SpringMVC 學習筆記(五) 基於RESTful的CRUD
1.1. 概述
當提交的表單帶有_method字段時,通過HiddenHttpMethodFilter 將 POST 請求轉換成 DELETE、PUT請求,加上@PathVariable註解從而實現 RESTful 風格的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 能夠將 POST 請求轉為 DELETE、PUT 請求 --> <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 通過POST 請求添加員工信息
② 通過PUT 請求改動員工信息
③ 通過DELETE 請求刪除員工信息
④ 通過GET 請求 獲取全部的 員工信息
1.4. 代碼
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;
/**
* 基於Restful風格的增刪改查
* @author bigsea
*/
@Controller
@RequestMapping("/restful")
public class RestfulController {
@Autowired
private EmployeeDao employeeDao;
@Autowired
private DepartmentDao departmentDao;
/**
* 由於改動的時候不能改動員工姓名,
* 所以通過 @ModelAttribute 註解,
* 表示在運行目標方法時,先獲取該員工對象
* 將員工對象存入 implicitMode 中
* @param id 員工ID
* @param map 實際傳入的是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));
}
}
/**
* 查看全部的員工信息
* @param map
* @return
*/
@RequestMapping("/list")
public String list(Map<String, Object> map){
map.put("emps", employeeDao.getAll());
return "list";
}
/**
* 跳轉到員工加入頁面
* @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";
}
/**
* 加入員工
* @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";
}
/**
* 刪除員工信息
* @param id
* @return
*/
@RequestMapping(value="/delete/{id}",method=RequestMethod.DELETE)
public String delete(@PathVariable("id") Integer id){
employeeDao.delEmpById(id);
return "redirect:/restful/list";
}
/**
* 由於先運行了 @ModelAttribute 註解的方法,
* 獲取了該員工ID所相應的員工信息
* 然後在將前臺獲取的員工數據存入獲取的員工信息中,
* 這樣就不用提交name屬性也能夠獲取到值
* @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";
}
/**
* 跳轉到員工改動頁面
* @param id 員工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>();
/**
* 初始化員工信息
*/
static {
emps.put(1001, new Employee(1001,"AA","[email protected]",0,new Department(101, "JAVA")));
emps.put(1002, new Employee(1002,"BB","[email protected]",0,new Department(102, ".NET")));
emps.put(1003, new Employee(1003,"CC","[email protected]",1,new Department(103, "PHP")));
emps.put(1004, new Employee(1004,"DD","[email protected]",0,new Department(104, "C")));
}
private static int employeeId = 1005;
/**
* 保存員工信息
* @param emp
*/
public void save(Employee emp){
if (emp.getId() == null) {
emp.setId(employeeId++);
}
emps.put(emp.getId(), emp);
}
/**
* 獲取全部的員工信息
* @return
*/
public Collection<Employee> getAll(){
return emps.values();
}
/**
* 依據ID獲取員工信息
* @param id
* @return
*/
public Employee getEmpById(Integer id){
return emps.get(id);
}
/**
* 依據ID刪除員工信息
* @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>();
/**
* 初始化部門信息
*/
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"));
}
/**
* 獲取全部的部門信息
* @return
*/
public Collection<Department> getAll(){
return depts.values();
}
/**
* 依據ID獲取部門信息
* @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>員工信息</title>
</head>
<body>
<c:if test="${ empty emps }">
沒有員工信息
</c:if>
<c:if test="${ !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">編輯</td>
<td width="40px">刪除</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">加入員工</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>員工信息</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. 靜態資源問題
由於配置了DispatcherServlet而且攔截了全部的請求,所以在加入靜態資源的時候會訪問不到靜態資源,在springMVC.xml配置
mvc:default-servlet-handler
將在 SpringMVC 上下文中定義一個DefaultServletHttpRequestHandler。它會對進入 DispatcherServlet 的請求進行篩查。假設發現是沒有經過映射的請求，就將該請求交由 WEB應用server默認的 Servlet 處理，假設不是靜態資源的請求。才由DispatcherServlet 繼續處理
mvc:annotation-driven
會自己主動註冊
RequestMappingHandlerMapping
RequestMappingHandlerAdapter
ExceptionHandlerExceptionResolver 三個bean。
就能訪問到靜態資源了
1.6. mvc:annotation-driven和mvc:default-servlet-handler
在配置SpringMVC配置文件時加入mvc:annotation-driven
<mvc:annotation-driven /> 會自己主動註冊三個Bean
2 RequestMappingHandlerMapping
2 RequestMappingHandlerAdapter
2 ExceptionHandlerExceptionResolver
還將提供下面支持：
– 支持使用 ConversionService 實例對表單參數進行類型轉換
– 支持使用 @NumberFormat 、@DateTimeFormat註解完畢數據類型的格式化
– 支持使用 @Valid 註解對 JavaBean 實例進行 JSR 303 驗證
– 支持使用 @RequestBody 和 @ResponseBody 註解
SpringMVC 學習筆記(五) 基於RESTful的CRUD