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02-Mybatis快速入门之一斑窥豹

程序员文章站 2024-01-29 22:49:58
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上一篇：01-Mybatis初识https://blog.csdn.net/fsjwin/article/details/109640386
需求：写一个mysql的插入和查询

开发补助如下：
1.新建表
2.加入maven坐标、mysql驱动
3. 创建Student实体类
4.创建Dao接口
5.创建mybatis使用的配置文件sql映射文件，一个表一个，是一个xml文件 写在所在的接口目录中，名字一样
6.创建mybatis的主配置文件，一个项目中就一个，提供数据库的连接信息和sql文件（第五步中）的所在的路径信息
7.创建使用mybatis的类，访问数据库

1.新建表

DROP TABLE IF EXISTS `student`;
CREATE TABLE `student`  (
  `id` int(0) NOT NULL,
  `name` varchar(80) CHARACTER SET utf8mb4 COLLATE utf8mb4_croatian_ci NOT NULL,
  `email` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_croatian_ci NOT NULL,
  `age` int(0) NOT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_croatian_ci ROW_FORMAT = Dynamic;

2.加入maven坐标、mysql驱动

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.yuhl</groupId>
  <artifactId>ch01_hello</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>ch01_hello</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>

    <!--mybatis-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.5</version>
    </dependency>

    <!--mysql-->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.48</version>
    </dependency>
  </dependencies>

  <build>
    <!--编译插件-->
    <resources>
      <resource>
        <!--所在目录-->
        <directory>src/main/java</directory>
        <includes>
          <!--properties、xml均回扫描进来-->
          <include>**/*.properties</include>
          <include>**/*.xml</include>

        </includes>
        <filtering>false</filtering>
      </resource>

      <!--包含resources文件夹以及子文件夹下所有资源-->
      <resource>
        <directory>src/main/resources</directory>
        <includes>
          <include>**/*</include>
        </includes>
      </resource>
    </resources>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.1</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

特别说明，如果resources下的xml文件没有被打包进编译文件中，使用：
02-Mybatis快速入门之一斑窥豹

3. 创建Student实体类

package com.yuhl.domain;

import java.io.Serializable;

/**
 * @author yuhl
 * @Date 2020/11/12 21:02
 * @Classname Student
 * @Description TODO
 */
public class Student implements Serializable {
    private Integer id;
    private String name;
    private String email;
    private Integer 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 getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Integer getAge() {
        return age;
    }

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

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

    public Student() {
    }

    public Student(Integer id, String name, String email, Integer age) {
        this.id = id;
        this.name = name;
        this.email = email;
        this.age = age;
    }
}

4.创建Dao接口

package com.yuhl.dao;

import com.yuhl.domain.Student;

import java.util.List;

/**
 * @author yuhl
 * @Date 2020/11/12 21:03
 * @Classname StudentDao
 * @Description stuentDao接口
 */
public interface StudentDao {

    //获取所有Student对象
    public List<Student> selectStudents();

    //插入操作

    /**
     *
     * @param student
     * @return 插入的条数，影响的条数
     */
    public int insertStudent(Student student);
}

5.创建mybatis使用的配置文件sql映射文件，一个表一个，是一个xml文件 写在所在的接口目录中，名字一样

StudentDao.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.yuhl.dao.StudentDao">

    <!--插入操作-->
    <insert id="insertStudent">
        insert into student(id, name, email, age) values (#{id},#{name},#{email},#{age})
    </insert>

    <!--查询学生-->
    <select id="selectStudents" resultType="com.yuhl.domain.Student">
        select id,name,email,age from student
    </select>

    <!--
    1. 约束文件：<!DOCTYPE mapper    PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    约束你使用的标签
    2. mapper 跟标签，不能改
    3. namespace 没有要求，唯一的，但是要求使用dao接口的权限定名称。com.yuhl.dao.StudentDao
    4. select 标签：可以使用特定标签，执行特殊操作
        其他：
            update：更新
            insert：插入
            delete：删除
            select：查询
                    id：你要执行的sql语句的唯一表示，mybatis会使用这个id找到唯一的值，可以自定义，但是要求使用接口中的方法名称。
                    resultType:表示sql执行后的结果的转换类型

    -->

</mapper>

6.创建mybatis的主配置文件，一个项目中就一个，提供数据库的连接信息和sql文件（第五步中）的所在的路径信息

mybatis.xml

<?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>
    <!--日志的添加 可以把sql打印在控制台上-->
    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>

    <!--环境配置，熟即可的配置信息
    default 选择下面environment中的某个作为默认值即可。
    -->
    <environments default="development">
        <!--id:唯一值，可以自定义-->
        <environment id="development">
            <!--事务类型， JDBC：使用jdbc中的commit和rollback的-->
            <transactionManager type="JDBC"/>
            <!--数据源 type：连接池的类型-->
            <dataSource type="POOLED">
                <!--连接数据库的集体信息的driver、url、username、password不能改哦-->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://127.0.0.1:3306/mybatis?useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>

        <!--表示生产数据库-->
        <environment id="product">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://192.168.220.11:3306/mybatis?useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="kdsjfdskl"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>

        <!--sql映射文件的位置
            一个<mapper表示一个mapper文件的位置，可以使用package标签哦！
            可以加载sql文件
            可以添加多个
            注意：是路径/表示
        -->
        <mapper resource="com/yuhl/dao/StudentDao.xml"/>
        <!--<mapper resource="com/yuhl/dao/User.xml"/>-->
    </mappers>
</configuration>


<!--
    mybatis：的主配置文件
-->

7.创建使用mybatis测试的类，访问数据库

package com.yuhl;

import static org.junit.Assert.assertTrue;

import com.yuhl.domain.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 org.junit.Test;

import javax.annotation.Resource;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class AppTest {
    @Test
    public void test1() throws IOException {
        //主配置文件
        String conf = "mybatis.xml";
        //加载文件
        InputStream in = Resources.getResourceAsStream(conf);
        //SqlSessionFactoryBuilder：创建SqlSessionFactory
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        //SqlSessionFactory 创建SqlSession
        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(in);
        //【重要】获取SqlSession对象 执行sql
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // 【重要】namespace+.+id 的方式获得sql
        List<Student> studentList = sqlSession.selectList("com.yuhl.dao.StudentDao.selectStudents");
        studentList.forEach(student -> System.out.println(student));
        sqlSession.close();

    }

    @Test
    public void test2() throws IOException {
        //主配置文件
        String conf = "mybatis.xml";
        //加载文件
        InputStream in = Resources.getResourceAsStream(conf);
        //SqlSessionFactoryBuilder：创建SqlSessionFactory
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        //SqlSessionFactory 创建SqlSession
        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(in);
        //【重要】获取SqlSession对象 执行sql
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // 【重要】namespace+.+id 的方式获得sql
        Student studnet = new Student(1004,"rll","aaa@qq.com",20);
        int insert = sqlSession.insert("com.yuhl.dao.StudentDao.insertStudent", studnet);
        System.out.println(insert);
        sqlSession.commit();
        sqlSession.close();
    }
}

查询测试结果：

Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
Opening JDBC Connection
Created connection 1345483087.
Setting autocommit to false on JDBC Connection [aaa@qq.com]
==>  Preparing: select id,name,email,age from student
==> Parameters: 
<==    Columns: id, name, email, age
<==        Row: 1001, 张三, aaa@qq.com, 20
<==        Row: 1002, 李四, aaa@qq.com, 28
<==        Row: 1003, yuhl, aaa@qq.com, 20
<==        Row: 1004, rll, aaa@qq.com, 20
<==      Total: 4
Student{id=1001, name='张三', email='aaa@qq.com', age=20}
Student{id=1002, name='李四', email='aaa@qq.com', age=28}
Student{id=1003, name='yuhl', email='aaa@qq.com', age=20}
Student{id=1004, name='rll', email='aaa@qq.com', age=20}
Resetting autocommit to true on JDBC Connection [aaa@qq.com]
Closing JDBC Connection [aaa@qq.com]
Returned connection 1345483087 to pool.

插入测试结果：

Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
Opening JDBC Connection
Created connection 1579957528.
Setting autocommit to false on JDBC Connection [aaa@qq.com]
==>  Preparing: insert into student(id, name, email, age) values (?,?,?,?)
==> Parameters: 1005(Integer), 大佬(String), aaa@qq.com(String), 20(Integer)
<==    Updates: 1
1
Committing JDBC Connection [aaa@qq.com]
Resetting autocommit to true on JDBC Connection [aaa@qq.com]
Closing JDBC Connection [aaa@qq.com]
Returned connection 1579957528 to pool.

7.其他

善于参考官方文档，mybatis的中文官方文档写的特别好：

02-Mybatis快速入门之一斑窥豹
2. 切换数据库环境
02-Mybatis快速入门之一斑窥豹

8.总结

使用mybaits开发有一定的套楼，知道即可，后面我们也不会这样开发，使用boot后，你将知道什么叫丝滑，但是基础不牢地动山摇。希望大家把基础打牢固。
02-Mybatis快速入门之一斑窥豹

下一篇：03-Mybatis的关键核心类说明https://blog.csdn.net/fsjwin/article/details/109661578

相关标签： Mybatis mybatis 入门实战 一斑窥豹 快速入门

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