NoUniqueBeanDefinitionException: No qualifying bean of type 'org.springframework.messaging.MessageChannel' available: expected single matching bean but found 2: nullChannel,errorChannel

根据抱错提示显示发现了两个channel的类，无法注入，这时就应该想到是channel创建错了之类的问题，由此可以想到可能包导错了。

看到我们导入的是这个包，而实际需要的是另一个包

现在再启动就正常了

NoUniqueBeanDefinitionException: No qualifying bean of type ‘org.springframework.messaging.MessageCh org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sendMessageController': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with Ch apter 1. Springing into action 1.1. Simplifying Java development 1.1.1. Unleashing the power of POJOs 1.1.2. Injecting dependencies 1.1.3. Applying aspects 1.1.4. Eliminating boilerplate code with templates 1.2. Containing your bea ns 1.2.1. Working with an application context 1.2.2. A bea n’s life 1.3. Surveying the Spring landscape 1.3.1. Spring modules 1.3.2. The Spring portfolio 1.4. What’s new in Spring 1.4.1. What was new in Spring 3.1? 1.4.2. What was new in Spring 3.2? 1.4.3. What’s new in Spring 4.0? 1.5. Summary Ch apter 2. Wiring bea ns 2.1. Exploring Spring’s configuration options 2.2. Automatically wiring bea ns 2.2.1. Creating discoverable bea ns 2.2.2. Naming a component-scanned bea n 2.2.3. Setting a base package for component scanning 2.2.4. Annotating bea ns to be automatically wired 2.2.5. Verifying automatic configuration 2.3. Wiring bea ns with Java 2.3.1. Creating a configuration class 2.3.2. Declaring a simple bea n 2.3.3. Injecting with Java Config 2.4. Wiring bea ns with XML 2.4.1. Creating an XML configuration specification 2.4.2. Declaring a simple < bea n> 2.4.3. Initializing a bea n with constructor injection 2.4.4. Setting properties 2.5. Importing and mixing configurations 2.5.1. Referencing XML configuration in Java Config 2.5.2. Referencing Java Config in XML configuration 2.6. Summary Ch apter 3. Advanced wiring 3.1. Environments and profiles 3.1.1. Configuring profile bea ns 3.1.2. Activating profiles 3.2. Conditional bea ns 3.3. Addressing ambiguity in autowiring 3.3.1. Designating a primary bea n 3.3.2. Qualifying autowired bea ns 3.4. Scoping bea ns 3.4.1. Working with request and session scope 3.4.2. Declaring scoped proxies in XML 3.5. Runtime value injection 3.5.1. Injecting external values 3.5.2. Wiring with the Spring Expression Language 3.6. Summary Ch apter 4. Aspect-oriented Spring 4.1. What is aspect-oriented programming? 4.1.1. Defining AOP terminology 4.1.2. Spring’s AOP support 4.2. Selecting join points with pointcuts 4.2.1. Writing pointcuts 4.2.2. Selecting bea ns in pointcuts 4.3. Creating annotated aspects 4.3.1. Defining an aspect 4.3.2. Creating around advice 4.3.3. Handling parameters in advice 4.3.4. Annotating introductions 4.4. Declaring aspects in XML 4.4.1. Declaring before and after advice 4.4.2. Declaring around advice 4.4.3. Passing parameters to advice 4.4.4. Introducing new functionality with aspects 4.5. Injecting AspectJ aspects 4.6. Summary 2. Spring on the web Ch apter 5. Building Spring web applications 5.1. Getting started with Spring MVC 5.1.1. Following the life of a request 5.1.2. Setting up Spring MVC 5.1.3. Introducing the Spittr application 5.2. Writing a simple controller 5.2.1. Testing the controller 5.2.2. Defining class-level request handling 5.2.3. Passing model data to the view 5.3. Accepting request input 5.3.1. Taking query parameters 5.3.2. Taking input via path parameters 5.4. Processing forms 5.4.1. Writing a form-handling controller 5.4.2. Validating forms 5.5. Summary Ch apter 6. Rendering web views 6.1. Understanding view resolution 6.2. Creating JSP views 6.2.1. Configuring a JSP-ready view resolver 6.2.2. Using Spring’s JSP libraries 6.3. Defining a layout with Apa ch e Tiles views 6.3.1. Configuring a Tiles view resolver 6.4. Working with Thymeleaf 6.4.1. Configuring a Thymeleaf view resolver 6.4.2. Defining Thymeleaf templates 6.5. Summary Ch apter 7. Advanced Spring MVC 7.1. Alternate Spring MVC configuration 7.1.1. Customizing Dispat ch erServlet configuration 7.1.2. Adding additional servlets and filters 7.1.3. Declaring Dispat ch erServlet in web.xml 7.2. Processing multipart form data 7.2.1. Configuring a multipart resolver 7.2.2. Handling multipart requests 7.3. Handling exception s 7.3.1. Mapping exception s to HTTP status codes 7.3.2. Writing exception -handling methods 7.4. Advising controllers 7.5. Carrying data across redirect requests 7.5.1. Redirecting with URL templates 7.5.2. Working with flash attributes 7.6. Summary Ch apter 8. Working with Spring Web Flow 8.1. Configuring Web Flow in Spring 8.1.1. Wiring a flow executor 8.1.2. Configuring a flow registry 8.1.3. Handling flow requests 8.2. The components of a flow 8.2.1. States 8.2.2. Transitions 8.2.3. Flow data 8.3. Putting it all together: the pizza flow 8.3.1. Defining the base flow 8.3.2. Collecting customer information 8.3.3. Building an order 8.3.4. Taking payment 8.4. Securing web flows 8.5. Summary Ch apter 9. Securing web applications 9.1. Getting started with Spring Security 9.1.1. Understanding Spring Security modules 9.1.2. Filtering web requests 9.1.3. Writing a simple security configuration 9.2. Selecting user details services 9.2.1. Working with an in-memory user store 9.2.2. Authenticating against database tables 9.2.3. Applying LDAP-backed authentication 9.2.4. Configuring a custom user service 9.3. Intercepting requests 9.3.1. Securing with Spring Expressions 9.3.2. Enforcing ch annel security 9.3.3. Preventing cross-site request f org ery 9.4. Authenticating users 9.4.1. Adding a custom login page 9.4.2. Enabling HTTP Basic authentication 9.4.3. Enabling remember-me functionality 9.4.4. Logging out 9.5. Securing the view 9.5.1. Using Spring Security’s JSP tag library 9.5.2. Working with Thymeleaf’s Spring Security dialect 9.6. Summary 3. Spring in the back end Ch apter 10. Hitting the database with Spring and JDBC 10.1. Learning Spring’s data-access philosophy 10.1.1. Getting to know Spring’s data-access exception hierar ch y 10.1.2. Templating data access 10.2. Configuring a data source 10.2.1. Using JNDI data sources 10.2.2. Using a pooled data source 10.2.3. Using JDBC driver-based data sources 10.2.4. Using an embedded data source 10.2.5. Using profiles to select a data source 10.3. Using JDBC with Spring 10.3.1. Tackling runaway JDBC code 10.3.2. Working with JDBC templates 10.4. Summary Ch apter 11. Persisting data with object-relational mapping 11.1. Integrating Hibernate with Spring 11.1.1. Declaring a Hibernate session factory 11.1.2. Building Spring-free Hibernate 11.2. Spring and the Java Persistence API 11.2.1. Configuring an entity manager factory 11.2.2. Writing a JPA-based repository 11.3. Automatic JPA repositories with Spring Data 11.3.1. Defining query methods 11.3.2. Declaring custom queries 11.3.3. Mixing in custom functionality 11.4. Summary Ch apter 12. Working with NoSQL databases 12.1. Persisting documents with MongoDB 12.1.1. Enabling MongoDB 12.1.2. Annotating model type s for MongoDB persistence 12.1.3. Accessing MongoDB with MongoTemplate 12.1.4. Writing a MongoDB repository 12.2. Working with graph data in Neo4j 12.2.1. Configuring Spring Data Neo4j 12.2.2. Annotating graph entities 12.2.3. Working with Neo4jTemplate 12.2.4. Creating automatic Neo4j repositories 12.3. Working with key-value data in Redis 12.3.1. Connecting to Redis 12.3.2. Working with RedisTemplate 12.3.3. Setting key and value serializers 12.4. Summary Ch apter 13. Ca ch ing data 13.1. Enabling ca ch e support 13.1.1. Configuring a ca ch e manager 13.2. Annotating methods for ca ch ing 13.2.1. Populating the ca ch e 13.2.2. Removing ca ch e entries 13.3. Declaring ca ch ing in XML 13.4. Summary Ch apter 14. Securing methods 14.1. Securing methods with annotations 14.1.1. Restricting method access with @Secured 14.1.2. Using JSR-250’s @RolesAllowed with Spring Security 14.2. Using expressions for method-level security 14.2.1. Expressing method access rules 14.2.2. Filtering method inputs and outputs 14.3. Summary 4. Integrating Spring Ch apter 15. Working with remote services 15.1. An overview of Spring remoting 15.2. Working with RMI 15.2.1. Exporting an RMI service 15.2.2. Wiring an RMI service 15.3. Exposing remote services with Hessian and Burlap 15.3.1. Exposing bea n functionality with Hessian/Burlap 15.3.2. Accessing Hessian/Burlap services 15.4. Using Spring’s HttpInvoker 15.4.1. Exposing bea ns as HTTP services 15.4.2. Accessing services via HTTP 15.5. Publishing and consuming web services 15.5.1. Creating Spring-enabled JAX-WS endpoints 15.5.2. Proxying JAX-WS services on the client side 15.6. Summary Ch apter 16. Creating REST APIs with Spring MVC 16.1. Getting REST 16.1.1. The fundamentals of REST 16.1.2. How Spring supports REST 16.2. Creating your first REST endpoint 16.2.1. Negotiating resource representation 16.2.2. Working with HTTP message converters 16.3. Serving more than resources 16.3.1. Communicating errors to the client 16.3.2. Setting headers in the response 16.4. Consuming REST resources 16.4.1. Exploring RestTemplate’s operations 16.4.2. GETting resources 16.4.3. Retrieving resources 16.4.4. Extracting response metadata 16.4.5. PUTting resources 16.4.6. DELETEing resources 16.4.7. POSTing resource data 16.4.8. Receiving object responses from POST requests 16.4.9. Receiving a resource location after a POST request 16.4.10. Ex ch anging resources 16.5. Summary Ch apter 17. Messaging in Spring 17.1. A brief introduction to asyn ch ronous messaging 17.1.1. Sending message s 17.1.2. Assessing the benefits of asyn ch ronous messaging 17.2. Sending message s with JMS 17.2.1. Setting up a message broker in Spring 17.2.2. Using Spring’s JMS template 17.2.3. Creating message -driven POJOs 17.2.4. Using message -based RPC 17.3. Messaging with AMQP 17.3.1. A brief introduction to AMQP 17.3.2. Configuring Spring for AMQP messaging 17.3.3. Sending message s with RabbitTemplate 17.3.4. Receiving AMQP message s NoUniqueBeanDefinitionException: No qualifying bean of type ‘org.springframework.messaging.MessageCh NoUniqueBeanDefinitionException: No qualifying bean of type ‘org.springframework.messaging.MessageCh 同样看的周阳老师的课，也是导入同样的包出的错 NoUniqueBeanDefinitionException: No qualifying bean of type ‘org.springframework.messaging.MessageCh 时间幻象: 有点强了，大佬 NoUniqueBeanDefinitionException: No qualifying bean of type ‘org.springframework.messaging.MessageCh CSDN-Ada助手: 不知道 Java 技能树是否可以帮到你：https://edu.csdn.net/skill/java?utm_source=AI_act_java NoUniqueBeanDefinitionException: No qualifying bean of type ‘org.springframework.messaging.MessageCh CSDN-Ada助手: 不知道 Java 技能树是否可以帮到你：https://edu.csdn.net/skill/java?utm_source=AI_act_java