SpringMVC实现与CRUD整合

SpringMVC实现与CRUD整合

说明,该demo中使用List模拟了一套数据源,可以实现简单的crud操作,其中修改使用了SpringMVC的问号传参,删除操作使用了路径传参。
对比问号传参与路径传参:

问号传参,需要使用问号来拼接参数,在接受方,使用request.getParameter(“key”)来获取问号所传递过来的值,如果数据类型不为String,还需要手动转换。可以传递多个值,如果使用多个值,使用&来拼接,不会改变路径级别

路径传参,使用路径符号来传递参数,优点,可以不用做类型转换来直接获取其值。

路径传参也可以使用统配规则,如果同时统配和具体的url都满足,则以最具体的url来处理该请求。

1.Emp.java

package com.qfedu.bean;

public class Emp {

    private int eid;
    private String name;
    private double salary;

    public Emp() {
    }

    public Emp(int eid, String name, double salary) {
        this.eid = eid;
        this.name = name;
        this.salary = salary;
    }

    @Override
    public String toString() {
        return "Emp{" +
                "eid=" + eid +
                ", name='" + name + '\'' +
                ", salary=" + salary +
                '}';
    }

    public int getEid() {
        return eid;
    }

    public void setEid(int eid) {
        this.eid = eid;
    }

    public String getName() {
        return name;
    }

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

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }
}

2.EmpController.java

​ 1.RequestMapping

​ 1.可以通过method来区分不同的请求方式
​ 2.@RequestMapping(value = “/updateEmp”, method = RequestMethod.POST)代表处理post请求
​ 3.@RequestMapping(value = “/updateEmp”, method = RequestMethod.GET)代表处理get请求
​ 2.GETMapping,可以简化代码,专门用来处理get请求(4.3以后的Spring版本可用)

​ 3.PostMapping,可以简化代码,专门用来处理post请求(4.3以后的Spring版本可用)

​ 4.PathVariable路径传参的注解,可以实现路径传参。

package com.qfedu.controller;

import com.qfedu.bean.Emp;
import com.qfedu.service.IEmpService;
import com.qfedu.service.impl.EmpServiceImpl;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.*;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import java.util.List;

@Controller
@RequestMapping("/emp")
public class EmpController {

    private IEmpService empService = new EmpServiceImpl();

    /**
     * 如果有了users请求,那么该方法会被调用,返回值为将来要渲染的页面
     * @return
     */
    @RequestMapping("/emps")
    public String getUsersPage(Model model, HttpSession session){

        List<Emp> list = empService.getAllEmps();

        model.addAttribute("list", list);

        session.setAttribute("list",  list);

        return "emp.jsp";
    }

    @RequestMapping("/getEmpByEid")
    public String getEmpByEid(HttpServletRequest request, Model model){

        String seid = request.getParameter("eid");

        int eid = seid == null ? -1 : Integer.parseInt(seid);

        Emp emp = empService.getEmpByEid(eid);

        model.addAttribute("emp", emp);

        return "updateEmp.jsp";
    }

    //@RequestMapping(value = "/updateEmp", method = RequestMethod.POST)
    @PostMapping("/updateEmp")
    //public String updateEmp(HttpServletRequest request){
    public String updateEmp(Emp e){

        //System.out.println(request.getParameter("eid"));
        System.out.println(e);

        boolean flag = empService.updateEmp(e);

        if(flag){
            return "redirect:/emp/emps";
        }

        return "";
    }


    @GetMapping("/deleteByEid/{eid}")
    public String deleteByEid(@PathVariable int eid){
        //System.out.println(eid);

        boolean flag = empService.deleteEmpByEid(eid);

        if(flag){
            return "redirect:/emp/emps";
        }

        return "";
    }
}

3.IEmpService.java

package com.qfedu.service;

import com.qfedu.bean.Emp;

import java.util.List;

public interface IEmpService {

    List<Emp> getAllEmps();

    Emp getEmpByEid(int eid);

    boolean updateEmp(Emp emp);

    boolean deleteEmpByEid(int eid);
}

4.EmpServiceImpl.java

package com.qfedu.service.impl;

import com.qfedu.bean.Emp;
import com.qfedu.dao.impl.EmpDaoImpl;
import com.qfedu.dao.IEmpDao;
import com.qfedu.service.IEmpService;

import java.util.List;

public class EmpServiceImpl implements IEmpService {

    private IEmpDao empDao = new EmpDaoImpl();

    @Override
    public List<Emp> getAllEmps() {
        return empDao.getAllEmps();
    }

    @Override
    public Emp getEmpByEid(int eid) {
        return empDao.getEmpByEid(eid);
    }

    @Override
    public boolean updateEmp(Emp emp) {
        return empDao.updateEmp(emp);
    }

    @Override
    public boolean deleteEmpByEid(int eid) {
        return empDao.deleteEmpByEid(eid);
    }
}

5.IEmpDao.java

package com.qfedu.dao;

import com.qfedu.bean.Emp;

import java.util.List;

public interface IEmpDao {

    List<Emp> getAllEmps();

    Emp getEmpByEid(int eid);

    boolean updateEmp(Emp emp);

    boolean deleteEmpByEid(int eid);
}

6.EmpDaoImpl.java

package com.qfedu.dao.impl;

import com.qfedu.bean.Emp;
import com.qfedu.dao.IEmpDao;

import java.util.ArrayList;
import java.util.List;

public class EmpDaoImpl implements IEmpDao {

    private static List<Emp> emps = new ArrayList<>();

    static {
        for(int i = 0; i < 20; i++){
            emps.add(new Emp(i + 1, "name " + i, 8000 + i * 100));
        }
    }

    @Override
    public List<Emp> getAllEmps() {
        return emps;
    }


    @Override
    public Emp getEmpByEid(int eid) {
        return emps.get(eid - 1);
    }

    @Override
    public boolean updateEmp(Emp emp) {

        try{
            emps.set(emp.getEid() - 1, emp);
            return true;
        }catch (Exception e){
            e.printStackTrace();
        }

        return false;
    }

    @Override
    public boolean deleteEmpByEid(int eid) {
        try{
            emps.remove(eid -1 );
            return true;
        }catch (Exception e){
            e.printStackTrace();
        }
        return false;
    }
}

7.emp.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
    <title>user</title>
</head>
<body>
    <h1>this is users page.</h1>

    <c:if test="${list != null}">
        <table border="1" align="center" width="80%">
            <tr>
                <th>eid</th>
                <th>name</th>
                <th>salary</th>
                <th>manage</th>
            </tr>

            <c:forEach items="${list}" var="e">
                <tr>
                    <td>&nbsp; ${e.eid}</td>
                    <td>&nbsp; ${e.name}</td>
                    <td>&nbsp; ${e.salary}</td>
                    <td>&nbsp; <a href="/emp/getEmpByEid?eid=${e.eid}">update</a> <a href="/emp/deleteByEid/${e.eid}">delete</a></td>
                </tr>
            </c:forEach>
        </table>
    </c:if>
</body>
</html>

8.updateEmp.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>update Emp</title>
</head>
<body>
    <h1>this is emp update page.</h1>


    <form method="post" action="/emp/updateEmp">
        eid:<input type="text" name="eid" value="${emp.eid}" readonly="readonly" /><br />
        name:<input type="text" name="name" value="${emp.name}" /><br />
        salary:<input type="text" name="salary" value="${emp.salary}" /><br />
        <%--salary:<input type="text" name="birth.year" value="${emp.salary}" /><br />--%>
        <input type="submit" value="submit" /><br />
    </form>
</body>
</html>

9.spring-mvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <!--
        配置SpringMVC的视图解析器
            可以分别指定前缀和后缀
                prefix: /WEB-INF/view/,那么控制器那边会在虚拟视图前拼接该字符串
                suffix:.jsp .html,那么控制器那边会在虚拟视图后面拼接该字符串

                拼接完字符串的效果
                    /WEB-INF/view/index.html
                    /WEB-INF/view/detail.jsp
        -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/view/" />
        <!--<property name="suffix" value=".jsp" />-->
    </bean>

    <!--配置缺省的servlet处理器,静态资源可以直接被访问-->
    <mvc:default-servlet-handler />

    <!--
        上下文的组件扫描
    -->
    <context:component-scan base-package="com.qfedu.controller" />

    <!--
        配置注解驱动
    -->
    <mvc:annotation-driven />

    <!--
        bean的id属性值不能包含特殊字符
        name可以,所以路径需要使用name来标识一个控制器的路径
            指定name对应路径交给哪个控制器来进行具体的处理
    -->
    <bean name="/ProductInput" class="com.qfedu.controller.ProductInputController" />
    <bean name="/SaveProductController" class="com.qfedu.controller.SaveProductController" />
</beans>

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