【mybatis】基础环境搭建
mybatis基本使用
1,建库建表
SQL脚本
CREATE TABLE `user` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`username` varchar(30) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
`password` varchar(30) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
`age` int(11) NULL DEFAULT NULL,
`gender` varchar(6) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
`addr` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 11 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = COMPACT;
INSERT INTO `user` VALUES (1, 'zhangsan', '123', 20, 'male', 'qd');
INSERT INTO `user` VALUES (2, 'lisi', '123', 21, 'male', 'bj');
INSERT INTO `user` VALUES (4, 'tom', '123', 19, 'male', 'nj');
INSERT INTO `user` VALUES (5, 'wangwu', '123', 20, 'male', 'sh');
INSERT INTO `user` VALUES (6, 'weihua', '111', 21, 'female', 'sz');
2，新建maven项目，导入相关jar包，配置java目录下的xml文件为资源文件，让Maven能够识别，从而进行编译。
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<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>org.example</groupId>
<artifactId>mybatis02</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.6</version>
</dependency>
<dependency>
<!-- 测试 test -->
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
<!--只在测试时有效，包括测试代码的编译，执行。-->
<scope>test</scope>
</dependency>
<dependency>
<!-- log for java -->
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
</dependencies>
<!-- 配置java目录下的xml文件为资源文件，让Maven能够识别，从而进行编译。 -->
<build>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
</resource>
</resources>
</build>
</project>
3，创建实体类
创建表示用户的实体类User
package com.bean;
public class User {
private Long id;
private String username;
private String password;
private Integer age;
private String gender;
private String addr;
//set、get
//toString
}
4，编写日志配置文件
log4j.properties
#
# Hibernate, Relational Persistence for Idiomatic Java
#
# License: GNU Lesser General Public License (LGPL), version 2.1 or later.
# See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
#
### direct log messages to stdout ###
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.err
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n
### direct messages to file hibernate.log ###
#log4j.appender.file=org.apache.log4j.FileAppender
#log4j.appender.file.File=hibernate.log
#log4j.appender.file.layout=org.apache.log4j.PatternLayout
#log4j.appender.file.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n
### set log levels - for more verbose logging change 'info' to 'debug' ###
log4j.rootLogger=debug, stdout
这个文件编写不需要掌握，用的时候直接拷贝即可。
4，编写UserMapper接口
接口的名字我们一般命名为XxxMapper，所在的包命名为xxx.xxx.mapper，这是一种习惯。
当然也可以命名为XxxDao。
package com.mapper;
public interface UserMapper {
List<User> findAll();
}
5，编写映射文件（UserMapper.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.mapper.UserMapper">
<select id="findAll" resultType="com.bean.User">
SELECT * FROM user
</select>
</mapper>
6，编写核心配置文件SqlMapConfig.xml
该文件在resources目录下
<?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>
<!-- 配置别名 -->
<typeAliases>
<!-- <package name="com.bean"/>-->
<typeAlias type="com.bean.User" alias="user"/>
</typeAliases>
<!-- 配置环境 -->
<environments default="dev">
<environment id="dev">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url"
value="jdbc:mysql://localhost:3306/db_test_mybatis?useSSL=false&jdbc:mysql://localhost:3306/test?useSSL=false&useUnicode=true&characterEncoding=utf8"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>
<!--加载映射文件，如果不添加 Type interface com.mapper.UserMapper is not known to the MapperRegistry. MapperRegistry不知道接口类型com.mapper.UserMapper。 -->
<mappers>
<package name="com.mapper"/>
<!-- <mapper resource="com/mapper/UserMapper.xml" />-->
</mappers>
</configuration>
7，编写测试类
public class MyTest {
private SqlSession sqlSession;
private UserMapper userMapper;
@Before
public void init() throws IOException {
//加载核心配置文件
InputStream resourceAsStream = Resources.getResourceAsStream("SqlMapConfig.xml");
//创建SqlSessionFactory
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(resourceAsStream);
//获取连接
sqlSession = factory.openSession();
//创建接口的代理对象
userMapper = sqlSession.getMapper(UserMapper.class);
}
@After
public void destroy() {
//关闭连接
sqlSession.close();
}
@Test
public void testFindById() {
User user = userMapper.findById(1);
System.out.println(user);
}
@Test
public void testFindAll() {
List<User> users = userMapper.findAll();
users.forEach(user -> System.out.println(user));
}
}
运行测试方法，进行测试。
