JSF 2 dropdown box example

In JSF, <h:selectOneMenu /> tag is used to render a dropdown box – HTML select element with “size=1” attribute.

//JSF...
<h:selectOneMenu value="#{user.favCoffee1}"><f:selectItem itemValue="Cream Latte" itemLabel="Coffee3 - Cream Latte" /><f:selectItem itemValue="Extreme Mocha" itemLabel="Coffee3 - Extreme Mocha" /><f:selectItem itemValue="Buena Vista" itemLabel="Coffee3 - Buena Vista" />
</h:selectOneMenu>

//HTML output...
<select name="j_idt6:j_idt8" size="1">  <option value="Cream Latte">Coffee3 - Cream Latte</option> <option value="Extreme Mocha">Coffee3 - Extreme Mocha</option> <option value="Buena Vista">Coffee3 - Buena Vista</option>
</select>

`h:selectOneMenu` example

A JSF 2.0 example to show the use of “h:selectOneMenu” tag to render a dropdow box, and populate the data in 3 different ways :

Hardcoded value in “f:selectItem” tag.
Generate values with a Map and put it into “f:selectItems” tag.
Generate values with an Object array and put it into “f:selectItems” tag, then represent the value with “var” attribute.

1. Backing Bean

A backing bean to hold and generate data for the dropdown box values.

package com.mkyong;import java.io.Serializable;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;@ManagedBean(name="user")
@SessionScoped
public class UserBean implements Serializable{public String favCoffee1;public String favCoffee2;public String favCoffee3;public String getFavCoffee1() {return favCoffee1;}public void setFavCoffee1(String favCoffee1) {this.favCoffee1 = favCoffee1;}public String getFavCoffee2() {return favCoffee2;}public void setFavCoffee2(String favCoffee2) {this.favCoffee2 = favCoffee2;}public String getFavCoffee3() {return favCoffee3;}public void setFavCoffee3(String favCoffee3) {this.favCoffee3 = favCoffee3;}//Generated by Mapprivate static Map<String,Object> coffee2Value;static{coffee2Value = new LinkedHashMap<String,Object>();coffee2Value.put("Coffee2 - Cream Latte", "Cream Latte"); //label, valuecoffee2Value.put("Coffee2 - Extreme Mocha", "Extreme Mocha");coffee2Value.put("Coffee2 - Buena Vista", "Buena Vista");}public Map<String,Object> getFavCoffee2Value() {return coffee2Value;}//Generated by Object arraypublic static class Coffee{public String coffeeLabel;public String coffeeValue;public Coffee(String coffeeLabel, String coffeeValue){this.coffeeLabel = coffeeLabel;this.coffeeValue = coffeeValue;}public String getCoffeeLabel(){return coffeeLabel;}public String getCoffeeValue(){return coffeeValue;}}public Coffee[] coffee3List;public Coffee[] getFavCoffee3Value() {coffee3List = new Coffee[3];coffee3List[0] = new Coffee("Coffee3 - Cream Latte", "Cream Latte");coffee3List[1] = new Coffee("Coffee3 - Extreme Mocha", "Extreme Mocha");coffee3List[2] = new Coffee("Coffee3 - Buena Vista", "Buena Vista");return coffee3List;}}

2. JSF Page

A JSF page to demonstrate the use “h:selectOneMenu” tag.

<?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:body><h1>JSF 2 dropdown box example</h1><h:form>1. Hard-coded with "f:selectItem" : <h:selectOneMenu value="#{user.favCoffee1}"><f:selectItem itemValue="Cream Latte" itemLabel="Coffee3 - Cream Latte" /><f:selectItem itemValue="Extreme Mocha" itemLabel="Coffee3 - Extreme Mocha" /><f:selectItem itemValue="Buena Vista" itemLabel="Coffee3 - Buena Vista" /></h:selectOneMenu><br /><br />2. Generated by Map :<h:selectOneMenu value="#{user.favCoffee2}"><f:selectItems value="#{user.favCoffee2Value}" /></h:selectOneMenu><br /><br />3. Generated by Object array and iterate with var :<h:selectOneMenu value="#{user.favCoffee3}"><f:selectItems value="#{user.favCoffee3Value}" var="c"itemLabel="#{c.coffeeLabel}" itemValue="#{c.coffeeValue}" /></h:selectOneMenu><br /><br /><h:commandButton value="Submit" action="result" /><h:commandButton value="Reset" type="reset" /></h:form></h:body>
</html>

result.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"><h:body><h1>JSF 2 dropdown box example</h1><h2>result.xhtml</h2><ol><li>user.favCoffee1 : #{user.favCoffee1}</li><li>user.favCoffee2 : #{user.favCoffee2}</li><li>user.favCoffee3 : #{user.favCoffee3}</li></ol></h:body></html>

3. Demo

When “submit” button is clicked, link to “result.xhtml” page and display the submitted dropdown box values.

How to pre-select a dropdown box value?

The value of “f:selectItems” tag is selected if it matched to the “value” of “h:selectOneMenu” tag. In above example, if you set “favCoffee1″ property to “Extreme Mocha” :

@ManagedBean(name="user")
@SessionScoped
public class UserBean{public String favCoffee1 = "Extreme Mocha";//...

The “favCoffee1″ dropdown box, values “Extreme Mocha” is selected by default.

转载于:https://www.cnblogs.com/ghgyj/p/4765389.html