Element e = es.next();
b = new Book();
book_attr = new lenve.test.Attribute();
for (Iterator<Attribute> as = e.attributeIterator();as.hasNext();) {
Attribute attr = as.next();
if(attr.getName().equals("category")){
book_attr.setCategory(attr.getText());
}else if(attr.getName().equals("edition")){
book_attr.setEdition(attr.getText());
}
}
b.setAttribute(book_attr);
// 4.再次迭代，获取子节点的子节点<id><name><price><author>
for (Iterator<Element> e_son = e.elementIterator(); e_son
.hasNext();) {
Element ee = e_son.next();
if (ee.getName().equals("id")) {
b.setId(Integer.parseInt(ee.getText().toString()));
} else if (ee.getName().equals("name")) {
b.setName(ee.getText());
} else if (ee.getName().equals("price")) {
b.setPrice(Integer.parseInt(ee.getText()));
} else if (ee.getName().equals("auhtor")) {
b.setAuthor(ee.getText());
} else if (ee.getName().equals("detail")) {
detail = new Detail();
for (Iterator<Element> ds = ee.elementIterator(); ds
.hasNext();) {
Element d = ds.next();
if (d.getName().equals("pressTime")) {
detail.setPressTime(d.getText());
} else if (d.getName().equals("storyTime")) {
detail.setStoryTime(d.getText());
}
}
b.setDetail(detail);
}
}
bs.add(b);
}
} catch (DocumentException e) {
e.printStackTrace();
}

for (Book bk : bs) {
System.out.println(bk.getName()+","+bk.getDetail().getPressTime()+","+bk.getAttribute().getCategory());
}
}

如果我们只想遍历某一个节点呢？比如我们只想遍历名称为id的节点，该怎么办？

private List<Book> bs;
private Book b;
@Test
public void test2() {
try {
// 1.读取xml文件，获取document对象
SAXReader reader = new SAXReader();
Document document = reader.read(new File("F:\\test\\books.xml"));
// 2.获取根节点<books>
Element root = document.getRootElement();
bs = new ArrayList<Book>();
// 3.迭代，获取根节点的所有子节点<book>
for (Iterator<Element> es = root.elementIterator(); es.hasNext();) {
Element e = es.next();
b = new Book();
// 4.再次迭代，获取子节点的子节点<id><name><price><author>
for (Iterator<Element> e_son = e.elementIterator("id"); e_son
.hasNext();) {
Element ee = e_son.next();
b.setId(Integer.parseInt(ee.getText().toString()));
}
bs.add(b);
}
} catch (DocumentException e) {
e.printStackTrace();
}

for (Book bk : bs) {
System.out.println(bk.getId()+","+bk.getAuthor());
}
}

输出：



最后一个问题，怎样以字符串的形式拿到一个xml文件：

@Test
public void test3(){
try {
SAXReader reader = new SAXReader();
Document document = reader.read(new File("F:\\test\\books.xml"));
String text = document.asXML();
System.out.println(text);
} catch (DocumentException e) {
e.printStackTrace();
}
}

二、使用程序写一个xml文件

1.怎样把一个字符串文件写成xml文件：

@Test
public void test4() {
try {
String text = "<fruits><fruit><name>苹果</name><color>red</color><price>3元</price></fruit></fruits>";
Document document = DocumentHelper.parseText(text);
//两种方式皆可
//          FileWriter out = new FileWriter(new File("F:\\test\\str2xml.xml"));
PrintWriter out = new PrintWriter(new File("F:\\test\\s2x.xml"));
document.write(out);
out.close();
} catch (DocumentException e) {
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

这样输出的xml文件没有格式，可读性较差，换个方式再看看：

@Test
public void test5() {
try {
String text = "<fruits><fruit><name>苹果</name><color>red</color><price>3元</price></fruit></fruits>";
Document document = DocumentHelper.parseText(text);
PrintWriter out = new PrintWriter(new File("F:\\test\\s2x1.xml"));
XMLWriter writer = new XMLWriter(out, new OutputFormat().createPrettyPrint());
writer.write(document);
writer.close();
} catch (DocumentException e) {
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

输出结果：



这样的输出格式也是极好的。

2.通过程序一个元素一个元素的写入：

@Test
public void test6(){
int res = createXMLFile();
if(res==1){
System.out.println("xml文件创建成功！");
}else{
System.out.println("xml文件创建失败！");
}
}

public int createXMLFile(){
//返回0表示创建成功，返回1表示创建失败
int result = 0;
Document document = DocumentHelper.createDocument();
//建立根节点
Element root = document.addElement("fruits");
//加入注释
root.addComment("this is a xml about fruit");
Element f1 = root.addElement("fruit");
f1.addAttribute("color", "red");
Element f11 = f1.addElement("price");
f11.setText("10元");
Element f12 = f1.addElement("shape");
f12.setText("圆形");
Element f13 = f1.addElement("name");
f13.setText("苹果");
//将xml写入文件中
try {
PrintWriter out = new PrintWriter(new File("F:\\test\\111.xml"));
XMLWriter writer = new XMLWriter(out, new OutputFormat().createPrettyPrint());
writer.write(document);
writer.close();
result = 1;
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return result;
}

再看看新创建的xml文件长什么样：



这里使用最多的就是三个方法，一个是addElement()，一个是addAttribute()，还有一个是setText(),对每一个节点都可以执行这三个操作，你想创建的任何形状的xml都可以通过层层的嵌套实现。

如果想手动指定输出编码格式：

@Test
public void test6(){
int res = createXMLFile();
if(res==1){
System.out.println("xml文件创建成功！");
}else{
System.out.println("xml文件创建失败！");
}
}

public int createXMLFile(){
//返回0表示创建成功，返回1表示创建失败
int result = 0;
Document document = DocumentHelper.createDocument();
//建立根节点
Element root = document.addElement("fruits");
//加入注释
root.addComment("this is a xml about fruit");
Element f1 = root.addElement("fruit");
f1.addAttribute("color", "red");
Element f11 = f1.addElement("price");
f11.setText("10元");
Element f12 = f1.addElement("shape");
f12.setText("圆形");
Element f13 = f1.addElement("name");
f13.setText("苹果");
//将xml写入文件中
try {
PrintWriter out = new PrintWriter(new File("F:\\test\\111.xml"));
OutputFormat format = OutputFormat.createPrettyPrint();//缩进显示
//默认输出编码是UTF-8，可以手动设置为GBK
format.setEncoding("GBK");
XMLWriter writer = new XMLWriter(out, format);
writer.write(document);
writer.close();
result = 1;
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return result;
}

输出的xml文件为（注意看编码）：

三、修改xml文件

我们要修改一下xml文件：

<books>
<book category="编程技术" edition="8">
<id>1</id>
<name>Java编程思想</name>
<price>80</price>
<author>张三</author>
<detail>
<pressTime>天朝</pressTime>
<storyTime>21世纪</storyTime>
</detail>
</book>
<book category="历史小说" edition="1">
<id>2</id>
<name>三国演义</name>
<price>30</price>
<author>罗贯中</author>
<detail>
<pressTime>明朝</pressTime>
<storyTime>汉末</storyTime>
</detail>
</book>
<book category="小说" edition="2">
<id>3</id>
<name>红楼梦</name>
<price>35</price>
<author>曹雪芹</author>
<detail>
<pressTime>清朝</pressTime>
<storyTime>不详</storyTime>
</detail>
</book>
<book category="神话小说" edition="4">
<id>4</id>
<name>西游记</name>
<price>25</price>
<author>吴承恩</author>
<detail>
<pressTime>明朝</pressTime>
<storyTime>大唐</storyTime>
</detail>
</book>
<book category="小说" edition="5">
<id>5</id>
<name>水浒传</name>
<price>30</price>
<author>施耐庵</author>
<detail>
<pressTime>明朝</pressTime>
<storyTime>大宋</storyTime>
</detail>
</book>
</books>

1.把所有的edition属性的值为8的修改为100

使用xpath查找对象时，依赖于jaxen.jar包，所以要先下载这个包。查找对象时，如果查找的是节点，直接写名称，如：/books/book/name，如果查找的是属性，要在属性前加上@，如：/books/book/@edition

@Test
public void modifyXmlFile(){
try {
SAXReader reader = new SAXReader();
Document document = reader.read(new File("F:\\test\\books.xml"));
//先利用xpath查找对象
List<Node> ns = document.selectNodes("/books/book/@edition");
Iterator<Node> iter = ns.iterator();
while(iter.hasNext()){
Attribute attr = (Attribute) iter.next();
if(Integer.parseInt(attr.getValue())==8){
attr.setValue("100");
}
}
//输出修改后的文件
PrintWriter out = new PrintWriter(new File("F:\\test\\m1.xml"));
XMLWriter w = new XMLWriter(out,OutputFormat.createPrettyPrint());
w.write(document);
w.close();
} catch (DocumentException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

2.把“Java编程思想”修改为“Java语言程序设计”并在该name属性所在的book节点中添加buyTime节点，节点值为2015-04-27：

@Test
public void modifyXmlFile(){
try {
SAXReader reader = new SAXReader();
Document document = reader.read(new File("F:\\test\\books.xml"));
//先利用xpath查找对象
List<Node> ns = document.selectNodes("/books/book/name");
Iterator<Node> iter = ns.iterator();
while(iter.hasNext()){
Element e = (Element) iter.next();
if(e.getText().equals("Java编程思想")){
e.setText("Java语言程序设计");
Element pe = e.getParent();
Element new_e = pe.addElement("buyTime");
new_e.setText("2015-04-27");
}
}
//输出修改后的文件
PrintWriter out = new PrintWriter(new File("F:\\test\\m2.xml"));
XMLWriter w = new XMLWriter(out,OutputFormat.createPrettyPrint());
w.write(document);
w.close();
} catch (DocumentException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

3.若edition属性值为8，则删除该属性

@Test
public void modifyXmlFile(){
try {
SAXReader reader = new SAXReader();
Document document = reader.read(new File("F:\\test\\books.xml"));
List<Node> ns = document.selectNodes("/books/book/@edition");
Iterator<Node> iter = ns.iterator();
while(iter.hasNext()){
Attribute attr = (Attribute) iter.next();
if(Integer.parseInt(attr.getValue())==8){
attr.getParent().remove(attr);
}
}
try {
PrintWriter out = new PrintWriter(new File("F:\\test\\m3.xml"));
XMLWriter w = new XMLWriter(out,OutputFormat.createPrettyPrint());
w.write(document);
w.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

} catch (DocumentException e) {
e.printStackTrace();
}
}

4.把id为3的书的name节点删除：

@Test
public void modifyXmlFile(){
try {
SAXReader reader = new SAXReader();
Document document = reader.read(new File("F:\\test\\books.xml"));
List<Node> ns = document.selectNodes("/books/book/id");
Iterator<Node> iter = ns.iterator();
while(iter.hasNext()){
Element e = (Element) iter.next();
if(e.getText().equals("3")){
e.getParent().remove(e.getParent().element("name"));
}
}
PrintWriter out = new PrintWriter(new File("F:\\test\\m4.xml"));
XMLWriter w = new XMLWriter(out, OutputFormat.createPrettyPrint());
w.write(document);
w.close();
} catch (DocumentException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

}

5.移除所有文件的id属性：

方式一：

直接查找id节点，再删除

@Test
public void modifyXmlFile(){
try {
SAXReader reader = new SAXReader();
Document document = reader.read(new File("F:\\test\\books.xml"));
List<Node> ns = document.selectNodes("/books/book/id");
Iterator<Node> iter = ns.iterator();
while(iter.hasNext()){
Element e = (Element) iter.next();
e.getParent().remove(e);
}
PrintWriter out = new PrintWriter(new File("F:\\test\\m5.xml"));
XMLWriter w = new XMLWriter(out,OutputFormat.createPrettyPrint());
w.write(document);
w.close();
} catch (DocumentException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

方法二：

查找book节点，再删除book节点的id节点：

@Test
public void modifyXmlFile(){
try {
SAXReader reader = new SAXReader();
Document document = reader.read(new File("F:\\test\\books.xml"));
List<Node> ns = document.selectNodes("/books/book");
Iterator<Node> iter = ns.iterator();
while(iter.hasNext()){
Element e = (Element) iter.next();
e.remove(e.element("id"));
}
PrintWriter out = new PrintWriter(new File("F:\\test\\m6.xml"));
XMLWriter w = new XMLWriter(out,OutputFormat.createPrettyPrint());
w.write(document);
w.close();
} catch (DocumentException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

好了，先写这么多，这些东东基本上够项目使用了。