I'll write down all the steps. A bad pen is better than a good memory. It doesn't feel anything just by looking at it. Let's do it manually. cheer up

1. Create projects

Projects are created in maven's most basic way

Modify to a Web project [pom.xml]

packaging

! packaging War /packagingCopy the code

Project code

! - set the encoding -   properties   project. Build. SourceEncoding  utf-8  / project. Build. SourceEncoding   / properties Copy the code

Dependent libraries

It depends on the situation

! -- dependencies ! -- Servlet + JSP -- dependency groupIdjavax.servlet/groupId artifactIdjavax.servlet-api/artifactId version4.0.1/version scope Provided /scope /dependency dependency groupIdjavax.servlet.jsp/groupId artifactIdjavax.servlet.jsp- API /artifactId version2.3.3/version scopeprovided/scope /dependency ! -- Log -- dependency groupIdch.qos.logback/groupId artifactIdlogback-classic/artifactId The  version  1.2.3  / version   / dependency  ! -- Spring + SpringMVC -- dependency groupIdorg.springframework/groupId artifactIdspring-webmvc/artifactId  version  5.2.8. RELEASE  / version   / dependency   the dependency   groupId  org. Aspectj  / groupId   artifactId  aspectjweaver  / artifactId   version  1.9.6  / version   / dependency   the dependency  groupIdorg.aspectj/groupId artifactId aspectJrt /artifactId version1.9.6/version /dependency dependency  the groupId  com. Fasterxml. Jackson. Core  / groupId   artifactId  Jackson - databind  / artifactId   version  2.11.0  / version  /dependency ! -- MyBatis -- dependency groupIdorg. MyBatis /artifactId version3.5.5/version /dependency dependency groupIdorg.mybatis/groupId artifactIdmybatis-spring/artifactId  version  at 2.0.5  / version   / dependency   the dependency   groupId  org. Springframework  / groupId    artifactId  spring - JDBC/artifactId   version  5.2.8. RELEASE  / version   / dependency   the dependency   the groupId  mysql  / groupId   artifactId  mysql connector - Java  / artifactId   version  5.1.49  / version   / dependency  dependency groupIdcom.alibaba/groupId artifactIddruid/artifactId version1.1.22/version /dependency ! -- dependency groupId artifactIdjunit/artifactId version4.13/version scopetest/scope /dependency /dependenciesCopy the code

Project structure core configuration file [web.xml]

War is already a Web project because of the packaging method configured in POM.xml

Press the shortcut key to enter the project configuration

The initial interface

Add web.xml (change path oh)

src/main/webapp

Create a directory

The effect

2. Start the web

Create index. The JSP

Create index.jsp under webApp

Configuration tomact

Configure the Application Context

Enable bug debug

3. Create a service

Create a domain

Skill class

private Integer id;
private Date createdTime;
private String name;
private Integer level;
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Create a dao layer

Create interface interface because use mybatis

boolean save(Skill skill);
boolean update(Skill skill);
boolean remove(Integer id);
@Select("SELECT * FROM skill")
ListSkill list();
@Select("SELECT * FROM skill WHERE id = #{id}")
Skill get(Integer id);
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Create the mappers folder under Resources to create the file skill.xml

? The 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.mj.dao.SkillDao" insert id="save" parameterType="com.mj.domain.Skill" INSERT INTO skill(name, level) VALUES (#{name}, #{level}) /insert update id="update" parameterType="com.mj.domain.Skill" UPDATE skill SET name = #{name}, level = #{level} WHERE id = #{id} /update delete id="remove" parameterType="int" DELETE FROM skill WHERE id = #{id} /delete /mapperCopy the code

Create the applicationContext. XML

The mybatis SqlSessionFatoryBean

• Introduces a configuration file for database drivers

# jdbc
jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/xr
jdbc.username=root
jdbc.password=root
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• The applicationcontext.xml added

! - data source (Druid) -- -   context: the property - placeholder location = "classpath: main. The properties" /   bean id = "dataSource" class="com.alibaba.druid.pool.DruidDataSource" property name="driverClassName" value="${jdbc.driverClassName}"/ property name="url" value="${jdbc.url}"/ property name="username" value="${jdbc.username}"/ property name="password" value="${jdbc.password}"/ /bean bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean" property name="dataSource" ref="dataSource"/ property name="mapperLocations" value="classpath:mappers/*.xml"/ /bean bean id="configurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer" property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/ property name="basePackage" value="com.mj.dao"/ /beanCopy the code

Test Tests a wave

4. Return json

Start with the service and Controller layers

Remember to inject it

Create a dispatcherServlet. The XML

Remember to scan the custom package in applicationContext.xml to add

context:component-scan base-package="com.mj.service"/
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The dispatcherServlet. XML is added

context:component-scan base-package="com.mj.controller"/
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Web.xml configures DispatcherServlet (parent-child container)

servlet servlet-nameDispatcherServlet/servlet-name ! / web-inf /${servlet-name}-servlet.xml-- servlet-classorg.springframework.web.servlet.DispatcherServlet/servlet-class !  init-param param-namecontextConfigLocation/param-name ! - children -   param - value  classpath: dispatcherServlet. XML value   param -  / init - param  ! Create a servlet as soon as the project is deployed to the Web. -- load-on-startup0/load-on-startup /servlet servlet-mapping servlet-nameDispatcherServlet/servlet-name ! - intercept all requests -   url - the pattern  /  / url - the pattern   / servlet - mapping  ! - the parent container -   listener   listener - class  org. Springframework. Web. Context. ContextLoaderListener  / listener - class   / listener   context-param param-namecontextConfigLocation/param-name param-valueclasspath:applicationContext.xml/param-value /context-paramCopy the code

The ContextLoaderListener is used to automatically assemble configuration information for Applicationcontenxt.xml when the Web container is started. Because it implements the ServletContextLister interface, when the web.xml listener is configured, the methods it implements are executed by default when the container is started.

Web. XML configures garbled POST requests

filter
    filter-nameCharacterEncodingFilter/filter-name
    filter-classorg.springframework.web.filter.CharacterEncodingFilter/filter-class
    init-param
        param-nameencoding/param-name
        param-valueUTF-8/param-value
    /init-param
/filter

filter-mapping
    filter-nameCharacterEncodingFilter/filter-name
    url-pattern/*/url-pattern
/filter-mapping
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Dispatcherservlet. XML Configures garbled response data

mvc:annotation-driven
    mvc:message-converters
        bean class="org.springframework.http.converter.StringHttpMessageConverter"
            property name="defaultCharset" value="UTF-8"/
        /bean
        bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"
            property name="defaultCharset" value="UTF-8"/
        /bean
    /mvc:message-converters
/mvc:annotation-driven
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MyBatis supplement

If the Mapper file is placed in the same directory as dao and the file name is the same as DAO

• You can find the Mapper file through MapperScannerConfigurer
• You no longer need to configure the mapperLocations property of SqlSessionFactoryBean

Solution: Keep the names the same

Create mybatis - config. XML

? The 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 setting name="mapUnderscoreToCamelCase" value="true"/ /settings /configurationCopy the code

Configuration configLocation

! -- property name="mapperLocations" value="classpath:mappers/*.xml"/-- property name="configLocation" value="classpath:mybatis-config.xml"/Copy the code

Maven Supplement (with Mabatis supplement)

By default, Maven does not package configuration files in the source folder so it does

• Problem with Dao layer XML in the same folder as Dao layer

build ! -- resources ! resource directory SRC /main/resources/directory /resource ! resource directory SRC /main/ Java /directory includes include**/*. Properties /include include**/*.xml/include /includes /resource /resources /buildCopy the code

To solve the problem

Attributes in XML report red

The general druid properties also have problems with the solution is

This does not solve the problem, I will create a new project can be and prompt is not the network problem