MyBatis基础入门《二》Select查询

MyBatis基础入门《二》Select查询

　　使用MySQL数据库，创建表：

 SET NAMES utf8mb4;
 SET FOREIGN_KEY_CHECKS = 0;

 -- ----------------------------
 -- Table structure for tbl_client_copy1
 -- ----------------------------
 DROP TABLE IF EXISTS `tbl_client_copy1`;
 CREATE TABLE `tbl_client_copy1`  (
   `id` int(5) NOT NULL AUTO_INCREMENT,
   `client_name` varchar(255) CHARACTER SET utf8 COLLATE utf8_unicode_ci NULL DEFAULT NULL,
   `client_address` varchar(255) CHARACTER SET utf8 COLLATE utf8_unicode_ci NULL DEFAULT NULL,
   `client_birthday` datetime NULL DEFAULT NULL,
   PRIMARY KEY (`id`) USING BTREE
 ) ENGINE = InnoDB AUTO_INCREMENT = 1 CHARACTER SET = utf8 COLLATE = utf8_unicode_ci ROW_FORMAT = Compact;

 SET FOREIGN_KEY_CHECKS = 1;

项目工程：

　　

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.dao.ClientMapper">

     <!-- 查询数据库 -->
     <select id="getCount" resultType="int">
         SELECT COUNT(*) FROM tbl_client
     </select>    

 </mapper>

TblClient.java

 package com.charles.entity;

 import java.io.Serializable;

 public class TblClient implements Serializable {

     private static final long serialVersionUID = -5993993584624176849L;

     private Integer cid;
     private String cname;
     private String caddress;
     private String 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 String getCbirthday() {
         return cbirthday;
     }

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

 }

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>

     <!-- 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/dao/ClientMapper.xml" />
     </mappers>

 </configuration>

database.properties

　　这个是链接数据库的配置，未做改动，不在显示：见《Mybatis基础入门《一》环境搭建》

log4j.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

　

JunitMybatisConfig.java

 package com.charles.junit;

 import static org.junit.Assert.fail;

 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;
 import org.apache.log4j.Logger;
 import org.apache.log4j.PropertyConfigurator;
 import org.junit.Test;

 public class JunitMybatisConfig {

     @Test
     public void test() {
         fail("Not yet implemented");
     }

     @Test
     public void testLog4j() {
         PropertyConfigurator.configure("D:/DISK WORKSPACE/STS MAVEN/mybatis-base/src/main/resources/lo4j.properties");
         Logger logger = Logger.getLogger(JunitMybatisConfig.class);
         logger.debug(" debug ");
         logger.error(" error ");
     }

     @Test
     public void testMybaits() {

         try {
             /** 1.获取mybatis-config.xml文件 **/
             String resource = "mybatis/mybatis-config.xml";
             InputStream is = Resources.getResourceAsStream(resource);

             /** 2.创建SQLSessionFactory对象 **/
             SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

             /** 3.创建SQLSession **/
             SqlSession session = sqlSessionFactory.openSession();

             /** 4.输出SQLSession对象 **/
             System.out.println(session);
         } catch (IOException e) {
             e.printStackTrace();
         }
     }
 }

　　注意：

　　　　sqlSessionFactory.openSession(boolean autoCommit); 这里的openSession的方法中有一个boolean类型的参数。

　　　　　　true：关闭事物控制（默认）

　　　　　　false：开启事物控制 

JunitMybatisSelect.java

 package com.charles.junit;

 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;
 import org.junit.Test;

 public class JunitMybatisSelect {

     @Test
     public void junitSelect() {
         SqlSession session = null;
         try {
             /** 1.获取mybatis-config.xml文件 **/
             String resource = "mybatis/mybatis-config.xml";
             InputStream is = Resources.getResourceAsStream(resource);

             /** 2.创建SQLSessionFactory对象 **/
             SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

             /** 3.创建SQLSession **/
             session = sqlSessionFactory.openSession();

             /** 4.输出SQLSession对象 **/
             System.out.println(session);
             String resoruce = "com.charles.dao.ClientMapper.getCount";
             int count = session.selectOne(resoruce);
             System.out.println(count);

         } catch (IOException e) {
             e.printStackTrace();
         } finally {
             if(null != session) {
                 session.close();
             }
         }
     }
 }

　　注意：

　　　　String resource = "com.charles.dao.ClientMapper.getCount", 这个不是随便写的，这是由：ClientMapper.xml 文件中的namespace + select标签ID的值 组成。

　　　　SQLSession的使用方式有两种:

　　　　　　1. 通过SQLSession的实例直接运行映射的SQL语句。

　　　　　　2. 基于Mapper接口方式操作数据。

　　　　由于是初步搭建学习MyBatis，这里我使用的是第一种。一步一步的深入，后面会改成第二种方式。

　　　　

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-base</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.slf4j</groupId> -->
 <!--             <artifactId>slf4j-api</artifactId> -->
 <!--             <version>1.7.7</version> -->
 <!--         </dependency> -->
 <!--         <dependency> -->
 <!--             <groupId>org.slf4j</groupId> -->
 <!--             <artifactId>slf4j-log4j12</artifactId> -->
 <!--             <version>1.7.7</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>

如有问题，欢迎纠正！！！

如有转载，请标明源处：https://www.cnblogs.com/Charles-Yuan/p/9861099.html