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>
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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;
}
}
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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 ;
}
}
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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>
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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 >
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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 >
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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: