<f:validateLength>标签用于验证字符串值的长度。我们可以使用<f:validateLength>标签，如下所示。
<f:validateLength minimum="5" maximum="8" />
JSF验证字符串长度实例
打开 NetBeans IDE 创建一个Web工程：ValidateStringLength，其目录结构如下所示 -
创建以下文件代码，文件：index.xhtml 的代码内容如下所示 -
<?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"
xmlns:c="http://java.sun.com/jsp/jstl/core">
<h:body>
<h:form>
<h:panelGrid columns="3">
Enter UserName :
<h:inputText id="username" value="#{user.username}"
size="20" required="true"
label="UserName" >
<f:validateLength minimum="5" maximum="10" />
</h:inputText>
<h:message for="username" style="color:red" />
</h:panelGrid>
<h:commandButton value="Submit" action="result" />
</h:form>
</h:body>
</html>
文件：result.xhtml 的代码内容如下所示 -
<?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"
xmlns:c="http://java.sun.com/jsp/jstl/core">
<h:body>
UserName : <h:outputText value="#{user.username}" />
</h:body>
</html>
文件：User.java 的代码内容如下所示 -
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package com.yiibai;
/**
*
* @author Administrator
*/
import java.io.Serializable;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
@ManagedBean(name = "user")
@SessionScoped
public class User implements Serializable {
String username;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
}
右键运行工程：ValidateStringLength，如果没有任何错误，打开浏览器访问：
http://localhost:8084/ValidateStringLength/
应该会看到以下结果 -
简单写入一些信息(超过10个字符)，然后提交 -
