MyBatis基础入门《十七》动态SQL

MyBatis基础入门《十七》动态SQL

描述：

　　>> 完成多条件查询等逻辑实现

　　>> 用于实现动态SQL的元素主要有：

　　　　> if

　　　　> trim

　　　　> where

　　　　> set

　　　　> choose( when , otherwise )

　　　　> foreach

　　动态SQL为Mybatis重要部分，项目也重新新建了一个：mybatis-dynamic-sql

项目结构：

TblClient.java

 package com.charles.entity;

 import java.io.Serializable;
 import java.util.Date;

 public class TblClient implements Serializable {

     private static final long serialVersionUID = -5993993584624176849L;

     private Integer cid;
     private String cname;
     private String caddress;
     private Date cbirthday;

     public TblClient() {

     }

     public Integer getCid() {
         return cid;
     }

     public void setCid(Integer cid) {
         this.cid = cid;
     }

     public String getCname() {
         return cname;
     }

     public void setCname(String cname) {
         this.cname = cname;
     }

     public String getCaddress() {
         return caddress;
     }

     public void setCaddress(String caddress) {
         this.caddress = caddress;
     }

     public Date getCbirthday() {
         return cbirthday;
     }

     public void setCbirthday(Date cbirthday) {
         this.cbirthday = cbirthday;
     }
 }

ClientMapper.java

 package com.charles.mapper;

 import java.util.List;

 import com.charles.entity.TblClient;

 public interface ClientMapper {

     /***
      * 注意这个名字，必须要和ClientMapper.xml文件中的select标签id属性值一样。
      * @return List<TblClient> 集合
      */
     public List<TblClient> getClientAll();

 }

ClientMapper.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="com.charles.mapper.ClientMapper">

     <resultMap type="com.charles.entity.TblClient" id="tblClientID">
         <id property="cid" column="id" />
         <result property="cname" column="client_name"/>
         <result property="caddress" column="client_address"/>
         <result property="cbirthday" column="client_birthday"/>
     </resultMap>    

     <select id="getClientAll" resultMap="tblClientID">
         SELECT
                 id ,
                 client_name ,
                 client_address ,
                 client_birthday
         FROM tbl_client
     </select>

 </mapper>

MyBatisUtil.java

 package com.charles.util;

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

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

 public class MyBatisUtil {

     private static SqlSessionFactory factory = null;

     /** 在静态代码块下，factory只会被创建一次 **/
     static {
         try {
             InputStream inputStream = Resources.getResourceAsStream("mybatis/mybatis-config.xml");
             factory = new SqlSessionFactoryBuilder().build(inputStream);
         } catch (IOException e) {
             e.printStackTrace();
         }
     }

     // 获取factory
     public static SqlSessionFactory getSessionFactory() {

         return factory;
     }

     /**
      * 获取SQLSession方法
      *
      * @return SQLSession
      **/
     public static SqlSession getSqlSession() {

         // 开启事物
         return factory.openSession(false);
     }

     /**
      * 关闭SQLSession方法
      *
      * @param SQLSession对象
      */
     public static void closeSqlSession(SqlSession sqlSession) {

         if (sqlSession != null) {
             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>

     <!--
         注意：
             这个配置文件的标签是有顺序的，必须按照这个顺序书写。
             例如：settings标签就必须放在properties标签的后面。
      -->

     <!-- 引入database.properties文件 -->
     <properties resource="properties/database.properties"></properties>

     <!-- 配置mybatis的log实现log4j -->
     <settings>
         <setting name="logImpl" value="STDOUT_LOGGING" />
     </settings>

     <!-- 配置别名 -->
     <typeAliases>
         <typeAlias type="com.charles.entity.TblClient" alias="baitang" />
     </typeAliases>

     <!-- 配置Mybatis的环境 -->
     <environments default="development">
         <environment id="development">
             <!-- 配置事物管理 -->
             <transactionManager type="JDBC" />
             <dataSource type="POOLED">
                 <property name="driver" value="${jdbc.driver}" />
                 <property name="url" value="${jdbc.url}" />
                 <property name="username" value="${jdbc.username}" />
                 <property name="password" value="${jdbc.password}" />
             </dataSource>
         </environment>
     </environments>

     <!-- 将Mapper文件加入到mybatis的配置文件中 -->
     <mappers>
         <mapper resource="com/charles/mapper/ClientMapper.xml" />
     </mappers>

 </configuration>

database.properties

jdbc.driver=com.mysql.jdbc.Driver
#jdbc.url=jdbc:mysql://IP地址:3306/test
jdbc.url=jdbc:mysql://IP地址:3306/test
jdbc.username=charles
jdbc.password=charles

lo4j.properties

# Global logging configuration
log4j.rootLogger=ERROR, stdout
# MyBatis logging configuration...
log4j.logger.com.charles=TRACE
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

JunitSelect.java

 package com.charles.junit;

 import java.util.List;

 import org.apache.ibatis.session.SqlSession;
 import org.junit.Test;

 import com.charles.entity.TblClient;
 import com.charles.mapper.ClientMapper;
 import com.charles.util.MyBatisUtil;

 public class JunitSelect {

     @Test
     public void selectif() {

         /** 1. 获取SQLSession **/
         SqlSession session = MyBatisUtil.getSqlSession();

         /** 2. 调度方法,从数据库中获取数据 **/
         List<TblClient> list = session.getMapper(ClientMapper.class).getClientAll();

         /** 3. 关闭SQLSession **/
         MyBatisUtil.closeSqlSession(session);

         for (TblClient client : list) {
             System.out.println(client.getCid() + "\t" + client.getCname() + "\t" + client.getCaddress() + "\t"
                     + client.getCbirthday());
         }
     }
 }

pom.xml

 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.charles.mybatis</groupId>
     <artifactId>mybatis-dynamic-sql</artifactId>
     <version>0.0.1-SNAPSHOT</version>

     <dependencies>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
             <version>4.11</version>
         </dependency>
         <dependency>
             <groupId>log4j</groupId>
             <artifactId>log4j</artifactId>
             <version>1.2.17</version>
         </dependency>
         <dependency>
             <groupId>org.mybatis</groupId>
             <artifactId>mybatis</artifactId>
             <version>3.4.6</version>
         </dependency>
         <dependency>
             <groupId>mysql</groupId>
             <artifactId>mysql-connector-java</artifactId>
             <version>5.1.29</version>
         </dependency>
     </dependencies>

 </project>

运行测试代码：JunitSelect.java 的测试结果：

如有问题，欢迎纠正！！！

如有转载，请标明源处：https://www.cnblogs.com/Charles-Yuan/p/9902779.html