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
                 + "]";
     }
 }

Employee

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+ "]";
     }
 }

Department

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);
     }
 }

EmployeeDao

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);
     }
 }

DepartmentDao

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