一、pom配置FastJson

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.83</version>
</dependency>

配置 FastJson

@Configuration
public class JsonConfig implements WebMvcConfigurer {
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        FastJsonConfig config = new FastJsonConfig();
        config.setSerializerFeatures(SerializerFeature.PrettyFormat);
        // 创建配置类
        config.setSerializerFeatures(
                SerializerFeature.WriteNullListAsEmpty,
                SerializerFeature.WriteMapNullValue,
                SerializerFeature.WriteNullStringAsEmpty
        );
        //此处是全局处理方式
        config.setDateFormat("yyyy-MM-dd HH:mm:ss");
        config.setCharset(StandardCharsets.UTF_8);
        // 创建MediaType的集合
        List<MediaType> supportedMediaTypes = new ArrayList<MediaType>();
        // 设置编码格式为UTF8
        supportedMediaTypes.add(MediaType.APPLICATION_JSON_UTF8);
        // 将supportedMediaTypes对象赋值给fastJsonHttpMessageConverter的SupportedMediaTypes属性
        fastJsonHttpMessageConverter.setSupportedMediaTypes(supportedMediaTypes);
        fastJsonHttpMessageConverter.setFastJsonConfig(config);
        converters.add(fastJsonHttpMessageConverter);
    }
}

三、创建实体类

public class BaseModel {
    public BaseModel(boolean state, String msg, Object data) {
        this.state = state;
        this.msg = msg;
        this.data = data;
    }

    private boolean state;
    private String msg;
    private Object data;

    public boolean getState() {
        return state;
    }

    public void setState(boolean state) {
        this.state = state;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public Object getObject() {
        return data;
    }

    public void setObject(Object data) {
        this.data = data;
    }
}

四、Controller 中返回Json数据 usersService.selectAll() 查询数据库数据

@RestController
public class HelloController {
    @Autowired
    private UsersService usersService;
    @RequestMapping(value = "/",method = RequestMethod.GET)
    public BaseModel index(){
        return new BaseModel(true,null,usersService.selectAll());
    }
}