当前位置：网站首页>SSM integrated notes easy to understand version

SSM integrated notes easy to understand version

2022-07-06 10:51:00 【Bolus acidophilus】

Video link ：【 Sangeng thatched cottage 】SSM Integrate easy to understand version

1.SSM Integrate

1.0 Step analysis

Let's first analyze how to put Spring,SpringMVC,Mybatis Put it all together .

1.0.1 step

①Spring On Integration Mybatis

adopt Service layer Dao Layer injection Spring In the container

② Import configuration SpringMVC

hold Controller Layer injection SpringMVC In the container

③ Give Way web Automatically read when the project starts Spring Profile to create Spring Containers

have access to ContextLoaderListener To achieve Spring Container creation .

1.0.2 Common doubts

Why use two containers ？
because Controller If you don't put it in MVC There will be no effect in the container , Unable to process request . and Service If you don't put it in Spring In the container , Declarative transactions cannot be used .
SpringMVC In container Controller Need to rely on Service, Can from Spring Get the dependent Service The object ？
Spring The container is equivalent to the parent container ,MVC The container is equivalent to a sub container . In addition to using the objects in its own container, a child container can also use the objects in its parent container .
How to realize such a parent-child container relationship ？
See the video of the source code analysis stage for details . But now we can use code to simulate .
When did you make two containers have this parent-child relationship ？
stay ContextLoaderListener in , After the container is created, it will be stored in servletContext Domain . In this way DispatcherServlet Startup time , Created SpringMVC The container will be removed from servletContext Get Spring Container object , Set to its parent container , In this way, the child container can get the bean 了 . See the source code analysis video for details .

SpringMVC In container Controller Need to rely on Service, Can from Spring Get the dependent Service The object ？

How to realize such a parent-child container relationship ？

1.1 preparation

Introduce all dependencies

 <!--Spring-context-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>
        <!--AOP Related dependencies -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.13</version>
        </dependency>
        <!-- spring-jdbc -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>
        <!-- mybatis Integrate to Spring The integration package  -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.4</version>
        </dependency>
        <!--mybatis rely on -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.4</version>
        </dependency>
        <!--log4j rely on , Print mybatis journal -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <!-- Paging query ,pagehelper-->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper</artifactId>
            <version>4.0.0</version>
        </dependency>

        <!--mysql drive -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <!-- druid data source  -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.16</version>
        </dependency>

        <!-- junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <!-- spring Integrate junit Dependence  -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
            <scope>provided</scope>
        </dependency>


        <!-- servlet rely on  -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <!--jsp rely on  -->
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.1</version>
            <scope>provided</scope>
        </dependency>
        <!--springmvc Dependence -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>

        <!-- jackson, To help carry out json transformation -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.0</version>
        </dependency>

        <!--commons Upload files , If you need the file upload function , You need to add this dependency -->
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.4</version>
        </dependency>

Database initialization statement

CREATE DATABASE /*!32312 IF NOT EXISTS*/`mybatis_db` /*!40100 DEFAULT CHARACTER SET utf8 */;
USE `mybatis_db`;
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(50) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  `address` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;
insert  into `user`(`id`,`username`,`age`,`address`) values (1,'UZI',19,' Shanghai '),(2,'PDD',25,' Shanghai ');

1.2 Related configuration

① Integrate Spring and Mybatis

stay resources Create under directory Spring Core profile ： applicationContext.xml The contents are as follows

<?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:aop="http://www.springframework.org/schema/aop" 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 http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd">

    <!-- Component scan , exclude controller-->
    <context:component-scan base-package="com.sangeng">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"></context:exclude-filter>
    </context:component-scan>

    <!-- Read properties file -->
    <context:property-placeholder location="classpath:jdbc.properties"></context:property-placeholder>
    <!-- Create connection pool injection container -->
    <bean class="com.alibaba.druid.pool.DruidDataSource" id="dataSource">
        <property name="url" value="${jdbc.url}"></property>
        <property name="username" value="${jdbc.username}"></property>
        <property name="password" value="${jdbc.password}"></property>
        <property name="driverClassName" value="${jdbc.driver}"></property>
    </bean>
    <!--spring Integrate mybatis Creation and acquisition of post control SqlSessionFactory The object of -->
    <bean class="org.mybatis.spring.SqlSessionFactoryBean" id="sessionFactory">
        <!-- Configure connection pool -->
        <property name="dataSource" ref="dataSource"></property>
        <!-- To configure mybatis The path to the configuration file -->
        <property name="configLocation" value="classpath:mybatis-config.xml"></property>
    </bean>

    <!--mapper Scan configuration , Scanned mapper Objects will be injected Spring In the container -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer" id="mapperScannerConfigurer">
        <property name="basePackage" value="com.sangeng.dao"></property>
    </bean>

    <!-- Turn on aop Annotation support -->
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>

    <!-- Declarative transaction related configuration -->
    <bean class="org.springframework.jdbc.datasource.DataSourceTransactionManager" id="transactionManager">
        <property name="dataSource" ref="dataSource"></property>
    </bean>
    <tx:annotation-driven transaction-manager="transactionManager"></tx:annotation-driven>

</beans>

stay resources Create under directory jdbc.properties file , The contents are as follows ：

jdbc.url=jdbc:mysql://localhost:3306/mybatis_db?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC
jdbc.driver=com.mysql.jdbc.Driver
jdbc.username=root
jdbc.password=root

stay resources Create under directory mybatis-config.xml , The contents are as follows ：

<?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>
    <settings>
        <!-- Specify the use of log4j Print Mybatis journal -->
        <setting name="logImpl" value="LOG4J"/>
    </settings>
    <!-- Configure alias package -->
    <typeAliases>
        <package name="com.sangeng.domain"></package>
    </typeAliases>
    <plugins>
        <!--  Be careful ： Plug in for paging assistant , Configuration in general mapper Before  -->
        <plugin interceptor="com.github.pagehelper.PageHelper">
            <!--  To designate a dialect  -->
            <property name="dialect" value="mysql"/>
        </plugin>
    </plugins>
</configuration>

stay resources Create under directory log4j.properties , The contents are as follows ：

### direct log messages to stdout ###
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n

### direct messages to file mylog.log ###
log4j.appender.file=org.apache.log4j.FileAppender
log4j.appender.file.File=c:/mylog.log
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n

### set log levels - for more verbose logging change 'info' to 'debug' ###

log4j.rootLogger=debug, stdout

②SpringMVC introduce

stay resources Create under directory spring-mvc.xml , The contents are as follows ：

<?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: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 https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <!-- SpringMVC Just scan controller Bag can  -->
    <context:component-scan base-package="com.sangeng.controller"/>
    <!--  Solve the problem of static resource access , If not mvc:annotation-driven Can result in inaccessibility handler-->
    <mvc:default-servlet-handler/>
    <!-- Solve the response garbled code -->
    <mvc:annotation-driven>
        <mvc:message-converters>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <constructor-arg value="utf-8"/>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>


    <!-- Configure the view parser   The front and rear ends are not separated, and the project is used -->
<!-- <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="viewResolver"> &lt;!&ndash; Prefix required for splicing &ndash;&gt; <property name="prefix" value="/WEB-INF/page/"></property> &lt;!&ndash; Suffix to splice &ndash;&gt; <property name="suffix" value=".jsp"></property> </bean>-->

    <!-- Configure interceptors -->
<!-- <mvc:interceptors> <mvc:interceptor> &lt;!&ndash; &ndash;&gt; <mvc:mapping path="/**"/> &lt;!&ndash; Configure the path to exclude interception &ndash;&gt; <mvc:exclude-mapping path="/"/> &lt;!&ndash; Configure interceptor object injection container &ndash;&gt; <bean class=""></bean> </mvc:interceptor> </mvc:interceptors>-->

    <!--  File upload parser   Be careful ：id  It has to be for  multipartResolver  If you need to upload files, you can release the corresponding configuration  -->
    <!--<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">-->
        <!--&lt;!&ndash;  Set the default character encoding  &ndash;&gt;-->
        <!--<property name="defaultEncoding" value="utf-8"/>-->
        <!--&lt;!&ndash;  The maximum total size of the file to be uploaded at one time , Unit is byte &ndash;&gt;-->
        <!--<property name="maxUploadSize" value="#{1024*1024*100}"/>-->
        <!--&lt;!&ndash;  The maximum size of each uploaded file , Unit is byte &ndash;&gt;-->
        <!--<property name="maxUploadSizePerFile" value="#{1024*1024*50}"/>-->
    <!--</bean>-->
</beans>

modify web.xml file

 <servlet>
        <servlet-name>DispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--  by DispatcherServlet Provide initialization parameters   Set up springmvc The path to the configuration file  name Is constant , Must be contextConfigLocation value refer to SpringMVC The location of the configuration file  -->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-mvc.xml</param-value>
        </init-param>
        <!--  Specifies that the project is initialized as soon as it starts DispatcherServlet -->
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>DispatcherServlet</servlet-name>
        <!-- /  At present servlet Mapping Division jsp All requests except （ Contains static resources ） *.do  Express .do The end of the request path can be SpringMVC Handle ( Old projects will appear ) /*  At present servlet Map all requests （ Contains static resources ,jsp）, Its configuration should not be used DispatcherServlet -->
        <url-pattern>/</url-pattern>
    </servlet-mapping>


    <!-- Scrambling filter , from SpringMVC Provide -->
    <!--  Handle post Ask for random code  -->
    <filter>
        <filter-name>CharacterEncodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <!-- name Fixed ,value Set values as needed  -->
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>CharacterEncodingFilter</filter-name>
        <!--  All requests are set utf-8 The coding  -->
        <url-pattern>/*</url-pattern>
    </filter-mapping>

③Spring Integration into web project

Give Way web It can be created when the project starts Spring Containers . have access to Spring The monitor provided ContextLoaderListener, So we need to web.xml Configure this listener in , And configuration Spring The path to the configuration file .

    <!-- To configure spring Profile path for -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext.xml</param-value>
    </context-param>
    <!-- Configure listeners , It can be created when the application is deployed spring Containers -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

1.3 To write Controller,Service,Dao

Let's write according to id Query the user interface to test

@RestController
public class UserController {
    

    @Autowired
    private UserService userService;

    @GetMapping("/user/{id}")
    public User findById(@PathVariable("id") Integer id){
    
        User user = userService.findById(id);
        return user;
    }
}

public interface UserService {
    
    User findById(Integer id);
}

@Service
public class UserServiceImpl implements UserService {
    
    @Autowired
    private UserDao userDao;

    public User findById(Integer id) {
    
        return userDao.findById(id);
    }
}

public interface UserDao {
    
    /** *  according to id Query the user  * @param id * @return */
    User findById(Integer id);
}

<?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.sangeng.dao.UserDao">


    <select id="findById" resultType="com.sangeng.domain.User">
        select * from user where id = #{id}
    </select>
</mapper>

2. Case study

2.0 Unified response format

We should ensure that the data format returned by all interfaces in a project is unified . In this way, it is more convenient for both front-end and mobile development to conduct unified processing after obtaining our data .

So we define the following result encapsulation classes

@JsonInclude(JsonInclude.Include.NON_NULL)
public class ResponseResult<T> {
    
    /** *  Status code  */
    private Integer code;
    /** *  Prompt information , If there is an error , The front end can get this field to prompt  */
    private String msg;
    /** *  The query result data , */
    private T data;

    public ResponseResult(Integer code, String msg) {
    
        this.code = code;
        this.msg = msg;
    }

    public ResponseResult(Integer code, T data) {
    
        this.code = code;
        this.data = data;
    }

    public Integer getCode() {
    
        return code;
    }

    public void setCode(Integer code) {
    
        this.code = code;
    }

    public String getMsg() {
    
        return msg;
    }

    public void setMsg(String msg) {
    
        this.msg = msg;
    }

    public T getData() {
    
        return data;
    }

    public void setData(T data) {
    
        this.data = data;
    }

    public ResponseResult(Integer code, String msg, T data) {
    
        this.code = code;
        this.msg = msg;
        this.data = data;
    }
}

The previous interface is modified to ：

@RestController
public class UserController {
    

    @Autowired
    private UserService userService;

    @GetMapping("/user/{id}")
    public ResponseResult findById(@PathVariable("id") Integer id){
    
        User user = userService.findById(id);
        if(user==null){
    
            // Description: there is no corresponding user 
            return new ResponseResult(500," There is no such user ");
        }
        return new ResponseResult(200," Successful operation ",user);
    }
}

2.1 Query all users

@RestController
public class UserController {
    

    @Autowired
    private UserService userService;

	// Omit other extraneous code 
    @GetMapping("/user")
    public ResponseResult findAll(){
    
        List<User> list = userService.findAll();
        return new ResponseResult(200," Successful operation ",list);
    }

}

public interface UserService {
    
    User findById(Integer id);

    List<User> findAll();
}

@Service
public class UserServiceImpl implements UserService {
    
    @Autowired
    private UserDao userDao;
	// Omit other extraneous code 

    public List<User> findAll() {
    
        return userDao.findAll();
    }
}


public interface UserDao {
    
	// Omit other extraneous code 
    List<User> findAll();
}

<?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.sangeng.dao.UserDao">
    <select id="findAll" resultType="com.sangeng.domain.User">
        select * from user
    </select>
</mapper>

2.2 Paging query users

The result of paging query should include not only the found user data, but also the current number of pages , Number of entries per page , Total number of records these paging data .

Paging data encapsulation class


public class PageResult<T> {
    

    private Integer currentPage;

    private Integer pageSize;

    private Integer total;
    
    private List<T> data;

    public PageResult(Integer currentPage, Integer pageSize, Integer total, List<T> data) {
    
        this.currentPage = currentPage;
        this.pageSize = pageSize;
        this.total = total;
        this.data = data;
    }

    public Integer getCurrentPage() {
    
        return currentPage;
    }

    public void setCurrentPage(Integer currentPage) {
    
        this.currentPage = currentPage;
    }

    public Integer getPageSize() {
    
        return pageSize;
    }

    public void setPageSize(Integer pageSize) {
    
        this.pageSize = pageSize;
    }

    public Integer getTotal() {
    
        return total;
    }

    public void setTotal(Integer total) {
    
        this.total = total;
    }

    public List<T> getData() {
    
        return data;
    }

    public void setData(List<T> data) {
    
        this.data = data;
    }
}


@RestController
public class UserController {
    

    @Autowired
    private UserService userService;

    @GetMapping("/user/{pageSize}/{pageNum}")
    public ResponseResult findByPage(@PathVariable("pageSize") Integer pageSize,@PathVariable("pageNum") Integer pageNum){
    
        PageResult pageResult =  userService.findByPage(pageSize,pageNum);
        return new ResponseResult(200," Successful operation ",pageResult);
    }

}

@Service
public class UserServiceImpl implements UserService {
    
    @Autowired
    private UserDao userDao;


    public PageResult findByPage(Integer pageSize, Integer pageNum) {
    
        PageHelper.startPage(pageNum,pageSize);
        List<User> list = userDao.findAll();
        PageInfo pageInfo = new PageInfo(list);
        PageResult pageResult = new PageResult(pageInfo.getPageNum(),pageInfo.getPageSize(), (int) pageInfo.getTotal(),list);
        return pageResult;
    }
}

2.3 Insert user

Controller layer

    @PostMapping("/user")
    public ResponseResult insertUser(@RequestBody User user){
    
        userService.insertUser(user);
        return new ResponseResult(200," Successful operation ");
    }

Service layer

stay Service Add method definitions in the interface

    void insertUser(User user);

Implement this method in the implementation class :

  public void insertUser(User user) {
    
        userDao.insertUser(user);
    }

Dao layer

Defining methods in an interface

    void insertUser(User user);

stay mapper In the mapping file

    <insert id="insertUser">
        insert into user values(null,#{username},#{age},#{address})
    </insert>

test

{
    "username":" Sangeng thatched cottage ","age":15,"address":" Excuse me, "}

2.4 Delete user

Controller layer

    @DeleteMapping("/user/{id}")
    public ResponseResult deleteUser(@PathVariable("id") Integer id){
    
        userService.deleteUser(id);
        return new ResponseResult(200," Successful operation ");
    }

Service layer

stay Service Add method definitions in the interface

    void deleteUser(Integer id);

Implement this method in the implementation class :

    public void deleteUser(Integer id) {
    
        userDao.deleteUser(id);
    }

Dao layer

Defining methods in an interface

    void deleteUser(Integer id);

stay mapper In the mapping file

    <delete id="deleteUser">
        delete from user where id = #{id}
    </delete>

2.5 Update user

Controller layer

    @PutMapping("/user")
    public ResponseResult updateUser(@RequestBody User user){
    
        userService.updateUser(user);
        return new ResponseResult(200," Successful operation ");
    }

Service layer

stay Service Add method definitions in the interface

    void updateUser(User user);

Implement this method in the implementation class :

    public void updateUser(User user) {
    
        userDao.updateUser(user);
    }

Dao layer

Defining methods in an interface

    void updateUser(User user);

stay mapper In the mapping file

    <update id="updateUser">
        update user set username = #{username},age = #{age},address = #{address} where id = #{id}
    </update>

3. Exception handling

We can use @ControllerAdvice Realize unified handling of exceptions . When an exception occurs, it can also return a response JSON.

The code is as follows ：

@ControllerAdvice
public class SGControllerAdvice {
    

    @ExceptionHandler(Exception.class)
    @ResponseBody
    public ResponseResult handleException(Exception e){
    
        return new ResponseResult(500,e.getMessage());
    }
}

4. Interceptor

public class SGHandlerInterceptor implements HandlerInterceptor {
    

    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    
        System.out.println("preHandle");
        return true;
    }

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    
        System.out.println("postHandle");
    }

    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
    
        System.out.println("afterCompletion");
    }
}

    <!-- Configure interceptors -->
        <mvc:interceptors>

            <mvc:interceptor>
                <!-- -->
                <mvc:mapping path="/**"/>
                <!-- Configure the path to exclude interception -->
                <!--<mvc:exclude-mapping path="/"/>-->
                <!-- Configure interceptor object injection container -->
                <bean class="com.sangeng.interceptor.SGHandlerInterceptor"></bean>
            </mvc:interceptor>
        </mvc:interceptors>

5. Declarative transactions

The corresponding configuration has been made , As long as service Just annotate the method

    @Transactional
    public void test() {
    
        userDao.insertUser(new User(null,"test1",11,"cc"));
// System.out.println(1/0);
        userDao.insertUser(new User(null,"test2",12,"cc2"));
    }

6.AOP

Be careful , Use it by yourself AOP When enhancing , It should be right Service enhanced . Not right Controller enhanced , Because the faceted class will be put into the parent container , And ours Controller It's in a sub container . Parent container cannot access child container .

And if we need to be right Controller enhanced , Using interceptors will also be easier to use .

@Aspect
@Component
public class SGAspect {
    

    // Defining cut-off points 
    @Pointcut("execution(* com.sangeng.service..*.*(..))")
    public void pt(){
    

    }

    // enhanced 
    @Before("pt()")
    public void before(){
    
        System.out.println("before");
    }
}