问Springboot :扫描bean时失败
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Stack Overflow用户

提问于 2020-08-18 12:13:23

回答 2查看 311关注 0票数 0

我在试着理解弹跳力的概念。

我有如下所述的项目结构。有两个包，我在每个包中有一个类。

 src/main/java
      > com.emerald.paymentengine
         ApplicationRun.java
      > com.emerald.paymentengine.config
         DataSourceDbConfig.java

当我试图按照上面的结构运行ApplicationRun.java时，我得到的错误如下：

错误：

2020-08-19 01:33:08.673  INFO 30128 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2020-08-19 01:33:08.673  INFO 30128 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.37]
2020-08-19 01:33:08.749  INFO 30128 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2020-08-19 01:33:08.750  INFO 30128 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 657 ms
2020-08-19 01:33:08.779  WARN 30128 --- [  restartedMain] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'applicationRun': Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.emerlad.paymentengine.config.DataSourceDbConfig' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
2020-08-19 01:33:08.781  INFO 30128 --- [  restartedMain] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2020-08-19 01:33:08.791  INFO 30128 --- [  restartedMain] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2020-08-19 01:33:08.883 ERROR 30128 --- [  restartedMain] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 0 of constructor in com.emerald.paymentengine.ApplicationRun required a bean of type 'com.emerlad.paymentengine.config.DataSourceDbConfig' that could not be found.


Action:

Consider defining a bean of type 'com.emerlad.paymentengine.config.DataSourceDbConfig' in your configuration.

但是，当我在下面提到的同一个包中移动DataSourceDbConfig.java时，它正在运行，并且我的输出低于：

src/main/java
      > com.emerald.paymentengine
         ApplicationRun.java
         DataSourceDbConfig.java

输出:

2020-08-19 01:37:24.726  INFO 34364 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2020-08-19 01:37:24.726  INFO 34364 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.37]
2020-08-19 01:37:24.810  INFO 34364 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2020-08-19 01:37:24.810  INFO 34364 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 722 ms
2020-08-19 01:37:24.849  INFO 34364 --- [  restartedMain] f.a.AutowiredAnnotationBeanPostProcessor : Autowired annotation is not supported on static fields: static com.emerald.paymentengine.DataSourceDbConfig com.emerald.paymentengine.ApplicationRun.dbConfig
Connection established !!
2020-08-19 01:37:24.981  INFO 34364 --- [  restartedMain] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2020-08-19 01:37:25.116  INFO 34364 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2020-08-19 01:37:25.140  INFO 34364 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8082 (http) with context path ''
2020-08-19 01:37:25.148  INFO 34364 --- [  restartedMain] c.emerald.paymentengine.ApplicationRun   : Started ApplicationRun in 1.335 seconds (JVM running for 2.406)

我认为@SpringBootApplication将自动扫描主包和子包，并能够选择所需的bean。正如第一个场景中提到的那样，如何通过将Config.java文件放置在不同的包中来使其工作呢？

代码:

ApplicationRun.java

package com.emerald.paymentengine;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class ApplicationRun {
    
    @Autowired
    static
     DataSourceDbConfig dbConfig;
    
    
    public ApplicationRun(DataSourceDbConfig dbConfig){
        ApplicationRun.dbConfig = dbConfig  ;
    }
    

    public static void main(String[] args) {
        SpringApplication.run(ApplicationRun.class, args);
        
        dbConfig.dataSource();
    
    }

}

DataSourceDbConfig.java

package com.emerlad.paymentengine.config;;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;

import oracle.jdbc.pool.OracleDataSource;
import java.sql.SQLException;
import javax.sql.DataSource;

@Component
@Configuration
@ConfigurationProperties("spring.datasource")

public class DataSourceDbConfig {
    
    @Value("${spring.datasource.url}")
    private String dbUrl;
        
    @Value("${spring.datasource.username}")
    private String dbUser;
        
    @Value("${spring.datasource.secure}")
    private String dbPasswrd;
    
    @Bean
    public DataSource dataSource() {
        
        OracleDataSource dataSource = null;
        try {
            dataSource = new OracleDataSource();
            dataSource.setUser(dbUser);
            dataSource.setPassword(dbPasswrd);
            dataSource.setURL(dbUrl);
            
            System.out.println("Connection established !!");
            
        } catch (SQLException e) {
            System.out.println("An issue occured while establishing connection !!");
            e.printStackTrace();
        }
        
        return dataSource;
    }

}

spring-boot

spring-bean

回答 2

Stack Overflow用户

发布于 2020-08-18 12:42:01

老实说，我不明白您想要实现什么，但这就是如何在您的主要方法中获得DataSource bean：

ApplicationRun.java：

package com.emerald.paymentengine;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import com.emerlad.paymentengine.config.DataSourceDbConfig;
import org.springframework.context.annotation.Import;
import javax.sql.DataSource;

@SpringBootApplication
@Import(DataSourceDbConfig.class)
public class ApplicationRun {
    public static void main(String[] args) {
        ApplicationContext context = SpringApplication.run(ApplicationRun.class, args);
        
        DataSource dataSource = context.getBean(DataSource.class)
    }
}

DataSourceDbConfig.java：

package com.emerlad.paymentengine.config;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;

import oracle.jdbc.pool.OracleDataSource;
import java.sql.SQLException;
import javax.sql.DataSource;

@Configuration
@ConfigurationProperties("spring.datasource")
public class DataSourceDbConfig {
    @Value("${spring.datasource.url}")
    private String dbUrl;
        
    @Value("${spring.datasource.username}")
    private String dbUser;
        
    @Value("${spring.datasource.secure}")
    private String dbPasswrd;
    
    @Bean
    public DataSource dataSource() {
        OracleDataSource dataSource = null;
        try {
            dataSource = new OracleDataSource();
            dataSource.setUser(dbUser);
            dataSource.setPassword(dbPasswrd);
            dataSource.setURL(dbUrl);
            System.out.println("Connection established !!");
        } catch (SQLException e) {
            System.out.println("An issue occured while establishing connection !!");
            e.printStackTrace();
        }
        return dataSource;
    }
}

票数 0

Stack Overflow用户

发布于 2020-08-18 12:45:39

使用@

类DataSourceDbConfig --使用@Configuration包括@Component，这样您就可以摆脱它
类ApplicationRun --我将保持它的简单性并删除

@SpringBootApplication
public class ApplicationRun {
    
    public static void main(String[] args) {
        ApplicationContext appContext = SpringApplication.run(ApplicationRun.class, args);

        // Getting datasource from application context.
        DataSource dataSource = appContext.getBean(DataSource.class);
    
    }

}