BindingResult.hasErrors() 始终返回 false，即使 @NotEmpty 字段的 @Valid 为 true

问题描述

嘿，当客户在主页上填写我的表格时，我正在尝试处理空条目。问题是 BindingResult 有错误方法总是返回 false。我不知道为什么，因为我相信我的 POM 中有正确的依赖项，并且我在 UserInfoDTO 中用 @NotEmpty 注释了我的字段属性，所以我不确定我做错了什么。我想在客户填写表格时防止出现空条目。

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
    <head>
        <title>Home Page</title>
    </head>
    <body>
        <h1 align="center">love Calculator</h1>
        <form:form action="process-homepage" method="get" modelattribute="userInfo" >
            <div align="center">
                <p>
                    <label for="yn">Your Name:</label>
                    <form:input id="yn" path="userName"/>
                </p>
                <p>
                    <label for="cn">Crush Name:</label>
                    <form:input id="cn" path="crushName"/>
                </p>
                <input type="submit" value="calculate">
            </div>
        </form:form>
    </body>
</html>

import com.seleniumexpress.selenium_express.api.UserInfoDTO;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.validation.ObjectError;
import org.springframework.web.bind.annotation.modelattribute;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.validation.Valid;
import java.util.List;

@Controller
public class LCAppController {

    @RequestMapping("/")
    public String showHomePage(@modelattribute("userInfo") UserInfoDTO userInfoDTO) {
        return "home-page";
    }

    @RequestMapping("/process-homepage")
    public String processHomePage(@Valid @modelattribute("userInfo") UserInfoDTO userInfoDTO,BindingResult bindingResult) {
        if (bindingResult.hasErrors()) {
            List<ObjectError> allErrors = bindingResult.getAllErrors();
            for (ObjectError objectError : allErrors)
                System.out.println(objectError);
            return "home-page";
        }

        System.out.println("No errors...");
        return "result-page";
    }
}

import javax.validation.constraints.NotBlank;

public class UserInfoDTO {
    @NotBlank(message = "* User Name cannot be blank")
    private String userName;
    private String crushName;

    public UserInfoDTO() {
        System.out.println("UserInfoDTO constructor being called...");
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getCrushName() {
        return crushName;
    }

    public void setCrushName(String crushName) {
        this.crushName = crushName;
    }

    @Override
    public String toString() {
        return "UserInfoDTO{" +
                "userName='" + userName + '\'' +
                ",crushName='" + crushName + '\'' +
                '}';
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.seleniumexpress</groupId>
    <artifactId>selenium-express</artifactId>
    <version>1.0-SNAPSHOT</version>
    <name>selenium-express</name>
    <packaging>war</packaging>

    <properties>
        <maven.compiler.target>1.8</maven.compiler.target>
        <maven.compiler.source>1.8</maven.compiler.source>
        <junit.version>5.7.0</junit.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>javax.validation</groupId>
            <artifactId>validation-api</artifactId>
            <version>2.0.1.Final</version>
        </dependency>
        <dependency>
            <groupId>jstl</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp.jstl</groupId>
            <artifactId>javax.servlet.jsp.jstl-api</artifactId>
            <version>1.2.1</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.3.2</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-engine</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>7.0.0.Final</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.3.0</version>
            </plugin>
        </plugins>
    </build>
</project>

解决方法

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hibernate-validator java java model-view-controller spring validation