Mybatis

1.搭建环境

https://mybatis.org/mybatis-3/zh/index.html

创建一个mavan项目

导入依赖


     
      mysql
         mysql-connector-java
      5.1.47
     
     
         org.mybatis
         mybatis
         3.5.2
     
     
         junit
         junit
         4.12

修改配置，能够自动导入所有xml和properties 文件

    
        
            
                src/main/resources
                
                    **/*.xml
                    **/*.properties
                
            
            
                src/main/java
                
                    **/*.xml
                    **/*.properties

在resources 配置mysql数据库

${driver} : 使用的驱动一般使用com.mysql.jdbc.Driver
${url}:数据库地址
${username}:用户名
${password}:密码

创建一个数据库
```
CREATE DATABASE blogData;
```

创建数据表

use blogData;
CREATE TABLE IF NOT EXISTS `Category`(
    `id` INT UNSIGNED AUTO_INCREMENT,
    `name` VARCHAR(100) NOT NULL,
    PRIMARY KEY(`id`)
) ENGINE =InnoDB DEFAULT CHARSET =utf8;
CREATE TABLE IF NOT EXISTS `Tag`(
    `id` INT UNSIGNED AUTO_INCREMENT,
    `name` VARCHAR(100) NOT NULL ,
    PRIMARY KEY (`id`)
)ENGINE = InnoDB DEFAULT CHARSET = utf8;
CREATE TABLE IF NOT EXISTS `Post`(
     `id` INT UNSIGNED AUTO_INCREMENT,
     `content` VARCHAR(1000) NOT NULL,
     `author` VARCHAR(100) NOT NULL,
     `cid` INT UNSIGNED,
     `tid` INT UNSIGNED,
     PRIMARY KEY (id),
     FOREIGN KEY (cid) REFERENCES Category(id),
     FOREIGN KEY (tid) REFERENCES Tag(id)
) ENGINE=InnoDB DEFAULT CHARSET = utf8;

创建实体类
- 在src下创建一个pojo目录

image-20200529003522307.png

编写实体类

这里可以使用lombok插件

        
            org.projectlombok
            lombok
            1.18.10

代码：

package com.test.pojo;

import lombok.Data;

@Data
public class Category {
    int id;
    String name;
}

package com.test.pojo;

import lombok.Data;

@Data
public class Tag {
    int id;
    String name;
}

package com.test.pojo;

import lombok.Data;

import java.util.List;
@Data
public class Post {
    int id;
    String author;
    String content;
    Category category;
    Tag tag;
}

   注意 ： 类名和属性名要和数据表匹配

创建工具类
- 创建一个utils包

image-20200529135921661.png

创建MyBatisUtils 获取sqlsession

package com.test.utils;

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;

public class MyBatisUtils {
    private static SqlSessionFactory sqlSessionFactory;
    static {
        try{
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession(true);
    }
}

openSession(true) :可以设置自动提交

创建一个mapper包

[图片上传失败...(image-1b690d-1590759226404)]

编写实体类的映射类

使用注解开发

package com.test.mapper;

import com.test.pojo.Category;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

public interface CategoryMapper {
    @Select("select * from Category")
    Category getCategorys();
    @Insert("insert into Category values(#{id},#{name})")
    void addCategory(Category category);
    @Delete("delete from Category where id=#{id}")
    void deleteCatogory(int id);
    @Update("update Category set name=#{name} where id=#{id}")
    void updateCategory(Category category);
}

使用xml 映射

package com.test.mapper;

import com.test.pojo.Tag;

import java.util.List;

public interface TagMapper {
    List getTags();
    void addTag(Tag tag);
    void deleteTag(int id);
    void updateTag(Tag tag);
}





    
    
        insert into tag values (#{id}, #{name});
    
    
        delete from tag where id=#{id};
    
    
        update tag set name=#{name} where id=#{id};

xml 文件：

namespace: 命名空间，就是映射类的包名+类名

类型别名：使用类型别名可以简化类的导入





    
    
        insert into tag values (#{id}, #{name});
    
    
        delete from tag where id=#{id};
    
    
        update tag set name=#{name} where id=#{id};

一对多和多对一：





    
        
        
    

    
    
        insert into post(content, author, cid, tid) values ( #{content},#{author},#{category.id},#{tag.id});
    
    
        delete from post where id=#{id};
    
    
        update post set content=#{content}, author=#{author}, cid=#{category.id}, tid=#{tag.id};

package com.test.mapper;

import com.test.pojo.Post;

import java.util.List;

public interface PostMapper {
    List getPosts();
    void addPost(Post post);
    void deletePost(int id);
    void updatePost(Post post);
}

Mybatis

Mybatis

1.搭建环境

其他内容

动态sql+map 做多条件查询

你可能感兴趣的:(Mybatis)