一小時迅速入門Mybatis之bind與多數據源支持 Java API

// 測試bind
List<Person> testBind(@Param("name") String name);

<!--測試bind-->
<!--相當於SQL select * from person where name like '%小強%' -->
<select id="testBind" resultType="entity.Person">
    <bind name="bidname" value="'%'+name+'%'" />
    select * from person where name like #{bidname}
</select>

import dao.PersonMapper;
import entity.Person;
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.InputStream;
import java.util.*;

/**
 * @author 發現更多精彩  關註公眾號：木子的晝夜編程
 * 一個生活在互聯網底層，做著增刪改查的碼農,不諳世事的造作
 */
public class TestMain03 {
    public static void main(String[] args) throws Exception {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        try (SqlSession session = sqlSessionFactory.openSession()) {
            // 通過sesson獲取Mapper 這個Mapper會編程Mybatis的代理Mapper
            PersonMapper mapper = session.getMapper(PersonMapper.class);
            List<Person> list = mapper.testBind("小強");
            Optional.ofNullable(list).orElse(new ArrayList<>()).forEach(item -> {
                System.out.println(item);
            });
        }
    }
}

<?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>testDB</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>
        <!-- 引入Mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>
        <!-- mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
    </dependencies>
</project>

<?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://127.0.0.1:3306/test?useUnicode=true&amp;characterEncoding=utf-8&amp;useSSL=false&amp;serverTimezone=GMT%2B8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <!--DB_VENDOR是默認實現  這裡可以定義自己的實現類 下一篇寫-->
    <databaseIdProvider type="DB_VENDOR" >
        <!--這裡是因為原名稱太長瞭 指定一下縮寫 xml中判斷類型就用縮寫名稱判斷-->
        <property name="DB2" value="db2" />
        <property name="Oracle" value="oracle" />
        <property name="Adaptive Server Enterprise" value="sybase" />
        <property name="MySQL" value="mysql" />
    </databaseIdProvider>
    <!--掃描-->
    <mappers>
        <mapper resource="PersonMapper.xml"/>
    </mappers>
</configuration>

package dao;


/**
 * @author 發現更多精彩  關註公眾號：木子的晝夜編程  分享一個生活在互聯網底層做著增刪改查的碼農的感悟與學習
 * @create 2021-08-30 21:54
 */
public interface PersonMapper {
    // 測試返回當前時間
    String testDb();
}

<?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="dao.PersonMapper">
    <!--選擇不同的數據庫-->
    <select id="testDb" resultType="string" >
        <!--如果是mysql 執行這個 -->
        <if test="_databaseId == 'mysql'">
            select CONCAT("mysql-->",#{_databaseId},"-->",now()) from dual
        </if>
        <!--如果是oracle 執行這個-->
        <if test="_databaseId == 'oracle'">
            select "oracle-->"||#{_databaseId}  from dual
        </if>
    </select>

</mapper>

import dao.PersonMapper;
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.InputStream;

/**
 * @author 發現更多精彩  關註公眾號：木子的晝夜編程
 * 一個生活在互聯網底層，做著增刪改查的碼農,不諳世事的造作
 * @create 2021-09-02 21:42
 */
public class TestMain {
    public static void main(String[] args) throws Exception {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
            // 通過sesson獲取Mapper 這個Mapper會編程Mybatis的代理Mapper
            PersonMapper mapper = session.getMapper(PersonMapper.class);
            String type = mapper.testDb();
            System.out.println("數據庫類型："+type);
    }
}