json - 如何用 Resteasy 装饰 json 响应

Question

我正在使用将由 Extjs 客户端使用的 Resteasy 实现一个 restfull 服务，并且我想用更多属性来装饰在 http 响应中检索到的 json 对象，而无需在服务方法中使用具有附加属性的包装类或覆盖 JacksonJsonProvider
示例：

原始对象：

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

装饰物：

{
   "success":"true",
   "root":{
             "id":"1",
             "name":"Diego"
          }
}

我找到了JAXB 装饰器，但我无法为 json 类型实现装饰器。

我尝试使用拦截器替换将用包装器序列化的实体，但如果替换为集合的实体，它将不起作用。

有什么建议么？

Answer 1

您可以编写一个拦截器，在将 JSON 响应传递给客户端之前对其进行包装。这是一个示例代码：

1. 定义自定义 HTTPServletResponseWrapper

   public class MyResponseWrapper extends HttpServletResponseWrapper {
       private ByteArrayOutputStream byteStream;
   
       public MyResponseWrapper(HttpServletResponse response, ByteArrayOutputStream byteStream) {
           super(response);
           this.byteStream = byteStream;
       }
   
       @Override
       public ServletOutputStream getOutputStream() throws IOException {
           return new ServletOutputStream() {
               @Override
               public void write(int b) throws IOException {
                   byteStream.write(b);
               }
           };
       }
       @Override
       public PrintWriter getWriter() throws IOException {
           return new PrintWriter(byteStream);
       }
   }
   

2. 定义过滤器类：

   @WebFilter("/rest/*")
   public class JSONResponseFilter implements Filter {
   
       private final String JSON_RESPONSE = " { \"success\":\"true\", \"root\": ";
       private final String JSON_RESPONSE_CLOSE = "}";
   
       /* .. */
   
       @Override
       public void doFilter(ServletRequest request, ServletResponse response,
               FilterChain chain) throws IOException, ServletException {
   
           // capture result in byteStream by using custom responseWrapper
           final HttpServletResponse httpResponse = (HttpServletResponse) response;
           final ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
           HttpServletResponseWrapper responseWrapper = new MyResponseWrapper(httpResponse, byteStream);
   
           // do normal processing but capture results in "byteStream"
           chain.doFilter(request, responseWrapper);
   
           // finally, wrap response with custom JSON
         // you can do fancier stuff here, but you get the idea
           out.write(JSON_RESPONSE.getBytes());
           out.write(byteStream.toByteArray());
           out.write(JSON_RESPONSE_CLOSE.getBytes());
       }
   }