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...

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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 <= 0) {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[0]);}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 = 0; 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 {@Overridepublic 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;}@Referencepublic void setBookmarksFolderLocalService(BookmarksFolderLocalService bookmarksFolderLocalService) {_bookmarksFolderLocalService = bookmarksFolderLocalService;}@Referencepublic 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>