如何用Spring框架的<form:form>标签实现REST风格的增删改查操作

1、首先创建两个bean类，Employee（职工）和Department（部门），一个部门可以有多个职工

Employee类（属性：职工ID：id；姓名：lastName；邮箱：email；性别：gender；所属部门：department）

package com.bwlu.bean;
public class Employee {
    private Integer id;
    private String lastName;
    private String email;
    //1 male, 0 female
    private Integer gender;
    private Department department;
    public Employee() {
        
    }
    public Employee(Integer id, String lastName, String email, Integer gender,
            Department department) {
        super();
        this.id = id;
        this.lastName = lastName;
        this.email = email;
        this.gender = gender;
        this.department = department;
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public Integer getGender() {
        return gender;
    }
    public void setGender(Integer gender) {
        this.gender = gender;
    }
    public Department getDepartment() {
        return department;
    }
    public void setDepartment(Department department) {
        this.department = department;
    }
    @Override
    public String toString() {
        return "Employee [id=" + id + ", lastName=" + lastName + ", email="
                + email + ", gender=" + gender + ", department=" + department
                + "]";
    }
}

Department类（属性：部门ID：id；部门名称：departmentName）

package com.bwlu.bean;
public class Department {
    private Integer id;
    private String departmentName;
    public Department() {
        
    }    
    public Department(int i, String string) {
        this.id = i;
        this.departmentName = string;
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getDepartmentName() {
        return departmentName;
    }
    public void setDepartmentName(String departmentName) {
        this.departmentName = departmentName;
    }
    @Override
    public String toString() {
        return "Department [id=" + id + ", departmentName=" + departmentName+ "]";
    }
}

2、然后分别实现两个bean类的Dao层方法（没有连接数据库，采用Map存储数据）

EmployeeDao类（添加和更新：save()；获取：getAll()和get()；删除：delete()）

package com.bwlu.dao;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import com.bwlu.bean.Department;
import com.bwlu.bean.Employee;
@Repository
public class EmployeeDao {
    private static Map<Integer, Employee> employees = null;
    @Autowired
    private DepartmentDao departmentDao;
    static{
        employees = new HashMap<Integer, Employee>();

        employees.put(1001, new Employee(1001, "E-AA", "aa@163.com", 1, new Department(101, "D-AA")));
        employees.put(1002, new Employee(1002, "E-BB", "bb@163.com", 1, new Department(102, "D-BB")));
        employees.put(1003, new Employee(1003, "E-CC", "cc@163.com", 0, new Department(103, "D-CC")));
        employees.put(1004, new Employee(1004, "E-DD", "dd@163.com", 0, new Department(104, "D-DD")));
        employees.put(1005, new Employee(1005, "E-EE", "ee@163.com", 1, new Department(105, "D-EE")));
    }
    private static Integer initId = 1006;
    public void save(Employee employee){
        if(employee.getId() == null){
            employee.setId(initId++);
        }    
        employee.setDepartment(departmentDao.getDepartment(employee.getDepartment().getId()));
        employees.put(employee.getId(), employee);
    }
    public Collection<Employee> getAll(){
        return employees.values();
    }
    public Employee get(Integer id){
        return employees.get(id);
    }
    public void delete(Integer id){
        employees.remove(id);
    }
}

DepartmentDao类（获取：getDepartments()和getDepartment()）

package com.bwlu.dao;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import org.springframework.stereotype.Repository;
import com.bwlu.bean.Department;
@Repository
public class DepartmentDao {
    private static Map<Integer, Department> departments = null;
    static{
        departments = new HashMap<Integer, Department>();    
        departments.put(101, new Department(101, "D-AA"));
        departments.put(102, new Department(102, "D-BB"));
        departments.put(103, new Department(103, "D-CC"));
        departments.put(104, new Department(104, "D-DD"));
        departments.put(105, new Department(105, "D-EE"));
    }
    public Collection<Department> getDepartments(){
        return departments.values();
    }
    public Department getDepartment(Integer id){
        return departments.get(id);
    }
}

3、前端页面的实现，一共有三个页面，显示页面（showEmployee.jsp），详情页面（detail.jsp），添加和修改页面（addOrEdit.jsp）

showEmployee.jsp，采用jstl标签进行遍历，

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%
    String path = request.getContextPath();
    String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>员工列表</title>
<script type="text/javascript" src="<%=basePath %>public/js/jquery-3.2.1.min.js"></script>
<script type="text/javascript">
function delConfirm(id){
    var b=confirm("确定删除吗？");
    if(b){
        $(function(){
            //REST请求风格的url【delete】
            var url="${pageContext.request.contextPath}/Employee/delete/"+id;
            //将REST请求风格的url绑定到form表单的action属性中，并做提交
            $("#delForm").attr("action",url).submit();
        });
    }
}
</script>
</head>
<body>
<div align="center">
    <a class="aBtn" id="add" href='<c:url value="/Employee/goAddOREdit?id="></c:url>'>添加</a>
    <table>
        <c:choose>
            <c:when test="${not empty employeeList }">
                <tr><th>ID</th><th>姓名</th><th>邮箱</th><th>性别</th><th>部门</th><th>操作</th></tr>
                <c:forEach var="employee" items="${employeeList }">
                <tr><td>${employee.id }</td><td>${employee.lastName }</td><td>${employee.email }</td>
                    <td>${employee.gender==0?'女':'男'}</td>
                    <td>${employee.department.departmentName }</td>
                    <td><a href='<c:url value="/Employee/detail/${employee.id }"></c:url>'>详情</a>
                        <a href='<c:url value="/Employee/goAddOREdit?id=${employee.id }"></c:url>'>修改</a>
                        <a onclick="delConfirm(${employee.id })">删除</a></td></tr>
                </c:forEach>
            </c:when>
            <c:otherwise>
                暂无数据
            </c:otherwise>
        </c:choose>
    </table>
</div>
<!-- 用来将post请求转化为delete请求 -->
<form id="delForm" action="" method="post">
    <input type="hidden" name="_method" value="delete">
</form>
</body>
</html>

detail.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@taglib uri="http://www.springframework.org/tags/form" prefix="form" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>详情页面</title>
</head>
<body>
<div align="center">
    <form:form action="" menthod="post"modelAttribute="employee"><!-- modelAttribute属性指定绑定的模型属性 -->
        ID：<form:input path="id"/><br><!-- path就是input标签的name属性 -->
        姓名：<form:input path="lastName"/><br>
        邮箱：<form:input path="email"/><br>
        性别：<input type="text" value="${employee.gender==0?'女':'男'}"><br><!-- 这里不知道用form标签怎么处理 -->
        部门：<form:input path="department.departmentName"/><br>
        <a href="${pageContext.request.contextPath}/Employee/show">返回</a>
    </form:form>
</div>
</body>
</html>

addOrEdit.jsp

<%@page import="java.util.HashMap"%>
<%@page import="java.util.Map"%>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@taglib uri="http://www.springframework.org/tags/form" prefix="form"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>新增和修改页面</title>
</head>
<body>
<div align="center">
    <form:form action="${pageContext.request.contextPath}/Employee/addOrUpdate" menthod="post" modelAttribute="employee">
        <!-- 如果employee.id不为null，则将post请求转化为put请求 -->
        <c:if test="${not empty employee.id }">
            <input type="hidden" name="_method" value="put">
        </c:if>
        <input type="hidden" name="id" value="${employee.id }">
        姓名：<form:input path="lastName"/><br>
        邮箱：<form:input path="email"/><br>
        <%
            Map<String,Object> genderMap=new HashMap<String,Object>();
            genderMap.put("0", "女");
            genderMap.put("1", "男");
            request.setAttribute("genderMap", genderMap);
        %>
        <!-- 进行修改时，性别和部门会自动匹配，不用我们自己设置 -->
        性别：<form:radiobuttons path="gender"items="${genderMap }"/><br><!-- 运行时自动生成单选钮 -->
        部门：<form:select path="department.id"items="${departList }" 
itemLabel="departmentName"itemValue="id"><!-- 运行时自动生成下拉列表 -->
        </form:select><br>
        <input type="submit" value="提交">
    </form:form>
</div>
</body>
</html>

SpringMVC的<form:form>标签简介

4、在后台写相应的方法

@Controller
@RequestMapping("/Employee")
public class EmployeeController {
    @Autowired
    private EmployeeDao employeeDao;
    @Autowired
    private DepartmentDao departmentDao;
    @RequestMapping(value="/show",method=RequestMethod.GET)
    public String showEmployee(Model m){//显示所有职工
        Collection<Employee> employeeList=new ArrayList<Employee>();
        Collection<Department> departList=new ArrayList<Department>();
        employeeList=employeeDao.getAll();
        departList=departmentDao.getDepartments();
        m.addAttribute("employeeList", employeeList);
        m.addAttribute("departList", departList);
        return "employee/showEmployee";
    }
    @RequestMapping(value="/goAddOREdit",method=RequestMethod.GET)
    public String goAddOREdit(Model m,@RequestParam(value="id") Integer id){//去添加和修改页面
        Employee employee=new Employee();
        Collection<Department> departList=new ArrayList<Department>();
        if(id!=null)
            employee=employeeDao.get(id);
        departList=departmentDao.getDepartments();
        m.addAttribute("employee", employee);
        m.addAttribute("departList", departList);
        return "employee/addOrEdit";
    }
    @RequestMapping(value="/addOrUpdate",method=RequestMethod.POST)
    public String add(Employee employee){//添加职工
        employeeDao.save(employee);
        return "redirect:/Employee/show";
    }
    @RequestMapping(value="/addOrUpdate",method=RequestMethod.PUT)
    public String update(Employee employee){//修改职工
        employeeDao.save(employee);
        return "redirect:/Employee/show";
    }
    @RequestMapping(value="/detail/{id}",method=RequestMethod.GET)
    public String detail(Model m,@PathVariable(value="id") Integer id){//职工详情
        Employee employee=employeeDao.get(id);
        m.addAttribute("employee", employee);
        return "employee/detail";
    }
    @RequestMapping(value="/delete/{id}",method=RequestMethod.DELETE)
    public String delete(@PathVariable(value="id") Integer id) throws IOException{//删除职工
        employeeDao.delete(id);
        return "redirect:/Employee/show";
    }
}

使用REST请求风格需要在web.xml中进行配置，请参见 如何使用REST请求风格