MyBatis注解（单表）

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1、MyBatis 注解开发前的准备

1.1、MyBatis 常用注解

@Insert: 实现新增 
@Update: 实现更新
@Delete: 实现删除
@Select: 实现查询
@Result: 实现结果集封装
@Results: 可以与 @Result 一起使用，封装多个结果集 
@ResultMap: 实现引用 @Results 定义的封装
@One: 实现一对一结果集封装 
@Many: 实现一对多结果集封装 
@SelectProvider: 实现动态 SQL 映射 
@CacheNamespace: 实现注解二级缓存的使用

1.2、注解开发前的准备

1.2.1、创建项目

GroupId:com.tyschool
ArtifactId:mb005
Version:1.0-SNAPSHOT

1.2.2、编写 pom.xml 配置文件

<?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.tyschool</groupId>
    <artifactId>mb005</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.9</maven.compiler.source>
        <maven.compiler.target>1.9</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.11</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

1.2.3、编写 SqlMapConfig.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>
    <properties resource="db.properties"></properties>
    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING" />
    </settings>
    <typeAliases>
        <package name="com.tyschool.mb005.javabean"/>
    </typeAliases>
 
    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
</configuration>

数据源文件 db.properties

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://192.168.1.123:3306/mybatis?serverTimezone=UTC
jdbc.username=root
jdbc.password=Root12345

2、完成单表的 CRUD

2.1、需求介绍

完成学生表的 CRUD

2.2、编写 Students.java 文件

import java.io.Serializable;
 
public class Students implements Serializable {private int sid;
    private String sname;
    private String ssex;
    private int sage;
    private int cid;
 
    public int getSid() {return sid;
    }
 
    public void setSid(int sid) {this.sid = sid;
    }
 
    public String getSname() {return sname;
    }
 
    public void setSname(String sname) {this.sname = sname;
    }
 
    public String getSsex() {return ssex;
    }
 
    public void setSsex(String ssex) {this.ssex = ssex;
    }
 
    public int getSage() {return sage;
    }
 
    public void setSage(int sage) {this.sage = sage;
    }
 
    public int getCid() {return cid;
    }
 
    public void setCid(int cid) {this.cid = cid;
    }
 
    @Override
    public String toString() {return "Students{" +
                "sid=" + sid +
                ", sname='" + sname + '\'' +
                ", ssex='" + ssex + '\'' +
                ", sage=" + sage +
                ", cid=" + cid +
                '}';
    }
}

2.3、编写 IStudentsDao.java 文件

import java.util.List;
import com.tianyi.javabean.Students;
public interface IStudentsDao {List<Students> findAll();
    Students findById(int sid);
    int addStudents(Students students);
    int updateStudents(Students students);
    int deleteStudents(int sid);
    int addCount();
    List<Students> findByName(String name);
}

配置映射

<mappers>
        <package name="com.tyschool.mb005.students.dao"/>
</mappers>

2.4、创建测试类 MbStudentsTest.java

package com.tianyi.test;
 
 
import com.tianyi.dao.IStudentsDao;
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.After;
import org.junit.Before;
 
import java.io.IOException;
import java.io.InputStream;
 
public class MbStudentsTest {private InputStream in;
    private SqlSession session;
    private IStudentsDao studentsDao;
 
 
    @Before
    public void init()throws IOException {in= Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSessionFactoryBuilder builder=new SqlSessionFactoryBuilder();
        SqlSessionFactory factory=builder.build(in);
        session=factory.openSession(true);
        studentsDao=session.getMapper(IStudentsDao.class);
    }
    @After
    public void destroy() throws IOException {//session.commit();
        session.close();
        in.close();}
}

3、CRUD 操作 - 上

3.1、查询所有学生信息

3.1.1、修改 findAll() 方法

@Select("select * from students")
    @Results(id="studentsMap",value={@Result(id=true,column = "sid",property = "sid"),
            @Result(column = "sname",property = "sname"),
            @Result(column = "ssex",property = "ssex"),
            @Result(column = "sage",property = "sage")
    })
List<Students> findAll();

3.3.2、编写测试方法

@Test
public void findAll(){List<Students> list=studentsDao.findAll();
        for (Students s:list) {System.out.println(s);
        }
}

3.2、根据 ID 查询学生信息

3.2.1、修改 findByID() 方法

@Select("select * from students where sid=#{sid}")
@ResultMap("studentsMap")
Students findById(int sid);

3.2.2、编写测试方法

@Test
public void findById(){Students s=studentsDao.findById(3);
        System.out.println(s);
}

3.3、增加学生的记录

3.3.1、修改 addStudents() 方法

@Insert("insert into students(sname,ssex,sage)values(#{sname},#{ssex},#{sage})")
@SelectKey(keyColumn = "sid",keyProperty="sid",resultType = Integer.class,before = false,statement = {"select last_insert_id()"})
int addStudents(Students students);

3.3.2、编写测试方法

@Test
public void addStudents(){Students s=new Students();
        s.setSname("张九");
        s.setSsex("男");
        s.setSage(19);
        studentsDao.addStudents(s);
}

4、CRUD 操作 - 下

4.1、修改学生的信息

4.1.1、修改 updateStudents() 方法

@Update("update students set sname=#{sname},ssex=#{ssex},sage=#{sage} where sid=#{sid}")
int updateStudents(Students students);

4.1.2、编写测试方法

@Test
public void updateStudents(){Students s=studentsDao.findById(2);
        s.setSname("李好");
        studentsDao.updateStudents(s);
}

4.2、删除指定 ID 的学生信息

4.2.1、修改 deleteStudents() 方法

@Delete("delete from students where sid=#{sid}")
int deleteStudents(int sid);

4.2.2、编写测试方法

@Test
public void deleteStudents(){studentsDao.deleteStudents(9);
}

5、统计与模糊查询

5.1、查询学生表中所有记录

5.1.1、修改 addCount() 方法

@Select("select count(*) from students")
int addCount();

5.1.2、编写测试方法

@Test
public void addCount(){int n=studentsDao.addCount();
        System.out.println(n);
}

5.2、通过学生姓名模糊查询学生信息

5.2.1、修改 findByName() 方法

@Select("select * from students where sname like #{sname}")
List<Students> findByName(String sname);

5.2.2、编写测试方法

@Test
public void findByName(){List<Students> list =studentsDao.findByName("李 %");
        for(Students s:list){System.out.println(s);
        }
}