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JAVA MyBatis入门学习过程记录

作者：wangweizu99　　发布时间：2022-04-23 13:49:24　

标签：JAVA,MyBatis,入门

一、Mybatis

1、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>

<properties resource="db.properties"/>
<settings>


<setting name="logImpl" value="log4j"/>

<setting name="mapUnderscoreToCamelCase" valie="true"
</settings>

<typeAliases> <typeAlias type="com.wang.pojo.User" alias="User"/>
</typeAliases>
<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>
<mappers>
<mapper resource="com/wang/dao/UserMapper.xml"/>
</mappers>
</configuration>

2、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="com.wang.dao.UserDao">
<select id="getUserList" resultType="User">
select * from mybatis.user
</select>
</mapper>

3、db.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis
username=root
password=123456

4、MybatisUtils工具类

package com.wang.utils;
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 MybatisUtils {
private static SqlSessionFactory sqlSessionFactory;
static {
InputStream inputStream = null;
try {
String resource = "mybatis-config.xml";
inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession getsqlsession() {
return sqlSessionFactory.openSession();
}
}

5、多对一AND多对一：

在Mapper.xml中配置

association 对象多对一

collection 集合一对多

从用参数解释：

javaType java类型
ofType 泛型约束类型

6、使用注解开发

可在接口中使用注解进行开发，省去Mapper.xml

@Select("select * from mybatis.User")
List<User> getUserList();

在mybatis-config.xml中配置
<mappers>
<mapper class="com.wang.Dao.UserMapper"
</mappers>

7、自定义缓存：ehcache

8、mybatis 其他工具

mybatis Hepler：https://pagehelper.github.io/

二、MAVEN资源导出错误解决

<build>
<resources>
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>true</filtering>
</resource>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>true</filtering>
</resource>
</resources>
</build>

三、常用依赖导入

<dependencies>

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.49</version>
</dependency>

<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.2</version>
</dependency>

<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
</dependency>

<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.20</version>
</dependency>

<dependency>
<groupId>org.mortbay.jetty</groupId>
<artifactId>servlet-api-2.5</artifactId>
<version>6.1.7</version>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.1</version>
</dependency>

<dependency>
<groupId>org.apache.karaf.assemblies.features</groupId>
<artifactId>standard</artifactId>
<version>2.4.4</version>
</dependency>
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>1.1.2</version>
</dependency>

<dependency>
<groupId>javax.servlet.jsp.jstl</groupId>
<artifactId>jstl-api</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>org.glassfish.web</groupId>
<artifactId>jstl-impl</artifactId>
<version>1.2</version>
</dependency>

<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.76</version>
</dependency>

<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
</dependencies>

四、LOG4J

1、log4j.properties 配置文件

<dependencies>

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.49</version>
</dependency>

<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.2</version>
</dependency>

<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
</dependency>

<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.20</version>
</dependency>

<dependency>
<groupId>org.mortbay.jetty</groupId>
<artifactId>servlet-api-2.5</artifactId>
<version>6.1.7</version>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.1</version>
</dependency>

<dependency>
<groupId>org.apache.karaf.assemblies.features</groupId>
<artifactId>standard</artifactId>
<version>2.4.4</version>
</dependency>
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>1.1.2</version>
</dependency>

<dependency>
<groupId>javax.servlet.jsp.jstl</groupId>
<artifactId>jstl-api</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>org.glassfish.web</groupId>
<artifactId>jstl-impl</artifactId>
<version>1.2</version>
</dependency>

<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.76</version>
</dependency>

<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
</dependencies>

2、log4j 在mybatis-config.xml的配置

<settings>
<setting name="logImpl" value="LOG4J"/>
</settings>

3、使用场景

在具体类中引入

Logger logger = Logger.getLogger(UserDaoTest.class);
logger.error();
logger.debug();

好用的插件：

1、lombok

常用注解：

@Data 自动生成geter seter
@AllArgsConstructor 生成有参构造函数
@NoArgsConstructor 生成无参构造函数

=“logImpl” value=“LOG4J”/>

## 3、使用场景

- 在具体类中引入

```java
Logger logger = Logger.getLogger(UserDaoTest.class);
logger.error();
logger.debug();