Struts2自定义返回Json类型result

本来Struts2有自己的json类型的返回结果，并提供了插件，但是它有一个问题，那就是它会将所有序列化的字段都返回，如果想要制定返回Action的某一个属性，则需要在配置result时，配置参数（这里只是举个例子）：

<param name="root">responseMap</param>  

配置了这个参数，返回结果就会从Action中的responseMap为根进行返回。

但是如果自定义结果类型，就可以自己控制了，而且不需要struts2-json-result插件，以下是配置信息：

<package name="default" extends="struts-default" namespace="/login">
    <result-types>
            <result-type name="jsonResult" class="com.lxl.erp.base.JSONResult" />
    </result-types>

    <action name="*/*" class="{1}" method="{2}">
        <result type="jsonResult" name="success" />
    </action>
</package>

com.lxl.erp.base.JSONResult为我们自己需要实现的返回类型的实现类：

package com.lxl.erp.base;

import java.io.PrintWriter;
import java.lang.reflect.UndeclaredThrowableException;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.ResourceBundle;

import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.ServletActionContext;
import org.apache.struts2.dispatcher.StrutsResultSupport;

import com.lxl.erp.common.HttpConstant;
import com.lxl.erp.common.ResourceLanguage;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.ExceptionHolder;
import com.opensymphony.xwork2.util.ValueStack;

import net.sf.json.JSONObject;

/**
 * @ClassName: JsonResult
 * @Description: Result fomed by json
 * @author aaron
 * @date Nov 7, 2011 4:27:06 PM
 * @version V1.0
 */
public final class JSONResult extends StrutsResultSupport
{
    private static final long serialVersionUID = 1L;

    @Override
    protected void doExecute(String finalLocation, ActionInvocation invocation)
            throws Exception
    {
        BaseAction bas = (BaseAction) invocation.getAction();
        bas.clearErrorsAndMessages();

        HttpServletResponse response = (HttpServletResponse) invocation
                .getInvocationContext().get(HTTP_RESPONSE);
        response.setContentType(HttpConstant.RESPONSE_CONTENT_TYPE);

        @SuppressWarnings("unchecked")
        Map<String, Object> responseMap = (Map<String, Object>) invocation
                .getStack().findValue(HttpConstant.RESPONSEMAP);
        if (responseMap == null)
        {
            responseMap = new HashMap<String, Object>(3);
        }
        else if (responseMap.get(HttpConstant.RETCODE) == null)
        {
            ValueStack s = invocation.getStack();
            for (int i = s.size(); i > 0; i--)
            {
                Object obj = s.pop();
                if (obj instanceof ExceptionHolder)
                {
                    responseMap.put(HttpConstant.RETCODE,
                            HttpConstant.ERROR_CODE);
                    responseMap.put(HttpConstant.RETMSG,
                            HttpConstant.UNKNOWNERROR);

                    Object o = ((ExceptionHolder) obj).getException();

                    if (o instanceof ServiceException)
                    {
                        String accept_language = ServletActionContext
                                .getRequest()
                                .getHeader(HttpConstant.REQUEST_HEADER_LANG);
                        String language = accept_language.split(",")[0];
                        Locale locale = Locale.getDefault();
                        if (language.toLowerCase()
                                .indexOf(ResourceLanguage.CHINESE) > -1)
                        {
                            locale = Locale.CHINA;
                        }
                        else if (language.toLowerCase()
                                .indexOf(ResourceLanguage.ENGLISH) > -1)
                        {
                            locale = Locale.US;
                        }
                        ResourceBundle bundle = ResourceBundle.getBundle(
                                ResourceLanguage.SOURCELOCATION, locale);

                        ServiceException exception = (ServiceException) o;

                        responseMap.put(HttpConstant.RETMSG,
                                exception.getErrorMsg(bundle));
                    }
                    else if (o instanceof Exception)
                    {
                        Exception exception = (Exception) o;
                        responseMap.put(HttpConstant.RETMSG,
                                exception.getCause().getMessage());
                    }
                    else if (o instanceof UndeclaredThrowableException)
                    {
                        o = ((UndeclaredThrowableException) o)
                                .getUndeclaredThrowable();
                    }
                    break;
                }
            }
        }

        PrintWriter pw = response.getWriter();
        pw.println(JSONObject.fromObject(responseMap));
        return;
    }
}

这样，只要在Action中添加一个属性responseMap(需要与自定义的结果类型中代码

(Map<String, Object>) invocati.getStack().findValue(HttpConstant.RESPONSEMAP)

中的HttpConstant.RESPONSEMAP对应哦，HttpConstant.RESPONSEMAP是自定义的常量）。

这样Action请求处理函数中，将要返回的请求数据结果放到responseMap中，然后返回SUCCESS就可以了，前台就可以通过ajax请求访问了。