Spring Boot 与 Kotlin 验证web表单信息

在做web开发的时候，我们需要验证表单，确认用户提交的信息是安全的，比如用户名不能超过多少位，密码不能少于多少位等等。

那么如何在Spring Boot 与 Kotlin中验证表单信息？

在springmvc工程中，需要检查表单信息，表单信息验证主要通过注解的形式。

表单验证

下面我们在之前《Spring Boot 与 kotlin 使用Thymeleaf模板引擎渲染web视图》项目的基础上，增加表单验证。

build.gradle 文件增加依赖

compile "org.hibernate:hibernate-validator"
compile "org.apache.tomcat.embed:tomcat-embed-el"

完整的build.gradle文件

group 'name.quanke.kotlin'
version '1.0-SNAPSHOT'

buildscript {
    ext.kotlin_version = '1.2.10'
    ext.spring_boot_version = '1.5.4.RELEASE'
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath("org.springframework.boot:spring-boot-gradle-plugin:$spring_boot_version")

//        Kotlin整合SpringBoot的默认无参构造函数，默认把所有的类设置open类插件
        classpath("org.jetbrains.kotlin:kotlin-noarg:$kotlin_version")
        classpath("org.jetbrains.kotlin:kotlin-allopen:$kotlin_version")
    }
}

apply plugin: 'kotlin'
apply plugin: "kotlin-spring" // See https://kotlinlang.org/docs/reference/compiler-plugins.html#kotlin-spring-compiler-plugin
apply plugin: 'org.springframework.boot'

jar {
    baseName = 'chapter11-5-5-service'
    version = '0.1.0'
}
repositories {
    mavenCentral()
}


dependencies {
    compile "org.jetbrains.kotlin:kotlin-stdlib-jre8:$kotlin_version"
    compile "org.springframework.boot:spring-boot-starter-web:$spring_boot_version"
    compile "org.springframework.boot:spring-boot-starter-thymeleaf:$spring_boot_version"
    compile "org.hibernate:hibernate-validator"
    compile "org.apache.tomcat.embed:tomcat-embed-el"

    testCompile "org.springframework.boot:spring-boot-starter-test:$spring_boot_version"
    testCompile "org.jetbrains.kotlin:kotlin-test-junit:$kotlin_version"

}

compileKotlin {
    kotlinOptions.jvmTarget = "1.8"
}
compileTestKotlin {
    kotlinOptions.jvmTarget = "1.8"
}

创建UserForm类

import javax.validation.constraints.Min
import javax.validation.constraints.NotNull
import javax.validation.constraints.Size

/**
 * Created by http://quanke.name on 2018/1/12.
 * https://stackoverflow.com/questions/36515094/kotlin-and-valid-spring-annotation
 * https://stonesoupprogramming.com/2017/06/21/spring-bean-validation-example-jsr-303-in-kotlin/
 */
data class UserForm(@get:NotNull(message = "{name.required}") @get:Size(min = 2, max = 5,message = "{name.size}") var name: String? = "", @get:Min(18) var age: Int? = 0)

如果是Spring boot 可以不增加 @get注解，如果使用kotlin 语言实现必须加@get

这个实体类，在2个属性:name,age.它们各自有验证的注解：

@Size(min=2, max=5) name的长度为2-30个字符
@NotNull 不为空
@Min(18)age不能小于18

创建WebController

import name.quanke.kotlin.chaper11_5_5.entity.UserForm
import org.springframework.stereotype.Controller
import org.springframework.validation.Errors
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.PostMapping
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter
import javax.validation.Valid


/**
 * Created by http://quanke.name on 2018/1/12.
 */

@Controller
class WebController : WebMvcConfigurerAdapter() {
    override fun addViewControllers(registry: ViewControllerRegistry?) {
        registry!!.addViewController("/results").setViewName("results")
    }

    @GetMapping("/")
    fun index(userForm: UserForm): String {
        return "index"
    }

    @PostMapping("/")
    fun checkPersonInfo(@Valid userForm: UserForm, errors: Errors): String {

        val result: String = when {
        //Test for errors
            errors.hasErrors() -> "index"
            else -> {
                //Otherwise proceed to the next page
                "redirect:/results"
            }
        }
        return result

    }
}

创建form表单src/main/resources/templates/index.html

<!DOCTYPE html>
<html xmlns:th="http://www.w3.org/1999/xhtml">
<head lang="en">
    <title>quanke.name</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
</head>
<body>

<h1>Form</h1>
<form action="#" th:action="@{/}" th:object="${userForm}" method="post">
    <table>
        <tr>
            <td>Name:</td>
            <td><input type="text" th:field="*{name}" /></td>
            <td th:if="${#fields.hasErrors('name')}" th:errors="*{name}">Name Error</td>
        </tr>
        <tr>
            <td>Age:</td>
            <td><input type="text" th:field="*{age}" /></td>
            <td th:if="${#fields.hasErrors('age')}" th:errors="*{age}">Age Error</td>
        </tr>
        <tr>
            <td><button type="submit">Submit</button></td>
        </tr>
    </table>
</form>
</body>
</html>

成功页面src/main/resources/templates/results.html

<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
    <title>quanke</title>
</head>
<body>
<h1>quanke.name</h1>
Congratulations! You are old enough to sign up for this site
</body>
</html>

在src/main/resources/目录下增加ValidationMessages.properties文件

# \u8FD9\u91CC\u8981\u6CE8\u610F\u7F16\u7801\u95EE\u9898
name.required=\u540D\u5B57\u4E0D\u80FD\u4E3A\u7A7A
name.size=\u540D\u5B57\u957F\u5EA6\u8FD4\u56DE\u53EA\u80FD\u662F2-5

Spring Boot 启动

import org.springframework.boot.SpringApplication
import org.springframework.boot.autoconfigure.SpringBootApplication


/**
 * Created by http://quanke.name on 2018/1/9.
 */

@SpringBootApplication
class Application

fun main(args: Array<String>) {
    SpringApplication.run(Application::class.java, *args)
}

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Spring Boot 与 Kotlin 验证web表单信息