struts2 返回一个字符串

<action name="getVersion" class="com.jwt.version.action.VersionAction"
			method="getVersionAction">
			<result type="stream" name="success">
				<param name="contentType">text/html</param>
				<param name="inputName">inputStream</param>
			</result>
			<result type="stream" name="error">
				<param name="contentType">text/html</param>
				<param name="inputName">inputStream</param>
			</result>
		</action>
           

public class VersionAction extends ActionSupport {
	
	private InputStream inputStream;

	public InputStream getInputStream() {
		return inputStream;
	}

	public void setInputStream(InputStream inputStream) {
		this.inputStream = inputStream;
	}
	
	public String getVersionAction() throws Exception {
		if(version<getVersion()){
			inputStream = new StringBufferInputStream("update");
			return ERROR;
		}else{
			inputStream = new StringBufferInputStream("success");
			return SUCCESS;
		}
	}

}