SpringMVC 学习笔记(五) 基于RESTful的CRUD

1.1. 概述

当提交的表单带有_method字段时,通过HiddenHttpMethodFilter 将 POST 请求转换成 DELETE、PUT请求,加上@PathVariable注解从而实现 RESTful 风格的CRUD

1.2. 配置信息

Web.xml

<?xml version="1.0" encoding="UTF-8"?

>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0" >
<!-- The front controller of this Spring Web application, responsible for handling all application requests -->
<servlet>
<servlet-name>springDispatcherServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring-mvc.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>

<!-- Map all requests to the DispatcherServlet for handling -->
<servlet-mapping>
<servlet-name>springDispatcherServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>

<!--配置  HiddenHttpMethodFilter 能够将   POST 请求转为 DELETE、PUT 请求 -->
<filter>
<filter-name>hiddenHttpMethodFilter</filter-name>
<filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>
</filter>

<filter-mapping>
<filter-name>hiddenHttpMethodFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>

1.3. 效果

① 通过POST 请求添加员工信息

② 通过PUT 请求改动员工信息

③ 通过DELETE 请求删除员工信息

④ 通过GET 请求 获取全部的 员工信息

1.4. 代码

Employee.java

package com.ibigsea.springmvc.model;

public class Employee {

private Integer id;
private String name;
private String email;
private int sex;

private Department department;

public Employee(Integer id, String name, String email, int sex,
Department department) {
super();
this.id = id;
this.name = name;
this.email = email;
this.sex = sex;
this.department = department;
}

public Employee() {
super();
}

public Integer getId() {
return id;
}

public void setId(Integer id) {
this.id = id;
}

public String getName() {
return name;
}

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

public String getEmail() {
return email;
}

public void setEmail(String email) {
this.email = email;
}

public int getSex() {
return sex;
}

public void setSex(int sex) {
this.sex = sex;
}

public Department getDepartment() {
return department;
}

public void setDepartment(Department department) {
this.department = department;
}

@Override
public String toString() {
return "Employee [id=" + id + ", name=" + name + ", email=" + email
+ ", sex=" + sex + ", department=" + department + "]";
}

}

Department.java

package com.ibigsea.springmvc.model;

import java.io.Serializable;

public class Department implements Serializable {

private static final long serialVersionUID = 6881984318733090395L;

private Integer id;
private String name;

public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}

@Override
public String toString() {
return "Department [id=" + id + ", name=" + name + "]";
}

}

RestfulController.java

package com.ibigsea.springmvc.rest;

import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

import com.ibigsea.springmvc.dao.DepartmentDao;
import com.ibigsea.springmvc.dao.EmployeeDao;
import com.ibigsea.springmvc.model.Employee;

/**
* 基于Restful风格的增删改查
* @author bigsea
*/
@Controller
@RequestMapping("/restful")
public class RestfulController {

@Autowired
private EmployeeDao employeeDao;

@Autowired
private DepartmentDao departmentDao;

/**
* 由于改动的时候不能改动员工姓名,
* 所以通过 @ModelAttribute 注解,
* 表示在运行目标方法时,先获取该员工对象
* 将员工对象存入 implicitMode 中
* @param id 员工ID
* @param map 实际传入的是implicitMode
*/
@ModelAttribute
public void getEmployee(@RequestParam(value="id",required=false) Integer id,Map<String,Object> map){
if (id != null) {
map.put("employee", employeeDao.getEmpById(id));
}
}

/**
* 查看全部的员工信息
* @param map
* @return
*/
@RequestMapping("/list")
public String list(Map<String, Object> map){
map.put("emps", employeeDao.getAll());
return "list";
}

/**
* 跳转到员工加入页面
* @param map
* @return
*/
@RequestMapping(value="/add",method=RequestMethod.GET)
public String add(Map<String, Object> map){
map.put("depts", departmentDao.getAll());
map.put("action", "add");
return "emp";
}

/**
* 加入员工
* @param emp
* @return
*/
@RequestMapping(value="/add",method=RequestMethod.POST)
public String add(Employee emp){
if (emp == null) {
return "emp";
}
if (emp.getDepartment().getId() != null) {
emp.setDepartment(departmentDao.getDepartmentById(emp.getDepartment().getId()));
}
employeeDao.save(emp);
return "redirect:/restful/list";
}

/**
* 删除员工信息
* @param id
* @return
*/
@RequestMapping(value="/delete/{id}",method=RequestMethod.DELETE)
public String delete(@PathVariable("id") Integer id){
employeeDao.delEmpById(id);
return "redirect:/restful/list";
}

/**
* 由于先运行了 @ModelAttribute 注解的方法,
* 获取了该员工ID所相应的员工信息
* 然后在将前台获取的员工数据存入获取的员工信息中,
* 这样就不用提交name属性也能够获取到值
* @param emp
* @return
*/
@RequestMapping(value="/edit",method=RequestMethod.PUT)
public String edit(Employee emp){
if (emp == null) {
return "emp";
}
if (emp.getDepartment().getId() != null) {
emp.setDepartment(departmentDao.getDepartmentById(emp.getDepartment().getId()));
}
employeeDao.save(emp);
return "redirect:/restful/list";
}

/**
* 跳转到员工改动页面
* @param id 员工ID
* @param map implicitMode
* @return
*/
@RequestMapping(value="/edit/{id}",method=RequestMethod.GET)
public String edit(@PathVariable("id") Integer id,Map<String, Object> map){
map.put("emp", employeeDao.getEmpById(id));
map.put("depts", departmentDao.getAll());
map.put("action", "edit");
return "emp";
}

}

EmployeeDao.java

package com.ibigsea.springmvc.dao;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import org.springframework.stereotype.Component;

import com.ibigsea.springmvc.model.Department;
import com.ibigsea.springmvc.model.Employee;

@Component
public class EmployeeDao {

private static Map<Integer,Employee> emps = new HashMap<Integer, Employee>();

/**
* 初始化员工信息
*/
static {
emps.put(1001, new Employee(1001,"AA","AA@ibigsea.com",0,new Department(101, "JAVA")));
emps.put(1002, new Employee(1002,"BB","BB@ibigsea.com",0,new Department(102, ".NET")));
emps.put(1003, new Employee(1003,"CC","CC@ibigsea.com",1,new Department(103, "PHP")));
emps.put(1004, new Employee(1004,"DD","DD@ibigsea.com",0,new Department(104, "C")));
}

private static int employeeId = 1005;

/**
* 保存员工信息
* @param emp
*/
public void save(Employee emp){
if (emp.getId() == null) {
emp.setId(employeeId++);
}
emps.put(emp.getId(), emp);
}

/**
* 获取全部的员工信息
* @return
*/
public Collection<Employee> getAll(){
return emps.values();
}

/**
* 依据ID获取员工信息
* @param id
* @return
*/
public Employee getEmpById(Integer id){
return emps.get(id);
}

/**
* 依据ID删除员工信息
* @param id
*/
public void delEmpById(Integer id){
emps.remove(id);
}

}

DepartmentDao.java

package com.ibigsea.springmvc.dao;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import org.springframework.stereotype.Component;

import com.ibigsea.springmvc.model.Department;

@Component
public class DepartmentDao {

public static Map<Integer, Department> depts = new HashMap<Integer, Department>();

/**
* 初始化部门信息
*/
static {
depts.put(101, new Department(101,"JAVA"));
depts.put(102, new Department(102,".NET"));
depts.put(103, new Department(103,"PHP"));
depts.put(104, new Department(104,"C"));
}

/**
* 获取全部的部门信息
* @return
*/
public Collection<Department> getAll(){
return depts.values();
}

/**
* 依据ID获取部门信息
* @param id
* @return
*/
public Department getDepartmentById(Integer id){
return depts.get(id);
}

}

List.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!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>员工信息</title>
</head>
<body>

<c:if test="${ empty emps }">
没有员工信息
</c:if>
<c:if test="${ !empty emps }">
<table border="1" bordercolor="black" cellspacing="0">
<tr>
<td width="40px">id</td>
<td width="30px">name</td>
<td width="80px">email</td>
<td width="30px">sex</td>
<td width="40px">编辑</td>
<td width="40px">删除</td>
</tr>
<c:forEach items="${emps }" var="emp">
<tr>
<td>${emp.id }</td>
<td>${emp.name }</td>
<td>${emp.email }</td>
<td>${emp.sex == 0 ?

'男' : '女'}</td>
<td><a href="${pageContext.request.contextPath}/restful/edit/${emp.id }">Edit</a></td>
<td><form action="${pageContext.request.contextPath}/restful/delete/${emp.id }" method="post">
<input type="hidden" name="_method" value="DELETE">
<input type="submit" value="Delete">
</form>
</td>
</tr>
</c:forEach>
</table>
</c:if>
<br><br>
<a href="${pageContext.request.contextPath}/restful/add">加入员工</a>
</body>
</html>

Emp.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!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>员工信息</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/restful/${action}" method="post">
<c:if test="${!empty emp}">
<input type="hidden" name="_method" value="PUT">
<input type="hidden" name="id" value="${emp.id }"><br/><br/>
</c:if>
<c:if test="${empty emp}">name : <input type="text" name="name" value="${emp.name }"><br/><br/></c:if>
email : <input type="text" name="email" value="${emp.email }"><br/><br/>
sex :<input type="radio" name="sex" value="0" <c:if test="${emp.sex == 0}">checked</c:if>>男    
<input type="radio" name="sex" value="1" <c:if test="${emp.sex == 1}">checked</c:if>>女<br/><br/>
department :<select name="department.id">
<c:forEach items="${depts }" var="dept">
<option value="${dept.id }" <c:if test="${emp.department.id == dept.id}">selected</c:if>>${dept.name }</option>
</c:forEach>
</select>
<br><br/>
<input type="submit" value="提交">
</form>
</body>
</html>

1.5. 静态资源问题

由于配置了DispatcherServlet而且拦截了全部的请求,所以在加入静态资源的时候会訪问不到静态资源,在springMVC.xml配置

mvc:default-servlet-handler

将在 SpringMVC 上下文中定义一个DefaultServletHttpRequestHandler。它会对进入 DispatcherServlet 的请求进行筛查。假设发现是没有经过映射的请求，就将该请求交由 WEB应用server默认的 Servlet 处理，假设不是静态资源的请求。才由DispatcherServlet 继续处理

mvc:annotation-driven

会自己主动注冊

RequestMappingHandlerMapping

RequestMappingHandlerAdapter

ExceptionHandlerExceptionResolver 三个bean。

就能訪问到静态资源了

1.6. mvc:annotation-driven和mvc:default-servlet-handler

在配置SpringMVC配置文件时加入mvc:annotation-driven

<mvc:annotation-driven /> 会自己主动注冊三个Bean

² RequestMappingHandlerMapping

² RequestMappingHandlerAdapter

² ExceptionHandlerExceptionResolver

还将提供下面支持：

– 支持使用 ConversionService 实例对表单參数进行类型转换

– 支持使用 @NumberFormat 、@DateTimeFormat注解完毕数据类型的格式化

– 支持使用 @Valid 注解对 JavaBean 实例进行 JSR 303 验证

– 支持使用 @RequestBody 和 @ResponseBody 注解