spring boot無法自動注入bean？原因在這兒
阿新 • • 發佈：2019-01-08
Description:
Field helloSpringBootService in com.zd.hellospringboot.HelloController required a bean of type 'com.zd.service.HelloSpringBootService' that could not be found.
Action:
Consider defining a bean of type 'com.zd.service.HelloSpringBootService' in your configuration.這段話的大致意思為：在com.zd.hellospringboot helloSpringBootService.HelloController需要一個com.zd.service型別的bean。無法找到HelloSpringBootService;
我的專案結構為：
APP 類的程式碼為：
package com.zd.hellospringboot; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; /** * Hello world! * */ // 此註解指定這是一個SpringBoot的應用程式，不加就會報異常 Unable to start // ServletWebServerApplicationContext due to missing ServletWebServerFactory // bean @SpringBootApplication public class App { public static void main(String[] args) { // SpringApplication用於從main方法中啟動Spring應用的類 SpringApplication.run(App.class, args); } }
controller類的程式碼為：
package com.zd.hellospringboot; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import com.zd.service.HelloSpringBootService; //RestController相當於SpringMVC中的 @Controller + @ResponseBody @RestController public class HelloController { @Autowired private HelloSpringBootService helloSpringBootService; // 對映"/hello"請求 @RequestMapping("/hello3") public String hello3() { return helloSpringBootService.sayHelloWord(); } }
service程式碼為：
package com.zd.service;
public interface HelloSpringBootService {
public String sayHelloWord();
}
serviceImpl程式碼為：
package com.zd.serviceimpl;
import org.springframework.stereotype.Service;
import com.zd.service.HelloSpringBootService;
@Service("helloSpringBootService")
public class HelloSpringBootImpl implements HelloSpringBootService {
@Override
public String sayHelloWord() {
String str = "這裡是springBoot實現類中的方法！";
return str;
}
}
程式碼沒有什麼問題，但是在這種專案結構下執行報錯為：
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.0.0.RELEASE)
2018-09-04 11:02:22.144 INFO 14200 --- [ main] com.zd.hellospringboot.App : Starting App on zdAdmin with PID 14200 (D:\workspace\helloSpringBoot\target\classes started by zdAdmin in D:\workspace\helloSpringBoot)
2018-09-04 11:02:22.147 INFO 14200 --- [ main] com.zd.hellospringboot.App : No active profile set, falling back to default profiles: default
2018-09-04 11:02:22.192 INFO 14200 --- [ main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.ser[email protected]2ea6137: startup date [Tue Sep 04 11:02:22 CST 2018]; root of context hierarchy
2018-09-04 11:02:22.993 INFO 14200 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2018-09-04 11:02:23.013 INFO 14200 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2018-09-04 11:02:23.013 INFO 14200 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.28
2018-09-04 11:02:23.018 INFO 14200 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [C:\Program Files\Java\jre1.8.0_172\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:/Program Files/Java/jre1.8.0_172/bin/server;C:/Program Files/Java/jre1.8.0_172/bin;C:/Program Files/Java/jre1.8.0_172/lib/amd64;D:\app\zdAdmin\product\11.2.0\client_1\bin;F:\app\zdAdmin\product\11.2.0\client_1\bin;E:\app\zdAdmin\product\11.2.0\dbhome_1\bin;C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\Program Files (x86)\Intel\iCLS Client\;C:\Program Files\Intel\iCLS Client\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Java\jdk1.8.0_172\bin;E:\Program Files\VisualSVN Server\bin;E:\Program Files\TortoiseSVN\bin;E:\tools\apache-maven-3.5.3\bin;E:\ue;D:\app\zdAdmin\product\11.2.0\client_1\BIN;E:\app\zdAdmin\product\11.2.0\dbhome_1\BIN;C:\Users\zdAdmin\AppData\Local\Microsoft\WindowsApps;;E:\開發軟體\eclipse;;.]
2018-09-04 11:02:23.110 INFO 14200 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2018-09-04 11:02:23.110 INFO 14200 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 927 ms
2018-09-04 11:02:23.213 INFO 14200 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Servlet dispatcherServlet mapped to [/]
2018-09-04 11:02:23.213 INFO 14200 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-09-04 11:02:23.213 INFO 14200 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-09-04 11:02:23.213 INFO 14200 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-09-04 11:02:23.213 INFO 14200 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]
2018-09-04 11:02:23.256 WARN 14200 --- [ main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'helloController': Unsatisfied dependency expressed through field 'helloSpringBootService'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.zd.service.HelloSpringBootService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
2018-09-04 11:02:23.258 INFO 14200 --- [ main] o.apache.catalina.core.StandardService : Stopping service [Tomcat]
2018-09-04 11:02:23.270 INFO 14200 --- [ main] ConditionEvaluationReportLoggingListener :
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2018-09-04 11:02:23.348 ERROR 14200 --- [ main] o.s.b.d.LoggingFailureAnalysisReporter :
***************************
APPLICATION FAILED TO START
***************************
Description:
Field helloSpringBootService in com.zd.hellospringboot.HelloController required a bean of type 'com.zd.service.HelloSpringBootService' that could not be found.
Action:
Consider defining a bean of type 'com.zd.service.HelloSpringBootService' in your configuration.
解決辦法：
根據英文提示報錯原因是在配置中找不到指定的自動注入型別bean；
去網上查詢相關問題，原因如下：
SpringBoot專案的Bean裝配預設規則是根據Application類所在的包位置從上往下掃描！
“Application類”是指SpringBoot專案入口類。這個類的位置很關鍵：
如果Application類所在的包為：com.boot.app，則只會掃描com.boot.app包及其所有子包，如果service或dao所在包不在com.boot.app及其子包下，則不會被掃描！
即, 把Application類放到dao、service所在包的上級，com.boot.Application
知道這一點非常關鍵，不知道Spring文件裡有沒有給出說明，如果不知道還真是無從解決。也就是說我這裡報錯是因為APP類（SpringBoot專案入口類）所在的包的子包和APP類不在同一個父包下面，所以會報錯；因此我修改service及serviceImpl所在包的包名為：
原先的是這樣的：
修改完成後啟動專案：
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.0.0.RELEASE)
2018-09-04 11:26:34.094 INFO 12536 --- [ main] com.zd.hellospringboot.App : Starting App on zdAdmin with PID 12536 (D:\workspace\helloSpringBoot\target\classes started by zdAdmin in D:\workspace\helloSpringBoot)
2018-09-04 11:26:34.098 INFO 12536 --- [ main] com.zd.hellospringboot.App : No active profile set, falling back to default profiles: default
2018-09-04 11:26:34.134 INFO 12536 --- [ main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.ser[email protected]52e677af: startup date [Tue Sep 04 11:26:34 CST 2018]; root of context hierarchy
2018-09-04 11:26:34.969 INFO 12536 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2018-09-04 11:26:34.985 INFO 12536 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2018-09-04 11:26:34.985 INFO 12536 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.28
2018-09-04 11:26:34.985 INFO 12536 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [C:\Program Files\Java\jre1.8.0_172\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:/Program Files/Java/jre1.8.0_172/bin/server;C:/Program Files/Java/jre1.8.0_172/bin;C:/Program Files/Java/jre1.8.0_172/lib/amd64;D:\app\zdAdmin\product\11.2.0\client_1\bin;F:\app\zdAdmin\product\11.2.0\client_1\bin;E:\app\zdAdmin\product\11.2.0\dbhome_1\bin;C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\Program Files (x86)\Intel\iCLS Client\;C:\Program Files\Intel\iCLS Client\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Java\jdk1.8.0_172\bin;E:\Program Files\VisualSVN Server\bin;E:\Program Files\TortoiseSVN\bin;E:\tools\apache-maven-3.5.3\bin;E:\ue;D:\app\zdAdmin\product\11.2.0\client_1\BIN;E:\app\zdAdmin\product\11.2.0\dbhome_1\BIN;C:\Users\zdAdmin\AppData\Local\Microsoft\WindowsApps;;E:\開發軟體\eclipse;;.]
2018-09-04 11:26:35.086 INFO 12536 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2018-09-04 11:26:35.087 INFO 12536 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 968 ms
2018-09-04 11:26:35.203 INFO 12536 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Servlet dispatcherServlet mapped to [/]
2018-09-04 11:26:35.208 INFO 12536 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-09-04 11:26:35.208 INFO 12536 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-09-04 11:26:35.209 INFO 12536 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-09-04 11:26:35.209 INFO 12536 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]
2018-09-04 11:26:35.495 INFO 12536 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.ser[email protected]52e677af: startup date [Tue Sep 04 11:26:34 CST 2018]; root of context hierarchy
2018-09-04 11:26:35.542 INFO 12536 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hello2]}" onto public java.lang.String com.zd.hellospringboot.HelloController.hello2()
2018-09-04 11:26:35.542 INFO 12536 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hello]}" onto public java.lang.String com.zd.hellospringboot.HelloController.hello()
2018-09-04 11:26:35.542 INFO 12536 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hello3]}" onto public java.lang.String com.zd.hellospringboot.HelloController.hello3()
2018-09-04 11:26:35.542 INFO 12536 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-09-04 11:26:35.542 INFO 12536 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2018-09-04 11:26:35.574 INFO 12536 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-09-04 11:26:35.574 INFO 12536 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-09-04 11:26:35.605 INFO 12536 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-09-04 11:26:35.742 INFO 12536 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2018-09-04 11:26:35.761 INFO 12536 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2018-09-04 11:26:35.776 INFO 12536 --- [ main] com.zd.hellospringboot.App : Started App in 1.948 seconds (JVM running for 2.652)
沒有再報錯，去瀏覽器訪問，成功執行：
