前端之家

  1. 首页
  2. 问答

在 Spring Boot 应用程序中添加分页时出错

• 问答

我从 Spring Boot 数据库教程开始，但想对 SQL 查询添加一些限制。

我添加了分页，但出现错误。

我有以下存储库类。

有什么想法吗？

谢谢。

package com.example.accessingdatamysql;

import org.springframework.data.domain.Example;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.repository.CrudRepository;

import com.example.accessingdatamysql.User;

// This will be AUTO IMPLEMENTED by Spring into a Bean called userRepository
// CRUD refers Create,Read,Update,Delete

public interface UserRepository extends CrudRepository<Consignment,Integer> {
    Page<Example> findByValidIsTrue(Pageable pageable);
}

错误如下

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'mainController': Unsatisfied dependency expressed through field 'userRepository'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userRepository' defined in com.example.accessingdatamysql.UserRepository defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration: invocation of init method failed; nested exception is org.springframework.data.repository.query.QueryCreationException: Could not create query for public abstract org.springframework.data.domain.Page com.example.accessingdatamysql.UserRepository.findConsignmentsByaccount(org.springframework.data.domain.Pageable)! Reason: Failed to create query for method public abstract org.springframework.data.domain.Page com.example.accessingdatamysql.UserRepository.findConsignmentsByaccount(org.springframework.data.domain.Pageable)! Method public abstract org.springframework.data.domain.Page com.example.accessingdatamysql.UserRepository.findConsignmentsByaccount(org.springframework.data.domain.Pageable) expects at least 1 arguments but only found 0. This leaves an operator of type SIMPLE_PROPERTY for property account unbound.; nested exception is java.lang.IllegalArgumentException: Failed to create query for method public abstract org.springframework.data.domain.Page com.example.accessingdatamysql.UserRepository.findConsignmentsByaccount(org.springframework.data.domain.Pageable)! Method public abstract org.springframework.data.domain.Page com.example.accessingdatamysql.UserRepository.findConsignmentsByaccount(org.springframework.data.domain.Pageable) expects at least 1 arguments but only found 0. This leaves an operator of type SIMPLE_PROPERTY for property account unbound.
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:660) ~[spring-beans-5.3.8.jar:5.3.8]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640) ~[spring-beans-5.3.8.jar:5.3.8]
at org.springframework.beans.factory.annotation.Injectionmetadata.inject(Injectionmetadata.java:119) ~[spring-beans-5.3.8.jar:5.3.8]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessproperties(AutowiredAnnotationBeanPostProcessor.java:399) ~[spring-beans-5.3.8.jar:5.3.8]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1413) ~[spring-beans-5.3.8.jar:5.3.8]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:601) ~[spring-beans-5.3.8.jar:5.3.8]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:524) ~[spring-beans-5.3.8.jar:5.3.8]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.8.jar:5.3.8]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.8.jar:5.3.8]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.8.jar:5.3.8]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.8.jar:5.3.8]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:944) ~[spring-beans-5.3.8.jar:5.3.8]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918) ~[spring-context-5.3.8.jar:5.3.8]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.8.jar:5.3.8]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.5.2.jar:2.5.2]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:754) ~[spring-boot-2.5.2.jar:2.5.2]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:434) ~[spring-boot-2.5.2.jar:2.5.2]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:338) ~[spring-boot-2.5.2.jar:2.5.2]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1343) ~[spring-boot-2.5.2.jar:2.5.2]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1332) ~[spring-boot-2.5.2.jar:2.5.2]
at com.example.accessingdatamysql.accessingDataMysqlApplication.main(accessingDataMysqlApplication.java:10) ~[classes/:na]
at java.base/jdk.internal.reflect.NativeMethodaccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodaccessorImpl.invoke(NativeMethodaccessorImpl.java:78) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodaccessorImpl.invoke(DelegatingMethodaccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) ~[spring-boot-devtools-2.5.2.jar:2.5.2]

下面是否使用了可能导致问题的控制器。我尝试删除@Autowired，但仍然无效。

package com.example.accessingdatamysql;
import com.google.gson.Gson;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.*;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;

@Controller // This means that this class is a Controller
@RequestMapping(path="/demo") // This means URL's start with /demo 
public class MainController {
@Autowired // This means to get the bean called userRepository
           // Which is auto-generated by Spring,we will use it to 
handle the data
private UserRepository userRepository;

@PostMapping(path="/add") // Map ONLY POST Requests
public @ResponseBody String addNewUser (@RequestParam String name,@RequestParam String email) {
    // @ResponseBody means the returned String is the response,not a view name
    // @RequestParam means it is a parameter from the GET or POST request

    return "Saved";
}

@GetMapping(path="/all")
@ResponseBody
public  String getallUsers() {
    // This returns a JSON or XML with the users

    PageRequest req = PageRequest.of(0,10); // I just want 10 record
    Page<Example> page =  userRepository.findByValidIsTrue(req );
    List<Example> nRecords = page.getcontent();

    Gson json = new Gson();
    return json.toJson(nRecords);

}

}

qwer879 回答：在 Spring Boot 应用程序中添加分页时出错

嗨@Chris，很少有问题CrudRepository 不支持 Pageable

如果要使用 Pageable 使用分页，请使用 JpaRepository 表单 Spring Data

public interface UserRepository extends JpaRepository<Example,Integer> {
    Page<Example> findByValidIsTrue(Pageable pageable);
}

注意：-您提供与返回类型类相同的类

,

你也可以用 PagingAnsSortingRespository 代替。

公共接口 UserRepository extends PagingAnsSortingRespository { Page findByValidIsTrue(Pageable pageable); }

,

在我看来，您的问题是 bean 创建问题。您可以在代码中验证以下步骤。

  1. 在 SpringBootApplication (Main Class)

    中添加或未添加基础包 
    @EntityScan("com.example.*") //packages for entity classes
@EnableJpaRepositories("com.example.*")//packages for repo classes

  2. 将 @Repository 和 JpaRepository 添加到存储库类

    @Repository
public interface UserRepository extends JpaRepository<Consignment,Integer> {
  Page<Example> findByValidIsTrue(Pageable pageable);
}

  3. 验证 @Configuration 类是否存在。

  4. 实体类应该有 @Entity、@Table。

  5. 主键 @Id 在 Consignment 中应该是整数类型。如接口签名中所述。 CrudRepository<Consignment,Integer>

javaspringspring-boot
本文链接：https://www.f2er.com/1444.html

大家都在问