小白大学生学习MyBatis（一）

2021-06-30 18:30:39 阅读：108 来源： 互联网

标签：xml java 大学生 mybatis 小白 MyBatis com public String

MyBatis（一）

MyBatis官网
https://mybatis.org/mybatis-3/zh/index.html（有需要的可以进去看一下）
2.在Maven的pom文件中加入依赖(Maven 有后续文章)
有两种方式
方式一：
在https://mvnrepository.com/网站中可以获取到
https://mvnrepository.com/artifact/org.mybatis/mybatis
方式二：
修改版本号即可

 <dependency>
   <groupId>org.mybatis</groupId>
   <artifactId>mybatis</artifactId>
   <version>x.x.x</version>
  </dependency>

需要的依赖还有

<!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.17</version>
        </dependency>
<!--junit单元测试-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>provided</scope>
        </dependency>
 
        <!--log4j依赖-->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

需要准备的还有
mybatis-mapper.xml模板

<?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="">
  <select id="" resultType="">

  </select>
</mapper>

mybatis-config.xml模板

<?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>

    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>

    <environments default="online">

        <!--唯一值 id  -->
        <environment id="mydev">
            <!-- 数据源 -->
            <transactionManager type="JDBC"/>
            <!-- 连接池 -->
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>


        <environment id="online">
            <!-- 数据源 -->
            <transactionManager type="JDBC"/>
            <!-- 连接池 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/student?serverTimezone=UTC&amp; characterEncoding=utf-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>

    </environments>

    <mappers>
        <mapper resource="mapper/StudentMapper.xml"/>
    </mappers>

</configuration>

其中 jdbc.properties配置参考为(这个先不用)

jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis
jdbc.username=root
jdbc.password=123456

需要在pom文件中的加入的下载插件和扫描文件所需代码

<build>
  <resources>
   <resource>
  	<directory>src/main/java</directory><!-- 所在的目录 -->

  	<includes>
  	<!-- 包括目录下的.properties.xml 文件都会扫描 -->
  	 <include>**/*.properties</include>
  	 <include>**/*.xml</include>
  	</includes>
  	
  	<filtering>false</filtering>
  	</resource>

  </resources>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.1</version>
        <configuration>
         <sorce>1.8</sorce>
         <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>
  </build>

3.测试
测试代码如下

 //访问mybatis读取student数据
        //1.定义mybatis主配置文件名称，从类路径的根开始（target/classes）
        String config = "mybatis.xml";
        //2.读取这个config表示的文件
        InputStream in = Resources.getResourceAsStream(config);
        //3.创建SqlSessionFactoryBuilder
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        //4.创建SqlSessionFactory对象
        SqlSessionFactory factory = builder.build(in);
        //5.获取SqlSession对象，从SqlSessionFactory中获取SqlSession
        SqlSession sqlSession = factory.openSession();
        //6.指定要执行的sql语句的标识，sql映射文件中的namespace + "."+标签的id值
        String sqlId = "com.sdyu.dao.StudentDao"+"."+"findAll";
        //7.执行sql语句，通过sqlId找到语句
        List<Student> studentList = sqlSession.selectList(sqlId);
        //8.输出结果
        for (Student stu : studentList) {
            System.out.println("账户:"+stu.getName()+"年龄:"+stu.getAge());
        }

        //9.关闭SqlSession对象
        sqlSession.close();

在这里插入图片描述

最终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>com.sdyu</groupId>
  <artifactId>mybatis</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>mybatis</name>
  <!-- FIXME change it to the project's website -->

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <!--mysql驱动-->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.17</version>
    </dependency>
    <!--junit单元测试-->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.6</version>
    </dependency>
  </dependencies>

  <build>
    <pluginManagement>
      <plugins>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.1</version>
          <configuration>
            <target>1.8</target>
          </configuration>
        </plugin>

      </plugins>
    </pluginManagement>

    <resources>
      <resource>
        <directory>src/main/java</directory><!-- 所在的目录 -->

        <includes>
          <!-- 包括目录下的.properties.xml 文件都会扫描 -->
          <include>**/*.properties</include>
          <include>**/*.xml</include>
        </includes>

        <filtering>false</filtering>
      </resource>
    </resources>
  </build>
</project>

mybatis.xml文件

<?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>

    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>

    <environments default="online">

        <!--唯一值 id  -->
        <environment id="mydev">
            <!-- 数据源 -->
            <transactionManager type="JDBC"/>
            <!-- 连接池 -->
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>


        <environment id="online">
            <!-- 数据源 -->
            <transactionManager type="JDBC"/>
            <!-- 连接池 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/student?serverTimezone=UTC&amp; characterEncoding=utf-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>

    </environments>

    <mappers>
        <mapper resource="mapper/StudentMapper.xml"/>
    </mappers>

</configuration>

StudentMapper.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.sdyu.dao.StudentDao">
    <select id="findAll" resultType="com.sdyu.bean.Student">
        SELECT id,name,age FROM student
  </select>
</mapper>

AppTest

```xml
package com.sdyu;
import com.sdyu.bean.Student;
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;

public class AppTest 
{
    public static void main(String[] args) throws IOException {
        //访问mybatis读取student数据
        //1.定义mybatis主配置文件名称，从类路径的根开始（target/classes）
        String config = "mybatis.xml";
        //2.读取这个config表示的文件
        InputStream in = Resources.getResourceAsStream(config);
        //3.创建SqlSessionFactoryBuilder
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        //4.创建SqlSessionFactory对象
        SqlSessionFactory factory = builder.build(in);
        //5.获取SqlSession对象，从SqlSessionFactory中获取SqlSession
        SqlSession sqlSession = factory.openSession();
        //6.指定要执行的sql语句的标识，sql映射文件中的namespace + "."+标签的id值
        String sqlId = "com.sdyu.dao.StudentDao"+"."+"findAll";
        //7.执行sql语句，通过sqlId找到语句
        List<Student> studentList = sqlSession.selectList(sqlId);
        //8.输出结果
        for (Student stu : studentList) {
            System.out.println("账户:"+stu.getName()+"年龄:"+stu.getAge());
        }

        //9.关闭SqlSession对象
        sqlSession.close();
    }

}

StudentDao.java
```java
package com.sdyu.dao;

import com.sdyu.bean.Student;

import java.util.List;

public interface StudentDao {
    List<Student> findAll();
}

Student.java

package com.sdyu.bean;

public class Student {
    private Integer id;
    private String name;
    private String age;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age='" + age + '\'' +
                '}';
    }
}

目录结构:
在这里插入图片描述
想一起学习的可以联系我
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标签：xml,java,大学生,mybatis,小白,MyBatis,com,public,String
来源： https://blog.csdn.net/hjs_75187712/article/details/118344894

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小白大学生学习MyBatis（一）

MyBatis（一）