springboot亂碼現象可以用以下方法來解決，本人是以防萬一，所以都設定了。

1.jsp檔案編碼方式設定為UTF-8,如果新建的jsp檔案，預設不是utf-8，在eclipse中，設定新建的jsp檔案為utf-8

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>

2.在application.properties中新增如下
spring.http.encoding.force=true
spring.http.encoding.charset=UTF-8
spring.http.encoding.enabled=true
server.tomcat.uri-encoding=UTF-8

3.在@RequestMapping中新增produces="application/json;charset=utf-8"，如下

@RequestMapping(value="hello",produces="application/json;charset=utf-8")

4.新增一個訊息轉換器

@Configuration
public class CustomMVCConfiguration extends WebMvcConfigurerAdapter {

    @Bean
    public HttpMessageConverter<String> responseBodyConverter() {
        StringHttpMessageConverter converter = new StringHttpMessageConverter(
                Charset.forName("UTF-8"));
        return converter;
    }

     public void configureMessageConverters(
            List<HttpMessageConverter<?>> converters) {
        super.configureMessageConverters(converters);
        converters.add(responseBodyConverter());
    }

     public void configureContentNegotiation(
            ContentNegotiationConfigurer configurer) {
        configurer.favorPathExtension(false);
    }