SpringBoot实现jsonp跨域通信的方法示例

jQuery39948237({key:3})

$.ajax({
    url:'http://localhost:8999/boot/dto',
    dataType:"jsonp",
    success:(response)=>{
      this.messages.push(response);
    }
  })

@RequestMapping("dto")
public Position dto() {
  return new Position(239, 43);
}

/**
 * 处理controller返回值，对于有callback值的使用jsonp格式，其余不处理
 */
@RestControllerAdvice(basePackageClasses = IndexController.class)
public class JsonpAdvice implements ResponseBodyAdvice {

  private Logger logger = LoggerFactory.getLogger(getClass());
  @Autowired
  private ObjectMapper mapper;

  //jquery默认是callback，其余jsonp库可能不一样
  private final String callBackKey = "callback";

  @Override
  public boolean supports(MethodParameter methodParameter, Class aClass) {
    logger.debug("返回的class={}", aClass);
    return true;
  }

  /**
   * 在此处对返回值进行处理，需要特别注意如果是非String类型，会被Json序列化，从而添加了双引号，解决办法见
   *
   * @param body        返回值
   * @param methodParameter  方法参数
   * @param mediaType     当前contentType，非String类型为json
   * @param aClass       convert的class
   * @param serverHttpRequest request，暂时支持是ServletServerHttpRequest类型，其余类型将会原样返回
   * @param serverHttpResponse response
   * @return 如果body是String类型，加上方法头后返回，如果是其他类型，序列化后返回
   * @see com.inkbox.boot.demo.converter.Jackson2HttpMessageConverter
   */
  @Override
  public Object beforeBodyWrite(Object body, MethodParameter methodParameter, MediaType mediaType, Class aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {

    if (body == null)
      return null;
    // 如果返回String类型，media是plain，否则是json，将会经过json序列化，在下方返回纯字符串之后依然会被序列化，就会添上多余的双引号
    logger.debug("body={},request={},response={},media={}", body, serverHttpRequest, serverHttpResponse, mediaType.getSubtype());


    if (serverHttpRequest instanceof ServletServerHttpRequest) {
      HttpServletRequest request = ((ServletServerHttpRequest) serverHttpRequest).getServletRequest();

      String callback = request.getParameter(callBackKey);

      if (!StringUtils.isEmpty(callback)) {
        //使用了jsonp
        if (body instanceof String) {
          return callback + "(\"" + body + "\")";
        } else {
          try {
            String res = mapper.writeValueAsString(body);
            logger.debug("转化后的返回值={},{}", res, callback + "(" + res + ")");

            return callback + "(" + res + ")";
          } catch (JsonProcessingException e) {
            logger.warn("【jsonp支持】数据body序列化失败", e);
            return body;
          }
        }
      }
    } else {
      logger.warn("【jsonp支持】不支持的request class ={}", serverHttpRequest.getClass());
    }
    return body;
  }
}

Jquery332({"x":239,"y":43})

"Jquery332({\"x\":239,\"y\":43})"

@Component
public class Jackson2HttpMessageConverter extends MappingJackson2HttpMessageConverter {

  private Logger logger = LoggerFactory.getLogger(getClass());

  @Override
  protected void writeInternal(Object object, Type type, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException {
    if (object instanceof String) {
      //绕开实际上返回的String类型，不序列化
      Charset charset = this.getDefaultCharset();
      StreamUtils.copy((String) object, charset, outputMessage.getBody());
    } else {
      super.writeInternal(object, type, outputMessage);
    }
  }
}


@Configuration
public class MvcConfig implements WebMvcConfigurer {

  private Logger logger = LoggerFactory.getLogger(getClass());

  @Autowired
  private MappingJackson2HttpMessageConverter converter;

  @Override
  public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
//    MappingJackson2HttpMessageConverter converter = mappingJackson2HttpMessageConverter();
    converter.setSupportedMediaTypes(new LinkedList<MediaType>() {{
      add(MediaType.TEXT_HTML);
      add(MediaType.APPLICATION_JSON_UTF8);
    }});
    converters.add(new StringHttpMessageConverter(StandardCharsets.UTF_8));
    converters.add(converter);
  }
}