天坑！
pringboot启动类里面添加这段代码
引入的包
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;import org.mybatis.spring.annotation.MapperScan;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer;import org.springframework.cloud.client.discovery.EnableDiscoveryClient;import org.springframework.context.annotation.Bean;import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
代码
@Bean("jackson2ObjectMapperBuilderCustomizer") public Jackson2ObjectMapperBuilderCustomizer jackson2ObjectMapperBuilderCustomizer() { Jackson2ObjectMapperBuilderCustomizer customizer = new Jackson2ObjectMapperBuilderCustomizer() { @Override public void customize(Jackson2ObjectMapperBuilder jacksonObjectMapperBuilder) { jacksonObjectMapperBuilder.serializerByType(Long.class, ToStringSerializer.instance) .serializerByType(Long.TYPE, ToStringSerializer.instance); } }; return customizer; }