Spring boot：使用xml的构造函数注入提供了"there is already n bean method"

Question

我很难使用XML工作进行构造函数注入。我有两个基本存储库类实现的实现，我想使用XML文件来指定使用哪个。

如果我切换到注释(将@primary放在其中一个实现类中(，则它有效，但是我不想更改每个类文件，而只是从一个存储库切换到另一个存储库。

我在做什么错？

基类

package com.iznogoud.cinj.repositories;
import java.util.ArrayList;
public abstract class StringRepository {
    public abstract ArrayList<String> getStrings();
}

两个实施类：

package com.iznogoud.cinj.repositories;
import java.util.ArrayList;
import org.springframework.stereotype.Repository;
@Repository
public class StringRepositoryImplOne extends StringRepository{
public StringRepositoryImplOne() {}
public ArrayList<String> getStrings() {
    ArrayList<String> result = new ArrayList<String>();
    result.add("One");
    result.add("Un");
    result.add("Eins");
    return result;
   }
}

...和...

package com.iznogoud.cinj.repositories;
import java.util.ArrayList;
import org.springframework.stereotype.Repository;
@Repository
public class StringRepositoryImplTwo extends StringRepository{
public StringRepositoryImplTwo() {}
public ArrayList<String> getStrings() {
    ArrayList<String> result = new ArrayList<String>();
    result.add("Two");
    result.add("Deux");
    result.add("Zwei");
    return result;
}
}

我想注入上面两个存储库之一的控制器：

package com.iznogoud.cinj.controllers;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.http.HttpSession;import 
org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.iznogoud.cinj.repositories.StringRepository;

@RestController
@RequestMapping("/cinj")
public class AController {
private StringRepository repository;

public AController(StringRepository _r) {
    repository = _r;
}

@GetMapping(path="/test", produces = MediaType.APPLICATION_JSON_VALUE)
List<String> getTimeSlots(HttpSession _session) throws IllegalArgumentException, ParseException  {
    ArrayList<String> availableStrings = repository.getStrings();
    return availableStrings;
 }
}

应用程序类

package com.iznogoud.cinj;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ImportResource;
import org.springframework.core.SpringVersion;

 @SpringBootApplication 
 @ImportResource("applicationContext.xml")
 public class CinjApplication {
    public static void main(String[] args) {
         System.err.println("Spring version: " + SpringVersion.getVersion());
        SpringApplication.run(CinjApplication.class, args);
     }
}

XML配置：

<?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:context="http://www.springframework.org/schema/context"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
                       http://www.springframework.org/schema/beans/spring-beans.xsd
                       http://www.springframework.org/schema/context
                       http://www.springframework.org/schema/context/spring-context.xsd">

<bean id="acont" class="com.iznogoud.cinj.controllers.AController">
    <constructor-arg ref="sr1"/>
</bean>  
<bean id="sr1" class="com.iznogoud.cinj.repositories.StringRepositoryImplOne" primary="true"/>
<bean id="sr2" class="com.iznogoud.cinj.repositories.StringRepositoryImplTwo" />
</beans>

pom.xml(由Spring Initializr生成，未修改(：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.6.RELEASE</version>
    <relativePath/> 
</parent>
<groupId>com.iznogoud</groupId>
<artifactId>cinj</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>cinj</name>
<description>Constructor injection</description>
<properties>
    <java.version>1.8</java.version>
</properties>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-rest</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>
</project>

最后，错误msg(简短版本(：

mvn clean spring-boot:run
[INFO] Scanning for projects...
[INFO]
[INFO] -------------------------< com.iznogoud:cinj >----------------------- 
[INFO] Building cinj 0.0.1-SNAPSHOT
[INFO] --------------------------------[ jar ]------------------------------    ---
[INFO]
[INFO] --- maven-clean-plugin:3.1.0:clean (default-clean) @ cinj ---
[INFO] Deleting D:Usersc82ssimeclipse-workspaceso_01target
[INFO]
[INFO] >>> spring-boot-maven-plugin:2.1.6.RELEASE:run (default-cli) > test-        compile @ cinj >>>
[INFO]
[INFO] --- maven-resources-plugin:3.1.0:resources (default-resources) @ cinj     ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO] Copying 1 resource
[INFO]
[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) @ cinj ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 5 source files to D:Usersc82ssimeclipse-work  spaceso_01targetclasses
[INFO]
[INFO] --- maven-resources-plugin:3.1.0:testResources (default-testResources) @ cinj ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory D:Usersc82ssimeclipse-    workspaceso_01srctestresources
[INFO]
[INFO] --- maven-compiler-plugin:3.8.1:testCompile (default-testCompile) @     cinj ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to D:Usersc82ssimeclipse-    workspaceso_01targettest-classes
[INFO]
[INFO] <<< spring-boot-maven-plugin:2.1.6.RELEASE:run (default-cli) < test-    compile @ cinj <<<
[INFO]
[INFO]
[INFO] --- spring-boot-maven-plugin:2.1.6.RELEASE:run (default-cli) @ cinj -    --
Spring version: 5.1.8.RELEASE
  .   ____          _            __ _ _
 /\ / ___'_ __ _ _(_)_ __  __ _    
( ( )___ | '_ | '_| | '_ / _` |    
 \/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |___, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.6.RELEASE)
2019-08-01 11:41:27.466  INFO 10612 --- [           main] com.iznogoud.cinj.CinjApplication        : Starting CinjApplication on     E82AAT4014 with PID 10612 (D:Usersc82ssimeclipse-    workspaceso_01targetclasses started by c82ssim in D:Usersc82ssimeclipse-    workspaceso_01)
2019-08-01 11:41:27.470  INFO 10612 --- [           main]     com.iznogoud.cinj.CinjApplication        : No active profile set, falling back     to default profiles: default
2019-08-01 11:41:28.482  INFO 10612 --- [           main]     trationDelegate$BeanPostProcessorChecker : Bean     'org.springframework.hateoas.config.HateoasConfiguration' of type     [org.springframework.hateoas.config.HateoasConfiguration$$EnhancerBySpringCGLIB$$bbc50a5] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2019-08-01 11:41:28.943  INFO 10612 --- [           main]     o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8084     (http)
2019-08-01 11:41:28.969  INFO 10612 --- [           main]     o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2019-08-01 11:41:28.970  INFO 10612 --- [           main]     org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.21]
2019-08-01 11:41:29.078  INFO 10612 --- [           main] o.a.c.c.C.    [Tomcat].[localhost].[/]       : Initializing Spring embedded     WebApplicationContext
2019-08-01 11:41:29.078  INFO 10612 --- [           main]     o.s.web.context.ContextLoader            : Root WebApplicationContext:     initialization completed in 1472 ms
2019-08-01 11:41:29.823  INFO 10612 --- [           main]     o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService     'applicationTaskExecutor'
2019-08-01 11:41:29.925  WARN 10612 --- [           main]     ConfigServletWebServerApplicationContext : Exception encountered during context     initialization - cancelling refresh attempt:     org.springframework.beans.factory.BeanCreationException: Error creating bean     with name 'requestMappingHandlerMapping' defined in class path resource     [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$Enab    leWebMvcConfiguration.class]: Invocation of init method failed; nested exception     is java.lang.IllegalStateException: Ambiguous mapping. Cannot map 'acont' method
java.util.List<java.lang.String>     com.iznogoud.cinj.controllers.AController.getTimeSlots(javax.servlet.http.HttpSe    ssion) throws java.lang.IllegalArgumentException,java.text.ParseException
to {GET /cinj/test, produces [application/json]}: There is already     'AController' bean method
java.util.List<java.lang.String>     com.iznogoud.cinj.controllers.AController.getTimeSlots(javax.servlet.http.HttpSe    ssion) throws java.lang.IllegalArgumentException,java.text.ParseException mapped.

更新1：如果我将控制器注释更改为：

@RestController(value="acont")

我得到这个例外：

[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.1.6.RELEASE:run (default-cli) on project cinj: An exception occurred while running. null: InvocationTargetException: Configuration problem: Failed to register bean definition with name 'acont'
[ERROR] Offending resource: class path resource [applicationContext.xml]; nested exception is 
org.springframework.beans.factory.support.BeanDefinitionOverrideException: 
Invalid bean definition with name 'acont' defined in class path resource 
[applicationContext.xml]: Cannot register bean definition [Generic bean: class 
[com.iznogoud.cinj.controllers.AController]; scope=; abstract=false; 
lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; 
primary=false; factoryBeanName=null; factoryMethodName=null; 
initMethodName=null; destroyMethodName=null; defined in class path resource 
[applicationContext.xml]] for bean 'acont': There is already [Generic bean: 
class [com.iznogoud.cinj.controllers.AController]; scope=singleton; 
abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; 
autowireCandidate=true; primary=false; factoryBeanName=null; 
factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in 
file 
[D:Usersc82ssimeclipse- 
workspaceso_01targetclassescomiznogoudcinj
controllersAController.class]] 
bound.here

Answer 1

如果问题是关于" Acont"豆的模棱两可的方法，也许您必须命名：

@Controller("/acont")
public class AController {...}

Answer 2

默认情况下，bean在弹簧中通过类型检测到。在您的情况下，您直接通过抽象类注射。

private StringRepository repository;

在这种情况下，您需要使用@Qualifier指示您完全参考的bean。

@Repository("ImplTwo)
public class StringRepositoryImplTwo extends StringRepository{

simillary，

@Repository("ImplOne)
public class StringRepositoryImplOne extends StringRepository{

并更新您的依赖注入为

@Qualifier("ImplTwo") // or "ImplOne" as per your requirement
private StringRepository repository;

或当您使用构造函数注入时，

private StringRepository repository;
public AController(@Qualifier("ImplTwo") StringRepository _r) {
    repository = _r;
}