Day 26：Dom4j修改xml

Dom4j：Writing a document to a file

import java.io.File;
import java.io.FileOutputStream;

import org.dom4j.Document;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

public class Demo1 {
    public static void main(String[] args) throws Exception {
        Document doc =new SAXReader().read("./src/contact.xml");
        FileOutputStream output = new FileOutputStream(new File("F:\a.xml"));
                
        XMLWriter writer = new XMLWriter(output);
        
        writer.write(doc);
        output.close();
    }
}

//没有空格换行
OutputFormat format = new OutputFormat().createCompactFormat();//不给人看用这种，产品上线时，内容小
//有空格换行
OutputFormat format1 = new OutputFormat().createPrettyPrint();//给人看用这种，调试的时候
//（空格也是内容）

//指定xml文档的编码
format.setEncoding("utf-8");

同时影响了xml文档保存时的编码  和  xml文档声明的encoding的编码（xml解析时的编码）

结论： 使用该方法生成的xml文档避免中文乱码问题。

import java.io.File;
import java.io.FileOutputStream;

import org.dom4j.Attribute;
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;
import org.junit.jupiter.api.Test;

/*
 * 修改xml内容
 * 增加：文档，标签 ，属性
 * 修改：属性值，文本
 * 删除：标签，属性
 */
public class Demo3 {
    /* @Test
     public void Test() throws Exception {
         //创建新文档
         Document doc = DocumentHelper.createDocument();
         //增加标签
         Element rootelem = doc.addElement("contactList");
         Element contactelem = rootelem.addElement("contact");
         contactelem.addElement("name");
         //增加属性
         contactelem.addAttribute("dsa", "454");
         contactelem.addAttribute("color", "red");
        //修改xml的document对象
            
            
        
        //把修改后的Document对象写出到xml文档中
         FileOutputStream output = new FileOutputStream(new File("F:\a.xml"));    
         OutputFormat format = OutputFormat.createPrettyPrint();
         XMLWriter writer = new XMLWriter(output,format);
         writer.write(doc);
         output.close();
     }*/
     @Test
     public void Test1() throws Exception {
         //读入文件
         Document doc =new SAXReader().read("./src/contact.xml");
        
         /**
          * 修改属性值
          * 方法一
          * 1.得到标签
          * 2.得到属性对象
          * 3.修改属性值
          */
         
         
         //方法一
         /*Element contacttelem = doc.getRootElement().element("contact");
         Attribute idattribute = contacttelem.attribute("id");
         idattribute.setValue("4564");*/
         
         //方法二
         /*Element contacttelem = doc.getRootElement().element("contact");
         //通过增加同名属性方法覆盖原来属性
         contacttelem.addAttribute("id", "4564564564");*/
         
         
         /**
          * 修改文本
          * 1.得到标签
          * 2.修改
          */
         
         /*
         Element nemeelem = doc.getRootElement().element("contact").element("name");
         nemeelem.setText("李四");*/
         
         //输出修改后的文件
         OutputFormat format = OutputFormat.createPrettyPrint();
         FileOutputStream output = new FileOutputStream(new File("F:\a.xml"));    
         XMLWriter writer = new XMLWriter(output,format);
            writer.write(doc);
         output.close();
     }
     
     @Test
     public void Test2() throws Exception {
         Document doc =new SAXReader().read("./src/contact.xml");
        /**
         * 删除标签
         * 得到标签。删除标签。 
         */
        // Element ageelem = doc.getRootElement().element("contact").element("age");
         //ageelem.detach();
         //ageelem.getParent().remove(ageelem);
         
         /**
          * 删除属性
          * 得到属性对象。删除属性
          */
         Element elem2 = (Element)doc.getRootElement().elements().get(1);
         Attribute attr= elem2.attribute("id");
         attr.detach();
         //attr.getParent().remove(attr);
        //输出修改后的文件
         OutputFormat format = OutputFormat.createPrettyPrint();
         FileOutputStream output = new FileOutputStream(new File("F:\a.xml"));    
         XMLWriter writer = new XMLWriter(output,format);
            writer.write(doc);
         output.close();
     }
}

 作业：

<!--使用dom4j的api来生成以下的xml文件--!>
<Students>
<Student id="1">
    <name>张三</name>
    <gender>男</gender>
    <grade>计算机1班</grade>
    <address>广州天河</address>
</Student>
<Student id="2">
    <name>李四</name>
    <gender>女</gender>
    <grade>计算机2班</grade>
    <address>广州越秀</address>
</Student>
</Students>

修改id为2的学生的姓名，改为“王丽”

删除id为2的学生

import java.io.File;
import java.io.FileOutputStream;
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;
import org.junit.Test;

public class Demo4 {
    //写文件
    @Test
    public void test() throws Exception{
        Document doc = DocumentHelper.createDocument();
        
        Element rootelem = doc.addElement("students");
        Element Elems1 = rootelem.addElement("student");
        Elems1.addAttribute("id", "001");
        Elems1.addElement("name").setText("李杰");
        Elems1.addElement("gender").setText("男");
        Elems1.addElement("grade").setText("计算机科学与技术班");
        
        Element Elems2 = rootelem.addElement("student");
        Elems2.addAttribute("id", "002");
        Elems2.addElement("name").setText("李英");
        Elems2.addElement("gender").setText("女");
        Elems2.addElement("grade").setText("计算机科学与技术班");
        
        FileOutputStream ouput = new FileOutputStream("F:\c.xml");
        OutputFormat format = new OutputFormat().createPrettyPrint();
        format.setEncoding("utf-8");
        XMLWriter writer= new XMLWriter(ouput,format);
        writer.write(doc);
        writer.close();
    }
    //修改id为002的学生的名字为李汉三
    @Test
    public void test1() throws Exception{
        Document doc = new SAXReader().read(new File("F：\c.xml"));
        Iterator<Element> it = doc.getRootElement().elementIterator("Student");
        while(it.hasNext()){
            Element stuElem = it.next();
            if(stuElem.attributeValue("id").equals("002")){
                stuElem.element("name").setText("李汉三");
                break;
            }
        }
    
        FileOutputStream out = new FileOutputStream("F：\c.xml");
        OutputFormat format = OutputFormat.createPrettyPrint();
        format.setEncoding("utf-8");
        XMLWriter writer = new XMLWriter(out,format);
        writer.write(doc);
        writer.close();
    }
    //删除id为002的学生的名字标签
    @Test
    public void test2() throws Exception{
        Document doc = new SAXReader().read(new File("F：\c.xml"));
        Iterator<Element> it = doc.getRootElement().elementIterator("Student");
        while(it.hasNext()){
            Element stuElem = it.next();
            if(stuElem.attributeValue("id").equals("002")){
                stuElem.detach();
                break;
            }
        }
        FileOutputStream out = new FileOutputStream("F：\c.xml");
        OutputFormat format = OutputFormat.createPrettyPrint();
        format.setEncoding("utf-8");
        XMLWriter writer = new XMLWriter(out,format);
        writer.write(doc);
        writer.close();
    }
}