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