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。