[Java知识库]SpringMVC实现数据的增删改查（源码）

SpringMVC实现数据增删改查

SpringMVC理解与环境配置

SpringMVC替换了Servlet的职能，降低了web层的耦合性。在 Spring MVC 框架中，Controller 替换 Servlet 来担负控制器的职责，用于接收请求，调用相应的 Model 进行处理，处理器完成业务处理后返回处理结果。Controller 调用相应的 View 并对处理结果进行视图渲染，最终客户端得到响应信息。
springmvc的优点：
1.清晰地角色划分，Spring MVC 在 Model、View 和 Controller 方面提供了一个非常清晰的角色划分，这 3 个方面真正是各司其职，各负其责。
2.灵活的配置功能，可以把类当作 Bean 通过 XML 进行配置。
3.提供了大量的控制器接口和实现类，开发者可以使用 Spring 提供的控制器实现类，也可以自己实现控制器接口。
4.真正做到与 View 层的实现无关。它不会强制开发者使用 JSP，可以根据项目需求使用 Velocity、FreeMarker 等技术。
5.国际化支持面向接口编程与 Spring 框架无缝集成

下图为springmvc的核心框架图：

从图中我们可以看出用户发送一个请求到前端控制器，并不是前端控制器去执行，而是交给自己解析器、处理器去完成工作，前端控制器只负责接受请求与发送响应，其他的渲染，试图解析都是交给其他模块去工作。

DispatcherServlet——>HandlerMapping，处理器映射器将会把请求映射为HandlerExecutionChain对象（包含一个Handler处理器对象、多个HandlerInterceptor拦截器）对象；
DispatcherServlet——>HandlerAdapter，处理器适配器将会把处理器包装为适配器，从而支持多种类型的处理器，即适配器设计模式的应用，从而很容易支持很多类型的处理器；
映射器：会把请求映射为HandlerExecutionChain 对象，包含一个Handler对象和多个拦截器对象。将XX.do映射到处理器Controller，映射器总共有三种BeanNameUrlHandlerMapping、SimpleUrlHandlerMapping和ControllerClassNameHandlerMapping。
处理器HandlerAdapter：处理器适配器有两种，可以共存，分别是SimpleControllerHandlerAdapter和HttpRequestHandlerAdapter。用于处理用户提交的请求, 通过调用service层代码, 实现对用户请求的计算响应, 并最终将计算所得数据及要响应的页面封装为一个ModelAndView 对象, 返回给前端控制器。
视图解析器ViewResolver：视图解析器负责将处理结果生成View视图. 这里介绍两种常用的视图解析器:InternalResourceViewResolver内部资源路径 = 前缀 + 视图名称 + 后缀.BeanNameViewResolverInternalResourceViewResolver视图解析器存在一个问题, 就是只可以完成将内部资源封装后的跳转, 无法跳转向外部资源, 如外部网页.

实现增删改查

1.环境搭建（十分关键）
搭建环境我采用的是maven，导入的依赖有：

 <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.12.1</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>5.3.5</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-beans -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>5.3.5</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.3.5</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-aop -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>5.3.5</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.3.5</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.6</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.26</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.aspectj/aspectjweaver -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.0</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/aopalliance/aopalliance -->
        <dependency>
            <groupId>aopalliance</groupId>
            <artifactId>aopalliance</artifactId>
            <version>1.0</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.aspectj/aspectjtools -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjtools</artifactId>
            <version>1.9.5</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.1</version>
            <scope>compile</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-jdbc -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.3.5</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-tx -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>5.3.5</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis-spring -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.6</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>javax.servlet.jsp-api</artifactId>
            <version>2.3.3</version>
            <scope>provided</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/javax.servlet/servlet-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.0</version>
            <scope>provided</scope>
        </dependency>

web.xml配置文件

<filter>
<!-- 解决字符编码乱码的情况-->
            <filter-name>encoding</filter-name>
            <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
            <init-param>
                <param-name>encoding</param-name>
                <param-value>utf-8</param-value>
            </init-param>
        </filter>
    <filter-mapping>
        <filter-name>encoding</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    
    <filter>
<!--  支持多种请求方式，例如delete、put-->
        <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>
<!--        相当于一个公用的servlet，前端的一个控制器-->
        <servlet-name>dispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-config.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

springmvc配置文件：

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

<context:annotation-config/>
<mvc:view-controller path="/" view-name="user"/>
<mvc:annotation-driven/>
<mvc:default-servlet-handler/>
//表示一个试图解析器bean对象，路径》后缀
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/views/"/>
    <property name="suffix" value=".jsp"/>
</bean>
部分源码：

<%--
  Created by IntelliJ IDEA.
  User: xiaoniu
  Date: 2021/9/22
  Time: 19:57
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
    <link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/css/bootstrap.min.css">
    <script src="https://cdn.staticfile.org/jquery/2.1.1/jquery.min.js"></script>
    <script src="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/js/bootstrap.min.js"></script> <title>用户信息</title>
    <script>
        $(function () {
            $.ajax({
                type: "GET",
                url: "${pageContext.request.contextPath}/user",
                 dataType:"json",
                success: function(json){
                   // alert(json);
                    $(json).each(function(i,v){
                        //alert(v.userid+"|"+v.username+"|"+v.password);
                        var str = "<tbody> <tr class='active'> <td>"+v.userid+"</td> <td>"+v.username+"</td> <td>"+v.password+"</td><td><button id='delete' type='button' class='btn btn-info'>删除</button></td><td><button id='modify' type='button' class='btn btn-danger' data-toggle='modal' data-target='#myModal'>修改</button></td></tr> </tbody>";
                        // alert(str);
                        $("table").append(str);
                    });
                }
            });
            $("#submit").click(function (){
               var id = $("[name='id']").val();

               if(id==''){
                   alert("添加");
                   $("[name='id']").hide();
                   $.ajax({
                       type: "POST",
                       url: "${pageContext.request.contextPath}/user",
                       data: "username="+$("[name='username']").val()+"&password="+$("[name='password']").val(),
                       //dataType:"json",
                       success: function(mesg){
                           alert(mesg);
                           if(mesg=='success'){
                               window.location.reload();
                           }
                       }
                   });
               }else{
                   alert("修改");
                   var data ="username="+$("[name='username']").val()+"&password="+$("[name='password']").val()+"&userid="+$("[name='id']").val()+"&_method=PUT";
                   alert(data);
                   $.ajax({
                       type: "POST",
                       //data:"_method=delete",
                       url: "${pageContext.request.contextPath}/user",
                       data: data,
                       //dataType:"json",
                       success: function(mesg){
                           alert(mesg);
                           //$(this).parents("tbody").remove();
                           window.location.reload();
                       },
                       error:function (){
                           alert("连接失败")
                       }
                   });
               }

            });
            $(document).on("click","#delete",function (){
                var userid = $(this).parents("tr").find("td:first").html();
              // alert(userid);
               //$(this).remove();
                $.ajax({
                    type: "DELETE",
                    //data:"_method=delete",
                    url: "${pageContext.request.contextPath}/user/"+userid,
                    //data: "username="+$("[name='username']").val()+"&password="+$("[name='password']").val(),
                    //dataType:"json",
                    success: function(mesg){
                        alert(mesg);
                        //$(this).parents("tbody").remove();
                        window.location.reload();
                    },
                    error:function (){
                      alert("连接失败")
                    }
                });
            });
            $(document).on("click","#modify",function (){
                var userid = $(this).parents("tr").find("td:first").html();
                var username = $(this).parents("tr").find("td:first").next().html();
                var password = $(this).parents("tr").find("td:first").next().next().html();
                alert(userid+"|"+username+"|"+password);
                $("#submit").html("修改");
                $("[name='id']").val(userid);
                $("[name='username']").val(username);
                $("[name='password']").val(password);
            });

        });
    </script>
</head>

<body>

<div style="width: 400px;height: 300px;margin: 0px auto;">
    <table class="table">
        <thead>
        <tr>
            <th>ID</th>
            <th>用户名</th>
            <th>密码</th></tr>
        </thead>

    </table>

    <button class="btn btn-primary btn-lg" data-toggle="modal" data-target="#myModal">添加用户</button>
    <!-- 模态框（Modal） -->
    <div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
        <div class="modal-dialog">
            <div class="modal-content">
                <div class="modal-header">
                    <button type="button" class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
                    <h4 class="modal-title" id="myModalLabel">用户信息</h4>
                    <form action="/user" method="post">
                        ID<input type="text" name="id"><br>
                        用户名<input type="text" name="username"><br>
                        密码<input type="text" name="password"><br>
                    </form>
                </div>
                <div class="modal-footer">
                    <button type="button" class="btn btn-default" data-dismiss="modal">关闭</button>
                    <button id="submit" type="button" class="btn btn-primary" data-dismiss="modal">添加</button>
                </div>
            </div>
        </div>
    </div>
</div>
</body>
</html>

效果图：