SpringBoot關于自動注入mapper為空的坑及解決

更新時間：2023年07月15日 08:40:06 作者：Tokey_W

這篇文章主要介紹了SpringBoot關于自動注入mapper為空的坑及解決方案，具有很好的參考價值，希望對大家有所幫助。如有錯誤或未考慮完全的地方，望不吝賜教

1、初始環(huán)境

配置類

package com.sofwin.yygh.config;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/**
 * @packageName: com.sofwin.yygh.config
 * @author: wentao
 * @date: 2022/12/12 17:34
 * @version: 1.0
 * @email 1660420659@qq.com
 * @description: 數(shù)據(jù)字典的配置類
 */
@Configuration
//發(fā)現(xiàn)映射器--可以動態(tài)生產mapper的實現(xiàn)類
@MapperScan(basePackages = "com.sofwin.yygh.mapper")
public class CmnConfig {
    /**
     * 分頁插件
     */
    @Bean
    public PaginationInterceptor paginationInterceptor() {
        PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
        // paginationInterceptor.setLimit(你的最大單頁限制數(shù)量，默認 500 條，小于 0 如 -1 不受限制);
        return paginationInterceptor;
    }
}

啟動類

package com.sofwin.yygh;
import com.sofwin.yygh.service.DictService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;
@SpringBootApplication
@ComponentScan("com.sofwin")
public class ServicecmnApplication {
    public static void main(String[] args) {
        SpringApplication.run(ServicecmnApplication.class, args);
    }
}

mapper接口

package com.sofwin.yygh.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.sofwin.yygh.model.cmn.Dict;
import com.sofwin.yygh.model.hosp.HospitalSet;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Repository;
/**
 * @packageName: com.sofwin.yygh.mapper
 * @author: wentao
 * @date: 2022/12/12 17:17
 * @version: 1.0
 * @email 1660420659@qq.com
 * @description: Dict的mapper接口
 */
@Repository
public interface DictMapper extends BaseMapper<Dict> {
}

2、測試

Test1

自動注入DictMapper

package com.sofwin.yygh;
import com.sofwin.yygh.mapper.DictMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
/**
 * @packageName: com.sofwin.yygh
 * @author: wentao
 * @date: 2022/12/21 10:56
 * @version: 1.0
 * @email 1660420659@qq.com
 * @description: TODO
 */
@Component
public class Test1 {
    @Autowired
    private DictMapper dictMapper;
    public void test() {
        System.out.println(dictMapper.selectList(null));
    }
}

Test2

自動注入DictMapper

package com.sofwin.yygh;
import com.sofwin.yygh.mapper.DictMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
/**
 * @packageName: com.sofwin.yygh
 * @author: wentao
 * @date: 2022/12/21 10:56
 * @version: 1.0
 * @email 1660420659@qq.com
 * @description: TODO
 */
@Component
public class Test2 {
    @Autowired
    private DictMapper dictMapper;
    public void test() {
        System.out.println(dictMapper.selectList(null));
    }
}

測試類

package com.sofwin.yygh;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
/**
 * @packageName: com.sofwin.yygh
 * @author: wentao
 * @date: 2022/12/21 10:57
 * @version: 1.0
 * @email 1660420659@qq.com
 * @description: TODO
 */
@SpringBootTest
@RunWith(SpringJUnit4ClassRunner.class)
public class MapperTest {
    @Test
    public void test() {
        //使用new的話 dictMapper是為空的
        Test1 test1 = new Test1();
        test1.test();
    }
    @Autowired
    private Test2 test2;
    @Test
    public void test2() {
        //使用自動注入的話 dictMapper不為空
        test2.test();
    }
}