IDEA+Mybatis连接数据库（一）

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：

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：