MyBatis基础入门《十七》动态SQL

Posted 2021-01-17 公子缘

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

 1 package com.charles.entity;
 2 
 3 import java.io.Serializable;
 4 import java.util.Date;
 5 
 6 public class TblClient implements Serializable {
 7 
 8     private static final long serialVersionUID = -5993993584624176849L;
 9 
10     private Integer cid;
11     private String cname;
12     private String caddress;
13     private Date cbirthday;
14 
15     public TblClient() {
16 
17     }
18 
19     public Integer getCid() {
20         return cid;
21     }
22 
23     public void setCid(Integer cid) {
24         this.cid = cid;
25     }
26 
27     public String getCname() {
28         return cname;
29     }
30 
31     public void setCname(String cname) {
32         this.cname = cname;
33     }
34 
35     public String getCaddress() {
36         return caddress;
37     }
38 
39     public void setCaddress(String caddress) {
40         this.caddress = caddress;
41     }
42 
43     public Date getCbirthday() {
44         return cbirthday;
45     }
46 
47     public void setCbirthday(Date cbirthday) {
48         this.cbirthday = cbirthday;
49     }
50 }

 

ClientMapper.java

 1 package com.charles.mapper;
 2 
 3 import java.util.List;
 4 
 5 import com.charles.entity.TblClient;
 6 
 7 public interface ClientMapper {
 8 
 9     /***
10      * 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。
11      * @return List<TblClient> 集合
12      */
13     public List<TblClient> getClientAll();
14     
15 }

 

ClientMapper.xml

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper
 3   PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4   "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 
 6 <mapper namespace="com.charles.mapper.ClientMapper">
 7  
 8     <resultMap type="com.charles.entity.TblClient" id="tblClientID">
 9         <id property="cid" column="id" />
10         <result property="cname" column="client_name"/>
11         <result property="caddress" column="client_address"/>
12         <result property="cbirthday" column="client_birthday"/>
13     </resultMap>    
14     
15     <select id="getClientAll" resultMap="tblClientID">
16         SELECT 
17                 id ,
18                 client_name ,
19                 client_address ,
20                 client_birthday 
21         FROM tbl_client 
22     </select>
23      
24 </mapper>

 

 MyBatisUtil.java

 1 package com.charles.util;
 2 
 3 import java.io.IOException;
 4 import java.io.InputStream;
 5 
 6 import org.apache.ibatis.io.Resources;
 7 import org.apache.ibatis.session.SqlSession;
 8 import org.apache.ibatis.session.SqlSessionFactory;
 9 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
10 
11 public class MyBatisUtil {
12 
13     private static SqlSessionFactory factory = null;
14     
15     /** 在静态代码块下，factory只会被创建一次 **/
16     static {
17         try {
18             InputStream inputStream = Resources.getResourceAsStream("mybatis/mybatis-config.xml");
19             factory = new SqlSessionFactoryBuilder().build(inputStream);
20         } catch (IOException e) {
21             e.printStackTrace();
22         }
23     }
24     
25     // 获取factory
26     public static SqlSessionFactory getSessionFactory() {
27         
28         return factory;
29     }
30     
31     /**
32      * 获取SQLSession方法
33      * 
34      * @return SQLSession 
35      **/
36     public static SqlSession getSqlSession() {
37         
38         // 开启事物
39         return factory.openSession(false);
40     }
41     
42     /**
43      * 关闭SQLSession方法
44      * 
45      * @param SQLSession对象
46      */
47     public static void closeSqlSession(SqlSession sqlSession) {
48         
49         if (sqlSession != null) {
50             sqlSession.close();
51         }
52     }
53 }

 

mybatis-config.xml

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE configuration
 3   PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 4   "http://mybatis.org/dtd/mybatis-3-config.dtd">
 5 
 6 <configuration>
 7 
 8     <!-- 
 9         注意：
10             这个配置文件的标签是有顺序的，必须按照这个顺序书写。
11             例如：settings标签就必须放在properties标签的后面。
12      -->
13 
14     <!-- 引入database.properties文件 -->
15     <properties resource="properties/database.properties"></properties>
16 
17     <!-- 配置mybatis的log实现log4j -->
18     <settings>
19         <setting name="logImpl" value="STDOUT_LOGGING" />
20     </settings>
21 
22     <!-- 配置别名 -->
23     <typeAliases>
24         <typeAlias type="com.charles.entity.TblClient" alias="baitang" />
25     </typeAliases>
26 
27     <!-- 配置Mybatis的环境 -->
28     <environments default="development">
29         <environment id="development">
30             <!-- 配置事物管理 -->
31             <transactionManager type="JDBC" />
32             <dataSource type="POOLED">
33                 <property name="driver" value="${jdbc.driver}" />
34                 <property name="url" value="${jdbc.url}" />
35                 <property name="username" value="${jdbc.username}" />
36                 <property name="password" value="${jdbc.password}" />
37             </dataSource>
38         </environment>
39     </environments>
40 
41     <!-- 将Mapper文件加入到mybatis的配置文件中 -->
42     <mappers>
43         <mapper resource="com/charles/mapper/ClientMapper.xml" />
44     </mappers>
45 
46 
47 </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

 1 package com.charles.junit;
 2 
 3 import java.util.List;
 4 
 5 import org.apache.ibatis.session.SqlSession;
 6 import org.junit.Test;
 7 
 8 import com.charles.entity.TblClient;
 9 import com.charles.mapper.ClientMapper;
10 import com.charles.util.MyBatisUtil;
11 
12 public class JunitSelect {
13 
14     @Test
15     public void selectif() {
16 
17         /** 1. 获取SQLSession **/
18         SqlSession session = MyBatisUtil.getSqlSession();
19 
20         /** 2. 调度方法,从数据库中获取数据 **/
21         List<TblClient> list = session.getMapper(ClientMapper.class).getClientAll();
22 
23         /** 3. 关闭SQLSession **/
24         MyBatisUtil.closeSqlSession(session);
25 
26         for (TblClient client : list) {
27             System.out.println(client.getCid() + "\\t" + client.getCname() + "\\t" + client.getCaddress() + "\\t"
28                     + client.getCbirthday());
29         }
30     }
31 }

 

pom.xml

 1 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 2     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 3     <modelVersion>4.0.0</modelVersion>
 4     <groupId>com.charles.mybatis</groupId>
 5     <artifactId>mybatis-dynamic-sql</artifactId>
 6     <version>0.0.1-SNAPSHOT</version>
 7 
 8     <dependencies>
 9         <dependency>
10             <groupId>junit</groupId>
11             <artifactId>junit</artifactId>
12             <version>4.11</version>
13         </dependency>
14         <dependency>
15             <groupId>log4j</groupId>
16             <artifactId>log4j</artifactId>
17             <version>1.2.17</version>
18         </dependency>
19         <dependency>
20             <groupId>org.mybatis</groupId>
21             <artifactId>mybatis</artifactId>
22             <version>3.4.6</version>
23         </dependency>
24         <dependency>
25             <groupId>mysql</groupId>
26             <artifactId>mysql-connector-java</artifactId>
27             <version>5.1.29</version>
28         </dependency>
29     </dependencies>
30 
31 
32 </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