搭建一個最簡單的SSM項目(Spring+SpringMVC+Mybatis

時間 2020-08-10 標籤搭建一個最簡單 ssm 項目 spring+springmvc+mybatis spring springmvc mybatis

首先根據我淺顯的認知，回顧一下Spring，Spring MVC，Mybatis各個小demo中須要作的配置工做。。。html

Spring的簡略配置

Spring是一個基於IOC和AOP的結構J2EE系統的框架，IOC 反轉控制是Spring的基礎，Inversion Of Control 。
簡單說就是建立對象由之前的程序員本身new 構造方法來調用，變成了交由Spring建立對象
DI 依賴注入 Dependency Inject. 簡單地說就是拿到的對象的屬性，已經被注入好相關值了，直接使用便可。java

Spring的核心配置文件是applicationContext.xml。能夠經過以下方式，不須要本身new對象，直接獲取已經被注入值的對象mysql

<bean name="u" class="com.spring.pojo.User">程序員

<property name="name" value="User 1" />web

</bean>spring

若是使用註解的方式進行配置，應該在applicationContext.xml中寫上<context:annotation-config/>。sql

屬性的註解方式有@Autowired（加在屬性前或者加在setter前），@Resource（加在屬性前，寫好值），這樣則無需在配置文件中寫<property>。對於實體類，也能夠進行註解，在class前寫上@Component，爲屬性賦值。數據庫

關於須要瞭解的SpringMVC知識：

WEB-INF目錄下須要建立web.xml。在其中進行servlet的配置。包括<servlet-name/>、<servlet-class/>、<url-pattern/>。express

在WEB-INF目錄下建立springmvc-servlet.xml。其中這裏的<servlet-name>與web.xml中的相同。此文件中對訪問路徑進行相應Controller配置，表面訪問某路徑交由對應的bean處理。而xxxController實現接口Controller，提供方法handleRequest，獲取ModelAndReview的數據，渲染頁面。數組

準備mysql的數據庫ssm，創建表格category_。插入必定數據。

在eclipse中創建pojo的package，創建Category.java實體類。

準備接口CategoryMapper，寫上各種增刪查改方法名。在mapper的package下，新建Category.xml。在Category.xml中，<mapper namespace="..."/>這裏必須寫上同一個包下CategoryMapper的完整類名，com.ssm.mapper.CategoryMapper。增刪查改內容同以前學過的Mybatis。代碼以下：

<?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">
 
    <mapper namespace="com.ssm.mapper.CategoryMapper">
        <insert id="add" parameterType="Category" >
            insert into category_ ( name ) values (#{name})    
        </insert>
         
        <delete id="delete" parameterType="Category" >
            delete from category_ where id= #{id}   
        </delete>
         
        <select id="get" parameterType="_int" resultType="Category">
            select * from   category_  where id= #{id}    
        </select>
 
        <update id="update" parameterType="Category" >
            update category_ set name=#{name} where id=#{id}    
        </update>
        <select id="list" resultType="Category">
            select * from   category_      
        </select>     
    </mapper>

分別創建service和service.impl的package。在兩個包下分別創建CategoryService和CategoryServiceImpl。值得注意的是CategoryServiceImpl必定要繼承CategoryService。因爲在applicationContext.xml中，已經進行了相關bean配置。因此能夠經過@Autowired的註解方式獲取CategoryMapper對象，並調用list方法。

package com.ssm.service;

import java.util.List;

import com.ssm.pojo.Category;

public interface CategoryService {
	List<Category> list();
}

package com.ssm.service.impl;

import java.util.List;

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

import com.ssm.mapper.CategoryMapper;
import com.ssm.pojo.Category;
import com.ssm.service.CategoryService;

@Service
public class CategoryServiceImpl implements CategoryService{
	@Autowired
	CategoryMapper categoryMapper;
	
	public List<Category> list(){
		return categoryMapper.list();
	}
}

如上所述，訪問請求先經過DispatcherServlet,而後訪問對應的xxxController類。也就是說，在xxxController類中，開始請求的任務。利用註解在類前標註@Controller，代表這是一個Controller的類。而後經過註解獲取categoryService對象。利用categoryService獲取種類數據以後，存放在數組中，最終渲染到頁面上。

package com.ssm.controller;

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.servlet.ModelAndView;

import com.ssm.pojo.Category;
import com.ssm.service.CategoryService;

@Controller
@RequestMapping("")
public class CategoryController {
	@Autowired
	CategoryService categoryService;
	
	 @RequestMapping("listCategory")
	    public ModelAndView listCategory(){
	        ModelAndView mav = new ModelAndView();
	        List<Category> cs= categoryService.list();
	         
	        // 放入轉發參數
	        mav.addObject("cs", cs);
	        // 放入jsp路徑
	        mav.setViewName("listCategory");
	        return mav;
	    }
}

如下是各種配置文件

web.xml

<?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" 
         xmlns:web="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_2_5.xsd" version="2.5">
	
	<!-- spring的配置文件-->
	<context-param>
		<param-name>contextConfigLocation</param-name>
		<param-value>classpath:applicationContext.xml</param-value>
	</context-param>
	<listener>
		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
	</listener>
	
	<!-- spring mvc核心：分發servlet -->
	<servlet>
		<servlet-name>mvc-dispatcher</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<!-- spring mvc的配置文件 -->
		<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>mvc-dispatcher</servlet-name>
		<url-pattern>/</url-pattern>
	</servlet-mapping>
	
</web-app>

SpringMVC.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:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.0.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd 
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">

    <context:annotation-config/>

    <context:component-scan base-package="com.ssm.controller">
          <context:include-filter type="annotation" 
          expression="org.springframework.stereotype.Controller"/>
    </context:component-scan>

    <mvc:annotation-driven />
    
    <mvc:default-servlet-handler />

	<!-- 視圖定位 -->
    <bean
        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass"
            value="org.springframework.web.servlet.view.JstlView" />
        <property name="prefix" value="/WEB-INF/jsp/" />
        <property name="suffix" value=".jsp" />
    </bean>
</beans>

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:aop="http://www.springframework.org/schema/aop"
	xmlns:tx="http://www.springframework.org/schema/tx" xmlns:jdbc="http://www.springframework.org/schema/jdbc"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xsi:schemaLocation="
     http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
     http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
     http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.0.xsd
     http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
     http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
     http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">
	
   <context:annotation-config />
	<context:component-scan base-package="com.ssm.service" />

	<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">  
	  <property name="driverClassName">  
	      <value>com.mysql.jdbc.Driver</value>  
	  </property>  
	  <property name="url">  
	      <value>jdbc:mysql://localhost:3306/ssm?characterEncoding=UTF-8</value>  
	
	  </property>  
	  <property name="username">  
	      <value>root</value>  
	  </property>  
	  <property name="password">  
	      <value>admin</value>  
	  </property>  	
	</bean>
	
	<bean id="sqlSession" class="org.mybatis.spring.SqlSessionFactoryBean">
		<property name="typeAliasesPackage" value="com.ssm.pojo" />
		<property name="dataSource" ref="dataSource"/>
		<property name="mapperLocations" value="classpath:com/ssm/mapper/*.xml"/>
	</bean>

	<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
		<property name="basePackage" value="com.ssm.mapper"/>
	</bean>
	
</beans>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" import="java.util.*"%>
  
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
  
<table align='center' border='1' cellspacing='0'>
    <tr>
        <td>id</td>
        <td>name</td>
    </tr>
    <c:forEach items="${cs}" var="c" varStatus="st">
        <tr>
            <td>${c.id}</td>
            <td>${c.name}</td>
               
        </tr>
    </c:forEach>
</table>