学生管理系统案例 查询、增加、删除

         添加

1、创建解析器

2、得到document

3、获取到根节点

4、在根节点上面创建class标签

5、在class标签依次添加id name age

6、在id name age分别添加值

7、回写xml

           删除

1、创建解析器

2、得到document

3、获取到所有的id  使用xpath 返回list集合

4、遍历list集合

5、判断集合里面的id和传递的id是否相同

6、如果相同，把id所在的class删除 （要用父节点去删除）

7、回写xmlx`

          查询

1、创建解析器

2、得到document

3、获取到所有的id，返回list集合并遍历

4、得到每一个id的节点，并获取值

5、判断id的值和传递的id是否相同

6、如果相同，获取到id的父节点class，通过class获取到name age值

7、创建student对象，并设置id name age的值

  代码

package StudentService;

import java.io.FileOutputStream;
import java.util.List;

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

import StudentObject.Student;

public class StuService {
	public static void main(String[] args) {

	}
	//通过查询id返回document 
  public static Student getStu(String id) throws Exception {
	  SAXReader sax = new SAXReader();
	  Document d = sax.read("src/Student.xml");
	  List<Node> list=d.selectNodes("//id");
	  Student s = new Student();
	  for (Node node : list) {
		String node1 =node.getText();
		if(node1.equals(id)) {
			Element par=node.getParent();
			String name1=par.element("name").getText();
			String age1= par.element("age").getText();
			s.setId(node1);
			s.setName(name1);
			s.setAge(age1);
		}
	}
	return s;
	  
  }
  //通过id进行删除，所以传递的是id值
	public static void delStu(String id) throws Exception {
		SAXReader sax = new SAXReader();
		Document d = sax.read("src/Student.xml");
		//通过xpath的方法获得id节点
		List<Node> list =d.selectNodes("//id");
		for (Node node : list) {
			String s =node.getText();
			if(s.equals(id)) {
				Element node1=node.getParent();
				Element node2 =node1.getParent();
				node2.remove(node1);
			}
		}
     XMLWriter xmlw = new XMLWriter(new FileOutputStream("src/Student.xml"), 
    		 OutputFormat.createPrettyPrint());
     xmlw.write(d);
     xmlw.close();
	}
    //传递的是得到getXX和 set方法的Student
	public static void addStu(Student s) throws Exception {
		SAXReader sax = new SAXReader();
		Document d = sax.read("src/Student.xml");
		Element root = d.getRootElement();
		Element class1 = root.addElement("class");
		Element id1 = class1.addElement("id");
		Element name1 = class1.addElement("name");
		Element age1 = class1.addElement("age");
		id1.setText(s.getId());
		name1.setText(s.getName());
		age1.setText(s.getAge());
		XMLWriter xmlw = new XMLWriter(new FileOutputStream("src/Student.xml"),
				OutputFormat.createPrettyPrint());
		xmlw.write(d);
		xmlw.close();

	}
}

　　

package StudentObject;

public class Student {
	private String id;
	private String name;
	private String age;
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getAge() {
		return age;
	}
	public void setAge(String age) {
		this.age = age;
	}
	@Override
	public String toString() {
		return "Student [id=" + id + ", name=" + name + ", age=" + age + "]";
	}
}
	

　　测试

package StudentTest;


import StudentObject.Student;
import StudentService.StuService;

public class Test {
	public static void main(String[] args) throws Exception {
//		Testadd();
//		Testdel();
		selectid();
	}
	public static void selectid() throws Exception {
		Student s=StuService.getStu("101");
		System.out.println(s.toString());
	}
public static void Testdel() throws Exception {
	StuService.delStu("103");
}
	public static void Testadd() throws Exception {
		Student stu = new Student();
		stu.setId("103");
		stu.setName("王五");
		stu.setAge("16");
		StuService.addStu(stu);

	}
}

　　xml 

<?xml version="1.0" encoding="UTF-8"?>

<Student> 
  <class> 
    <id>100</id>  
    <name>张三</name>  
    <age>20</age> 
  </class>  
  <class> 
    <id>101</id>  
    <name>李四</name>  
    <age>25</age> 
  </class> 
</Student>

　　

转载于:https://www.cnblogs.com/zengjiao/p/7246668.html