通过Struts2 Rest传输文件

我需要用Struts2 REST来传输文件。虽然流很好，但Web服务器抛出错误：

异常处理结果：java.io.IOException:UT010029:流已关闭

以下是行动代码：

    public HttpHeaders index() {

    try {

        // ...

        response.setContentType(vo.getContentType());
        response.setContentLength(bytes.length);
        response.addHeader("Content-disposition", "attachment;filename=\"" + fileName + "\"");
        response.getOutputStream().write(bytes);


    } catch( Exception e ) {
        log.error(e);
    }


    return new DefaultHttpHeaders("index");
}

Web服务器日志：

13-04-2018 16:01:28,335 INFO  [org.apache.struts2.rest.RestActionInvocation] (default task-15) Executed action [//api/blablaAction!index!json!200] took 208 ms (execution: 16 ms, result: 192 ms)
13-04-2018 16:02:08,927 ERROR [org.apache.struts2.rest.RestActionInvocation] (default task-16) Exception processing the result.: java.io.IOException: UT010029: Stream is closed
    at io.undertow.servlet.spec.ServletOutputStreamImpl.write(ServletOutputStreamImpl.java:136) [undertow-servlet-1.1.8.Final.jar:1.1.8.Final]
    at io.undertow.servlet.spec.ServletOutputStreamImpl.write(ServletOutputStreamImpl.java:128) [undertow-servlet-1.1.8.Final.jar:1.1.8.Final]
    at org.apache.struts2.rest.DefaultContentTypeHandlerManager.handleResult(DefaultContentTypeHandlerManager.java:199) [struts2-rest-plugin-2.3.34.jar:2.3.34]
    at org.apache.struts2.rest.RestActionInvocation.executeResult(RestActionInvocation.java:232) [struts2-rest-plugin-2.3.34.jar:2.3.34]
    at org.apache.struts2.rest.RestActionInvocation.processResult(RestActionInvocation.java:197) [struts2-rest-plugin-2.3.34.jar:2.3.34]
    at org.apache.struts2.rest.RestActionInvocation.invoke(RestActionInvocation.java:145) [struts2-rest-plugin-2.3.34.jar:2.3.34]
    at com.opensymphony.xwork2.DefaultActionProxy.execute(DefaultActionProxy.java:147) [xwork-core-2.3.34.jar:2.3.34]
    at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:575) [struts2-core-2.3.34.jar:2.3.34]
    at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:81) [struts2-core-2.3.34.jar:2.3.34]
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99) [struts2-core-2.3.34.jar:2.3.34]
    at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60) [undertow-servlet-1.1.8.Final.jar:1.1.8.Final]
    at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132) [undertow-servlet-1.1.8.Final.jar:1.1.8.Final]
    at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:85) [undertow-servlet-1.1.8.Final.jar:1.1.8.Final]
    at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62) [undertow-servlet-1.1.8.Final.jar:1.1.8.Final]
    at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36) [undertow-servlet-1.1.8.Final.jar:1.1.8.Final]

---

我能够通过使用自定义ContentTypeHandler解决这个问题