java代码对xml文件进行增删改查操作

1 、创建java项目，引入dom4j-1.6.1.jar

2 、在java项目中定义一个xml文档，命名为 student.xml，放在conf文件夹下。

       初始内容如下(包含一个students的根标签)

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

3 、定义student类，含有姓名，年龄，是否为男生 三个属性

package fileoperation;

public class Student {
	private String name;
	private int age;
	private boolean isBoy;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public boolean isBoy() {
		return isBoy;
	}

	public void setBoy(boolean isBoy) {
		this.isBoy = isBoy;
	}

	@Override
	public String toString() {
		return "student [name=" + name + ", age=" + age + ", isBoy=" + isBoy + "]";
	}
}

4 、定义对xml文件进行增删改查操作的类

package fileoperation;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

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

public class Operation {
	private static String FILE_PATH = "conf/student.xml";     //文件目录

 //在xml文件中添加一个学生信息
	public static void addStudent(Student student)
	{
		InputStream in = null;
		SAXReader reader = new SAXReader();
		Document doc = null;
		try
		{
			in = new FileInputStream(FILE_PATH);
			System.out.println(in);
			doc = reader.read(in);
			Element root = doc.getRootElement();   //获取xml根节点，即students节点
			Element element = root.addElement("student");
			element.addElement("name").addText(student.getName());
			element.addElement("age").addText(String.valueOf(student.getAge()));
			element.addElement("isBoy").addText(String.valueOf(student.isBoy()));

			XMLWriter writer = new XMLWriter();
			FileOutputStream fos = new FileOutputStream(FILE_PATH);
			System.out.println(fos);
			writer.setOutputStream(fos);
			writer.write(doc);
			writer.close();
		}
		catch (Exception e)
		{
			System.out.println("error");
		}
		finally
		{
			try
			{

				if(in != null)
					in.close();
			}
			catch (IOException e)
			{
				System.out.println("error");
			}
		}
	}

//更新学生信息，这里我们假设名称相同则为同一学生
	public static void updateStudent(Student student)
	{
		InputStream in = null;
		SAXReader reader = new SAXReader();
		Document doc = null;
		try
		{
			in = new FileInputStream(FILE_PATH);
			doc = reader.read(in);
			Element root = doc.getRootElement();
			for (Iterator it = root.elementIterator(); it.hasNext();)
			{
				Element element = (Element) it.next();
				if (student.getName().equals(element.element("name").getText()))
				{
					element.element("age").setText(String.valueOf(student.getAge()));
					element.element("isBoy").setText(String.valueOf(student.isBoy()));
					break;
				}
			}
			FileWriter writer = new FileWriter(FILE_PATH);
			doc.write(writer);
			writer.flush();
			writer.close();
		}
		catch (Exception e)
		{
			System.out.println("error");
		}
		finally
		{
			try
			{
				in.close();
			}
			catch (IOException e)
			{
				System.out.println("error");
			}
		}
	}

//列出xml中所有学生信息
	public static List<Student> getStudents()
	{
		InputStream in = null;
		SAXReader reader = new SAXReader();
		Document doc = null;
		List<Student> Students = new ArrayList<>();
		try
		{
			in = new FileInputStream(FILE_PATH);
			doc = reader.read(in);
			Element root = doc.getRootElement();
			List<Element> elements = root.elements();
			Students = new ArrayList<Student>();
			for (Element element : elements)
			{
				Student student = new Student();
				student.setName(element.elementText("name"));
				student.setAge(Integer.valueOf(element.elementText("age")));
				student.setBoy(Boolean.valueOf(element.elementText("isBoy")));
				Students.add(student);
			}
		}
		catch (Exception e1)
		{
			System.out.println("error");
		}
		finally
		{
			try
			{
				in.close();
			}
			catch (IOException e)
			{
				System.out.println("error");
			}
		}

		return Students;
	}

//判断某个学生是否存在该xml中
	public static boolean studentIsExist(String name) 
	{
		InputStream in = null;
		SAXReader reader = new SAXReader();
		Document doc = null;

		try {
			in = new FileInputStream(FILE_PATH);
			doc = reader.read(in);
			Element root = doc.getRootElement();
			List<Element> elements = root.elements();
			for (Element element : elements)
			{
				if(name != null && name.equals(element.elementText("name")))
					return true;
			}

		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (DocumentException e) {
			e.printStackTrace();
		}
		return false;
	}

        //删除xml文件中的所有学生信息，只剩下初始的xml文件
	public static boolean deleteAllStudents()
	{
		InputStream in = null;
		SAXReader reader = new SAXReader();
		Document doc = null;

		try {
			in = new FileInputStream(FILE_PATH);
			doc = reader.read(in);
			Element root = doc.getRootElement();
			List<Element> elements = root.elements();
			for(Element element : elements)
			{
				element.detach();
			}
			FileWriter writer = new FileWriter(FILE_PATH);
			doc.write(writer);
			writer.flush();
			writer.close();
		} catch (Exception e) {
			e.printStackTrace();
		} 
		return false;
	}

//删除xml中某个学生的信息
	public static boolean deleteStudent(String name)
	{
		InputStream in = null;
		SAXReader reader = new SAXReader();
		Document doc = null;

		try {
			in = new FileInputStream(FILE_PATH);
			doc = reader.read(in);
			Element root = doc.getRootElement();
			List<Element> elements = root.elements();
			for(Element element : elements)
			{
				if(name != null && name.equals(element.elementText("name")))
					element.detach();
			}
			FileWriter writer = new FileWriter(FILE_PATH);
			doc.write(writer);
			writer.flush();
			writer.close();
		} catch (Exception e) {
			e.printStackTrace();
		} 
		return false;
	}

}