Java Spring 错误，当页面加载 maven html 错误

Question

当我运行程序时，我收到一个错误：

2022-11-25 18:31:53.591 ERROR 8435 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Error during execution of processor 'org.thymeleaf.spring5.processor.SpringInputGeneralFieldTagProcessor' (template: "greeting" - line 15, col 23)] with root cause

java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'searchForm' available as request attribute
        at org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:153) ~[spring-webmvc-5.3.23.jar!/:5.3.23]
        at org.springframework.web.servlet.support.RequestContext.getBindStatus(RequestContext.java:903) ~[spring-webmvc-5.3.23.jar!/:5.3.23]
        at org.thymeleaf.spring5.context.webmvc.SpringWebMvcThymeleafRequestContext.getBindStatus(SpringWebMvcThymeleafRequestContext.java:227) ~[thymeleaf-spring5-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.spring5.util.FieldUtils.getBindStatusFromParsedExpression(FieldUtils.java:306) ~[thymeleaf-spring5-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.spring5.util.FieldUtils.getBindStatus(FieldUtils.java:253) ~[thymeleaf-spring5-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.spring5.util.FieldUtils.getBindStatus(FieldUtils.java:227) ~[thymeleaf-spring5-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.spring5.processor.AbstractSpringFieldTagProcessor.doProcess(AbstractSpringFieldTagProcessor.java:174) ~[thymeleaf-spring5-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:74) ~[thymeleaf-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95) ~[thymeleaf-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.util.ProcessorConfigurationUtils$ElementTagProcessorWrapper.process(ProcessorConfigurationUtils.java:633) ~[thymeleaf-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.engine.ProcessorTemplateHandler.handleStandaloneElement(ProcessorTemplateHandler.java:918) ~[thymeleaf-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.engine.StandaloneElementTag.beHandled(StandaloneElementTag.java:228) ~[thymeleaf-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.engine.TemplateModel.process(TemplateModel.java:136) ~[thymeleaf-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:661) ~[thymeleaf-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1098) ~[thymeleaf-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1072) ~[thymeleaf-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.spring5.view.ThymeleafView.renderFragment(ThymeleafView.java:366) ~[thymeleaf-spring5-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.thymeleaf.spring5.view.ThymeleafView.render(ThymeleafView.java:190) ~[thymeleaf-spring5-3.0.15.RELEASE.jar!/:3.0.15.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1405) ~[spring-webmvc-5.3.23.jar!/:5.3.23]
        at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1149) ~[spring-webmvc-5.3.23.jar!/:5.3.23]
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1088) ~[spring-webmvc-5.3.23.jar!/:5.3.23]
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:964) ~[spring-webmvc-5.3.23.jar!/:5.3.23]
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.23.jar!/:5.3.23]
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.23.jar!/:5.3.23]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:670) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.23.jar!/:5.3.23]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:779) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.68.jar!/:na]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.23.jar!/:5.3.23]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.23.jar!/:5.3.23]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.23.jar!/:5.3.23]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.23.jar!/:5.3.23]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.23.jar!/:5.3.23]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.23.jar!/:5.3.23]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:360) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1789) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.68.jar!/:na]
        at java.base/java.lang.Thread.run(Thread.java:1589) ~[na:na]

尽管我按照本指南做了一切：https://spring.io/guides/gs/validating-form-input/

这是我的代码：

问候.html

<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>Getting Started: Serving Web Content</title> 
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body bgcolor="#191724">
    <center>
        
        <h1 style="color: #e0def4;">
            Hello!
        </h1>
        
        <form action="#" method="post" th:action="@{/}" th:object="${searchForm}">
            <input type="text" th:field="*{search}">
            
            <button type="submit">
                Search
            </button>
            
        </form>
        
    </center>
</body>
</html>

搜索表单.java

package org.privatec.coogle;

public class SearchForm {
    private String search;
    
    public String getSearch() {
        return search;
    }
    
    public void setSearch(String search) {
        this.search = search;
    }
}

CookeController.java

package org.privatec.coogle.Controllers;

import org.privatec.coogle.SearchForm;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;

@Controller
public class PrivacoogleController {

    @GetMapping("/")
    public String greeting() {
        return "greeting";
    }
    
    @PostMapping("/")
    public void getPost(SearchForm searchForm) {
        System.out.println(searchForm.getSearch());
    }

}

我用:open JDK 19 . 0 . 1 2022-10-18 Apache Maven 3 . 8 . 6

我试图替换搜索表单.java和问候语中的一些元素.html，但我得到同样的错误。

Answer 1

你没有按照这个例子做所有事情。

您的获取请求不包含表单。

必须是：

@Controller
public class PrivacoogleController {

    @GetMapping("/")
    public String greeting(SearchForm searchForm) {
        return "greeting";
    }
    
    @PostMapping("/")
    public void getPost(SearchForm searchForm) {
        System.out.println(searchForm.getSearch());
    }

}