这里主要介绍一下如何在PrimeFaces中实现错误提示

官方参考文档如下：

https://www.primefaces.org/showcase/ui/message/messages.xhtml?jfwid=96ee4

https://primefaces.github.io/primefaces/10_0_0/#/components/messages

由于PrimeFaces有注释Bug，这里先介绍贴出一段带注释的代码作为参考

<?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:h="http://java.sun.com/jsf/html"
  xmlns:p="http://primefaces.org/ui"
  xmlns:c="http://java.sun.com/jsp/jstl/core">
  <h:head></h:head>
  <h:body style="margin-left:50px">
    <div class="card">
      <!-- 定义一个变量名 -->
      <c:set var="msg" value="#{messages}"/>
      <h:form>
        <h1>Validation</h1>
        <h:panelGrid id="grid" columns="3" cellpadding="7">
          <!-- 文本输入框 -->
          <p:inputText id="input" value="#{msg.quality}">
            <!-- 当元素失去焦点时发生 blur 事件，更新m1的值，添加error为监听事件 -->
            <p:ajax event="blur" update="m1" listener="#{msg.error(msg.quality)}"/>
          </p:inputText>
          <!-- 报错的文本提示框，关联文本输入框 -->
          <p:messages id="m1" for="input" display="input" showDetail="true"/>
        </h:panelGrid>
        <p:commandButton id="submitButton" value="Submit" update="grid" styleClass="p-mt-3"/>
      </h:form>
    </div>
  </h:body>
</html>

完整代码如下：

messages.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:h="http://java.sun.com/jsf/html"
        xmlns:p="http://primefaces.org/ui"
        xmlns:c="http://java.sun.com/jsp/jstl/core">
<h:head></h:head>
<h:body style="margin-left:50px">
    <div class="card">
        <c:set var="msg" value="#{messages}"/>
        <h:form>
            <h1>Validation</h1>
            <h:panelGrid id="grid" columns="3" cellpadding="7">
                <p:inputText id="input" value="#{msg.quality}">
                    <p:ajax event="blur" update="m1" listener="#{msg.error(msg.quality)}"/>
                </p:inputText>
                <p:messages id="m1" for="input" display="input" showDetail="true"/>
            </h:panelGrid>
            <p:commandButton id="submitButton" value="Submit" update="grid" styleClass="p-mt-3"/>
        </h:form>
    </div>
</h:body>
</html>

MessagesView.java

package com.daniel.model.menu;


import lombok.Getter;
import lombok.Setter;

import javax.faces.application.FacesMessage;
import javax.faces.bean.RequestScoped;
import javax.faces.context.FacesContext;
import javax.inject.Named;

/**
 * @Author Daniel
 * @Description primefaces 错误提示
 **/
@Named(value = "messages")
@RequestScoped
public class MessagesView {
    @Getter
    @Setter
    private int quality = 0;

    // 如果输入的值大于5，就给出提示信息
    public void error(int quality) {
        int max = 5;
        if (quality > max) {
            /*
            addMessage(前端要显示标签的id,(错误级别，错误显示的文本标题，错误显示的文本内容))
             */
            FacesContext.getCurrentInstance().addMessage("input", new FacesMessage(FacesMessage.SEVERITY_ERROR, "Error", "Message Content"));
        }
    }

}

默认访问URL：http://localhost:8080/messages.xhtml

效果展示：

PrimeFaces Error Messages实现_PrimeFaces

附：环境搭建与lombok依赖

<dependency>
  <groupId>org.projectlombok</groupId>
  <artifactId>lombok</artifactId>
  <version>1.18.8</version>
</dependency>