自定义HttpMessageConverter学习笔记

实现Content-Type为text/properties媒体类型的HttpMessageConverter

1. 编写HttpMessageConverter实现类（核心处理逻辑）

   // 参考MappingJackson2HttpMessageConverter
   public class PropertiesHttpMessageConverter extends AbstractGenericHttpMessageConverter<Properties> {
         
         
       public PropertiesHttpMessageConverter(){
         
         
           super(new MediaType("text", "properties"));
       }
       @Override
       protected void writeInternal(Properties properties, Type type, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException {
         
         
           OutputStream body = outputMessage.getBody();
           Charset charset = this.getCharset(outputMessage) ;
           Writer writer = new OutputStreamWriter(body,charset) ;
           // 这里要使用字符流，以防止中文乱码
           properties.store(writer,"form PropertiesHttpMessageConverter");
       }
       @Override
       protected Properties readInternal(Class<? extends Properties> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException {
         
         
           InputStream body = inputMessage.getBody();
           Properties properties = new Properties() ;
           // 从Content-Type解析编码
           Charset charset = getCharset(inputMessage) ;
           InputStreamReader reader = new InputStreamReader(body, charset) ;
           // 注意这里要使用字符流，否则会有中文乱码
           properties.load(reader);
           return properties;
       }
       private Charset getCharset(HttpMessage inputMessage){
         
         
           // 从Content-Type解析编码
           HttpHeaders headers = inputMessage.getHeaders();
           MediaType contentType = headers.getContentType();
           Charset charset = contentType.getCharset();
           charset = charset == null ? Charset.forName("UTF-8") : charset ;
           return charset ;
       }
       @Override
       public Properties read(Type type, Class<?> contextClass, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException {
         
         
           return readInternal(null, inputMessage);
       }
   }
   

2. 将自定义HttpMessageConverter添加到RequestMappingHandlerAdapter中

   @Configuration
   public class RestWebMvcConfigurer implements WebMvcConfigurer {
         
         
       @Override
       public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
         
         
           // 插入到第一位，其他Converter向后移动
           converters.add(0,new PropertiesHttpMessageConverter());
           // 添加到最后时，结果会被MappingJackson2HttpMessageConverter处理返回json
           //converters.add(new PropertiesHttpMessageConverter());
       }
   }
   

3. 编写业务Controller

   @RestController
   public class PropertiesRestController {
         
         
       @PostMapping(value = "/add/props",
           consumes = "text/properties;charset=UTF-8"/*,produces = "text/properties"*/)
       public Properties addProp(@RequestBody Properties properties){
         
         
           log.info("====> prop : {}" , properties);
           return properties ;
       }
   }
   

4. 使用PostMan发送请求，将Header的Content-Type设置为text/properties

   4.1 header内容
       Content-Type设置为text/properties
   4.1 body内容
       username=yicj
       addr=北京