CrudRepository上的错误.白标错误页面

Question

我有一个错误，我无法在 Spring boot 2.2.2 中使用我的存储库解决。这是一个简单的CRUD应用程序，使用带有JPA MySQL和Web-Starter的Spring boot 2。

错误是：

Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.
Mon Dec 16 10:03:20 GMT+01:00 2019
There was an unexpected error (type=Internal Server Error, status=500).
Invoked method public abstract java.lang.Iterable org.springframework.data.repository.CrudRepository.findAll() is no accessor method!
java.lang.IllegalArgumentException: Invoked method public abstract java.lang.Iterable org.springframework.data.repository.CrudRepository.findAll() is no accessor method!
at org.springframework.data.projection.Accessor.<init>(Accessor.java:50)
at org.springframework.data.projection.MapAccessingMethodInterceptor.invoke(MapAccessingMethodInterceptor.java:55)
at org.springframework.data.projection.ProjectingMethodInterceptor.invoke(ProjectingMethodInterceptor.java:65)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.data.projection.ProxyProjectionFactory$TargetAwareMethodInterceptor.invoke(ProxyProjectionFactory.java:245)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)
at com.sun.proxy.$Proxy133.findAll(Unknown Source)
at com.beroots.weblab2.controllers.TodoController.tplTodos(TodoController.java:32)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:888)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1591)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.base/java.lang.Thread.run(Thread.java:830)

我的存储库 ：

package com.beroots.weblab2.dao;
import java.sql.Date;
import java.util.List;
import org.springframework.data.repository.CrudRepository;
import com.beroots.weblab2.entities.Todo;
public interface TodoRepository extends CrudRepository<Todo, Long> {
List<Todo> findByName(String name);
List<Todo> findByCategory(String category);
List<Todo> findByDescription(String description);
List<Todo> findByDueDate(Date dueDate);
List<Todo> findByCreateDate(Date createDate);
List<Todo> findByState(boolean state);
}

还有我的控制器：

package com.beroots.weblab2.controllers;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Optional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.MessageSource;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import com.beroots.weblab2.controllers.exceptions.HashGenerationException;
import com.beroots.weblab2.dao.TodoRepository;
import com.beroots.weblab2.entities.Todo;
@Controller
public class TodoController {
@Autowired
MessageSource messageSource;
@Autowired
private TodoRepository todoRepository;
// --------------------------------------
@RequestMapping(value = "/todos", method = RequestMethod.GET)
public String tplTodos(Model model, TodoRepository todoRepository) {
Iterable<Todo> todos = todoRepository.findAll();
model.addAttribute("todos", todos);
return "v-todo-index";
}
}

我不明白为什么会出现此错误。我的代码似乎是正确的...

如果有人有想法;)

提前谢谢你。

Answer 1

用@Repository注释您的TodoRepository并从方法参数中删除 TodoRepository。

@RequestMapping(value = "/todos", method = RequestMethod.GET)
public String tplTodos(Model model) {
Iterable<Todo> todos = todoRepository.findAll();
model.addAttribute("todos", todos);
return "v-todo-index";
}
@Repository
public interface TodoRepository extends CrudRepository<Todo, Long> {
List<Todo> findByName(String name);
List<Todo> findByCategory(String category);
List<Todo> findByDescription(String description);
List<Todo> findByDueDate(Date dueDate);
List<Todo> findByCreateDate(Date createDate);
List<Todo> findByState(boolean state);
}

Answer 2

首先考虑： 你尝试基于构造函数的注入怎么样。因为无论如何，这是首选的注入方式。

private MessageSource messageSource;
private TodoRepository todoRepository
@Autowired
public TodoController(MessageSource messageSource, TodoRepository todoRepository) {
this.messageSource = messageSource;
this.todoRepository = todoRepository;
}

第二：

为什么不添加到存储库：

List<Todo> findAll();