Return String result type from Struts2

Question

Hi,

I want to send String as a response to the AJAX xhrPOST method. I am using Struts2 to implement the server side processing. But, I am not getting how to send the result "type" as string and the mapping which should be done to send the string from the struts2 action class to the AJAX response.

Answer 1

You could create a simple StringResult pretty easily by extending StrutsResultSupport, but nothing exists built-in to the framework as far as I know.

Here's an implementation that I've used in the past of a simple StringResult:

public class StringResult extends StrutsResultSupport {
private static final Log log = LogFactory.getLog(StringResult.class);
private String charset = "utf-8";
private String property;
private String value;
private String contentType = "text/plain";


@Override
protected void doExecute(String finalLocation, ActionInvocation invocation)
  throws Exception {
 if (value == null) {
  value = (String)invocation.getStack().findValue(conditionalParse(property, invocation));
 }
 if (value == null) {
  throw new IllegalArgumentException("No string available in value stack named '" + property + "'");
 }
 if (log.isTraceEnabled()) {
  log.trace("string property '" + property + "'=" + value);
 }
 byte[] b = value.getBytes(charset);

 HttpServletResponse res = (HttpServletResponse) invocation.getInvocationContext().get(HTTP_RESPONSE);

 res.setContentType(contentType + "; charset=" + charset);
 res.setContentLength(b.length);
 OutputStream out  = res.getOutputStream();
 try {
  out.write(b);
  out.flush();
 } finally {
  out.close(); 
 }
}


public String getCharset() {
 return charset;
}


public void setCharset(String charset) {
 this.charset = charset;
}


public String getProperty() {
 return property;
}


public void setProperty(String property) {
 this.property = property;
}


public String getValue() {
 return value;
}


public void setValue(String value) {
 this.value = value;
}


public String getContentType() {
 return contentType;
}


public void setContentType(String contentType) {
 this.contentType = contentType;
}

}

I've used the json plugin to do similar things. If you use that, you can use the following to expose a single String property in your action:

<result name="success" type="json">
  <param name="root">propertyToExpose</param>
</result>

Answer 2

You can have your action method return not a String result, but a result of type StreamResult.

In other words:

class MyAction {

 public StreamResult method() {
   return new StreamResult(new ByteArrayOuputStream("mystring".getBytes()));
 }
}

You don't necessarily have to return a String from a Struts2 action method. You can always return an implementation of the Result interface from xwork.