java项目实战-mybatis-基本配置01-day22

目录

• 0. mysql navicate链接分享
• 1. mvn坐标引入
• 2. mysql的核心配置文件
• 3. 返回值类型 别名
• 4. 将数据的配置提取配置文件
• 4. log4j修改日志输出

0. mysql navicate链接分享

链接：https://pan.baidu.com/s/1U9yWY5ENZXhOE9F9wC7ZvA?pwd=1111

提取码：1111

链接：https://pan.baidu.com/s/15yO3dYreuOjZ1RvrNql7gw?pwd=1111

提取码：1111

1. mvn坐标引入

mvn公共中心仓地址：https://mvnrepository.com/

输入jdbc找一个适当的版本

输入mysql找一个适当的版本

添加搭配mvn的 dependentcies

<?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.msb</groupId>
    <artifactId>TestMyBatis01</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.2.2</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.28</version>
        </dependency>

    </dependencies>

</project>

2. mysql的核心配置文件

搜索 mybatis中文网 https://mybatis.net.cn/getting-started.html

点击 入门

resource下面新建 mybatis.xml配置文件

<?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>
    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <!-- 1. mysql是数据库的名字 -->
                <!-- &amp; 是&符的转义符-->
                <property name="url" value="jdbc:mysql://127.0.0.1:3306/mysql?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8&amp;serverTimezone=Asia/Shanghai&amp;allowPublicKeyRetrieval=true"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mapper/BookMapper.xml"/>
    </mappers>
</configuration>

创建Book实体类

package com.msb.pojo;

/**
 * @Auther: jack.chen
 * @Date: 2023/11/8 - 11 - 08 - 23:22
 * @Description: com.msb.pojo
 * @version: 1.0
 */
public class Book {

    private int id;
    private String name;
    private String author;
    private Double price;

    public Book() {
    }

    public Book(int id, String name, String author, Double price) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.price = price;
    }

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public Double getPrice() {
        return price;
    }

    public void setPrice(Double price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "Book{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", author='" + author + '\'' +
                ", price=" + price +
                '}';
    }
}

创建mapper

<?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="a.b.c">
    <select id="selectAllBooks" resultType="com.msb.pojo.Book">
    select * from t_book
  </select>
</mapper>

创建Test类

import com.msb.pojo.Book;
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;

/**
 * @Auther: jack.chen
 * @Date: 2023/11/8 - 11 - 08 - 23:31
 * @Description: PACKAGE_NAME
 * @version: 1.0
 */
public class TestBook {
    public static void main(String[] args) throws IOException {

        String resource = "mybatis.xml";

        InputStream inputStream = Resources.getResourceAsStream(resource);

        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        List<Object> objects = sqlSession.selectList("a.b.c.selectAllBooks");
        for (Object object : objects) {
            Book b = (Book) object;
            System.out.println(b);
        }
        sqlSession.close();
        inputStream.close();

    }
}

运行

则说明查找ok

注意下 名称空间 a.b.c selectAllBooks可能有重名 所以 加上名称空间 a.b.c区分

3. 返回值类型 别名

BookMapper.xml里面定义了 返回值的类型 resultType

可以对这个resultType 取别名

1. mybatis.xml里面配置
   
   
   
   
   
   
   
   注意规范要求一定要放在environments 这个标签之前
   
   
   
   命名为bbbb

mapper.xml里面也定义成 bbbb

4. 将数据的配置提取配置文件

新建 db.properties

url=jdbc:mysql://127.0.0.1:3306/mysql?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true
driver=com.mysql.cj.jdbc.Driver
username=root
password=root

注意 url里面没有转义符

mybatis.xml里面修改基本配置

<?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>
    <properties resource="db.properties"></properties>

    <typeAliases>
        <typeAlias type="com.msb.pojo.Book" alias="bbbb"></typeAlias>
    </typeAliases>

    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"/>
            <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>
    </environments>
    <mappers>
        <mapper resource="mapper/BookMapper.xml"/>
    </mappers>
</configuration>

返回值的类型将包下面的内容都导入

    <typeAliases>
        <typeAlias type="com.msb.pojo.Book" alias="bbbb"></typeAlias>
        <package name="com.msb.pojo"/>
    </typeAliases>

对应的类名一定要对上

4. log4j修改日志输出

添加依赖

<!-- https://mvnrepository.com/artifact/log4j/log4j -->
<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

log4j.rootLogger = DEBUG , console

log4j.logger.a.b.c = TRACE

log4j.appender.console = org.apache.log4j.ConsoleAppender
log4j.appender.console.Target = System.out
log4j.appender.console.layout = org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern = [%p] [%-d{yyy-MM-dd HH\:mm\:ss}] %C.%M(%L) | %m%n