JSF复习系列(2)－－迭代器的直观体现dataTable使用详解

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一、标签简介

1.1 概念

　　JSF允许使用h:dataTable标签来放置组件，利用迭代器原理，遍历数据来创建html表格。

1.2 适用条件

　　遍历的内容应为以下类型的数据：
　

java对象
数组
java.util.List实例
java.sql.ResultSet实例
javax.servlet.jsp.jstl.sql.Result实例
javax.faces.model.DataModel实例

1.3 基本形式

< h:dataTable  value =""  var ="" >< h:column ></ h:column ></ h:dataTable >

　　h:dataTable标签的正文体只包含h:column标签，除了可
选的标题和脚注组件之外，每列都可以包含无数的组件。任何时候都可以在有自组建的组件内部指定模板文件（即不是JSF标签的其他东西），但必须将这些模板文本封装到f:verbatim标签的正文体内或者使h:outputText来产生该模板文本。
　　常用的显示数据信息的方式有:
　
1.

< h:dataTable  value =""  var ="" >< h:column ><f:facet name = ""></f:facet>#{}</ h:column ></ h:dataTable >

< h:dataTable  value =""  var ="" >< h:column ><h:outputText value="#{}" /></ h:column ></ h:dataTable >

1.4 相关参数

value　遍历对象，可以是数组、List集合等。
var　　value中数组对象、List对象。
（说不太明白）

二、代码示例

下面以遍历List集合为例子展示：（不太好描述，就借用了别人的代码）
Employee.java

package com.tutorialspoint.test;public class Employee {   private String name;   private String department;   private int age;   private double salary;   private boolean canEdit;   public Employee (String name,String department,int age,double salary) {      this.name = name;      this.department = department;      this.age = age;      this.salary = salary;      canEdit = false;   }   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 int getAge() {      return age;   }   public void setAge(int age) {      this.age = age;   }   public double getSalary() {      return salary;   }   public void setSalary(double salary) {      this.salary = salary;   }   public boolean isCanEdit() {      return canEdit;   }   public void setCanEdit(boolean canEdit) {      this.canEdit = canEdit;   }    }

UserData.java

package com.tutorialspoint.test;import java.io.Serializable;import java.util.ArrayList;import java.util.Arrays;import javax.faces.bean.ManagedBean;import javax.faces.bean.SessionScoped;@ManagedBean(name = "userData", eager = true)@SessionScoped//特别注意周期public class UserData implements Serializable {   private static final long serialVersionUID = 1L;   private String name;   private String dept;   private int age;   private double salary;   private static final ArrayList<Employee> employees      = new ArrayList<Employee>(Arrays.asList(      new Employee("John", "Marketing", 30,2000.00),      new Employee("Robert", "Marketing", 35,3000.00),      new Employee("Mark", "Sales", 25,2500.00),      new Employee("Chris", "Marketing", 33,2500.00),      new Employee("Peter", "Customer Care", 20,1500.00)   ));     public ArrayList<Employee> getEmployees() {      return employees;   }   public String addEmployee() {               Employee employee = new Employee(name,dept,age,salary);      employees.add(employee);      return null;   }   public String deleteEmployee(Employee employee) {      employees.remove(employee);             return null;   }   public String editEmployee(Employee employee) {      employee.setCanEdit(true);      return null;   }   public String saveEmployees() {      //set "canEdit" of all employees to false       for (Employee employee : employees) {         employee.setCanEdit(false);      }           return null;   }   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 int getAge() {      return age;   }   public void setAge(int age) {      this.age = age;   }   public double getSalary() {      return salary;   }   public void setSalary(double salary) {      this.salary = salary;   }}

home.xhtml

<?xml version = "1.0" encoding = "UTF-8"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns = "http://www.w3.org/1999/xhtml"   xmlns:h = "http://java.sun.com/jsf/html"xmlns:f = "http://java.sun.com/jsf/core">   <h:head>      <title>JSF tutorial</title>          </h:head>   <h:body>       <h2>DataTable Example</h2>      <h:form>         <h:dataTable value = "#{userData.employees}" var = "employee"            styleClass = "employeeTable"            headerClass = "employeeTableHeader"            rowClasses = "employeeTableOddRow,employeeTableEvenRow">            <h:column>                                 <f:facet name = "header">Name</f:facet>                                 #{employee.name}            </h:column>            <h:column>               <f:facet name = "header">Department</f:facet>               #{employee.department}            </h:column>            <h:column>               <f:facet name = "header">Age</f:facet>               #{employee.age}            </h:column>            <h:column>               <f:facet name = "header">Salary</f:facet>               #{employee.salary}            </h:column>         </h:dataTable>      </h:form>   </h:body></html>

三、易错点总结

1.var
var参数是value中List的一个实例化对象名；
2.生命周期问题
目前RequestScoped、SessionScoped两种生命周期可以实现正确显示。

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