Spring MVC中如何提取列表内designation为空的姓名至单独列表

1. 定义员工实体类 #

创建对应数据结构的Employee实体类，包含所需字段及对应的构造方法、Getter/Setter：

public class Employee {
    private String name;
    private String salary;
    private String designation;

    public Employee(String name, String salary, String designation) {
        this.name = name;
        this.salary = salary;
        this.designation = designation;
    }

    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public String getSalary() { return salary; }
    public void setSalary(String salary) { this.salary = salary; }
    public String getDesignation() { return designation; }
    public void setDesignation(String designation) { this.designation = designation; }
}

2. 编写Spring MVC Controller逻辑 #

在Controller中初始化员工数据，过滤出designation为空字符串的人员姓名，将结果存入Model传递给JSP：

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

@Controller
public class EmployeeController {

    @GetMapping("/empty-designation-staff")
    public String getEmptyDesignationStaff(Model model) {
        // 初始化给定的员工数据集
        List<Employee> employeeList = new ArrayList<>();
        employeeList.add(new Employee("zakir", "44003", ""));
        employeeList.add(new Employee("Sheela", "24303", "Developer"));
        employeeList.add(new Employee("Meghana", "100000", "Tester"));

        // 过滤出职位为空的员工姓名列表
        List<String> emptyDesigNames = employeeList.stream()
                .filter(emp -> emp.getDesignation().isEmpty())
                .map(Employee::getName)
                .collect(Collectors.toList());

        // 将列表存入Model，供JSP页面调用
        model.addAttribute("emptyDesigNames", emptyDesigNames);

        // 返回对应的JSP视图名称
        return "staff-view";
    }
}

3. 编写JSP页面渲染下拉框 #

在staff-view.jsp中使用JSTL标签循环生成下拉框选项：

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html>
<head>
    <title>职位为空员工列表</title>
</head>
<body>
    <h3>职位未填写的员工</h3>
    <select>
        <c:forEach items="${emptyDesigNames}" var="name">
            <option value="${name}">${name}</option>
        </c:forEach>
    </select>
</body>
</html>

注意事项 #

• 确保项目已引入JSTL依赖，否则JSP中的<c:forEach>标签无法正常生效。
• 若员工数据来自数据库或其他外部源，只需替换Controller中初始化employeeList的逻辑，过滤规则保持不变即可。

内容的提问来源于stack exchange，提问作者hussain