webwork中自定义的JSON result

webwork2.1.7没有带json类型的result，2.2.7中的json类型的result好像有bug，不支持encoding编码。这里写了一个result，可以通用，并且可以将普通的POJO转化成JSON对象。很好用

package com.xujun.framework.webwork;

import java.io.OutputStream;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Field;

import com.opensymphony.webwork.ServletActionContext;
import com.opensymphony.xwork.ActionContext;
import com.opensymphony.xwork.ActionInvocation;
import com.opensymphony.xwork.Result;
import org.json.JSONObject;

/**
 * 支持自动组装JSONObject的JSONResult，支持encoding编码。
 * @author 徐骏
 * @data 2009-11-25
 */
public class JSONResult implements Result
{

 private static final Log LOG = LogFactory.getLog(JSONResult.class);
 //action中的json对象的名词
 private String jsonObjectProperty = "jsonObject";
 private String contentType = "application/json";
 private String encoding = "utf-8";

 @Override
 public void execute(ActionInvocation invocation) throws Exception
 {

  if (LOG.isDebugEnabled())
  {
   LOG.debug("executing JSONResult");
  }
  // 通过xwork的invocation从webwork的action中获得JSONObject对象
  JSONObject jsonObject = getJSONObject(invocation);
  if (jsonObject != null)
  {
   String json = jsonObject.toString();
   HttpServletResponse response = getServletResponse(invocation);
   response.setContentType(getContentType());
   // encoding
   byte[] bs = json.getBytes(this.encoding);
   response.setContentLength(bs.length);
   OutputStream os = response.getOutputStream();
   os.write(bs);
   os.flush();

   if (LOG.isDebugEnabled())
   {
    LOG.debug("written [" + json
      + "] to HttpServletResponse outputstream");
   }
  }

 }

 protected JSONObject getJSONObject(ActionInvocation invocation)
   throws Exception
 {
  ActionContext actionContext = invocation.getInvocationContext();
  //从xwork配置中获得JSON对象名词
  Object obj = actionContext.getValueStack()
    .findValue(jsonObjectProperty);

  if (obj == null)
  {
   LOG.error("property [" + jsonObjectProperty
     + "] returns null, please check xwork.xml file");
   return null;
  }
  //如果Action中的对象是JSONObject，那么就不需要反射动态转换为JSONObject
  //如果Action中的对象就是POJO，那么这里自动组装JSONObject
  if (!JSONObject.class.isInstance(obj))
  {
   LOG.debug("build json object by reflection.");
   JSONObject jsonObj = new JSONObject();
   for (Field field : obj.getClass().getDeclaredFields())
   {
    String getter = "get"
      + Character.toUpperCase(field.getName().charAt(0))
      + field.getName().substring(1);
    jsonObj.append(field.getName(), obj.getClass()
      .getDeclaredMethod(getter).invoke(obj));
   }
   return jsonObj;
  }

  return (JSONObject) obj;
 }

 protected HttpServletResponse getServletResponse(ActionInvocation invocation)
 {
  return (HttpServletResponse) invocation.getInvocationContext()
    .getContextMap().get(ServletActionContext.HTTP_RESPONSE);
 }

 public void setEncoding(String encoding)
 {
  this.encoding = encoding;
 }

 public String getEncoding()
 {
  return encoding;
 }

 public void setJsonObjectProperty(String jsonObjectProperty)
 {
  this.jsonObjectProperty = jsonObjectProperty;
 }

 public String getJsonObjectProperty()
 {
  return jsonObjectProperty;
 }

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

 public String getContentType()
 {
  return contentType;
 }

}
xwork.xml配置

 <!--My Result-->
    <result-types>
      <result-type name="json" class="com.xujun.framework.webwork.JSONResult" />
    </result-types>

<action name="jsonTest" class="com.ntyl.action.JSONAction">
      <result name="success" type="json">
        <param name="jsonObjectProperty">user</param>
      </result>
    </action>

JSONAction.java 注意User对象是POJO，我自己写的一个对象，result会自动的转化成JSONObject，当然如果这里就是一个JSONObject，通过put方法设置属性，那么也完全没有问题.

public class JSONAction  implements Action{
 private User user;

 public User getUser()
 {
  return user;
 }
 /**
  * @see com.opensymphony.xwork.Action#execute()
  */
 public String execute() throws Exception
 {
  user = new User();
  user.setUserName("xujun");
  user.setPassword("123456");
  user.setUserId(1);
  return Action.SUCCESS;
 }

}