【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&amp;jdbc:mysql://localhost:3306/test?useSSL=false&amp;useUnicode=true&amp;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。