Common configuration files of SSM framework

All say SSM Is the configuration factory , Here is the SSM The commonly used configuration files of the framework are sorted out for future development and use .

maven rely on

        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>javax.servlet.jsp-api</artifactId>
            <version>2.3.3</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>jstl</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>taglibs</groupId>
            <artifactId>standard</artifactId>
            <version>1.1.2</version>
        </dependency>
        <!--mysql drive -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.21</version>
        </dependency>
        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.5</version>
        </dependency>
        <!--ssm-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.8.RELEASE</version>
        </dependency>
        <!-- Database connection pool -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.1.4.RELEASE</version>
        </dependency>
        <!--aop Woven in bag -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.6</version>
        </dependency>
        <!--junit unit testing -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13</version>
        </dependency>
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.2</version>
        </dependency>
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.3.3</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>
		<!--jackson-->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.9.8</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.8</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.9.8</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>

JSP The file header

<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" pageEncoding="UTF-8" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

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">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext.xml</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <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:spring-mvc.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>
    <filter>
        <filter-name>characterEncodingFilter</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>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>characterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <session-config>
        <session-timeout>15</session-timeout>
    </session-config>
</web-app>

applicationContext.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:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context" xmlns:aop="http://www.springframework.org/schema/aop" 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 http://www.springframework.org/schema/tx https://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--*****************************DAO*****************************-->
    <context:property-placeholder location="classpath:database.properties"/>
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc.driver}"/>
        <property name="jdbcUrl" value="${jdbc.url}"/>
        <property name="user" 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="configLocation" value="classpath:mybatis-config.xml"/>
    </bean>

    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer" id="mapperScannerConfigurer">
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        <property name="basePackage" value="com.botao.dao"/>
    </bean>
    <!--*****************************service*****************************-->
    <context:component-scan base-package="com.botao.service"/>
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <tx:annotation-driven transaction-manager="transactionManager"/>
    <aop:aspectj-autoproxy/>
</beans>

database.properties

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/library?useSSL=false&serverTimezone=UTC&characterEncoding=utf-8
jdbc.username=root
jdbc.password=123456

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

    <!--*****************************mvc*****************************-->
    <context:component-scan base-package="com.botao.controller"/>
    <mvc:annotation-driven>
        <mvc:message-converters>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter" id="converter">
                <property name="supportedMediaTypes">
                    <list>
                        <value>text/plain;charset=UTF-8</value>
                        <value>text/html;charset=UTF-8</value>
                    </list>
                </property>
            </bean>
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="objectMapper">
                    <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                        <property name="failOnEmptyBeans" value="false"/>
                    </bean>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>
    <mvc:cors>
        <mvc:mapping path="/**" allowed-origins="*" allowed-methods="POST, GET, OPTIONS, DELETE, PUT" allowed-headers="Content-Type, Access-Control-Allow-Headers, Authorization, X-Requested-With" allow-credentials="true"/>
    </mvc:cors>
    <mvc:default-servlet-handler/>
    <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

    <!--fileupload-->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="defaultEncoding" value="utf-8"/>
        <property name="maxUploadSize" value="10485760"/>
        <property name="maxInMemorySize" value="40960"/>
    </bean>
</beans>

MybatisUtil.java

package botao.util;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

public class MybatisUtil {
    
    private static SqlSessionFactory sqlSessionFactory;

    static {
    
        try {
    
            InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

        } catch (IOException e) {
    
            e.printStackTrace();
        }
    }

    public static SqlSession getSqlSession() {
    
        return sqlSessionFactory.openSession(false);
    }

    public static void close(SqlSession sqlSession) {
    
        sqlSession.close();
    }

}

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>
  <environments default="development">
    <environment id="development">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">
        <property name="driver" value="${driver}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${username}"/>
        <property name="password" value="${password}"/>
      </dataSource>
    </environment>
  </environments>
 <typeAliases>
  <typeAlias alias="Author" type="domain.blog.Author"/>
  <package name="domain.blog"/>
</typeAliases>
  <mappers>
     <mapper resource="org/mybatis/builder/BlogMapper.xml"/>
      <mapper url="file:///var/mappers/BlogMapper.xml"/>
      <mapper class="org.mybatis.builder.BlogMapper"/>
      <package name="org.mybatis.builder"/>
  </mappers>
</configuration>

mapper.xml

<?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="org.mybatis.example.BlogMapper">
  <select id="selectBlog" resultType="Blog">
    select * from Blog where id = #{id}
  </select>
</mapper>

Set up （settings）

This is a MyBatis The most important adjustment settings in , They will change MyBatis Runtime behavior for . The following table describes the meaning of the settings in the settings 、 Default value, etc .

Set name	describe	Valid values	The default value is
cacheEnabled	Globally turn on or off any cache configured in all mapper profiles .	true | false	true
lazyLoadingEnabled	Global switch for delayed loading . When opened , All associated objects delay loading . You can set fetchType Property to override the on / off state of the item .	true | false	false
aggressiveLazyLoading	On , A call to any method loads all the deferred load properties of the object . otherwise , Each delay load property is loaded on demand （ Reference resources lazyLoadTriggerMethods).	true | false	false （ stay 3.4.1 In previous versions, the default is true）
multipleResultSetsEnabled	Whether to allow a single statement to return multiple result sets （ Need database driver support ）.	true | false	true
useColumnLabel	Use column labels instead of column names . The actual performance depends on the database driver , For details, please refer to the relevant documents of database drive , Or through comparative tests to observe .	true | false	true
useGeneratedKeys	allow JDBC Support automatic generation of primary key , Need database driver support . If set to true, Automatic primary key generation will be enforced . Although some database drivers do not support this feature , But it still works （ Such as Derby）.	true | false	False
autoMappingBehavior	Appoint MyBatis How should columns be automatically mapped to fields or properties . NONE Indicates that automatic mapping is turned off ;PARTIAL Only fields with no nested result mapping defined will be automatically mapped . FULL Will automatically map any complex result set （ Whether nested or not ）.	NONE, PARTIAL, FULL	PARTIAL
autoMappingUnknownColumnBehavior	Specify unknown column for discovery auto map target （ Or unknown property type ） act .NONE: No reaction WARNING: Output warning log （'org.apache.ibatis.session.AutoMappingUnknownColumnBehavior' The log level of must be set to WARN）FAILING: Mapping failed ( Throw out SqlSessionException)	NONE, WARNING, FAILING	NONE
defaultExecutorType	Configure default actuator .SIMPLE It's a common actuator ;REUSE The executor reuses the preprocessing statement （PreparedStatement）; BATCH The executor not only reuses statements, but also performs batch updates .	SIMPLE REUSE BATCH	SIMPLE
defaultStatementTimeout	Set timeout , It determines the number of seconds the database driver waits for a response from the database .	Arbitrary positive integer	Not set (null)
defaultFetchSize	Get quantity for driven result set （fetchSize） Set a suggested value . This parameter can only be overridden in query settings .	Arbitrary positive integer	Not set (null)
defaultResultSetType	Specifies the default scrolling strategy for the statement .（ New at 3.5.2）	FORWARD_ONLY | SCROLL_SENSITIVE | SCROLL_INSENSITIVE | DEFAULT（ Equivalent to not set ）	Not set (null)
safeRowBoundsEnabled	Whether pagination is allowed in nested statements （RowBounds）. Set to if allowed false.	true | false	False
safeResultHandlerEnabled	Whether result processors are allowed in nested statements （ResultHandler）. Set to if allowed false.	true | false	True
mapUnderscoreToCamelCase	Whether to enable automatic mapping of hump naming , That is, from the classic database column name A_COLUMN Mapping to classic Java Property name aColumn.	true | false	False
localCacheScope	MyBatis Using local caching mechanism （Local Cache） Prevent circular references and accelerate repeated nested queries . The default value is SESSION, All queries executed in a session are cached . If the setting is STATEMENT, The local cache will only be used to execute statements , Yes, the same SqlSession Will not be cached .	SESSION | STATEMENT	SESSION
jdbcTypeForNull	When no specific... Is specified for the parameter JDBC Type , The default of null value JDBC type . Some database drivers need to specify columns of JDBC type , In most cases, just use the general type , such as NULL、VARCHAR or OTHER.	JdbcType Constant , Common values ：NULL、VARCHAR or OTHER.	OTHER
lazyLoadTriggerMethods	Specifies which methods of the object trigger a delayed load .	Comma separated list of methods .	equals,clone,hashCode,toString
defaultScriptingLanguage	Designated dynamic SQL The default scripting language used in the build .	A type alias or fully qualified class name .	org.apache.ibatis.scripting.xmltags.XMLLanguageDriver
defaultEnumTypeHandler	Appoint Enum Default for use TypeHandler .（ New at 3.4.5）	A type alias or fully qualified class name .	org.apache.ibatis.type.EnumTypeHandler
callSettersOnNulls	Specifies that when the result set value is null Whether to call the setter（map When object is put） Method , It depends on Map.keySet() or null Values are useful when initializing . Pay attention to basic types （int、boolean etc. ） Can't be set to null Of .	true | false	false
returnInstanceForEmptyRow	When all columns of the returned row are empty ,MyBatis Default return null. When this setting is turned on ,MyBatis An empty instance will be returned . Please note that , It also applies to nested result sets （ Such as a set or association ）.（ New at 3.4.2）	true | false	false
logPrefix	Appoint MyBatis Prefix added to log name .	Any string	Not set
logImpl	Appoint MyBatis The implementation of the logs used , Auto find when not specified .	SLF4J | LOG4J | LOG4J2 | JDK_LOGGING | COMMONS_LOGGING | STDOUT_LOGGING | NO_LOGGING	Not set
proxyFactory	Appoint Mybatis The proxy tool used to create lazy load objects .	CGLIB | JAVASSIST	JAVASSIST （MyBatis 3.3 above ）
vfsImpl	Appoint VFS The implementation of the	Customize VFS Class fully qualified name of , Separated by commas .	Not set
useActualParamName	Allow the name in the method signature as the statement parameter name . To use this feature , Your project must adopt Java 8 compile , And add -parameters Options .（ New at 3.4.1）	true | false	true
configurationFactory	Specify a provider Configuration Instance classes . This one was returned Configuration Instance is used to load the value of the deferred load property of the deserialized object . This class must contain a signature of static Configuration getConfiguration() Methods .（ New at 3.2.3）	A type alias or fully qualified class name .	Not set
shrinkWhitespacesInSql	from SQL Delete the extra space characters in the . Please note that , It will also affect SQL Text string in . ( New at 3.5.5)	true | false	false
defaultSqlProviderType	Specifies an sql provider class that holds provider method (Since 3.5.6). This class apply to the type(or value) attribute on sql provider annotation(e.g. @SelectProvider), when these attribute was omitted.	A type alias or fully qualified class name	Not set

A fully configured settings An example of the element is as follows ：

<settings>
  <setting name="cacheEnabled" value="true"/>
  <setting name="lazyLoadingEnabled" value="true"/>
  <setting name="multipleResultSetsEnabled" value="true"/>
  <setting name="useColumnLabel" value="true"/>
  <setting name="useGeneratedKeys" value="false"/>
  <setting name="autoMappingBehavior" value="PARTIAL"/>
  <setting name="autoMappingUnknownColumnBehavior" value="WARNING"/>
  <setting name="defaultExecutorType" value="SIMPLE"/>
  <setting name="defaultStatementTimeout" value="25"/>
  <setting name="defaultFetchSize" value="100"/>
  <setting name="safeRowBoundsEnabled" value="false"/>
  <setting name="mapUnderscoreToCamelCase" value="false"/>
  <setting name="localCacheScope" value="SESSION"/>
  <setting name="jdbcTypeForNull" value="OTHER"/>
  <setting name="lazyLoadTriggerMethods" value="equals,clone,hashCode,toString"/>
</settings>

select

<select id="selectPerson" parameterType="int" parameterMap="deprecated" resultType="hashmap" resultMap="personResultMap" flushCache="false" useCache="true" timeout="10" fetchSize="256" statementType="PREPARED" resultSetType="FORWARD_ONLY">

attribute	describe
id	Unique identifier in namespace , Can be used to refer to this statement .
parameterType	The class fully qualified name or alias of the parameter that will be passed into this statement . This property is optional , because MyBatis You can use the type processor （TypeHandler） Infer the parameters of the specific incoming statement , Default is not set （unset）.
parameterMap	Used to reference external parameterMap Properties of , It is now abandoned . Use inline parameter mapping and parameterType attribute .
resultType	The fully qualified name or alias of the class expected to return the result from this statement . Be careful , If you are returning a collection , That should be set to the type the collection contains , Rather than the type of the collection itself . resultType and resultMap Only one can be used at the same time .
resultMap	To the outside resultMap A named reference to . The resulting mapping is MyBatis The most powerful feature , If you understand it thoroughly , Many complex mapping problems can be solved easily . resultType and resultMap Only one can be used at the same time .
flushCache	Set it to true after , As long as the statement is called , Both the local cache and the secondary cache will be emptied , The default value is ：false.
useCache	Set it to true after , The result of this statement will be cached by the second level cache , The default value is ： Yes select Element is true.
timeout	This setting is before throwing an exception , The number of seconds the driver waits for the database to return the result of the request . Default is not set （unset）（ Rely on the database driver ）.
fetchSize	This is a recommended value for the driver , Try to make the number of rows returned by the driver in batches equal to this setting . Default is not set （unset）（ Dependency driven ）.
statementType	Optional STATEMENT,PREPARED or CALLABLE. It will make MyBatis Separate use Statement,PreparedStatement or CallableStatement, The default value is ：PREPARED.
resultSetType	FORWARD_ONLY,SCROLL_SENSITIVE, SCROLL_INSENSITIVE or DEFAULT（ Equivalent to unset） One of them , The default value is unset （ Rely on the database driver ）.
databaseId	If the database vendor ID is configured （databaseIdProvider）,MyBatis Will load all without databaseId Or match the current databaseId The sentence of ; If there are sentences with and without , What you don't bring will be ignored .
resultOrdered	This setting is only for nested results select sentence ： If true, It is assumed that nested result sets or groups are included , When a main result row is returned , There is no reference to the previous result set . This makes it possible to get nested result sets without running out of memory . The default value is ：false.
resultSets	This setting only applies to multiple result sets . It will list the result sets returned after the statement is executed and give each result set a name , Multiple names are separated by commas .

insert, update , delete

Data change statement insert,update and delete The implementation of is very close to ：

<insert id="insertAuthor" parameterType="domain.blog.Author" flushCache="true" statementType="PREPARED" keyProperty="" keyColumn="" useGeneratedKeys="" timeout="20">

<update id="updateAuthor" parameterType="domain.blog.Author" flushCache="true" statementType="PREPARED" timeout="20">

<delete id="deleteAuthor" parameterType="domain.blog.Author" flushCache="true" statementType="PREPARED" timeout="20">

attribute	describe
id	Unique identifier in namespace , Can be used to refer to this statement .
parameterType	The class fully qualified name or alias of the parameter that will be passed into this statement . This property is optional , because MyBatis You can use the type processor （TypeHandler） Infer the parameters of the specific incoming statement , Default is not set （unset）.
parameterMap	Used to reference external parameterMap Properties of , It is now abandoned . Use inline parameter mapping and parameterType attribute .
flushCache	Set it to true after , As long as the statement is called , Both the local cache and the secondary cache will be emptied , The default value is ：（ Yes insert、update and delete sentence ）true.
timeout	This setting is before throwing an exception , The number of seconds the driver waits for the database to return the result of the request . Default is not set （unset）（ Rely on the database driver ）.
statementType	Optional STATEMENT,PREPARED or CALLABLE. It will make MyBatis Separate use Statement,PreparedStatement or CallableStatement, The default value is ：PREPARED.
useGeneratedKeys	（ Only applicable to insert and update） This will make MyBatis Use JDBC Of getGeneratedKeys Method to retrieve the primary key generated inside the database （ such as ： image MySQL and SQL Server Such a relational database management system automatically incremental fields ）, The default value is ：false.
keyProperty	（ Only applicable to insert and update） Specify properties that uniquely recognize the object ,MyBatis Will use getGeneratedKeys Or insert Of the statement selectKey The child element sets its value , The default value is ： Not set （unset）. If you generate more than one column , Multiple attribute names can be separated by commas .
keyColumn	（ Only applicable to insert and update） Set the column name of the generated key value in the table , In some databases （ image PostgreSQL） in , When the primary key column is not the first column in the table , It must be set . If you generate more than one column , Multiple attribute names can be separated by commas .
databaseId	If the database vendor ID is configured （databaseIdProvider）,MyBatis Will load all without databaseId Or match the current databaseId The sentence of ; If there are sentences with and without , What you don't bring will be ignored .

dynamic sql

<select id="selectPostIn" resultType="domain.blog.Post">
  SELECT *
  FROM POST P
  WHERE ID in
  <foreach item="item" index="index" collection="list" open="(" separator="," close=")">
        #{item}
  </foreach>
</select>
<!-- Batch insert -->
<insert id="mAdd" parameterType="list">
        insert into student (id, name, sex, card, phone, department, banji, banjiid)
        values
        <foreach collection="list" separator="," item="stu">
            (#{stu.id}, #{stu.name}, #{stu.sex}, #{stu.card}, #{stu.phone}, #{stu.department}, #{stu.banji},1)
        </foreach>
</insert>
<!-- Batch update mysql Batch update settings need to be enabled allowMultiQueries=true-->
<update id="mUpdate" parameterType="java.util.List">
        <foreach collection="list" item="stu">
            update student
            <set>
                <if test="stu.name!=null">
                    name = #{stu.name},
                </if>
                <if test="stu.sex!=null">
                    sex = #{stu.sex},
                </if>
                <if test="stu.card!=null">
                    card = #{stu.card},
                </if>
                <if test="stu.phone!=null">
                    phone = #{stu.phone},
                </if>
                <if test="stu.department!=null">
                    department = #{stu.department},
                </if>
                <if test="stu.banji!=null">
                    banji = #{stu.banji},
                </if>
            </set>
            where id = #{stu.id};
        </foreach>
</update>
<!--bind Fuzzy query -->
<select id="queryLikebanji" resultType="top.scsoul.mybatis.pojo.Student">
            <bind name="banji" value="'%'+banji+'%'"/>
            select * from student where banji like #{banji};
</select>

Association mapping

Two labels

one-on-one association

One to many collection

Two ways

nested queries

Nesting results

<?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">
<!--suppress SqlNoDataSourceInspection -->
<mapper namespace="com.botao.mapper.UserMapper">
    <!-- Nesting results -->
    <resultMap id="getUserByIdRm" type="com.botao.pojo.User">
        <id property="id" column="user_id"/>
        <result property="username" column="user_name"/>
        <association property="cadId" column="user_card_id" javaType="com.botao.pojo.Card">
            <id property="id" column="dbcardId"/>
            <result property="createdBy" column="created_by"/>
        </association>
        <collection property="orders" ofType="order" javaType="list">
            <id property="id" column="order_id"/>
            <result property="name" column="order_name"/>
        </collection>
    </resultMap>
    <select id="getUserById" parameterType="int" resultMap="getUserByIdRm">
        select user.*, card.card_id as dbcardId, card.created_by, o.order_id, o.order_name
        from user
                 join card on card.card_id = user.user_card_id
                 join `order` as o on user.user_id = o.user_id
        where user.user_id = #{id};
    </select>
	<!-- nested queries -->
    <resultMap id="getUserByIdRm2" type="com.botao.pojo.User">
        <id property="id" column="user_id"/>
        <result property="username" column="user_name"/>
        <association property="cadId" column="user_card_id" select="com.botao.mapper.CardMapper.getCard">
        </association>
        <collection property="orders" ofType="com.botao.pojo.Order" column="user_id" select="com.botao.mapper.OrderMapper.getOrderByUserId">
        </collection>
    </resultMap>
    <select id="getUserById2" parameterType="int" resultMap="getUserByIdRm2">
        select user_id,user_name,user_card_id
        from user
        where user_id = #{id};
    </select>

</mapper>

tip: Try to use join More efficient .