jsf-2 – 自己的ResourceHandler从数据库中流式传输图像

我正忙着自己的资源实施.不会调用getInputStream方法.
我的经纪人：

public class ResourceHandlerWrapperImpl extends
        ResourceHandlerWrapper {

  private final ResourceHandler wrapped;

  public ResourceHandlerWrapper(final ResourceHandler wrapped)
  {
    this.wrapped = wrapped;
  }

  @Override
  public ResourceHandler getWrapped()
  {
    return wrapped;
  }

  @Override
  public Resource createResource(final String resourceName,final String libraryName)
  {
    if (AppConstants.RESOURCE_MEDIA_LIB.equals(libraryName))
    {
      return new MediaResource(resourceName);
    }
    else
    {
      return super.createResource(resourceName,libraryName);
    }
  }

  /**
   * @see javax.faces.application.ResourceHandlerWrapper#libraryExists(java.lang.String)
   */
  @Override
  public boolean libraryExists(final String libraryName)
  {
    if (AppConstants.RESOURCE_MEDIA_LIB.equals(libraryName))
    {
      return true;
    }
    else
    {
      return super.libraryExists(libraryName);
    }
  }

  /**
   * @see javax.faces.application.ResourceHandlerWrapper#isResourceRequest(javax.faces.context.FacesContext)
   */
  @Override
  public boolean isResourceRequest(final FacesContext context)
  {
    return super.isResourceRequest(context);
  }

}

我的资源实施：

public class MediaResource extends Resource {

    private final String mediaId;

    public MediaResource(final String mediaId) {
        setLibraryName(AppConstants.RESOURCE_MEDIA_LIB);
        setResourceName(mediaId);
        setContentType("image/png");
        this.mediaId = mediaId;
    }

    @Override
    public InputStream getInputStream() throws IOException {
        if (mediaId != null) {
            System.out.println("Yeahhh!!!");
        }

        return null;
    }

    @Override
    public Map<String,String> getResponseHeaders() {
        return new HashMap<String,String>();
    }

    @Override
    public String getRequestPath() {
        final FacesContext context = FacesContext.getCurrentInstance();
        return context
                .getApplication()
                .getViewHandler()
                .getResourceURL(
                        context,ResourceHandler.RESOURCE_IDENTIFIER + "/" + mediaId
                                + "?ln=" + AppConstants.RESOURCE_MEDIA_LIB);
    }

    @Override
    public URL getURL() {
        return null;
    }

    @Override
    public boolean userAgentNeedsUpdate(final FacesContext context) {
        return true;
    }

}

在我的faces-config.xml中：

<application>
    <resource-handler>com.foo.bbb.ResourceHandlerWrapperImpl</resource-handler>
</application>

在我的jsf中：

<h:graphicImage library="media_lib" name="66" width="50" />

以html输出：

<img src="/foo/javax.faces.resource/66?ln=media_lib" width="50" />

从getRequestPath返回：/foo/javax.faces.resource/66?ln=media_lib

调用并初始化MediaResource,但不调用getInputStream. FireBug在此URL上显示404(称为两次).
我完全不知道我在这里做错了什么.

谢谢
强尼

解决方法

@Override
    public String getRequestPath() {
        final FacesContext context = FacesContext.getCurrentInstance();
        return context
                .getApplication()
                .getViewHandler()
                .getResourceURL(
                        context,ResourceHandler.RESOURCE_IDENTIFIER + "/" + mediaId + Util.getFacesMapping(context)
                                + "?ln=" + AppConstants.RESOURCE_MEDIA_LIB);

现在一切都按预期工作了.

感谢BalusC的帮助.

干杯强尼

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