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JSF 2 listbox example

2015-08-28 07:12 841 查看
In JSF, 
<h:selectOneListbox />
tag is used to render a single select listbox – HTML select element with “size” attribute.

//JSF...
<h:selectOneListbox value="#{user.favYear1}">
<f:selectItem itemValue="2000" itemLabel="Year1 - 2000" />
<f:selectItem itemValue="2010" itemLabel="Year1 - 2010" />
<f:selectItem itemValue="2020" itemLabel="Year1 - 2020" />
</h:selectOneListbox>

//HTML output...
<select name="j_idt6:j_idt8" size="3">
<option value="2000">Year1 - 2000</option>
<option value="2010">Year1 - 2010</option>
<option value="2020">Year1 - 2020</option>
</select>

h:selectOneListbox
example

A JSF 2.0 example to show the use of “
h:selectOneListbox
” tag to render a single select listbox, 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 listbox 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 favYear1;
public String favYear2;
public String favYear3;

//getter and setter methods

//Generated by Map
private static Map<String,Object> year2Value;
static{
year2Value = new LinkedHashMap<String,Object>();
year2Value.put("Year2 - 2000", "2000"); //label, value
year2Value.put("Year2 - 2010", "2010");
year2Value.put("Year2 - 2020", "2020");
}

public Map<String,Object> getFavYear2Value() {
return year2Value;
}

//Generated by Object array
public static class Year{
public String yearLabel;
public String yearValue;

public Year(String yearLabel, String yearValue){
this.yearLabel = yearLabel;
this.yearValue = yearValue;
}

public String getYearLabel(){
return yearLabel;
}

public String getYearValue(){
return yearValue;
}

}

public Year[] year3List;

public Year[] getFavYear3Value() {

year3List = new Year[3];
year3List[0] = new Year("Year3 - 2000", "2000");
year3List[1] = new Year("Year3 - 2010", "2010");
year3List[2] = new Year("Year3 - 2020", "2020");

return year3List;
}

}

2. JSF Page

A JSF page to demonstrate the use “
h:selectOneListbox
” 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 listbox example</h1>
<h:form>

1. Hard-coded with "f:selectItem" :
<h:selectOneListbox value="#{user.favYear1}">
<f:selectItem itemValue="2000" itemLabel="Year1 - 2000" />
<f:selectItem itemValue="2010" itemLabel="Year1 - 2010" />
<f:selectItem itemValue="2020" itemLabel="Year1 - 2020" />
</h:selectOneListbox>

<br />

2. Generated by Map :
<h:selectOneListbox value="#{user.favYear2}">
<f:selectItems value="#{user.favYear2Value}" />
</h:selectOneListbox>

<br />

3. Generated by Object array and iterate with var :
<h:selectOneListbox value="#{user.favYear3}">
<f:selectItems value="#{user.favYear3Value}" var="y"
itemLabel="#{y.yearLabel}" itemValue="#{y.yearValue}" />
</h:selectOneListbox>

<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 listbox example</h1>

<h2>result.xhtml</h2>

<ol>
<li>user.favYear1 : #{user.favYear1}</li>
<li>user.favYear2 : #{user.favYear2}</li>
<li>user.favYear3 : #{user.favYear3}</li>
</ol>
</h:body>

</html>

3. Demo



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



How to pre-select a listbox value?

The value of “
f:selectItems
” tag is selected if it matched to the “
value
” of “
h:selectOneListbox
” tag. In above example, if you set favYear1 property to “
2010
” :

@ManagedBean(name="user")
@SessionScoped
public class UserBean{

public String favYear1 = "2010";

//...

The “
favYear1
″ listbox, value “
2010
” is selected by default.
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