Struts2 merge標籤

如果有兩個列表A和B的值，A1，A2和B1，B2。合併列表，會給出A1，B1，A2，B2。

創建動作類：

首先，讓我們創建一個簡單的類叫做Employee.java，它看起來像：

package com.yiibai.struts2; import java.util.ArrayList; import java.util.List; import org.apache.struts2.util.SubsetIteratorFilter.Decider; public class Employee { private String name; private String department; public Employee(){} public Employee(String name,String department) { this.name = name; this.department = department; } private List employees; private List contractors; public String execute() { employees = new ArrayList(); employees.add(new Employee("George","Recruitment")); employees.add(new Employee("Danielle","Accounts")); employees.add(new Employee("Melissa","Recruitment")); employees.add(new Employee("Rose","Accounts")); contractors = new ArrayList(); contractors.add(new Employee("Mindy","Database")); contractors.add(new Employee("Vanessa","Network")); return "success"; } public Decider getRecruitmentDecider() { return new Decider() { public boolean decide(Object element) throws Exception { Employee employee = (Employee)element; return employee.getDepartment().equals("Recruitment"); } }; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getDepartment() { return department; } public void setDepartment(String department) { this.department = department; } public List getEmployees() { return employees; } public void setEmployees(List employees) { this.employees = employees; } public List getContractors() { return contractors; } public void setContractors(List contractors) { this.contractors = contractors; } }

Employee類有兩個屬性 - name 和 department，我們也有兩個員工名單 - employees 和contractors。我們有一個方法叫做getRecruitmentDecider，返回Decider 對象。Decider 實現返回true，如果僱員招聘部門工作，否則返回false。

接下來，讓我們創建一個DepartmentComparator 比較Employee對象：

package com.yiibai.struts2; import java.util.Comparator; public class DepartmentComparator implements Comparator { public int compare(Employee e1, Employee e2) { return e1.getDepartment().compareTo(e2.getDepartment()); } @Override public int compare(Object arg0, Object arg1) { return 0; } }

在上面的例子所示，部門比較的基礎上按字母順序排列的部門員工進行比較。

創建視圖

創建一個文件叫做employee.jsp以下內容：

<%@ page contentType="text/html; charset=UTF-8"%> <%@ taglib prefix="s" uri="/struts-tags"%> Employees and Contractors Merged together
<s:merge id="allemployees"> <s:param value="employees" /> <s:param value="contractors" /> <s:iterator value="allemployees"> <s:property value="name"/>, <s:property value="department"/>

合併標記需要兩個或兩個以上的列表作爲參數。我們需要給合併一個id，這樣我們就可以重用它。在這個例子中，我們提供了作爲參數傳遞給員工和承包商的合併標籤。然後，我們使用「allemployees」ID合併列表遍歷並打印員工的細節。

配置文件

struts.xml中應該像這樣：

<constant name="struts.devMode" value="true" /> <package name="helloworld" extends="struts-default"> <action name="employee" class="com.yiibai.struts2.Employee" method="execute"> <result name="success">/employee.jsp

web.xml中，應該像這樣：

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app\_2\_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app\_3\_0.xsd" id="WebApp_ID" version="3.0"> Struts 2 index.jsp struts2 org.apache.struts2.dispatcher.FilterDispatcher struts2 /*

右鍵點擊項目名稱，並單擊 Export > WAR File創建一個WAR文件。然後部署此WAR在Tomcat的webapps目錄下。最後，啓動Tomcat服務器和嘗試訪問URL http://localhost:8080/HelloWorldStruts2/employee.action。這會給出以下畫面：