json - 根据 Jackson 和 Spring boot 的请求美化(或不美化)响应

Question

我正在使用 Spring boot、Spring MVC 和 Jackson。我正在编写一个 RESTful API，其中一个要求是在请求包含参数 prettify 的情况下美化响应 (json)。

例如，GET/examples/1 必须回答:{"id":1,"name":"example"}，和 GET/examples/1?prettify 使用:

{
    "id": 1,
    "name": "example"
}

我知道我可以定义我自己的 ObjectMapper 但我不能根据请求来实现。我可以将 spring.jackson.serialization.INDENT_OUTPUT 设置为 true 但我无法显示响应 not 美化。

有人对此有想法吗？

Answer 1

好的，我做到了。

所以，方法是使用注入(inject)的 Jackson2ObjectMapper 手动序列化响应:)

让我们看一下简单的主应用程序类:

@SpringBootApplication
public class StackoverflowApplication {

    public static void main(String[] args) {
        SpringApplication.run(StackoverflowApplication.class, args);
    }

    @Bean
    public Jackson2ObjectMapperBuilder objectMapperBuilder() {
        Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
        builder.indentOutput(true);
        return builder;
     }
}

一些休息 Controller 类:

@RestController
public class TestRestController {
    private static final Logger LOGGER = Logger.getLogger(TestRestController.class);

    @Autowired
    Jackson2ObjectMapperBuilder objectMapperBuilder;

    @RequestMapping(value = "/testendpoint/{somevalue}", method = RequestMethod.GET, produces="application/json")
    public @ResponseBody String customersLastVisit(@PathVariable(value = "somevalue") Integer number,
            @RequestParam(value = "pretify", defaultValue = "false") Boolean pretify) throws JsonProcessingException {
        if (pretify) {
            LOGGER.info("Pretify response!");
            objectMapperBuilder.indentOutput(true);
        }
        else {
            objectMapperBuilder.indentOutput(false);
        }

        ObjectMapper mapper = objectMapperBuilder.build();
        String jsonResponse = mapper.writeValueAsString(new TestDTO());
        return jsonResponse;
    }
}

和 DTO 类:

public class TestDTO implements Serializable {

    private static final long serialVersionUID = 1L;

    private Integer id;
    private String name;

    public TestDTO() {
        super();
        id = new Integer(1);
        name = new String("SomeName");
    }
    //getters, setters etc ...
}

http://localhost:8080/testendpoint/1返回 {"id":1,"name":"SomeName"}同时http://localhost:8080/testendpoint/1?pretify=true返回

{
  "id" : 1,
  "name" : "SomeName"
}

编辑:如果您想将它用于每个 Controller ，请执行以下操作:

public class PretifyingInterceptor extends HandlerInterceptorAdapter {

    private static final Logger LOGGER = Logger.getLogger(PretifyingInterceptor.class);

    @Autowired
    MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {

        String pretify = request.getParameter("pretify");
        Boolean isPretify = Boolean.parseBoolean(pretify);

        LOGGER.info("Should be pretified: " + isPretify);

        if (isPretify) {
            mappingJackson2HttpMessageConverter.setPrettyPrint(true);
        }
        else {
            mappingJackson2HttpMessageConverter.setPrettyPrint(false);
        }
        return true;
    }
}

现在添加新的拦截器:

@Configuration
public class InterceptorConfigurerAdapter extends WebMvcConfigurerAdapter{


    @Bean
    PretifyingInterceptor pretifyingInterceptor() {
        return new PretifyingInterceptor();
    }

     @Override
        public void addInterceptors(final InterceptorRegistry registry) {
            registry.addInterceptor(pretifyingInterceptor())
                    .addPathPatterns("/**");
        }

}

现在 Controller 看起来像:

@RequestMapping(value = "/testendpoint/{somevalue}", method = RequestMethod.GET, produces = "application/json")
    public @ResponseBody TestDTO customersLastVisit(@PathVariable(value = "somevalue") Integer number,
            @RequestParam(value = "pretify", defaultValue = "false") Boolean pretify) throws JsonProcessingException {
        return new TestDTO();
    }

Edit2:为了避免一些“拦截器的请求间共享状态”，定义具有范围 request 的拦截器 bean。

希望对您有所帮助:)