[SpringMVC] 整合SSM-优快云博客

本文链接：https://blog.youkuaiyun.com/m0_73104158/article/details/134642208

前言

本文将整合Spring、Mybatis、SpringMVC三大框架，并写一个简单的CRUD的Demo程序

一.准备工作

分析需求:没啥需求，就是单表CRUD

准备数据库和表：

CREATE DATABASE `ssmbuild`;
USE `ssmbuild`;
DROP TABLE IF EXISTS `books`;
CREATE TABLE `books` (
  `bookID` INT(10) NOT NULL AUTO_INCREMENT COMMENT '书id',
  `bookName` VARCHAR(100) NOT NULL COMMENT '书名',
  `bookCounts` INT(11) NOT NULL COMMENT '数量',
  `detail` VARCHAR(200) NOT NULL COMMENT '描述',
  KEY `bookID` (`bookID`)
) ENGINE=INNODB DEFAULT CHARSET=utf8
INSERT  INTO `books`(`bookID`,`bookName`,`bookCounts`,`detail`)VALUES 
(1,'Java',1,'从入门到放弃'),
(2,'MySQL',10,'从删库到跑路'),
(3,'Linux',5,'从进门到进牢');

查看数据：

搭建Maven环境，添加相应的依赖：

在构建maven项目的时候，记得去设置里面调一下maven的版本和仓库，不然会用idea自带的maven

<dependencies>
        <!--junit依赖-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
            <scope>test</scope>
        </dependency>
        <!--spring处理事物依赖-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>6.0.11</version>
        </dependency>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.33</version>
        </dependency>
        <!--mybatis依赖-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.10</version>
        </dependency>
        <!--druid连接池依赖-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.20</version>
        </dependency>
        <!--spring整合mybatis依赖-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.6</version>
        </dependency>
        <!--springmvc依赖-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>6.0.11</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/jakarta.servlet/jakarta.servlet-api -->
        <dependency>
            <groupId>jakarta.servlet</groupId>
            <artifactId>jakarta.servlet-api</artifactId>
            <version>6.0.0</version>
            <scope>provided</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/jakarta.servlet.jsp/jakarta.servlet.jsp-api -->
        <dependency>
            <groupId>jakarta.servlet.jsp</groupId>
            <artifactId>jakarta.servlet.jsp-api</artifactId>
            <version>3.1.1</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

依赖有点多，都配好就行了，注意一定要配本地仓库还有选自己maven的配置，要不然它默认去国外仓库下载，要等非常久!!!!(踩过坑)

二.开始搭建

1.首先建立包结构

老生常谈了，MVC架构模式的包：

2.编写Mybatis配置文件

编写的时候碰到这个爆红：

错误是： URI is not registered (Settings | Languages & Frameworks | Schemas and DTDs)

解决办法：在下面加入这个uri即可，不知道idea发什么颠，第一次碰见这问题

因为我们不是单纯使用Mybatis，所以Mybatis很多配置我们可以让Spring帮我们完成，所以在这个配置文件中只写一些系统级的配置；

在此之前我们先把与数据库表对应的pojo类还有Mapper接口给写了，到时候一起配置：

pojo类：标准的pojo，对应数据库表，可以使用lombok简化

package com.jtl.library.pojo;

import java.util.Objects;

/**
 *@description: pojo类，对应ssmbuild库中的books表
 *
 */

public class Book {

    private Integer bookId;
    private String bookName;
    private Integer bookCounts;
    private String detail;
    
    public Book(){
        
    }

    public Book(Integer bookId, String bookName, Integer bookCounts, String detail) {
        this.bookId = bookId;
        this.bookName = bookName;
        this.bookCounts = bookCounts;
        this.detail = detail;
    }

    public Integer getBookId() {
        return bookId;
    }

    public void setBookId(Integer bookId) {
        this.bookId = bookId;
    }

    public String getBookName() {
        return bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }

    public Integer getBookCounts() {
        return bookCounts;
    }

    public void setBookCounts(Integer bookCounts) {
        this.bookCounts = bookCounts;
    }

    public String getDetail() {
        return detail;
    }

    public void setDetail(String detail) {
        this.detail = detail;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Book book = (Book) o;
        return Objects.equals(bookId, book.bookId) && Objects.equals(bookName, book.bookName) && Objects.equals(bookCounts, book.bookCounts) && Objects.equals(detail, book.detail);
    }

    @Override
    public int hashCode() {
        return Objects.hash(bookId, bookName, bookCounts, detail);
    }

    @Override
    public String toString() {
        return "Book{" +
                "bookId=" + bookId +
                ", bookName='" + bookName + '\'' +
                ", bookCounts=" + bookCounts +
                ", detail='" + detail + '\'' +
                '}';
    }
}

BookMapper接口：

package com.jtl.library.mapper;
import com.jtl.library.pojo.Book;
import java.util.List;

/**
 * @author jtl
 * 操作books这张表的Mapper
 */
public interface BookMapper {
    //增加书籍
    int insert(Book book);
    //通过id删除书籍
    int deleteById(int id);
    //更新书籍
    int update(Book book);
    //通过id查找书籍
    Book selectById(int id);
    //通过名字模糊查询书籍
    List<Book> selectByName(String name);
    //查找所有书籍
    List<Book> selectAll();
}

准备工作做完了，下面是mybatis核心配置文件：

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


    <!--使用Mybatis自己的标准日志-->
    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>
<!--给pojo起别名-->
    <typeAliases>
        <package name="com.jtl.library.pojo"/>
    </typeAliases>

    <mappers>
<!--        <mapper resource="BookMapper.xml"/>-->
        <package name="com.jtl.library.mapper"/>
    </mappers>
</configuration>

首先配置了日志，然后给pojo包下面的类起别名，再配置了mapper所在包的位置，这样的话mybatis就知道你的接口都写着哪个包下面了，他就会去找对应的映射文件

BookMapper SQL映射文件：

<?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.jtl.library.mapper.BookMapper">

<insert id="insert">

    insert into books values
                          (#{bookName},#{bookCounts},#{detail});
</insert>

    <delete id="deleteById">
        delete from books where id = #{id};
    </delete>

    <update id="update">
        update books set
                     bookName = #{bookName},
                     bookCounts = #{bookCounts},
                     detail = #{detail}
                    where bookID = #{bookId};
    </update>

    <select id="selectById" resultType="com.jtl.library.pojo.Book">
            select * from books where bookID = #{bookId};
    </select>

    <select id="selectByName" resultType="com.jtl.library.pojo.Book">
            select * from books
                            where bookName like "%"#{bookName}"%"
    </select>

    <select id="selectAll" resultType="com.jtl.library.pojo.Book">
            select * from books;
    </select>
    
</mapper>

3.编写service层的接口和实现类

接口：

package com.jtl.library.service;

import com.jtl.library.pojo.Book;

import java.util.List;

/**
 * @author jtl
 * java学习用
 */
public interface BookService {

   int addBook(Book book);
  
   int deleteBookById(int id);
   
   int updateBook(Book book);
   
   Book queryBookById(int id);

   List<Book> queryBookByName(String name);
   
   List<Book> queryAllBook();

}

实现类：

package com.jtl.library.service.impl;

import com.jtl.library.mapper.BookMapper;
import com.jtl.library.pojo.Book;
import com.jtl.library.service.BookService;

import java.util.List;

/**
 * @description:
 */

public class BookServiceImpl implements BookService {

    private BookMapper bookMapper;
    @Override
    public int addBook(Book book) {
        return bookMapper.insert(book);
    }

    @Override
    public int deleteBookById(int id) {
        return bookMapper.deleteById(id);
    }

    @Override
    public int updateBook(Book book) {
        return bookMapper.update(book);
    }

    @Override
    public Book queryBookById(int id) {
        return bookMapper.selectById(id);
    }

    @Override
    public List<Book> queryBookByName(String name) {
        return bookMapper.selectByName(name);
    }

    @Override
    public List<Book> queryAllBook() {
        return bookMapper.selectAll();
    }
}

4.Spring层

首先是Spring整合Mybatis：

这里遇到一个问题，就是spring配置文件模板突然找不到了，试着刷新了一下依赖，发现又可以了，包括之前写Mapper文件时没有提示的问题也解决了，所以这些配置文件找不到或者没关联基本上是依赖的问题，尝试用maven重新构建一下即可：

先编写连接数据库的配置文件jdbc.properties.xml：

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssmbuild
jdbc.username=root
jdbc.password=jtl

编写spring整合mybatis的配置文件spring-mybatis.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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">

<!--1.引入关联数据库的文件:-->
    <context:property-placeholder location="classpath:jdbc.properties"/>

<!--2.配置数据库连接池(druid)-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${jdbc.driver}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>

<!--3.配置SqlSessionFactory对象
     需要配置数据库连接池
     配置mybatis核心配置文件-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
    </bean>

<!--4.配置扫描Mapper接口的包,，动态实现Mapper接口注入到spring容器中-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 注入sqlSessionFactory -->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        <!-- 给出需要扫描Mapper接口包 -->
        <property name="basePackage" value="com.jtl.library.mapper"/>
    </bean>
</beans>

然后是Spring整合service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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans 
       http://www.springframework.org/schema/beans/spring-beans.xsd 
       http://www.springframework.org/schema/context 
       https://www.springframework.org/schema/context/spring-context.xsd 
       http://www.springframework.org/schema/tx 
       https://www.springframework.org/schema/tx/spring-tx.xsd 
    ">
<!--扫描service相关的bean-->
    <context:component-scan base-package="com.jtl.library.service"/>
    <!-- 配置事务管理器 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <!-- 注入数据库连接池 -->
        <property name="dataSource" ref="dataSource" />
    </bean>
    <!--开启事物注解驱动器，这个配置告诉spring容器我们将使用注解去控制事物-->
    <tx:annotation-driven transaction-manager="transactionManager"/>
</beans>

这里注意，要让两个配置文件有关系才行，下面是一种配置方法，还有一种就是用import直接导入

最后，把两个配置文件合并成一个：

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

    <import resource="classpath:spring-service.xml"/>
    <import resource="spring-mybatis.xml"/>

</beans>

5.SpringMVC层

先配web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:ApplicationContext.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    
    <!--encodingFilter,过滤器解决中文乱码问题-->
    <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>

'/'表示该项目的所有请求路径；'/*'表示只能有一级子路径，它匹配'/a.jsp'但是不匹配'/jsp/a.jsp'。

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
       https://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">

    <!-- 配置SpringMVC -->
    <!-- 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.配置视图解析器-->
    <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
    <!-- 4.扫描web相关的bean -->
    <context:component-scan base-package="com.jtl.library.controller"/>
</beans>

最终整合：

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

    <import resource="spring-service.xml"/>
    <import resource="spring-mybatis.xml"/>
    <import resource="spring-mvc.xml"/>

</beans>

三.开始写程序

写程序的过程中又遇到几个配置上的问题：

第一个是tomcat启动的时候报错：

27-Nov-2023 19:05:27.463 严重 [RMI TCP Connection(2)-127.0.0.1] org.apache.catalina.core.StandardContext.startInternal 一个或多个筛选器启动失败。完整的详细信息将在相应的容器日志文件中找到
27-Nov-2023 19:05:27.463 严重 [RMI TCP Connection(2)-127.0.0.1] org.apache.catalina.core.StandardContext.startInternal 由于之前的错误，Context[/ssm01]启动失败

解决办法是手动把jar包导进去：

第二个是启动后报了个空指针异常：

java.lang.NullPointerException: Cannot invoke "com.jtl.library.mapper.BookMapper.selectAll()" because "this.bookMapper" is null

原因很简单，没有注入属性，把service实现类中的属性注入就行了：

 ···@Autowired
    private BookMapper bookMapper;

第三是web的小蓝点突然消失，然后index.jsp找不到了：

解决办法：

把这个web resource改成你当前项目的web目录即可

第四是关于数据库信息的配置，看这篇即可，注意你用的版本就好了

Java报错：org.springframework.jdbc.CannotGetJdbcConnectionException,Could not get JDBC Connection;-优快云博客