JSF验证字符串长度

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2023-03-14

<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 -