springmvc-实现增删改查


30. 尚硅谷_佟刚_SpringMVC_RESTRUL_CRUD_显示所有员工信息.avi
现在需要使用restful风格实现增删改查，需要将post风格的请求转换成PUT 请求和DELETE 请求
   1. 需要在web.xml文件中配置 HiddenHttpMethodFilter 
        <!-- 
            配置 org.springframework.web.filter.HiddenHttpMethodFilter: 可以把 POST 请求转为 DELETE 或 POST 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>
        2. 需要发送 POST 请求
        3. 需要在发送 POST 请求时携带一个 name="_method" 的隐藏域, 值为 DELETE 或 PUT
我们来看下web.xml的具体配置

<?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 -->
        <!-- 
            配置 org.springframework.web.filter.HiddenHttpMethodFilter: 可以把 POST 请求转为 DELETE 或 POST 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>
    <servlet>
        <servlet-name>springDispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!-- 加载spirng配置文件 -->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-mvc.xml</param-value>
        </init-param>
        <!-- 启动就加载 -->
        <load-on-startup>1</load-on-startup>
    </servlet>

    <!-- 拦截所有请求 -->
    <servlet-mapping>
        <servlet-name>springDispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

1.3. 效果

① 通过POST 请求增加员工信息

② 通过PUT 请求修改员工信息

③ 通过DELETE 请求删除员工信息

④ 通过GET 请求获取所有的员工信息

注意点1；

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

Table tr td th表格使用案例

<table width="300" border="1" cellspacing="0"> 
    <tr> 
        <th>班级</th> 
        <th>日期</th> 
        <th>标题</th> 
    </tr> 
    <tr> 
        <td>一班</td> 
        <td>2012-5-10</td> 
        <td>标题1</td> 
    </tr> 
    <tr> 
        <td>二班</td> 
        <td>2012-5-20</td> 
        <td>标题2</td> 
    </tr> 
</table>

DW软件里截图：

table布局案例截图
table案例教程布局截图

我们来看整个项目的工程如下所示：

代码如下：

DepartmentDao

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"));
    }
    
    /**
     * 获取所有的部门信息
     * @return
     */
    public Collection<Department> getAll(){
        return depts.values();
    }
    
    /**
     * 根据ID获取部门信息
     * @param id
     * @return
     */
    public Department getDepartmentById(Integer id){
        return depts.get(id);
    }
    
}

EmployeeDao

package com.ibigsea.springmvc.dao;

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

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

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

@Component
public class EmployeeDao {
    
    @Autowired
    DepartmentDao departmentDao;
    
    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++);
        }
        emp.setDepartment(departmentDao.getDepartmentById(emp.getDepartment().getId()));
        emps.put(emp.getId(), emp);
    }
    
    /**
     * 获取所有的员工信息
     * @return
     */
    public Collection<Employee> getAll(){
        return emps.values();
    }
    
    /**
     * 根据ID获取员工信息
     * @param id
     * @return
     */
    public Employee getEmpById(Integer id){
        return emps.get(id);
    }
    
    /**
     * 根据ID删除员工信息
     * @param id
     */
    public void delEmpById(Integer id){
        emps.remove(id);
    }
    
}

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'index.jsp' starting page</title>
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
  </head>
  
  <body>
    <a href="emps">查询所有员工的信息</a> <br>
  </body>
</html>

显示所有员工信息的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="${ empty employees }">
        没有员工信息
    </c:if>
    <c:if test="${ !empty employees }">
            <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="30px">department</td>
                    <td width="40px">编辑</td>
                    <td width="40px">删除</td>
                </tr>
                <c:forEach items="${employees }" var="emp">
                    <tr>
                        <td>${emp.id }</tdemployees>
                        <td>${emp.name }</td>
                        <td>${emp.email }</td>
                        <td>${emp.sex == 0 ? '男' : '女'}</td>
                        <td>${emp.department.name}</td>
                        <td><a href="${pageContext.request.contextPath}/edit/${emp.id }">Edit</a></td>
                        <td><form action="${pageContext.request.contextPath}/delete/${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}/emp">添加员工</a>
</body>
</html>

handle处理器

package com.ibigsea.springmvc.handler;

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

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

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

@Controller
public class EmployeeHandler {
    
    @Autowired
    private EmployeeDao employeeDao;
    /*
     * 查询所有的员工信息
     * */
    @RequestMapping(value="/emps",method=RequestMethod.GET)
    public String listAllEmployees(Map<String,Object> map){
    
        Collection<Employee> allEmployees = employeeDao.getAll();
        map.put("employees", allEmployees);
        
        return"list";
    }

}

web.xml配置文件

<?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" >
        <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>
    <servlet>
        <servlet-name>springDispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!-- 加载spirng配置文件 -->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-mvc.xml</param-value>
        </init-param>
        <!-- 启动就加载 -->
        <load-on-startup>1</load-on-startup>
    </servlet>

    <!-- 拦截所有请求 -->
    <servlet-mapping>
        <servlet-name>springDispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

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:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd">
    <!-- 配置自动扫描包  扫描com.ibigsea.springmvc 包下的类，后期会使用spring进行管理 -->
    <context:component-scan base-package="com.ibigsea.springmvc"/>
<!-- 配置视图解析器 如返回helloworld     
                         为 [/WEB-INF/pages/helloworld.jsp] -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
     <!-- 前缀 -->
        <property name="prefix" value="/WEB-INF/pages/"/>
         <!-- 后缀 -->
        <property name="suffix" value=".jsp"/>
    </bean>
    

</beans>

项目有几个地方需要注意的：

1、在DepartMentdao 需要使用spring的@AutoWier功能，需要使用@Component进行注解

2、在spring-xml中需要添加自动扫描 <context:component-scan base-package="com.ibigsea.springmvc"/>

运行效果如下所述

31. 尚硅谷_佟刚_SpringMVC_RESTRUL_CRUD_添加操作&表单标签.avi

1、这里在添加员工的时候使用的是springmvc的表单标签

正式介绍SpringMVC的表单标签之前，我们需要先在JSP中声明使用的标签，具体做法是在JSP文件的顶部加入以下指令：

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

2、

1.用form select标签为例，在书写JSP时，有时笔误可能会写成<form:select path="departmet" items="departments" itemLabel="departmentName" itemValue="id"></form:select>

这种写法是错误的，应该是

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

3、

使用Spring的form标签主要有两个作用，第一是它会自动的绑定来自Model中的一个属性值到当前form对应的实体对象，默认是command对象，这样我们就可以在form表单体里面方便的使用该对象的属性了；

第二是它支持我们在提交表单的时候使用除GET和POST之外的其他方法进行提交，包括DELETE和PUT等。

现在我们在input.jsp中

<%@page import="java.util.Map"%>
<%@page import="java.util.HashMap"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
 <%@taglib uri="http://www.springframework.org/tags/form" prefix="form" %>  
<!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>添加员工信息</title>
</head>
<body>
<!-- 这里是使用springmvc的form标签
    private Integer id;
    private String name;
    private String email;
    private int sex;
    private Department department;
 -->
<form:form action="addEmp" method="post" modelAttribute="employ" >
 id:<form:input path="id"/><br>
 <br> 
   姓名:<form:input path="name"/>
 <br>  
   邮箱:<form:input path="email"/>
 <br> 
 <%
   Map<String,String> genders = new HashMap();
   genders.put("1", "男");
   genders.put("0", "女");  
   request.setAttribute("sexMap",genders);
 %>
    性别:<form:radiobuttons path="sex" items="${sexMap }"/>  
<br> 
  department: <form:select path="department.id" itemLabel="name"
       items="${departments}" itemValue="id"></form:select>
  <br> 
     <input type="submit" value="submit"/>
</form:form>
</body>
</html>

我们需要绑定的域对象不在是默认的command对象，二是表单标签在不进行数据绑定是无法操作的，在运行程序的时候会报错，因为表单标签是依赖于数据绑定操作的。"employ" 对于的employ对象，该对象来自handle中map.put("employ", employee);对象，如果form表达中没有对于的对象进行绑定，form表单

就会抛出异常，所以在使用springmvc 表单中即使不显示任何数据，也要创建下面这样一个空的employee对象，这样显示表单标签才不会异常。如果employee对象中存在name值，email值，跳转到input.jsp页面的时候会把对应的值显示出来，该功能可以用于修改联系人，把联系人原来的信息显示在表单标签中。

总结：表单标签在不进行数据绑定是无法操作的，在运行程序的时候会报错，因为表单标签是依赖于数据绑定操作的。绑定对象可以使用modelAttribute制定需要绑定对象的名称，<form:form action="addEmp" method="post" modelAttribute="employ" >这个配置相当的关键，指定springmvc表单和那个对象就是自动绑定，

@RequestMapping(value="/emp",method=RequestMethod.GET)
    public String input(Map<String,Object> map){
    Collection<Department> departments = departmentDao.getAll();
    map.put("departments", departments);
    Employee employee = new Employee();
    map.put("employ", employee);
    return"input";
    }

4、在添加联系人的页面中，提交的部门的时候

department: <form:select path="department.id" itemLabel="name"
items="${departments}" itemValue="id"></form:select>
<br>

对于的path是department.id，对应的是部门的id，保存的时候依据部门的id值，查询出部门，再把部门保存到联系人中

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

handler控制成的代码为

package com.ibigsea.springmvc.handler;

import java.util.Collection;
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.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.Department;
import com.ibigsea.springmvc.model.Employee;

@Controller
public class EmployeeHandler {
    
    @Autowired
    private EmployeeDao employeeDao;
    @Autowired
    private DepartmentDao departmentDao;
    
    /*
     * 执行添加联系人操作，重定向到显示所有联系人的页面
     * */
    @RequestMapping(value="/addEmp", method=RequestMethod.POST)
    public String addEmp(Employee em){
        employeeDao.save(em);
        //employeeDao.save(employ);
        return "redirect:/emps";
    }
    
    
    /**
     * 点击添加联系人，跳转到添加联系人页面
     * */
    @RequestMapping(value="/emp",method=RequestMethod.GET)
    public String input(Map<String,Object> map){
    Collection<Department> departments = departmentDao.getAll();
    map.put("departments", departments);
    Employee employee = new Employee();
    map.put("employ", employee);
    return"input";
    }
    /*
     * 查询所有的员工信息
     * */
    @RequestMapping(value="/emps",method=RequestMethod.GET)
    public String listAllEmployees(Map<String,Object> map){
    
        Collection<Employee> allEmployees = employeeDao.getAll();
        map.put("employees", allEmployees);
        
        return"list";
    }

}

添加联系人可以总结成下面的三个步骤：

第一档点击添加联系人按钮的时候，请求经过handle处理跳转到handle进行处理，handle返回添加联系人的页面

添加联系人的页面使用到了spring mvc的表单标签，为了便于数据的回显，这里设置了一个modelAttribute="employ"，所以在handle中跳转到添加联系人界面input.jsp的时候都必须在请求域中设置一个空的employ对象，否则会抛出异常

map.put("departments", departments);
    Employee employee = new Employee();
    map.put("employ", employee);
第三步：添加联系人成功之后，重定向到url为emps的handle进行处理，再次查询出数据库中的所有数据，然后跳转到list.jsp将所有的数据显示出来

32. 尚硅谷_佟刚_SpringMVC_RESTRUL_CRUD_删除操作&处理静态资源.avi

删除操作需要使用HiddenHttpMethodFilter将post请求转化成对应的delete请求，其中表达中的name值必须是_method,vale值必须是DELETE

下面的这种方式

<td><a id="sub123" href="${pageContext.request.contextPath}/delete/${emp.id }" >Delete</a></td>

对应的是get请求，我们如何将get请求转化成post请求了，可以使用下面的方式，也可以采用视频中的方式

        <td><form action="${pageContext.request.contextPath}/delete/${emp.id }" method="post">
                                <input type="hidden" name="_method" value="DELETE">
                                <input type="submit" value="Delete">
                            </form>
                        </td>

我们来看list.jsp的代码

<%@ 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">
<!-- 因为jquery文件 -->
<script type="text/javascript" src="/jquery-3.3.1.min.js"></script>
<script type="text/javascript">

</script>
<title>员工信息</title>
</head>
<body>

  <!-- 添加一个表单将post请求转换成delete请求 
   name必须是_method
   value必须是DELETE名字不能被修改
  -->
  </form>

    <c:if test="${ empty employees }">
        没有员工信息
    </c:if>
    <c:if test="${ !empty employees }">
            <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="30px">department</td>
                    <td width="40px">编辑</td>
                    <td width="40px">删除</td>
                </tr>
                <c:forEach items="${employees }" var="emp">
                    <tr>
                        <td>${emp.id }</tdemployees>
                        <td>${emp.name }</td>
                        <td>${emp.email }</td>
                        <td>${emp.sex == 0 ? '男' : '女'}</td>
                        <td>${emp.department.name}</td>
                        <td><a href="${pageContext.request.contextPath}/edit/${emp.id }">Edit</a></td>
                        <td><form action="${pageContext.request.contextPath}/delete/${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}/emp">添加员工</a>
</body>
</html>

我们来看handler的代码

package com.ibigsea.springmvc.handler;

import java.util.Collection;
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.Department;
import com.ibigsea.springmvc.model.Employee;

@Controller
public class EmployeeHandler {
    
    @Autowired
    private EmployeeDao employeeDao;
    @Autowired
    private DepartmentDao departmentDao;
    
    /*
     * 执行添加联系人操作，重定向到显示所有联系人的页面
     * */
    @RequestMapping(value="/delete/{id}", method=RequestMethod.DELETE)
    public String deletEmp(@PathVariable("id") Integer id ){
        employeeDao.delEmpById(id);
        //employeeDao.save(employ);
        return "redirect:/emps";
    }
    
    /*
     * 执行添加联系人操作，重定向到显示所有联系人的页面
     * */
    @RequestMapping(value="/addEmp", method=RequestMethod.POST)
    public String addEmp(Employee em){
        employeeDao.save(em);
        return "redirect:/emps";
    }
    
    
    /**
     * 点击添加联系人，跳转到添加联系人页面
     * */
    @RequestMapping(value="/emp",method=RequestMethod.GET)
    public String input(Map<String,Object> map){
    Collection<Department> departments = departmentDao.getAll();
    map.put("departments", departments);
    Employee employee = new Employee();
    map.put("employ", employee);
    return"input";
    }
    /*
     * 查询所有的员工信息
     * */
    @RequestMapping(value="/emps",method=RequestMethod.GET)
    public String listAllEmployees(Map<String,Object> map){
    
        Collection<Employee> allEmployees = employeeDao.getAll();
        map.put("employees", allEmployees);
        
        return"list";
    }

}

注意点：

在web.xml中配置

  <!-- 拦截所有请求 -->
    <servlet-mapping>
        <servlet-name>springDispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

拦截所以的请求，如果访问静态资源文件也会被拦截。但是对于的访问静态资源的文件没有在handler中进行映射处理，就会导出错误，为了能够直接访问静态资源文件不会出现问题，需要在spring-mvc.xml文件中进行下面的配置

  <!-- 配置运行可以访问静态资源文化 -->
    <mvc:default-servlet-handler/>
    <mvc:annotation-driven></mvc:annotation-driven>

spring-mvc.xml的代码如下

<?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:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd">
    <!-- 配置自动扫描包  扫描com.ibigsea.springmvc 包下的类，后期会使用spring进行管理 -->
    <context:component-scan base-package="com.ibigsea.springmvc"/>
<!-- 配置视图解析器 如返回helloworld     
                         为 [/WEB-INF/pages/helloworld.jsp] -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
     <!-- 前缀 -->
        <property name="prefix" value="/WEB-INF/pages/"/>
         <!-- 后缀 -->
        <property name="suffix" value=".jsp"/>
    </bean>

    <!-- 配置运行可以访问静态资源文化 -->
    <mvc:default-servlet-handler/>
    <mvc:annotation-driven></mvc:annotation-driven>
    

</beans>

33. 尚硅谷_佟刚_SpringMVC_RESTRUL_CRUD_修改操作.avi

修改操作

1、在修改页面显示需要修改的联系人，但是联系人的name属性不能被修改

2、修改联系人需要使用PUT方式提交

这里因为要在input.jsp中显示需要修改的联系人，需要对input.jsp做下面的修改

 <c:if test="${ employ.id != null}">
  <form:hidden path="id"/>
  <input type="hidden" name="_method" value="PUT"/> 
 </c:if>

我们来看下程序的代码

<%@page import="java.util.Map"%>
<%@page import="java.util.HashMap"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
 <%@taglib uri="http://www.springframework.org/tags/form" prefix="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>添加员工信息</title>
</head>
<body>
<!-- 这里是使用springmvc的form标签
    private Integer id;
    private String name;
    private String email;
    private int sex;
    private Department department;
 -->
<form:form action="${pageContext.request.contextPath}/addEmp" method="post" modelAttribute="employ" >
 <!-- 判断id的值是否存在，如果存在就是修改联系人，不显示id标签 -->
  <!-- 判断id的值是否存在，如果存在就是修改联系人，联系人的name属性不能被修改 -->
 <c:if test="${ employ.id == null}">
  id:<form:input path="id"/><br>
   <br> 
        姓名:<form:input path="name"/>
 <br> 
 </c:if>

<!-- 不等于null，需要将联系人id的值重新传递到handle进行处理 
对象中存在id属性，可以直接传递,并且需要将表单的post请求转化成put请求。我们需要传递一个_method属性，对应的value值是PUT传递到handle中-->
 <c:if test="${ employ.id != null}">
  <form:hidden path="id"/>
  <input type="hidden" name="_method" value="PUT"/> 
 </c:if>
 

 
   邮箱:<form:input path="email"/>
 <br> 
 <%
   Map<String,String> genders = new HashMap();
   genders.put("1", "男");
   genders.put("0", "女");  
   request.setAttribute("sexMap",genders);
 %>
    性别:<form:radiobuttons path="sex" items="${sexMap }"/>  
<br> 
  department: <form:select path="department.id" itemLabel="name"
       items="${departments}" itemValue="id"></form:select>
  <br> 
     <input type="submit" value="submit"/>
</form:form>
</body>
</html>

我们来看下handle层的代码

package com.ibigsea.springmvc.handler;

import java.util.Collection;
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.Department;
import com.ibigsea.springmvc.model.Employee;

@Controller
public class EmployeeHandler {
    
    @Autowired
    private EmployeeDao employeeDao;
    @Autowired
    private DepartmentDao departmentDao;
    
    /**
     * 点击修改联系人，跳转到修改联系人页面，显示需要修改的联系人信息，其中联系人的名字不能被修改
     * */
    @RequestMapping(value="/edit/{id}",method=RequestMethod.GET)
    public String input(@PathVariable("id") Integer id,Map<String,Object> map){
        
    Collection<Department> departments = departmentDao.getAll();
    map.put("departments", departments);
    //通过id查找需要修改的联系人
    Employee employee = employeeDao.getEmpById(id);
    map.put("employ", employee);
    return"input";
    }
    
    /**
     * 这里需要在执行修改联系人在保存的时候先查询出来，否则自己保存
     *  m is :Employee [id=1002, name=null, email=BB@ibigsea.com, sex=0, department=Department [id=101, name=null]]
     *  会存在联系人名字为空的情况，修改修改联系人页面没有传递联系人姓名的属性值
     * */
    @ModelAttribute
    public void getEmployee(@RequestParam(value="id",required = false) Integer id ,Map<String,Object> map){
        if(id != null){
            Employee employee = employeeDao.getEmpById(id);
            //map.put("employ", employee)名字和@ModelAttribute("employ")中的一一对应
            map.put("employ", employee);
        }
    }
    
    /***
     * 保存修改联系人页面，修改的联系人，对应的action是addEmp
     * <form:form action="addEmp" method="post" modelAttribute="employ" >
     * 对应的访问方式是对应的访问方式是PUT方式
     *  <input type="hidden" name="_method" value="PUT"/> 
     *  
     *  注意点2:
     *  这里在修改修改联系人的时候，需要被修改联系人的name属性不能被修改
     *  m is :Employee [id=1002, name=null, email=BB@ibigsea.com, sex=0, department=Department [id=101, name=null]]
     * */
    @RequestMapping(value="/addEmp", method=RequestMethod.PUT)
    public String update(@ModelAttribute("employ")Employee em){
        System.out.println("em is :"+em.toString());
        employeeDao.save(em);
        return "redirect:/emps";
    }
    
    /*
     * 执行添加联系人操作，重定向到显示所有联系人的页面
     * */
    @RequestMapping(value="/delete/{id}", method=RequestMethod.DELETE)
    public String deletEmp(@PathVariable("id") Integer id ){
        employeeDao.delEmpById(id);
        //employeeDao.save(employ);
        return "redirect:/emps";
    }
    
    /*
     * 执行添加联系人操作，重定向到显示所有联系人的页面
     * */
    @RequestMapping(value="/addEmp", method=RequestMethod.POST)
    public String addEmp(Employee em){
        employeeDao.save(em);
        return "redirect:/emps";
    }
    
    
    /**
     * 点击添加联系人，跳转到添加联系人页面
     * */
    @RequestMapping(value="/emp",method=RequestMethod.GET)
    public String input(Map<String,Object> map){
    Collection<Department> departments = departmentDao.getAll();
    map.put("departments", departments);
    Employee employee = new Employee();
    map.put("employ", employee);
    return"input";
    }
    /*
     * 查询所有的员工信息
     * */
    @RequestMapping(value="/emps",method=RequestMethod.GET)
    public String listAllEmployees(Map<String,Object> map){
    
        Collection<Employee> allEmployees = employeeDao.getAll();
        map.put("employees", allEmployees);
        
        return"list";
    }

}

整个工程的代码下载路径地址是：

https://pan.baidu.com/s/1vP_BYybJnAByqSsp35o3Cg

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原文地址：https://www.cnblogs.com/kebibuluan/p/8855057.html