第2部分：

Question

在Java中使用MongoDB

请注意，这个常规查询只是为了查看其功能，所以请不要告诉我休眠中有其他选择（我已经知道，我只想运行它）

错误

Exception in thread "main" java.lang.NullPointerException
    at repository.serviceclass.getjsondatamongo(serviceclass.java:25)
    at springbootwebsocketexample.SpringBootWebsocketExampleApplication.main(SpringBootWebsocketExampleApplication.java:58)

对于UR HELP   （serviceclass.java:25）== return userrep2.obj1();   SpringBootWebsocketExampleApplication.java:58=== JSONObject jsOn1=cc1.getjsondatamongo();

这是我的存储库。UserRepository.java

package repository;

import java.util.ArrayList;
import java.util.*;
import org.json.*;

//import org.springframework.data.mongodb.core.query.Query;
import org.springframework.data.mongodb.repository.*;

import com.mongodb.connection.*;
import document.Users;
public interface UserRepository extends MongoRepository<Users,Integer> {




    @Query("db.users.find()")
    JSONObject obj1(); 
}

这是我的repository.serviceclass

package repository;

import java.util.*;

import org.json.*;
import org.springframework.beans.factory.annotation.*;
import org.springframework.stereotype.*;
import document.*;
@Service
public class serviceclass {
    @Autowired
    UserRepository userrep2;
    public JSONObject getjsondatamongo()
    {
        return userrep2.obj1();
    }
}

这是我的SpringBootWebsocketExampleApplication.java

package springbootwebsocketexample;

import org.json.JSONObject;
import org.springframework.beans.factory.annotation.*;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.*;
import org.springframework.context.annotation.*;
import org.springframework.context.annotation.*;
import org.springframework.stereotype.*;
import repository.*;
import document.Users;
import repository.*;

import java.awt.*;
import java.util.*;
import java.util.List;

import org.json.*;
@SpringBootApplication
@ComponentScan(basePackages= {"resource"})
@ComponentScan(basePackages= {"document"})
@ComponentScan(basePackages= {"repository"})
@ComponentScan(basePackages= {"config"})
public class SpringBootWebsocketExampleApplication implements CommandLineRunner {

    @Autowired
    public serviceclass cc1 ;
    public static void main(String[] args) {


        SpringApplication.run(SpringBootWebsocketExampleApplication.class, args);

    }


      @Override
        public void run(String... args) throws Exception {
             List<Users> kk=new ArrayList<Users>();
             JSONObject jsOn1=cc1.getjsondatamongo();
             System.out.println(jsOn1);
        }
}

更新我已经更新了我的SpringBootWebsocketExampleApplication.java 新错误=造成原因：com.mongodb.util.JSONParseException：db.users.find（）

15:45:36.951 [main] DEBUG org.springframework.boot.devtools.settings.DevToolsSettings - Included patterns for restart : []
15:45:36.954 [main] DEBUG org.springframework.boot.devtools.settings.DevToolsSettings - Excluded patterns for restart : [/spring-boot-starter/target/classes/, /spring-boot-autoconfigure/target/classes/, /spring-boot-starter-[\w-]+/, /spring-boot/target/classes/, /spring-boot-actuator/target/classes/, /spring-boot-devtools/target/classes/]
15:45:36.954 [main] DEBUG org.springframework.boot.devtools.restart.ChangeableUrls - Matching URLs for reloading : [file:/C:/Users/vaibhav.chhabra/Documents/workspace-sts-3.9.7.RELEASE/DB_Mongo_exapme_name/target/classes/]

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::       (v1.5.10.RELEASE)

2019-02-12 15:45:37.110  INFO 3048 --- [  restartedMain] s.SpringBootWebsocketExampleApplication  : Starting SpringBootWebsocketExampleApplication on VNL-VaibhavC with PID 3048 (C:\Users\vaibhav.chhabra\Documents\workspace-sts-3.9.7.RELEASE\DB_Mongo_exapme_name\target\classes started by vaibhav.chhabra in C:\Users\vaibhav.chhabra\Documents\workspace-sts-3.9.7.RELEASE\DB_Mongo_exapme_name)
2019-02-12 15:45:37.110  INFO 3048 --- [  restartedMain] s.SpringBootWebsocketExampleApplication  : No active profile set, falling back to default profiles: default
2019-02-12 15:45:37.150  INFO 3048 --- [  restartedMain] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@1599273b: startup date [Tue Feb 12 15:45:37 IST 2019]; root of context hierarchy
2019-02-12 15:45:38.032  INFO 3048 --- [  restartedMain] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2019-02-12 15:45:38.038  INFO 3048 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2019-02-12 15:45:38.039  INFO 3048 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.27
2019-02-12 15:45:38.089  INFO 3048 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2019-02-12 15:45:38.089  INFO 3048 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 941 ms
2019-02-12 15:45:38.183  INFO 3048 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2019-02-12 15:45:38.185  INFO 3048 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2019-02-12 15:45:38.186  INFO 3048 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2019-02-12 15:45:38.186  INFO 3048 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2019-02-12 15:45:38.186  INFO 3048 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2019-02-12 15:45:38.448  INFO 3048 --- [  restartedMain] org.mongodb.driver.cluster               : Cluster created with settings {hosts=[localhost:27017], mode=MULTIPLE, requiredClusterType=UNKNOWN, serverSelectionTimeout='30000 ms', maxWaitQueueSize=500}
2019-02-12 15:45:38.448  INFO 3048 --- [  restartedMain] org.mongodb.driver.cluster               : Adding discovered server localhost:27017 to client view of cluster
2019-02-12 15:45:38.489  INFO 3048 --- [localhost:27017] org.mongodb.driver.connection            : Opened connection [connectionId{localValue:1, serverValue:225}] to localhost:27017
2019-02-12 15:45:38.490  INFO 3048 --- [localhost:27017] org.mongodb.driver.cluster               : Monitor thread successfully connected to server with description ServerDescription{address=localhost:27017, type=STANDALONE, state=CONNECTED, ok=true, version=ServerVersion{versionList=[4, 0, 5]}, minWireVersion=0, maxWireVersion=7, maxDocumentSize=16777216, roundTripTimeNanos=459434}
2019-02-12 15:45:38.491  INFO 3048 --- [localhost:27017] org.mongodb.driver.cluster               : Discovered cluster type of STANDALONE
2019-02-12 15:45:38.622  WARN 3048 --- [  restartedMain] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'springBootWebsocketExampleApplication': Unsatisfied dependency expressed through field 'cc1'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'serviceclass': Unsatisfied dependency expressed through field 'userrep2'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userRepository': Invocation of init method failed; nested exception is com.mongodb.util.JSONParseException: 
db
^
2019-02-12 15:45:38.626  INFO 3048 --- [  restartedMain] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2019-02-12 15:45:38.634  INFO 3048 --- [  restartedMain] utoConfigurationReportLoggingInitializer : 

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2019-02-12 15:45:38.641 ERROR 3048 --- [  restartedMain] o.s.boot.SpringApplication               : Application startup failed

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'springBootWebsocketExampleApplication': Unsatisfied dependency expressed through field 'cc1'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'serviceclass': Unsatisfied dependency expressed through field 'userrep2'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userRepository': Invocation of init method failed; nested exception is com.mongodb.util.JSONParseException: 
db
^
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) ~[spring-context-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543) ~[spring-context-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at springbootwebsocketexample.SpringBootWebsocketExampleApplication.main(SpringBootWebsocketExampleApplication.java:65) [classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_201]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_201]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_201]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_201]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-1.5.10.RELEASE.jar:1.5.10.RELEASE]
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'serviceclass': Unsatisfied dependency expressed through field 'userrep2'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userRepository': Invocation of init method failed; nested exception is com.mongodb.util.JSONParseException: 
db
^
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    ... 24 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userRepository': Invocation of init method failed; nested exception is com.mongodb.util.JSONParseException: 
db
^
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1628) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    ... 37 common frames omitted
Caused by: com.mongodb.util.JSONParseException: 
db
^
    at com.mongodb.util.JSONParser.parse(JSON.java:230) ~[mongodb-driver-3.4.3.jar:na]
    at com.mongodb.util.JSONParser.parse(JSON.java:155) ~[mongodb-driver-3.4.3.jar:na]
    at com.mongodb.util.JSON.parse(JSON.java:92) ~[mongodb-driver-3.4.3.jar:na]
    at com.mongodb.util.JSON.parse(JSON.java:73) ~[mongodb-driver-3.4.3.jar:na]
    at org.springframework.data.mongodb.repository.query.StringBasedMongoQuery$ParameterBindingParser.parseAndCollectParameterBindingsFromQueryIntoBindings(StringBasedMongoQuery.java:230) ~[spring-data-mongodb-1.10.10.RELEASE.jar:na]
    at org.springframework.data.mongodb.repository.query.StringBasedMongoQuery.<init>(StringBasedMongoQuery.java:93) ~[spring-data-mongodb-1.10.10.RELEASE.jar:na]
    at org.springframework.data.mongodb.repository.query.StringBasedMongoQuery.<init>(StringBasedMongoQuery.java:72) ~[spring-data-mongodb-1.10.10.RELEASE.jar:na]
    at org.springframework.data.mongodb.repository.support.MongoRepositoryFactory$MongoQueryLookupStrategy.resolveQuery(MongoRepositoryFactory.java:169) ~[spring-data-mongodb-1.10.10.RELEASE.jar:na]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.<init>(RepositoryFactorySupport.java:449) ~[spring-data-commons-1.13.10.RELEASE.jar:na]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:222) ~[spring-data-commons-1.13.10.RELEASE.jar:na]
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.initAndReturn(RepositoryFactoryBeanSupport.java:277) ~[spring-data-commons-1.13.10.RELEASE.jar:na]
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.afterPropertiesSet(RepositoryFactoryBeanSupport.java:263) ~[spring-data-commons-1.13.10.RELEASE.jar:na]
    at org.springframework.data.mongodb.repository.support.MongoRepositoryFactoryBean.afterPropertiesSet(MongoRepositoryFactoryBean.java:117) ~[spring-data-mongodb-1.10.10.RELEASE.jar:na]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1687) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1624) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    ... 47 common frames omitted

Answer 1

用@Repository注释您的存储库类。

也不要这样做：

ServiceClass cc1 = new ServiceClass();

相反，应该在其中注入@Autowired批注以让Spring框架完成其工作，如下所示：

public class SpringBootWebsocketExampleApplication implements CommandLineRunner {

    @Autowired
    private ServiceClass serviceClass;

    public static void main(String[] args) {
        SpringApplication.run(SpringBootWebsocketExampleApplication.class, args);

    }

    @Override
    public void run(String... args) throws Exception {
         List<Users> kk=new ArrayList<Users>();
         JSONObject jsOn1=cc1.getjsondatamongo();
         System.out.println(jsOn1);
    }

}

这是春天的方法。其他阅读：https://www.baeldung.com/inversion-control-and-dependency-injection-in-spring

还有一点建议：遵循命名约定/标准。班级应以大写字母命名，并以大写字母命名，例如UserRepository，UserService

第2部分：

假设您的最新/当前异常。我认为将查询结果解析为JSONObject时存在问题。我对此不太确定，但通常您想返回POJO的列表，即List<User>。

此外，您可能可以使用findAll()之类的“内置”方法-无需在此处使用native query。试试这个：

@Service
public class ServiceClass {
    @Autowired
    UserRepository userRepository;
    public JSONObject getjsondatamongo()
    {
        return userRepository.findAll();
    }
}

part3

通过一些互联网教程和阅读文档，我认为您应该简单地省略db.collection.find()并在{}中提供@Query。如要返回全部数据，则类似于@Query("{}")。

使用MongoDB错误com.mongodb.util.JSONParseException（uPDATED）

1 个答案:

第2部分：

part3