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在JSON.org上看到java實現的源碼，想著自己寫一個Result支持JSON的返回，但是一看webwork的新版本2.2.7版本已經支持JSON了
，但是有bug，第一,jsonObjectProperty的setter方法寫成了setJSONObjectProperty所以，在配置中若使用了jsonObjectProperty做為參數名，那么是不能set參數進去的。另外，它不支持自定義返回js的編碼，造成亂碼，或者干脆都無法正常調用js，還有就是我覺得可以再封裝得好一點，對于JSONObject的生成，可以利用反射來做，而不是在每個Action中都手工的寫生成JSONObject的代碼，所以我做了一下改進：

package com.csair.hunan.common.web;
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import java.io.OutputStream;
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import java.lang.reflect.Field;
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import javax.servlet.http.HttpServletResponse;
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import org.apache.commons.logging.Log;
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import org.apache.commons.logging.LogFactory;
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import org.json.JSONObject;
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import com.opensymphony.webwork.ServletActionContext;
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import com.opensymphony.webwork.WebWorkException;
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import com.opensymphony.xwork.ActionContext;
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import com.opensymphony.xwork.ActionInvocation;
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import com.opensymphony.xwork.Result;
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public class JSONResult implements Result {
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private static final Log LOG = LogFactory.getLog(JSONResult.class);
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private String jsonObjectProperty = "jsonObject";
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private String contentType = "application/json";
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private String encoding = "utf-8";
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public void setEncoding(String encoding) {
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this.encoding = encoding;
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}
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/**
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* Returns the property which will be used to lookup {@link JSONObject} in WebWork's ValueStack. Default to
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* 'jsonObject'.
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*
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* @return String
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*/
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public String getJsonObjectProperty() {
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return jsonObjectProperty;
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}
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/**
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* Set the property which will be used to lookup {@link JSONObject} in WebWork's ValueStack. Default to
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* 'jsonObject'.
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*
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* @param jsonObject
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*/
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public void setJsonObjectProperty(String jsonObjectProperty) {
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this.jsonObjectProperty = jsonObjectProperty;
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}
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/**
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* Returns the content-type header to be used. Default to 'application/json'.
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*
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* @return String
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*/
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public String getContentType() {
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return contentType;
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}
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/**
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* Set the content-type header to be used. Default to 'application/json'.
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*
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* @param contentType
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*/
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public void setContentType(String contentType) {
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this.contentType = contentType;
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}
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/**
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* Writes the string representation of {@link JSONObject} defined through {@link #getJSONObjectProperty()}
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* to {@link javax.servlet.http.HttpServletResponse}'s outputstream.
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*
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* @param invocation
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* @throws Exception
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*/
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public void execute(ActionInvocation invocation) throws Exception {
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if (LOG.isDebugEnabled()) {
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LOG.debug("executing JSONResult");
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}
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JSONObject jsonObject = getJSONObject(invocation);
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if (jsonObject != null) {
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String json = jsonObject.toString();
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HttpServletResponse response = getServletResponse(invocation);
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response.setContentType(getContentType());
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//encoding
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byte[] bs = json.getBytes(this.encoding);
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response.setContentLength(bs.length);
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OutputStream os = response.getOutputStream();
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os.write(bs);
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os.flush();
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if (LOG.isDebugEnabled()) {
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LOG.debug("written ["+json+"] to HttpServletResponse outputstream");
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}
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}
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}
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/**
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* Attempt to look up a {@link com.opensymphony.webwork.dispatcher.json.JSONObject} instance through the property
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* ({@link #getJSONObjectProperty()}) by looking up the property in WebWork's ValueStack. It shall be found if there's
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* accessor method for the property in WebWork's action itself.
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* <p/>
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* Returns null if one cannot be found.
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* <p/>
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* We could override this method to return the desired JSONObject when writing testcases.
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*
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* @param invocation
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* @return {@link JSONObject} or null if one cannot be found
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*/
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protected JSONObject getJSONObject(ActionInvocation invocation) throws Exception {
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ActionContext actionContext = invocation.getInvocationContext();
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Object obj = actionContext.getValueStack().findValue(jsonObjectProperty);
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if (obj == null) {
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LOG.error("property ["+ jsonObjectProperty +"] returns null, expecting JSONObject", new WebWorkException());
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return null;
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}
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//if the assigned object is not an instance of JSONObject, try to build one use reflection
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if (! JSONObject.class.isInstance(obj)) {
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LOG.warn("property ["+ jsonObjectProperty +"] is ["+obj+"] especting an instance of JSONObject", new WebWorkException());
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LOG.debug("build json object by reflection.");
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JSONObject jsonObj = new JSONObject();
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for (Field field : obj.getClass().getDeclaredFields()) {
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String getter = "get" + Character.toUpperCase(field.getName().charAt(0)) + field.getName().substring(1);
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jsonObj.append(field.getName(), obj.getClass().getDeclaredMethod(getter).invoke(obj));
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}
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return jsonObj;
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}
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return (JSONObject) obj;
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}
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/**
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* Returns a {@link javax.servlet.http.HttpServletResponse} by looking it up through WebWork's ActionContext Map.
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* </p>
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* We could override this method to return the desired Mock HttpServletResponse when writing testcases.
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*
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* @param invocation
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* @return {@link javax.servlet.http.HttpServletResponse}
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*/
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protected HttpServletResponse getServletResponse(ActionInvocation invocation) {
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return (HttpServletResponse) invocation.getInvocationContext().getContextMap().get(ServletActionContext.HTTP_RESPONSE);
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}
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}
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posted on 2008-05-23 16:47 vulcan 閱讀(2243) 評論(0) 編輯收藏

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