Preliminary construction of SSM project environment

ssm First time to know

ssm The frame is spring,spring web mvc and mybatis The combination of , In the building ssm The framework does not need to have the foundation of the three frameworks .

You also need to master the following technical specifications ：

development environment ：

1. Install and configure jdk8 above （ Configure environment variables ）
2. Install and configure mysql8.0 above
3. download tomcat,maven middleware
4. Java Integrated development environment ide

Maven Configure central warehouse ：

Maven Configure local warehouse ：

IDEA To configure maven：

New project directory ：

change pom To configure ：

build ssm frame

pom Import required dependencies ：

    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>javax.servlet.jsp-api</artifactId>
      <version>2.3.1</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>5.1.19.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>5.1.19.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.1.19.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-aspects</artifactId>
      <version>5.1.19.RELEASE</version>
    </dependency>

    <!--jdbc Of orm Used to integrate other persistence layer frameworks -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>5.1.19.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>5.1.19.RELEASE</version>
    </dependency>

    <!--spring The default tool for parsing data , Import is ready to use without configuration -->
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.12.3</version>
    </dependency>


    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.11</version>
    </dependency>

    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.5</version>
    </dependency>

    <!--mybatis And spring combination -->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>1.3.1</version>
    </dependency>

    <!-- Druid connection pool -->
    <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>druid</artifactId>
      <version>1.2.5</version>
    </dependency>

To configure datasource(db.properties)：
Use druid The connection pool and datasource, Not default mybatis Of .

druid.driver=com.mysql.cj.jdbc.Driver
druid.url=jdbc:mysql://localhost:3306/db?characterEncoding=utf-8&useSSL=false&serverTimezone=GMT%2B8&allowPublicKeyRetrieval=true
druid.username=root
druid.password=root

# Connection pool 
druid.pool.init=1
druid.pool.minIdle=3
druid.pool.maxActive=20
druid.pool.timeout=30000

Whereas spring Of Aop The characteristics of everything bean Can be handed over to Ioc Container management ,DataSource Objects will also be handed over to spring Container management , No need to mybatis The configuration file of .
This file configures the parameters related to the database connection .

To configure mybatis Configuration file for （mybatis-config.xml）：

<?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>
<!--datasource Leave it to spring Container management does not need to be imported -->
</configuration>

To configure mybatis-config.xml The meaning of is to generate a SqlSessionFactory And then through mybatis-spring Leave it to IoC Container management .

To configure spring Configuration file for (spring-config.xml)：

spring The main function of the configuration file is to enable annotation driven .

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" 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 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/context/spring-mvc.xsd">


    <!-- Annotation development -->
    <context:annotation-config></context:annotation-config>
    <context:component-scan base-package="com.ssm"></context:component-scan>


    <!-- Turn on mvc Annotation scan -->
    <mvc:annotation-driven></mvc:annotation-driven>


</beans>

spring And mybatis combination
Previous pair spring Configured , After that, we need to spring And mybatis combination , Need to use mybatis-spring The dependency package of .

Specific configuration ：

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx" 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 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
    <!--  Import configuration information  -->
    <context:property-placeholder location="classpath:druid.properties"/>
    <!--  be based on IoC The container creates a data source DataResource -->
    <bean id="druidDataResource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${druid.driver}"/>
        <property name="url" value="${druid.url}"/>
        <property name="username" value="${druid.username}"/>
        <property name="password" value="${druid.password}"/>
        <property name="initialSize" value="${druid.pool.init}"/>
        <property name="minIdle" value="${druid.pool.minIdle}"/>
        <property name="maxActive" value="${druid.pool.maxActive}"/>
        <property name="maxWait" value="${druid.pool.timeout}"/>
    </bean>
    <!--  The assignment expression will automatically assign the imported configuration information to the corresponding attribute by name  -->
    <!--  production mybatis-spring Provided SqlSessionFactoryBean receive mybatis Of SqlSessionFactory -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- SqlSessionFactory You need to configure Mapper and DataResource -->
        <property name="dataSource" ref="druidDataResource"/>
        <property name="mapperLocations" value="classpath:mapper/*.xml"/>
        <!--  Query result mapping POJO,typeAliasesPackage Make the first letter of the interface lower case id, adopt id obtain  -->
        <property name="typeAliasesPackage" value="cms.ssm.model"/>
        <!--  load mybatis-config.xml The file is used to create SqlSessionFactory -->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
    </bean>
    <!--  scanning dao Interface , And name it and submit it to IoC Container management , Easy java Get in code  -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        <property name="basePackage" value="cms.ssm.dao"/>
    </bean>
    <!--  Declarative transaction management , Configure transaction manager  -->
    <bean class="org.springframework.jdbc.datasource.DataSourceTransactionManager" id="transactionManager">
        <property name="dataSource" ref="druidDataResource"/>
    </bean>
    <!--  Enable transaction annotation scanning  -->
    <tx:annotation-driven transaction-manager="transactionManager"/>
</beans>

The first step is to import the information of the Druid connection pool and the database connection information ; The second part configures through the imported link information DataSource Of bean object , Hand over to IoC Container management ; The third part introduces mybatis The configuration file , Create... From a configuration file SqlSessionFactory Object and handed over to IoC Container management （ The object has mybatis Create a configuration file for , The original file does not require any configuration , stay bean You can configure properties in the initialization object of ）; Step four ,BolgMapper The creation of ,SqlSessionFactory The main function of is for each mapper Create a query channel , That is to say SqlSession Objects are dynamically created and destroyed ,MapperScannerConfigurer Object manages this process for us , Dynamically create and destroy .

To configure Dispachterservlet

dispacherservlet The configuration of is an important part ,spring mvc The core of DispatcherServlet This is a general servlet Control several controllers , The annotation of the annotation controller will be annotated by DispatcherServlet To control .

<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>

  <servlet>
    <servlet-name>SpringMVC</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>

    <!-- The server starts loading web.xml file contextConfigLocation Used for loading spring Related configuration files -->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:spring-*.xml</param-value>
    </init-param>
    <!--classpath It maps to resources Under the table of contents ,file Mapped to the root directory  spring-* Identify and load all files starting with this -->


    <load-on-startup>1</load-on-startup>

  </servlet>

  <!-- Processing of static resources -->
  <servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>*.js</url-pattern>
  </servlet-mapping>

  <servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>*.css</url-pattern>
  </servlet-mapping>

  <servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>/images/*</url-pattern>
  </servlet-mapping>

  <servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>/calender/*</url-pattern>
  </servlet-mapping>


  <servlet-mapping>
    <servlet-name>SpringMVC</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

</web-app>

DispatcherServlet yes spring mvc The core , It is the entrance of each controller .

The interface test
After the above configuration , Each controller is controlled by DispatcherServlet forward , Write controller test mvc Configuration ：

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {
    

    @GetMapping(value = "/test")
    public String method1(){
    
        return "hello world";
    }
}

If you enter the correct url There is hello world Indicates that the controller configuration is complete .

Database connection interface test

The back-end data ultimately comes from the database , Use mysql For example , You've created properties file , The database is configured ,spring-mybatis Yes SqlSessionFactory To configure , Therefore, you can query the database directly .

Interface for querying database ：

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import java.util.List;

@RestController
public class TestController {
    

    @Resource
    private TestMapper testMapper;

    @GetMapping(value = "/test")
    public String method1(){
    
        return "hello world";
    }


    @GetMapping(value = "/mybatis")
    public List<User> users(){
    
        List<User> method = testMapper.method();
        return method;
    }
}

Configured with jackson, Will automatically java bean or java The basic data type of is converted to json type .

maper Mapping and normal mvc Model as ,mapper Unwanted @Coponent annotation , because spring-mybatis Already configured mapper Of scanning bean Will bring all mapper Inject after scanning IoC; Corresponding java Bean There is no need for comments , Because of the configuration SqlSessionFactory Will scan the java bean All into the IoC Containers .

This error was encountered during development ：

Because in spring-mybatis Configuration of the , Three bean Is initialized bean contain DataSource,SqlSessionFactory,MapperScannerConfigurer（ scanning mapper Of bean, So you don't have to use it every time @Component Annotations for dependency injection ）.

The above error is Mapper Scanned bag , To configure MapperScannerConfigurer The scanning position of does not correspond to the actual position , You can modify the corresponding .

Start the server after the interface is written , The basic configuration is completed when the corresponding data is queried ：

On the basis of spring mvc The architecture of is built , image AOP,TX Self access to information about things , To configure .