IDEA+Mybatis连接数据库（一）

￡神魔★判官ぃ 2022-03-01 07:28 447阅读 0赞

首先创建Maven项目，在pom.xml中添加依赖：

<dependency>
          <groupId>org.mybatis</groupId>
          <artifactId>mybatis</artifactId>
          <version>3.4.6</version>
        </dependency>
    
        <dependency>
          <groupId>mysql</groupId>
          <artifactId>mysql-connector-java</artifactId>
          <version>5.1.38</version>
        </dependency>

这是项目工程的结构图：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMyMjUyOTE3_size_16_color_FFFFFF_t_70][]

在mybatis-config.xml文件中，配置连接数据库的基本信息，如下：

<?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>
    
        <environments default="development">
    
            <environment id="development">
                <transactionManager type="JDBC"/>
                <dataSource type="POOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql://localhost:3306/j2ee"/>
                    <property name="username" value="root"/>
                    <property name="password" value="000000"/>
                </dataSource>
            </environment>
        </environments>
    
        <mappers>
            <mapper resource="mapper/StudentMapper.xml"></mapper>
        </mappers>
    </configuration>

在StudentMapper.xml文件中配置查询表的信息，如下：

<?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="Student">
        <select id="queryAll" resultType="hashmap">
            SELECT * FROM student
        </select>
    
    </mapper>

最后使用Junit单元测试进行测试：

package com.test;
    
    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;
    import java.util.List;
    import java.util.Map;
    
    public class Test {
    
        @org.junit.Test
        public void selectAll() {
    
            String resource = "mybatis-config.xml";
            InputStream inputStream;
            SqlSession sqlSession = null;
    
            try {
                inputStream = Resources.getResourceAsStream(resource);
                SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    
                sqlSession = sqlSessionFactory.openSession();
    
                List<Map> list = sqlSession.selectList("Student.queryAll");
    
                for (Map map : list) {
                    System.out.println(map);
                }
    
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                sqlSession.close();
            }
    
        }
    }

测试结果如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMyMjUyOTE3_size_16_color_FFFFFF_t_70 1][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMyMjUyOTE3_size_16_color_FFFFFF_t_70]: /images/20220301/9c698afae09049e6820a086f8a7cd7ce.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMyMjUyOTE3_size_16_color_FFFFFF_t_70 1]: /images/20220301/2af800692d614f0db1d692e508466410.png