初次使用SSM框架编写列表的增删改查以及分页

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目录

前言

一、框架搭建

二、具体方法的编写步骤

1.Controller层方法

2.Service层方法

3.Dao层方法

三、具体网页显示

总结

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前言

这是在做课程设计的项目之前，学习如何使用SSM的一个练手项目，其中有框架搭建以及列表的增删改查和分页功能的实现，此下内容大多是个人学习感悟，如有不妥请多指正交流。

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一、框架搭建

本人的SSM框架搭建是在b站学习的，框架搭建不需要自己编写，从其他地方将框架复制过来学会即可，知道框架中的各个位置所发挥的作用即可。 

ssm项目搭建_哔哩哔哩_bilibili

在此附上框架学习的视频，UP主讲的很清晰，还有相应的文件。

SSM框架中三个板块，Dao层，Service层以及Controller层。

Dao层是最底层，负责调用与修改数据库的数据；Service层是中间层，负责Dao层与Controller层之间的数据传输与连接，Controller层是最上层，负责处理网页传来的相关数据并返回数据给网页。

举个例子就是，饭店。

顾客（网页）来吃饭，先向服务员（Controller层）点餐（数据请求），服务员将顾客点的菜（数据请求）写到后厨窗口（Service层），后厨（Dao层）根据窗口要求处理食材（数据库数据）并放到窗口，服务员取菜给顾客。

这样想会不会好理解SSM的大致作用呢？

接下来说说具体的项目，一个学生信息列表，建议是在分别学习好Spring，SpringMVC以及MyBatis三大板块后学着做整合。

 最后我的文件与框架创建如下图所示。

jsp页面文件如下图所示，后续配置文件会设置好jsp文件的前后缀

web.xml的作用是用来配置DispatcherServlet的，用于拦截网页url请求以及分发。

下面的filter用于解决编码乱码问题。

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">
  <display-name>springLearn</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
	 <servlet>
	    <servlet-name>DispatcherServlet</servlet-name>
	    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
	    <init-param> 
	    	
	         <param-name>contextConfigLocation</param-name>
	         <!--一定要注意:我们这里加载的是总的配置文件，之前被这里坑了！-->
	         <param-value>classpath:applicationContext.xml</param-value>
	    </init-param>
	    <load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
	    <servlet-name>DispatcherServlet</servlet-name>
	    <!--注意这里不能配置成/*-->
	    <url-pattern>/</url-pattern>
	</servlet-mapping>
	
	<!--encodingFilter-->
	<filter>
	    <filter-name>encodingFilter</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>encodingFilter</filter-name>
	    <url-pattern>/*</url-pattern>
	</filter-mapping>
  
</web-app>

此框架是将applicationContext.xml中的内容分成三个部分进行编写，此文件就是将三个分文件进行整合。

applicationContext.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:tx="http://www.springframework.org/schema/tx"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="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.xsd 
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/tx 
        http://www.springframework.org/schema/tx/spring-tx.xsd">
        
        <import resource="classpath:spring-dao.xml"/>
        <import resource="classpath:spring-service.xml"/>
        <import resource="classpath:spring-mvc.xml"/>
        
</beans>

 Mybatis-config.xml文件用于配置别名和扫描dao层接口文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>
	<!-- 配置别名 -->
    <typeAliases>
    	<package name="com.pojo"/>
	</typeAliases>
	<!-- 配置扫描dao层接口 -->
	<mappers>
	    <package name="com.dao"/>
	</mappers>
</configuration>

 spring-dao.xml用于SSM框架中最底层的相关文件配置，也就是与数据库连接那一层。

<?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:tx="http://www.springframework.org/schema/tx"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="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.xsd 
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/tx 
        http://www.springframework.org/schema/tx/spring-tx.xsd">
        
        <!-- 数据库连接池 -->
		<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
		    <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
            <!-- cj是mysql8.0的一个特性 -->
		    <property name="url" value="jdbc:mysql://localhost:3306/student?serverTimezone=UTC"/>
		    <property name="username" value="root"/>
		    <property name="password" value="123456"/>
		</bean>
		
		<!-- 配置SqlSessionFactory对象 -->
		<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
		    <property name="dataSource" ref="dataSource" />
		    <!-- mybatis配置文件的位置 -->
		    <property name="configLocation" value="classpath:mybatis-config.xml"/>
		</bean>
		
		
		<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        	<property name="basePackage" value="com.dao"/>
    	</bean>

		
		
</beans>

spring-mvc.xml是视图解析器与注解的配置，即配置jsp文件的前后缀以及pojo层实体类方法的别名扫描，便于写方法更加方便

<?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:tx="http://www.springframework.org/schema/tx"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="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.xsd 
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/tx 
        http://www.springframework.org/schema/tx/spring-tx.xsd">

   		<!-- 1.开启SpringMVC注解驱动 -->
		<mvc:annotation-driven/>
		
		<!-- 2.静态资源默认servlet配置-->
		<mvc:default-servlet-handler/>
		
		<!-- 3.配置jsp 显示ViewResolver视图解析器 -->
		<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		    <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
		    <!-- /WEB-INF/jsp/+视图名+.jsp -->
		    <!-- 前缀 -->
		    <property name="prefix" value="/WEB-INF/jsp/" />
		    <!-- 后缀 -->
		    <property name="suffix" value=".jsp" />
		</bean>
		
		<context:component-scan base-package="com.controller"></context:component-scan>
		

</beans>

spring-service就是service方法的扫描

<?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:tx="http://www.springframework.org/schema/tx"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="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.xsd 
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/tx 
        http://www.springframework.org/schema/tx/spring-tx.xsd">
        
        <context:component-scan base-package="com.service"></context:component-scan>
        
</beans>

二、具体方法的编写步骤

1.Controller层方法

@RequestMapping中填写的是网页的url，即在浏览器输入http://localhost:8080/StudentSSM/pagelistStudent，这里的StudentSSM是项目名称，后面的pagelistStudent就是@的内容

而要跳转的页面就是setViewName中的内容，这里面填的应该是jsp页面的名称（由于在配置文件中已经设置了前缀和后缀，此处直接填jsp页面名称即可）

package com.controller;

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

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.RequestParam;
import org.springframework.web.servlet.ModelAndView;

import com.pojo.Page;
import com.pojo.Student;
import com.service.StudentService;

@Controller
public class Studentcontroller {
	@Autowired
	StudentService studentservice;
	@RequestMapping("/listStudent")
	public ModelAndView listStudent() {
		ModelAndView mav = new ModelAndView();
		List<Student> stduents=studentservice.list();
		mav.addObject("students",stduents);
		mav.setViewName("listStudent");
		return mav;
	}
	@RequestMapping("/pagelistStudent")
	public ModelAndView pagelistStudent(Page page) {
		
		ModelAndView mav = new ModelAndView();
		int total = studentservice.total();
        //设置页码防溢出
		if(page.getstart()<0)
			page.setstart(0);
		if(page.getstart()>total)
			page.setstart(total-1);
		page.calculatelast(total);
		List<Student> pagestudents=studentservice.pagelist(page);
		mav.addObject("pagestudents",pagestudents);
		mav.setViewName("listStudent");
		return mav;
	}
	@RequestMapping("/getStudent")
	public ModelAndView getStudent(int sno) {
		ModelAndView mav = new ModelAndView();
		Student student = studentservice.get(sno);
		List<Student> get = new ArrayList<Student>();
		get.add(student);
		mav.addObject("get",get);
		mav.setViewName("getStudent");
		return mav;
	}
	@RequestMapping("/deleteStudent")
	public ModelAndView deleteStudent(int sno,Page page) {
		ModelAndView mav = new ModelAndView();
		studentservice.delete(sno);
		int total = studentservice.total();
		if(page.getstart()<0)
			page.setstart(0);
		if(page.getstart()>total)
			page.setstart(total-1);
		page.calculatelast(total);
		List<Student> delete=studentservice.pagelist(page);
		mav.addObject("delete",delete);
		mav.setViewName("listStudent");
		return mav;
	}
	@RequestMapping("/beforeinsertStudent")
	public ModelAndView beforeinsertStudent() {
		ModelAndView mav = new ModelAndView();
		mav.setViewName("insertStudent");
		return mav;
	}

	@RequestMapping("/insertStudent")
	public ModelAndView insertStudent(int sno,String sname,Page page) {
		ModelAndView mav = new ModelAndView();
		studentservice.insert(sno,sname);
		int total = studentservice.total();
		if(page.getstart()<0)
			page.setstart(0);
		if(page.getstart()>total)
			page.setstart(total-1);
		page.calculatelast(total);
		List<Student> insert=studentservice.pagelist(page);
		mav.addObject("insert",insert);
		mav.setViewName("listStudent");
		return mav;
	}
	@RequestMapping("/beforeupdateStudent")
	public ModelAndView beforeupdateStudent(int id,int sno,String sname) {
		ModelAndView mav = new ModelAndView();
		mav.addObject("id",id);
		mav.addObject("sno",sno);
		mav.addObject("sname",sname);
		mav.setViewName("updateStudent");
		return mav;
	}
	@RequestMapping("/updateStudent")
	public ModelAndView updateStudent(int id,int sno,String sname) {
		ModelAndView mav = new ModelAndView();
		studentservice.update(id,sno,sname);
		List<Student> update = studentservice.list();
		mav.addObject("update",update);
		mav.setViewName("listStudent");
		return mav;
	}
}

2.Service层方法

 通过接口以实现Controller层调用方法与调用Dao层的方法

package com.service;

import java.util.List;

import com.pojo.Page;
import com.pojo.Student;

public interface StudentService {
	
	List<Student> list();
	
	List<Student> pagelist(Page page);
	int total();
	
	void delete(int sno);
	
	Student get(int sno);
	
	void insert(int sno,String sname);
	
	void update(int id,int sno,String sname);

}

package com.service.impl;

import java.util.List;

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

import com.dao.StudentMapper;
import com.pojo.Page;
import com.pojo.Student;
import com.service.StudentService;

@Service
public class StudentServiceImpl implements StudentService{
	
	@Autowired
	StudentMapper studentmapper;
	
	@Override
	public List<Student> list(){
		return studentmapper.list();
	}
	
	@Override
	public Student get(int sno) {
		return studentmapper.get(sno);
	}
	
	@Override
	public void delete(int sno) {
		studentmapper.delete(sno);
	}
	
	@Override
	public void insert(int sno,String sname) {
		studentmapper.insert(sno,sname);
	}
	
	@Override
	public void update(int id,int sno,String sname) {
		studentmapper.update(id,sno,sname);
	}

	@Override
	public List<Student> pagelist(Page page) {
		// TODO Auto-generated method stub
		return studentmapper.pagelist(page);
	}

	@Override
	public int total() {
		// TODO Auto-generated method stub
		return studentmapper.total();
	}
}

3.Dao层方法

 Dao层就调用底层方法

package com.dao;

import java.util.List;

import org.apache.ibatis.annotations.Param;

import com.pojo.Page;
import com.pojo.Student;

public interface StudentMapper {
	
	public List<Student> list();
	
	public List<Student> pagelist(Page page);
	
	public int total();
	
	public void delete(int sno);
	
	public Student get(int sno);
	
	public void insert(@Param("sno")int sno,@Param("sname")String sname);
	
	public void update(@Param("id")int id,@Param("sno")int sno,@Param("sname")String sname);
	
	
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  <!-- namespace：命名空间，填写对应接口的全限定类名 -->      
<mapper namespace="com.dao.StudentMapper">
	<!-- id：list 对应接口的方法-->
	<select id="list" resultType="Student">
		select * from student
	</select>
	<select id="pagelist" resultType="Student">
		select * from student
		<if test="start!=null and count!=null">
			limit #{start},#{count}
		</if>
	</select>
	<select id="total" resultType="int">
		select count(*) from student
	</select>
	<select id="get" resultType="Student" parameterType="int">
		select * from student where Sno = #{sno}
	</select>
	
	<delete id="delete" parameterType="Student">
		delete from student where Sno = #{sno}
	</delete>
	<insert id="insert" parameterType="Student">
		insert into student(Sno,Sname) value(#{sno},"${sname}")
	</insert>
	<update id="update" parameterType="Student">
		update student set Sno=#{sno},Sname=#{sname} where id=#{id}
	</update>
</mapper>

三、具体网页显示

最后会显示这样的一个表格，其中名字学号都与实际无关，只是用作表单内数据。

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总结

总的来说，将框架搭建好并且理解相关方法的编写后，会让工作变得极其简单，付出时间理解就好了。