Spring Boot入门——集成Mybatis

步骤：

1、新建maven项目

2、在pom.xml文件中引入相关依赖

    <!-- mysql依赖 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.42</version>
    </dependency>
    
　　<!-- mybatis依赖 -->
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>1.1.1</version>
    </dependency>

3、在application.properties文件中添加配置信息

#mysql数据库配置
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/test
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

4、编写Grade类

package com.wyl.bean;

public class Grade {

    private int id;
    private String gradeNm;
    private int teacherId;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getGradeNm() {
        return gradeNm;
    }
    public void setGradeNm(String gradeNm) {
        this.gradeNm = gradeNm;
    }
    public int getTeacherId() {
        return teacherId;
    }
    public void setTeacherId(int teacherId) {
        this.teacherId = teacherId;
    }
}

5、编写mapper

import java.util.List;

import org.apache.ibatis.annotations.Select;

import com.wyl.bean.Grade;

public interface GradeMapper {
    
    @Select("select * from grade where grade_nm=#{name}")
    public List<Grade> getByGradeNm(String name);

　　@Insert("insert into grade(grade_nm,teacher_id) values(#{gradeNm},#{teacherId})")
    @Options(useGeneratedKeys=true,keyColumn="id",keyProperty="id")//设置id自增长
    public void save(Grade grade);
}

6、编写service

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.wyl.bean.Grade;
import com.wyl.dao.GradeMapper;

@Service
public class GradeService {
    
    @Autowired
    private GradeMapper gradeMapper;
    
    public List<Grade> getByGradeNm(String name){
        return gradeMapper.getByGradeNm(name);
    }
    
}

7、编写Controller

import java.util.List;

import javax.annotation.Resource;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.wyl.bean.Grade;
import com.wyl.service.GradeService;

@RestController
public class GradeController {

    @Resource
    private GradeService gradeService;
    
    @RequestMapping("/getByGradeNm")
    public List<Grade> getByGradeNm(String name){
        return gradeService.getByGradeNm(name);
    }
}

8、创建启动类App.java，添加自动扫描mapper

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * Hello world!
 *
 */
@SpringBootApplication
@MapperScan("com.wyl.dao")//告诉mapper所在的包名
public class App 
{
    public static void main( String[] args )
    {
        System.out.println( "Hello World!" );
        SpringApplication.run(App.class, args);
    }
}

5、测试结果

　　

　　在上述结果中，输出的gradeNm字段的值为空，是由于设置接收的属性为name，可以在mapper中设置属性和数据库中字段的匹配

public interface GradeMapper {
    
    @Select("select * from grade where grade_nm=#{name}")
    @Results({
            @Result(column="id", property="id"),
            @Result(column="grade_nm", property="gradeNm"),
            @Result(column="teacher_id", property="teacherId")
    })
    public List<Grade> getByGradeNm(String name);
}

之后结果为：

　　

9、使用PageHelper分页插件

　　a、引入springboot自带的分页插件

　　<!-- 引入spring boot自带的pagehelper插件 -->
    <dependency>
        <groupId>com.github.pagehelper</groupId>
        <artifactId>pagehelper-spring-boot-starter</artifactId>
        <version>1.1.1</version>
    </dependency>

　　@RequestMapping("/getByGradeNm2")
    public List<Grade> getByGradeNm2(String name){
        PageHelper.startPage(1,2);  //显示第一页2条数据
        return gradeService.getByGradeNm(name);
    }

　　b、引入外部分页插件

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper</artifactId>
    <version>5.0.2</version>
</dependency>

　　新建配置类，配置pagehelper的属性

import java.util.Properties;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.github.pagehelper.PageHelper;

@Configuration
public class MybatisConfiguration {

    @Bean
    public PageHelper pageHelper(){
        PageHelper pageHelper = new PageHelper();
        Properties properties = new Properties();
        properties.setProperty("offsetAsPageNum","true");
        properties.setProperty("rowBoundsWithCount","true");
        properties.setProperty("reasonable","true");
        
        pageHelper.setProperties(properties);
        return pageHelper;
    }
}

　　@RequestMapping("/getByGradeNm2")
    public List<Grade> getByGradeNm2(String name){
        PageHelper.startPage(1,2);  //显示第一页2条数据
        return gradeService.getByGradeNm(name);
    }