java - 如何使用 ServeletFilter 完成 Servlet 处理后更新响应 Content-Type

Question

我尝试使用 ServletFilter 更改 ServletResponse Content-Type。但是，当 chain.doFilter() 调用时，servlet(在我的内容中为 AxisServlet)会更新该 Content-Type。但其他响应 header 已正确更新。

我尝试在调用 doFilter 后设置响应 header 。当时没有更新响应 header 。

有谁知道Servlet完成后更新ServletResponse的Content-Type的方法吗？

代码:

public class HeaderFilter implements Filter {

    private HashMap<String,String> rsCustomHeaders = new HashMap<String,String>();

    public void init(FilterConfig config) throws ServletException {

        Enumeration<String> initParameterNames = config.getInitParameterNames();

        while (initParameterNames.hasMoreElements()) {

            String initParameterName = initParameterNames.nextElement();

            rsCustomHeaders.put(initParameterName, config.getInitParameter(initParameterName));

        }

        System.out.println("init().rsCustomHeaders : " + rsCustomHeaders);
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {

        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        HttpServletResponse httpServletResponse = (HttpServletResponse) response;

        for (Map.Entry<String, String> rsCustomHeaderEntry : rsCustomHeaders.entrySet()) {
            httpServletResponse.addHeader(rsCustomHeaderEntry.getKey(), rsCustomHeaderEntry.getValue());
        }

        System.out.println("doFilter().encoding :Set Response Headers Done");

        chain.doFilter(httpServletRequest, httpServletResponse);

        System.out.println("doFilter().HeaderFilter is Done!!!");


    }

    public void destroy() {
        System.out.println("destroy(). : Destroy is called!");
    }
}

web.xml

  <filter>
    <filter-name>HeaderFilter</filter-name>
    <filter-class>filters.HeaderFilter</filter-class>
      <init-param>
        <param-name>content-type</param-name>
        <param-value>application/xml; charset=utf-8</param-value>
      </init-param>
      <init-param>
        <param-name>Content_type</param-name>
        <param-value>text/xml; charset=utf-8</param-value>
      </init-param>
      <init-param>
        <param-name>rq_content-type</param-name>
        <param-value>text/xml; charset=utf-8</param-value>
      </init-param>
      <init-param>
        <param-name>Header-X</param-name>
        <param-value>Value-X</param-value>
      </init-param>
  </filter>

  <filter-mapping>
    <filter-name>HeaderFilter</filter-name>
    <url-pattern>/services/GradeThreeMath</url-pattern>
  </filter-mapping>

Answer 1

设置原始响应的内容类型。使用HttpServletResponseWrapper使用覆盖的 setContentType 来包装传递给 child.doFilter 的 response。重写的 setContentType 应该忽略任何更改内容类型的尝试。

代码片段:

// Setting content type
httpServletResponse.setContentType("you-content-type");
chain.doFilter(httpServletRequest, new HttpServletResponseWrapper(httpServletResponse) {
    @Override
    public void setContentType(final String type) {
        // Ignore any further attempts to change content type
    }
});