REST风格的增删改查（2）

时间：2023-03-09 05:26:39
REST风格的增删改查（2）

一、源码

1.页面

index.jsp

    <a href="emps">List All Employee</a>

    <br><br>

list.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!-- SpringMVC 中没有遍历循环的标签，所以使用JSTL -->

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<!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>Insert title here</title>

<!--

    1.使用RESTFUL风格的crud，其中需要将删除操作的请求方式改成DELETE，所以可以使用在web.xml文件中配置的Filter

将POST请求转化为DELETE请求，但是删除按钮是一个超链接，即GET请求，所以要使用JS处理GET请求。

    2.SpringMVC处理静态资源，优雅的REST风格的资源URL不希望带.html或.do等后缀，若将DispatcherServlet请求映射

配置为/，则SpringMVC将捕获web容器的所有请求，包括静态资源的请求，SpringMVC会把他们当成普通请求处理，因找不到对应的处理器

将导致错误。

    解决办法：在SpringMVC的配置文件中配置<mvc:default-servlet-handler/>的方式解决静资源的问题

 -->

<script type="text/javascript" src="scripts/jquery-1.9.1.min.js"></script>

<script type="text/javascript">

    $(function(){

        $(".delete").click(function(){

            var href = $(this).attr("href");

            $("form").attr("action", href).submit();

            return false;

        });

    })

</script>

</head>

<body>

    <br>

    <p align="center">员工信息管理</p>

    <br>

    <!-- 添加员工操作 -->

    <p align="center">

        <a href="emp">Add New Employee</a>

    </p>

    <!-- 将GET请求转化为POST请求 -->

    <form action="" method="post">

        <input type="hidden" name="_method" value="DELETE" />

    </form>

    <!-- 首先判断跳转过来之前，请求域中是否包含有数据 -->

    <c:if test="${empty requestScope.employees}">

        没有任何员工信息

    </c:if>

    <!-- 请求域中包含的有数据 -->

    <c:if test="${!empty requestScope.employees}">

        <table border="1" cellspacing="0" align="center">

            <tr>

                <th>ID</th>

                <th>LastName</th>

                <th>Email</th>

                <th>Gender</th>

                <th>Departmet</th>

                <th>Edit</th>

                <th>Delete</th>

            </tr>

        <c:forEach items="${requestScope.employees }" var="emp">

            <tr>

                <td>${emp.id }</td>

                <td>${emp.lastName }</td>

                <td>${emp.email }</td>

                <td>${emp.gender == 0 ? 'Female' : 'Male' }</td>

                <td>${emp.department.departmentName }</td>

                <td><a href="emp/${emp.id }">Edit</a></td>

                <td><a class="delete" href="emp/${emp.id }">Delete</a></td>

            </tr>

        </c:forEach>

        </table>

    </c:if>

</body>

</html>

input.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<%@page import="java.util.HashMap"%>

<%@page import="java.util.Map"%>

<!-- 使用SpringMVC的表单标签 -->

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<!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>Insert title here</title>

</head>

<body>

    <!--

        把表单提交的数据转换成Employee对象

     -->

    <form action="testConversionServiceConverer" method="POST">

        <!-- lastname-email-gender-department.id，例如：GG-gg@163.com-0-105 -->

        Employee：<input type="text" name="employee"/>

        <input type="submit" value="Submit"/>

    </form>

    <br><br>

    <!--

        1.该页面用于添加记录操作，同时又用于修改操作

        2.使用SpringMVC标签的好处：快速开发，方便表单值的回显

        3.注意：可以通过modelAttribute属性指定绑定的模型属性，若没有指定该属性，则默认中request域对象中读取command表单的

        Bean，如果该属性值也不存在，则会发生错误。

    -->

    <form:form action="${pageContext.request.contextPath }/emp" method="POST"

        modelAttribute="employee">

        <!-- 显示错误信息 -->

        <form:errors path="*"></form:errors>

        <br>

        <%-- <form:input path=""/>, 其中path属性对应着HTML表单标签中的name属性 --%>

        <!-- 判断是否有ID，因为这个页面是添加操作和修改操作一同使用的，所以使用有无ID来区别 -->

        <c:if test="${employee.id == null }">

            LastNmae:<form:input path="lastName"/>

                     <form:errors path="lastName"></form:errors>

            <br>

        </c:if>

        <c:if test="${employee.id != null }">

            <form:hidden path="id"/>

            <input type="hidden" name="_method" value="PUT"/>

            <%-- 对于_method不能使用form:hidden标签，因为methodAttribute对应的bean中没有_method这个属性

                <form:hidden path="_method" value="PUT"/>

             --%>

        </c:if>

        Email:<form:input path="email"/>

              <form:errors path="email"></form:errors>

        <br>

        <%

            Map<String, String> genders = new HashMap();

            genders.put("1","Male");

            genders.put("0","Female");

            request.setAttribute("genders", genders);

        %>

        Gender：<form:radiobuttons path="gender" items="${genders }"/>

        <br>

        <!--

            临时添加一个出生日期的属性Birth，这时会遇见一些问题：

            1.数据类型转换

            2.数据类型格式化

            3.数据校验

         -->

        Birth：<form:input path="birth"/>

              <form:errors path="birth"></form:errors>

        <br>    

        Salary：<form:input path="salary"/>

        <br>    

        Department：<form:select path="department.id"

            items="${departments }" itemLabel="departmentName" itemValue="id"></form:select>

        <br>

        <input type="submit" value="添加"/>

    </form:form>

    </p>

</body>

</html>

2.实体类

Employee.java

package com.springmvc.crud.entities;

import java.util.Date;

import javax.validation.constraints.Past;

import org.hibernate.validator.constraints.Email;

import org.hibernate.validator.constraints.NotEmpty;

import org.springframework.format.annotation.DateTimeFormat;

import org.springframework.format.annotation.NumberFormat;

/**

 * 实体类

 *

 */

public class Employee {

    private Integer id;

    //校验lastname不为空

    @NotEmpty

    private String lastName;

    @Email

    private String email;

    //1 male, 0 female

    private Integer gender;

    private Department department;

    //校验日期为当前系统时间之前的时间

    @Past

    //对日期进行格式化，由字符串转化成yyyy-MM-dd

    @DateTimeFormat(pattern="yyyy-MM-dd")

    private Date birth;

    //格式化字符串1,234,567.8为1234567.8

    @NumberFormat(pattern="#,###,###.#")

    private Float salary;

    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;

    }

    public Date getBirth() {

        return birth;

    }

    public void setBirth(Date birth) {

        this.birth = birth;

    }

    public Float getSalary() {

        return salary;

    }

    public void setSalary(Float salary) {

        this.salary = salary;

    }

    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 Employee() {

    }

    @Override

    public String toString() {

        return "Employee [id=" + id + ", lastName=" + lastName + ", email="

                + email + ", gender=" + gender + ", department=" + department

                + ", birth=" + birth + ", salary=" + salary + "]";

    }

}

Department.java

package com.springmvc.crud.entities;

/**

 * 实体类

 */

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

                + "]";

    }

}

3.dao类

EmployeeDao.java

package com.springmvc.crud.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.springmvc.crud.entities.Department;

import com.springmvc.crud.entities.Employee;

@Repository

public class EmployeeDao {

    private static Map<Integer, Employee> employees = null;

    @Autowired

    private DepartmentDao departmentDao;

    //模拟数据库

    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", 0, new Department(102, "D-BB")));

        employees.put(1003, new Employee(1003, "E-CC", "cc@163.com", 1, 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")));

    }

    //定义初始化变量

    private static Integer initId = 1006;

    //添加一条记录

    public void save(Employee employee){

        //当员工的Id为空值时，就在1006的基础上加加，作用类似于数据库中主键的自增

        if(employee.getId() == null){

            employee.setId(initId++);

        }

        //设置employee中department的属性值

        employee.setDepartment(departmentDao.getDepartment(employee.getDepartment().getId()));

        //向数据库中添加记录

        employees.put(employee.getId(), employee);

    }

    //获取所有的记录

    public Collection<Employee> getAll(){

        return employees.values();

    }

    //获取一条记录

    public Employee get(Integer id){

        return employees.get(id);

    }

    //删除一条记录

    public void delete(Integer id){

        employees.remove(id);

    }

}

DepartmentDao.java

package com.springmvc.crud.dao;

import java.util.Collection;

import java.util.HashMap;

import java.util.Map;

import org.springframework.stereotype.Repository;

import com.springmvc.crud.entities.Department;

@Repository

public class DepartmentDao {

    private static Map<Integer, Department> departments = null;

    //模拟数据库

    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);

    }

}

4.Handler

EmployeeHandler.java

package com.springmvc.crud.handlers;

import java.util.Map;

import javax.validation.Valid;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Controller;

import org.springframework.validation.BindingResult;

import org.springframework.validation.FieldError;

import org.springframework.web.bind.WebDataBinder;

import org.springframework.web.bind.annotation.InitBinder;

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.springmvc.crud.dao.DepartmentDao;

import com.springmvc.crud.dao.EmployeeDao;

import com.springmvc.crud.entities.Employee;

/**

 * 控制跳转，并传递参数

 */

@Controller

public class EmployeeHandler {

    @Autowired

    private EmployeeDao employeeDao;

    //因为要在页面上显示部门信息，所以引入DepartmentDao

    @Autowired

    private DepartmentDao departmentDao;

    /**

     * 1.控制跳转到查询所有员工信息的操作

     * 当请求到这个方法，把查到员工的集合放到Map中，同时自动的放入到请求域中，跳转到目标页面之后就可以直接获取

     * @param map

     * @return

     */

    @RequestMapping("/emps")

    public String list(Map<String, Object> map){

        map.put("employees", employeeDao.getAll());

        return "list";

    }

    /**

     * 2.控制跳转到添加一条记录的页面，因为要在页面显示部门信息，所以使用Map映射

     * @param map

     * @return

     */

    @RequestMapping(value="/emp", method=RequestMethod.GET )

    public String input(Map<String, Object> map){

        //把查找到的部门信息放入到map中，同时放到请求域中

        map.put("departments", departmentDao.getDepartments());

        map.put("employee", new Employee());

        return "input";

    }

    @RequestMapping(value="/emp", method=RequestMethod.POST)

    public String save(@Valid Employee employee, BindingResult result,

            Map<String, Object> map){

        System.out.println("save：" + employee);

        if(result.getErrorCount() > 0){

            System.out.println("出错了！");

            for(FieldError error : result.getFieldErrors()){

                System.out.println(error.getField() + "：" + error.getDefaultMessage());

            }

            //若校验出错，则跳转到指定页面

            map.put("departments", departmentDao.getDepartments());

            return "input";

        }

        //执行保存操作

        employeeDao.save(employee);

        return "redirect:/emps";

    }

    /**

     * 3.控制跳转到删除一条记录

     * @param id

     * @return

     */

    @RequestMapping(value="/emp/{id}", method=RequestMethod.DELETE)

    public String delete(@PathVariable("id") Integer id){

        employeeDao.delete(id);

        return "redirect:/emps";

    }

    /**

     * 4.控制跳转到修改一条记录页面

     * @param id

     * @param map

     * @return

     */

    @RequestMapping(value="/emp/{id}", method=RequestMethod.GET)

    public String input(@PathVariable("id") Integer id, Map<String, Object> map){

        System.out.println("修改");

        //根据ID，查到记录，用于回显

        map.put("employee", employeeDao.get(id));

        //所有的部门都放到map中

        map.put("departments", departmentDao.getDepartments());

        return "input";

    }

    @RequestMapping(value="/emp", method=RequestMethod.PUT)

    public String update(Employee employee){

        System.out.println("提交修改");

        employeeDao.save(employee);

        return "redirect:/emps";

    }

    @ModelAttribute

    public void getEmployee(@RequestParam(value="id", required=false) Integer id,

            Map<String, Object> map){

        System.out.println("@ModelAttribute"+id);

        if(id != null){

            map.put("employee", employeeDao.get(id));

        }

    }

    /**

     * 功能：对lastName属性，不赋值

     * @param binder

     */

    /*@InitBinder

    public void initBinder(WebDataBinder binder){

        binder.setDisallowedFields("lastName");

    }*/

}

5.配置文件

web.xml

  <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:springmvc.xml</param-value>

    </init-param>

    <load-on-startup>1</load-on-startup>

  </servlet>

  <servlet-mapping>

    <servlet-name>springDispatcherServlet</servlet-name>

    <url-pattern>/</url-pattern>

  </servlet-mapping>

 <!-- 配置把post请求转化成PUT或DELETE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>

springmvc.xml

<!-- 1.配置自动扫描的包 -->

    <context:component-scan base-package="com.springmvc.crud"></context:component-scan>

<!-- 2.配置视图解析器 -->

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">

        <property name="prefix" value="/WEB-INF/views/"></property>

        <property name="suffix" value=".jsp"></property>

    </bean>

<!-- 3.解决静态资源文件的问题 -->

    <mvc:default-servlet-handler/>

    <mvc:annotation-driven></mvc:annotation-driven>

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