Liferay7 BPM门户开发之29: 核心kernel.util包下面的通用帮助类ParamUtil、GetterUtil使用

与其闭门造车，不如直接开动原装、进口、免费的法拉利。 -- 作者说

不多说废话，直接上代码。

ParamUtil

ParamUtil、GetterUtil是Liferay最重要的帮助类

• ParamUtil用途：获取PortletRequest的参数值，并作类型转换和判空处理（内部机制是通过GetterUtil）
• GetterUtil用途：对输入做类型转换、判空处理、赋予默认值（即期望的获取值为空时侯的初始值）

ParamUtil的使用例子1：

public void deleteInterview(
        ActionRequest actionRequest, ActionResponse actionResponse)
    throws Exception {

    long interviewId = ParamUtil.getLong(actionRequest, "interviewId");
    InterviewLocalServiceUtil.deleteInterview(interviewId);

    sendRedirect(actionRequest, actionResponse);
}

ParamUtil的使用例子2：

public void updateQuestion(
        ActionRequest actionRequest, ActionResponse actionResponse)
    throws Exception {

    long questionId = ParamUtil.getLong(actionRequest, "questionId");
    long questionSetId = ParamUtil.getLong(actionRequest, "questionSetId");
    String title = ParamUtil.getString(actionRequest, "title");
    String description = ParamUtil.getString(actionRequest, "description");
    int type = ParamUtil.getInteger(actionRequest, "type");

    ServiceContext serviceContext = ServiceContextFactory.getInstance(
        actionRequest);

    try {
        if (questionId <= ) {
            QuestionLocalServiceUtil.addQuestion(
                questionSetId, title, description, type, serviceContext);
        }
        else {
            QuestionLocalServiceUtil.updateQuestion(
                questionId, title, description, type, serviceContext);
        }
    }
    catch (Exception e) {
        ...
    }

    sendRedirect(actionRequest, actionResponse);
}

ParamUtil可以通过get来直接获取PortletRequest参数，如：

public static short get(
         PortletRequest portletRequest, String param, short defaultValue) {

         return GetterUtil.get(portletRequest.getParameter(param), defaultValue);
     }

     public static String get(
         PortletRequest portletRequest, String param, String defaultValue) {

         String returnValue =
             GetterUtil.get(portletRequest.getParameter(param), defaultValue);

         if (returnValue != null) {
             return returnValue.trim();
         }

         return null;
     }

也可以通过类似getInteger、getLong 获取单一值和获取数组的getIntegerValues、getLongValues之类的方法（用于checkbox的提交）实际都是一样的。

区别是getIntegerValues、getLongValues的返回值是通过调用GetterUtil

public static int getInteger(HttpServletRequest request, String param) {
         return GetterUtil.getInteger(request.getParameter(param));
     }

     public static int getInteger(
         HttpServletRequest request, String param, int defaultValue) {

         return get(request, param, defaultValue);
     }

     public static int[] getIntegerValues(
         HttpServletRequest request, String param) {

         return getIntegerValues(request, param, new int[]);
     }

     public static int[] getIntegerValues(
         HttpServletRequest request, String param, int[] defaultValue) {

         return GetterUtil.getIntegerValues(
             request.getParameterValues(param), defaultValue);
     }

同时，还可以通过print来打印参数输出，方便程序员使用

public static void print(PortletRequest portletRequest) {
         Enumeration<String> enu = portletRequest.getParameterNames();

         while (enu.hasMoreElements()) {
             String param = enu.nextElement();

             String[] values = portletRequest.getParameterValues(param);

             for (int i = ; i < values.length; i++) {
                 System.out.println(param + "[" + i + "] = " + values[i]);
             }
         }
     }     

另外较高版本增加了ServiceContext的参数

static float getFloat(ServiceContext serviceContext, String param, float defaultValue) 

static float[] getFloatValues(ServiceContext serviceContext, String param, float[] defaultValue) 

GetterUtil

GetterUtil的代码，就不具体解释了
可以访问：
https://docs.liferay.com/portal/5.1/javadocs/portal-kernel/com/liferay/portal/kernel/util/GetterUtil.java.html

GetterUtil的使用例子：发送request属性到jsp

//java：

package com.liferay.docs.exampleserviceconsumerportlet;

import java.io.IOException;
import javax.portlet.Portlet;
import javax.portlet.PortletException;
import javax.portlet.RenderRequest;
import javax.portlet.RenderResponse;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Reference;
import com.liferay.portal.kernel.portlet.bridges.mvc.MVCPortlet;
import com.liferay.portal.service.UserLocalService;
import com.liferay.bookmarks.service.BookmarksFolderLocalService;

@Component(
        immediate = true,
        property = {
                "com.liferay.portlet.display-category=category.sample",
                "com.liferay.portlet.instanceable=true",
                "javax.portlet.display-name=Example Service Consumer Portlet",
                "javax.portlet.init-param.template-path=/",
                "javax.portlet.init-param.view-template=/view.jsp",
                "javax.portlet.security-role-ref=power-user,user"
        },
        service = Portlet.class
)
public class ExampleServiceConsumerPortlet extends MVCPortlet {

    @Override
    public void doView(RenderRequest request, RenderResponse response)
            throws IOException, PortletException {

        int userCount = getUserLocalService().getUsersCount();
        request.setAttribute("USER_COUNT", userCount);

        int bookmarksFolderCount =
                getBookmarksFolderLocalService().getBookmarksFoldersCount();
        request.setAttribute("BOOKMARKS_FOLDER_COUNT", bookmarksFolderCount);

        super.doView(request, response);
    }

    public BookmarksFolderLocalService getBookmarksFolderLocalService() {
        return _bookmarksFolderLocalService;
    }

    public UserLocalService getUserLocalService() {
        return _userLocalService;
    }

    @Reference
    public void setBookmarksFolderLocalService(
            BookmarksFolderLocalService bookmarksFolderLocalService) {

        _bookmarksFolderLocalService = bookmarksFolderLocalService;
    }

    @Reference
    public void setUserLocalService(UserLocalService userLocalService) {
        _userLocalService = userLocalService;
    }

    private UserLocalService _userLocalService;
    private BookmarksFolderLocalService _bookmarksFolderLocalService;
}

//jsp：

<%@ taglib uri="http://java.sun.com/portlet_2_0" prefix="portlet" %>
<%@ page import="com.liferay.portal.kernel.util.GetterUtil" %>
<portlet:defineObjects />

<%
int userCount = GetterUtil.getInteger(renderRequest.getAttribute("USER_COUNT"));
int bookmarksFolderCount = GetterUtil.getInteger(renderRequest.getAttribute("BOOKMARKS_FOLDER_COUNT"));
%>

<p>The portal has <%= userCount %> users.</p>
<p>The portal has <%= bookmarksFolderCount %> bookmarks folders.</p>

GetterUtil和ParamUtil的区别是：ParamUtil是解析请求专用类，而GetterUtil是通用的类型转换输出类
使用这两个类ParamUtil、GetterUtil的好处显而易见，如果配合Validator类，像判空、类型转换、验证的大段代码可以大大的省略，非常简洁