spring boot 跨域，options 400错误

之前的跨域 都是 写在一个 filter 中：

@Order(2)
@WebFilter(filterName = "CrossDomainFilter",urlPatterns = "*/
/*")
public class CrossDomainFilter extends OncePerRequestFilter {
	@Override
	protected void doFilterInternal(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, FilterChain filterChain) throws ServletException, IOException {
		setOrigin(httpServletRequest,httpServletResponse,filterChain);
		filterChain.doFilter(httpServletRequest, httpServletResponse);
	}
	*/
/**
	 * 设置Access-Control-Allow-Origin消息头
	 * @param request
	 * @param response
	 * @param filterChain
	 * @throws ServletException
	 * @throws IOException
	 *//*

	public static void setOrigin(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException{
		System.out.println("----------");
		System.out.println("Origin:"+request.getHeader("Origin"));
		System.out.println("----------");
		String headerOrigin = request.getHeader("origin");
//		response.setContentType("application/json;charset=UTF-8");
		response.setHeader("Content-type", "application/json;charset=UTF-8");
		if(headerOrigin != null){
			response.setHeader("Access-Control-Allow-Origin",headerOrigin);
		}
		response.setHeader("Access-Control-Expose-Headers","page, per_page,status,total_count");
		response.setHeader("Access-Control-Allow-Credentials", "true");
		response.setHeader("Access-Control-Allow-Headers",request.getHeader("Access-Control-Request-Headers"));
		System.out.println(request.getHeader("Access-Control-Request-Headers"));
		response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE,PUT");
		response.setHeader("XDomainRequestAllowed","1");
	}
}

然后发现这样写 ，当前端传的content-type是 application/json 的时候，会出现 options method  400 错误 。然后 接口调用不了。

去官网看了下 发现 spring 官网的推荐 是这样写:

@Configuration
@EnableWebMvc
//@EnableAspectJAutoProxy(proxyTargetClass = true)
public class WebConfig implements WebMvcConfigurer {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**").allowedOrigins("*")
                .allowedMethods("*").allowCredentials(false).exposedHeaders("status")
                .maxAge(30*1000);
    }

    @Bean
    public RequestMappingHandlerAdapter requestMappingHandlerAdapter() {
        RequestMappingHandlerAdapter adapter = new RequestMappingHandlerAdapter();
        // @ResponseBody注解靠HttpMessageConverter解析
        List> converters = adapter.getMessageConverters();
        Iterator> iterator = converters.iterator();
        while (iterator.hasNext()) {
            HttpMessageConverter converter = iterator.next();
            if (converter instanceof StringHttpMessageConverter) {  // 移除默认编码为ISO8859-1的字符串解析器
                iterator.remove();
            }
        }
        converters.add(new StringHttpMessageConverter(Charset.forName("UTF-8")));  // 字符串才使用UTF-8解析
        converters.add(new MappingJackson2HttpMessageConverter());  // 解析json
        adapter.setMessageConverters(converters);
        return adapter;
    }

    @Bean
    public static PropertySourcesPlaceholderConfigurer propertyConfigIn() {
        return new PropertySourcesPlaceholderConfigurer();
    }
}

然后 琢磨了一下 发现 在原来的 filter 的 基础上也可以这样加上一个判断实现:

		if ("OPTIONS".equals(httpServletRequest.getMethod())) {

			try {
				httpServletResponse.getWriter().print("OK");
				httpServletResponse.getWriter().flush();
			} catch (IOException e) {
				e.printStackTrace();
			}
		} else {
			filterChain.doFilter(httpServletRequest, httpServletResponse);
		}

PS：参考文档 https://spring.io/blog/2015/06/08/cors-support-in-spring-framework#global-cors-configuration