检查详细示例（Check Detailed Example）3

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2023-12-01

假设您有两个列表A和B，其值为A1，A2和B1，B2。合并列表将为您提供A1，B1，A2，B2。

创建动作类

首先让我们创建一个名为Employee.java的简单类，它看起来像 -

package cn.xnip.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 ，我们还有两个员工列表 - 永久employees和contractors 。我们有一个名为getRecruitmentDecider的方法，它返回一个Decider对象。如果员工在recruitment部门工作，则Decider实现返回true，否则返回false 。

接下来，让我们创建一个DepartmentComparator来比较Employee对象 -

package cn.xnip.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;
   }
}

如上例所示，部门比较器按字母顺序比较基于部门的员工。

创建视图 (Create Views)

使用以下内容创建名为employee.jsp的文件 -

<%@ 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>

merge标记将两个或多个列表作为参数。我们需要为合并提供一个id以便我们以后可以重用它。在此示例中，我们将员工和承包商作为参数提供给merge标记。然后，我们使用“allemployees”id迭代合并列表并打印员工详细信息。

配置文件 (Configuration Files)

你的struts.xml看起来应该像 -

<?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 = "cn.xnip.struts2.Employee"
         method = "execute">
         <result name = "success">/employee.jsp</result>
      </action>
   </package>
</struts>

您的web.xml应该如下所示 -

<?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>

右键单击项目名称，然后单击“ Export 》 WAR File以创建War文件。然后在Tomcat的webapps目录中部署此WAR。最后，启动Tomcat服务器并尝试访问URL http://localhost:8080/HelloWorldStruts2/employee.action 。这将产生以下屏幕 -