merge标签合并标记需要两个或两个以上的列表作为参数,并把它们合并在一起,如下所示:
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<s:merge var= "myMergedIterator" > <s:param value= "%{myList1}" /> <s:param value= "%{myList2}" /> <s:param value= "%{myList3}" /> </s:merge> <s:iterator value= "%{#myMergedIterator}" > <s:property /> </s:iterator> |
如果有两个列表A和B的值,A1,A2和B1,B2。合并列表,会给出A1,B1,A2,B2。
创建动作类:
首先,让我们创建一个简单的类叫做Employee.java,它看起来像:
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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类有两个属性 - name 和 department,我们也有两个员工名单 - employees 和contractors。我们有一个方法叫做getRecruitmentDecider,返回Decider 对象。Decider 实现返回true,如果雇员招聘部门工作,否则返回false。
接下来,让我们创建一个DepartmentComparator 比较Employee对象:
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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,部门比较的基础上按字母顺序排列的部门员工进行比较。
创建视图
创建一个文件叫做employee.jsp以下内容:
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<%@ page contentType= "text/html; charset=UTF-8" %> <%@ taglib prefix= "s" uri= "/struts-tags" %> <html> <head> <title>Employees</title> </head> <body> <b>Employees and Contractors Merged together</b> <br /> <s:merge id= "allemployees" > <s:param value= "employees" /> <s:param value= "contractors" /> </s:merge> <s:iterator value= "allemployees" > <s:property value= "name" />, <s:property value= "department" /><br/> </s:iterator> </body> </html> |
合并标记需要两个或两个以上的列表作为参数。我们需要给合并一个id,这样我们就可以重用它。在这个例子中,我们提供了作为参数传递给员工和承包商的合并标签。然后,我们使用“allemployees”ID合并列表遍历并打印员工的细节。
配置文件
struts.xml中应该像这样:
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<? xml version = "1.0" encoding = "UTF-8" ?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd"> < struts > < 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</ result > </ action > </ package > </ struts > |
web.xml中,应该像这样:
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<? xml version = "1.0" encoding = "UTF-8" ?> < 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" > < display-name >Struts 2</ display-name > < welcome-file-list > < welcome-file >index.jsp</ welcome-file > </ welcome-file-list > < filter > < filter-name >struts2</ filter-name > < filter-class > org.apache.struts2.dispatcher.FilterDispatcher </ filter-class > </ filter > < filter-mapping > < filter-name >struts2</ filter-name > < url-pattern >/*</ url-pattern > </ filter-mapping > </ web-app > |
右键点击项目名称,并单击 Export > WAR File创建一个WAR文件。然后部署此WAR在Tomcat的webapps目录下。最后,启动Tomcat服务器和尝试访问URL http://localhost:8080/HelloWorldStruts2/employee.action。这会给出以下画面: