Spring MVC学习随笔-控制器(Controller)开发详解：调用业务对象、父子工厂拆分（applicationContext.xml、dispatcher.xml）

2023-11-28 20:54 由扬眉剑出鞘发表于 #后端开发

学习视频：孙哥说SpringMVC：结合Thymeleaf，重塑你的MVC世界！｜前所未有的Web开发探索之旅

第四章、SpringMVC控制器开发详解二

4.1 核心要点

4.2 SpringMVC控制器调用业务对象【SSM整合】

4.2.1 核心思路分析

4.2.2 编码

dispatcher.xml

<!--设置注解扫描的路径-->
<context:component-scan base-package="com.baizhi"/>

<!--引入SpringMVC的核心功能-->
<mvc:annotation-driven/>

<!--整合跳转路径，解耦合-->
<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/"/>
    <property name="suffix" value=".jsp"/>
</bean>

<!--连接池-->
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    <property name="url" value="jdbc:mysql://localhost:3306/myschool?useSSL=false&amp;allowPublicKeyRetrieval=true"/>
    <property name="username" value="root"/>
    <property name="password" value="123456"/>
</bean>
<!-- 创建SqlSessionFactory SqlSessionFactoryBean-->
<bean id="sqlSessionFactoryBean" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource"/>
    <property name="typeAliasesPackage" value="com.baizhi.entity"/>
    <property name="mapperLocations">
        <list>
            <value>classpath:com.baizhi.mapper/*Mapper.xml</value>
        </list>
    </property>
</bean>
<!--创建DAO对象 MapperScannerConfigure-->
<bean id="scanner" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="sqlSessionFactoryBeanName" value="sqlSessionFactoryBean"/>
    <property name="basePackage" value="com.baizhi.dao"/>
</bean>

<!-- 配置事务-->
<bean id="dataSourceTransactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource"/>
</bean>

<tx:annotation-driven transaction-manager="dataSourceTransactionManager"/>

DAO

// **POJO**
public class User implements Serializable {
    private Integer id;
    private String name;
    private String password;
// **建表**
create table t_user(
    id integer primary key auto_increment;
    name varchar(12),
    password varchar(12)
);
// **DAO**
public interface UserDAO {
    void save(User user);
}
// **Mapper**
<mapper namespace="com.baizhi.dao.UserDAO">

    <insert id="save">
        insert into admin(name,password) values(#{name},#{password})
    </insert>
</mapper>

Service

public interface UserService {
    void register(User user);
}

Service
@Transactional
public class UserServiceImpl implements UserService {

    @Autowired
    private UserDAO userDAO;

    @Override
    public void register(User user) {
        userDAO.save(user);
    }
}

Controller

@Controller
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping("/register")
    public String register(User user) {
        userService.register(user);
        return "regOk";
    }
}

4.2.3 父子工厂（父子容器）拆分

现有SSM开发中存在的问题

MVC层的对象（Controller，mvc:annotation-driven/,视图解析器）与非MVC层的（连接池 DAO Service 事务），都配置在dispatcher.xml中，最终交给DispatcherServlet创建的工厂来进行实例化，存在着耦合问题，后续一旦替换MVC的实现，代码会受到影响，不利于项目的维护
如何解决

将非MVC的配置放在applicationContext.xml(引入ContextLoaderListener工厂读取配置)
1. 把目前单一的工厂进行父子工厂的拆分
  1. 子工厂（DispatcherServlet）读取dispatcher.xml
    
    完成与SpringMVC相关对象的创建：视图解析器、自定义类型转换器、拦截器等
  2. 父工厂（ContextLoaderListener）读取applicationContext.xml
    
    完成与非SpringMVC相关对象的创建：连接池、DAO、Service、事务、Redis、ES、MQ等
2. 工厂（容器）在需要获取对象进行操作时，首先获取子容器所创建的对象，如果没有则继续获得父容器所创建的对象

编码

子工厂（子容器）

# dispatcher.xml
# SpringMVC相关的配置
<!--设置注解扫描的路径-->
<context:component-scan base-package="com.baizhi"/>

<!--引入SpringMVC的核心功能-->
<mvc:annotation-driven/>

<!--整合跳转路径，解耦合-->
<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/"/>
    <property name="suffix" value=".jsp"/>
</bean>

# web.xml子容器的配置
<servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:dispatcher.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>

父工厂（父容器）

# applicationContext.xml
# Spring相关配置
<context:component-scan base-package="com.baizhi"/>
<!--连接池-->
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    <property name="url" value="jdbc:mysql://localhost:3306/myschool?useSSL=false&amp;allowPublicKeyRetrieval=true"/>
    <property name="username" value="root"/>
    <property name="password" value="123456"/>
</bean>
<!-- 创建SqlSessionFactory SqlSessionFactoryBean-->
<bean id="sqlSessionFactoryBean" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource"/>
    <property name="typeAliasesPackage" value="com.baizhi.entity"/>
    <property name="mapperLocations">
        <list>
            <value>classpath:com.baizhi.mapper/*Mapper.xml</value>
        </list>
    </property>
</bean>
<!--创建DAO对象 MapperScannerConfigure-->
<bean id="scanner" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="sqlSessionFactoryBeanName" value="sqlSessionFactoryBean"/>
    <property name="basePackage" value="com.baizhi.dao"/>
</bean>

<!-- 配置事务-->
<bean id="dataSourceTransactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource"/>
</bean>

<tx:annotation-driven transaction-manager="dataSourceTransactionManager"/>

# web.xml父容器的配置
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:applicationContext.xml</param-value>
</context-param>

4.2.4 父子容器问题

问题

按照现有父子工厂（容器）的开发方式，Service层没有添加事务。
问题成因

获取的是子容器的UserService，而子容器中没有事务配置，所以获取不到事务。

解决方案

之所以在子容器没有实现事务，是因为包扫描的全部的包，将service的包也交给子容器管理。

子容器：只扫描控制器及与MVC相关的内容
<context:component-scan base-package="com.baizhi.controller"/>

父容器：不扫描控制器与MVC相关的内容
<context:component-scan base-package="com.baizhi">
    <context:exclude-filter type="aspectj" expression="com.baizhi.controller"/>
</context:component-scan>
注意：在SpingBoot中不会出现父子容器的问题。

4.3 SpringMVC控制器调用业务对象总结（SSM）

4.3.1 完整编码总结

web.xml

<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:applicationContext.xml</param-value>
</context-param>

<servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:dispatcher.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>

<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>

dispatcher.xml

<context:component-scan base-package="com.baizhi.controller"/>
<mvc:annotation-driven/>

<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/"/>
    <property name="suffix" value=".jsp"/>
</bean>

applicationContex.xml

<context:component-scan base-package="com.baizhi">
    <context:exclude-filter type="aspectj" expression="com.baizhi.controller"/>
</context:component-scan>
<!--连接池-->
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    <property name="url" value="jdbc:mysql://localhost:3306/myschool?useSSL=false&amp;allowPublicKeyRetrieval=true"/>
    <property name="username" value="root"/>
    <property name="password" value="123456"/>
</bean>
<!-- 创建SqlSessionFactory SqlSessionFactoryBean-->
<bean id="sqlSessionFactoryBean" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource"/>
    <property name="typeAliasesPackage" value="com.baizhi.entity"/>
    <property name="mapperLocations">
        <list>
            <value>classpath:com.baizhi.mapper/*Mapper.xml</value>
        </list>
    </property>
</bean>
<!--创建DAO对象 MapperScannerConfigure-->
<bean id="scanner" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="sqlSessionFactoryBeanName" value="sqlSessionFactoryBean"/>
    <property name="basePackage" value="com.baizhi.dao"/>
</bean>

<!-- 配置事务-->
<bean id="dataSourceTransactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource"/>
</bean>

<tx:annotation-driven transaction-manager="dataSourceTransactionManager"/>

DAO

// **POJO**
public class User implements Serializable {
    private Integer id;
    private String name;
    private String password;
// **建表**
create table t_user(
    id integer primary key auto_increment;
    name varchar(12),
    password varchar(12)
);
// **DAO**
public interface UserDAO {
    void save(User user);
}
// **Mapper**
<mapper namespace="com.baizhi.dao.UserDAO">

    <insert id="save">
        insert into admin(name,password) values(#{name},#{password})
    </insert>
</mapper>

Service

public interface UserService {
    void register(User user);
}

Service
@Transactional
public class UserServiceImpl implements UserService {

    @Autowired
    private UserDAO userDAO;

    @Override
    public void register(User user) {
        userDAO.save(user);
    }
}

Controller

@Controller
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping("/register")
    public String register(User user) {
        userService.register(user);
        return "regOk";
    }
}

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