写入文件时数据会重复

Question

我在使用 JAXB 或 BufferedWriter 时遇到问题。当我将员工添加到员工列表然后编组列表时，我得到写入 xml 文件的员工列表，但它写入列表两次。这是我的代码。

主要Class

package schleusner.cameron;

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

public class Main {
    public static void main(String[] args) throws IOException, JAXBException         {

        Employees employees = new Employees();
        employees.setEmployees(new ArrayList<Employee>());

        Employee e1 = new Employee();
        e1.setName("codippa");
        e1.setLogin("4:30Pm");


        Employee e2 = new Employee();
        e2.setName("emp1");
        e2.setLogin("5:00PM");


        Employee e3 = new Employee();
        e3.setName("emp2");
        e3.setLogin("8:00AM");


        Employee e4 = new Employee();
        e4.setName("emp3");
        e4.setLogin("1:20AM");


        employees.getEmployees().add(e1);
        employees.getEmployees().add(e2);
        employees.getEmployees().add(e3);
        employees.getEmployees().add(e4);

        BufferedWriter writer1 = new BufferedWriter(new FileWriter("C:\Users\Cameron\Desktop\xmltest\Employees.xml"));
        JAXBContext context = JAXBContext.newInstance(Employees.class);
        Marshaller m = context.createMarshaller();

        m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);

        m.marshal(employees, writer1);
        writer1.close();
    }
}

员工人数class

package schleusner.cameron;
import java.util.List;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="Employees")
@XmlAccessorType (XmlAccessType.FIELD)
public class Employees {
  private List<Employee> employee;

  @XmlElement(name="Employee")
  public List<Employee> getEmployees() {
      return employee;
  }

  public void setEmployees(List<Employee> employeeList) {
      this.employee = employeeList;
  }
}

员工Class

package schleusner.cameron;
import javax.xml.bind.annotation.XmlElement;

public class Employee {
    private String name;
    private String password;
    private String login;
    private String logout;
    private String lunchin;
    private String lunchout;

    @XmlElement
    public String getName() {
        return name;
    }

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

    @XmlElement
    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @XmlElement
    public String getLogin() {
        return login;
    }

    public void setLogin(String login) {
        this.login = login;
    }

    @XmlElement
    public String getLogout() {
        return logout;
    }

    public void setLogout(String logout) {
        this.logout = logout;
    }

    @XmlElement
    public String getLunchin() {
        return lunchin;
    }

    public void setLunchin(String lunchin) {
        this.lunchin = lunchin;
    }

    @XmlElement
    public String getLunchout() {
        return lunchout;
    }

    public void setLunchout(String lunchout) {
        this.lunchout = lunchout;
    }
}

文件输出: https://pastebin.com/raw/aTqmqwHh

Answer 1

将 @XmlAccessorType(XmlAccessType.FIELD) 更改为 @XmlAccessorType (XmlAccessType.PROPERTY) Employees class。

或者将 @XmlElement(name = "Employee") 移动到 private List<Employee> employee;。

问题是，JAXB 考虑了 @XmlAccessorType 以及显式注释。所以基本上你有两个属性 employee 和 employees，都映射到 Employee 元素。这会导致重复输出。

写入文件时数据会重复

Data gets duplicated when written to file

java

jaxb

bufferedwriter