没有“javax.persistence.EntityManager”类型的合格bean可用：需要一个匹配bean，但找到2个

Question

我有两个实体管理器配置用于两个单独的数据库，但当我尝试自动连接实体管理器来配置GraphQLExecutor bean时，我得到一个异常，指出有两个bean符合条件，尽管我在PersistenceContext中指定了一个单元名。

例外情况

package com.ogl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.Database;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;

import javax.sql.DataSource;

@Configuration
@EnableJpaRepositories(basePackages = "com.ogl.system", entityManagerFactoryRef = "companyEntityManagerFactory", transactionManagerRef = "companyTransactionManager")
public class SystemJpaConfig {

  private final Environment environment;

  @Autowired
  public SystemJpaConfig(Environment environment) {
    this.environment = environment;
  }

  @Bean("systemEntityManagerFactory")
  public LocalContainerEntityManagerFactoryBean systemEntityManagerFactory() {
    LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
    entityManagerFactoryBean.setPackagesToScan("com.ogl.system");
    entityManagerFactoryBean.setPersistenceUnitName("system");
    entityManagerFactoryBean.setDataSource(systemDataSource());

    HibernateJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
    adapter.setDatabase(Database.POSTGRESQL);
    adapter.setShowSql(true);
    adapter.setGenerateDdl(false);

    entityManagerFactoryBean.setJpaVendorAdapter(adapter);

    return entityManagerFactoryBean;
  }

  @Bean
  DataSource systemDataSource() {
    DriverManagerDataSource dataSource = new DriverManagerDataSource();
    dataSource.setDriverClassName(environment.getProperty("p4.datasource.driver"));
    dataSource.setUrl(environment.getProperty("p4.system.url"));
    dataSource.setUsername(environment.getProperty("p4.system.user"));
    dataSource.setPassword(environment.getProperty("p4.system.password"));

    return dataSource;
  }

  @Bean
  public PlatformTransactionManager systemTransactionManager() {
    JpaTransactionManager transactionManager = new JpaTransactionManager();
    transactionManager.setEntityManagerFactory((systemEntityManagerFactory().getObject()));

    return transactionManager;
  }
}

package com.ogl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.Database;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;

import javax.sql.DataSource;

@Configuration
@EnableJpaRepositories(basePackages = "com.ogl.company", entityManagerFactoryRef = "companyEntityManagerFactory", transactionManagerRef = "companyTransactionManager")
public class CompanyJpaConfig {

  private final Environment environment;

  @Autowired
  public CompanyJpaConfig(Environment environment) {
    this.environment = environment;
  }

  @Primary
  @Bean("companyEntityManagerFactory")
  public LocalContainerEntityManagerFactoryBean companyEntityManagerFactory() {
    LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
    entityManagerFactoryBean.setPackagesToScan("com.ogl.company");
    entityManagerFactoryBean.setPersistenceUnitName("company");
    entityManagerFactoryBean.setDataSource(companyDataSource());

    HibernateJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
    adapter.setDatabase(Database.POSTGRESQL);
    adapter.setShowSql(true);
    adapter.setGenerateDdl(false);

    entityManagerFactoryBean.setJpaVendorAdapter(adapter);

    return entityManagerFactoryBean;
  }

  @Bean
  DataSource companyDataSource() {
    DriverManagerDataSource dataSource = new DriverManagerDataSource();
    dataSource.setDriverClassName(environment.getProperty("p4.datasource.driver"));
    dataSource.setUrl(environment.getProperty("p4.company.url"));
    dataSource.setUsername(environment.getProperty("p4.company.user"));
    dataSource.setPassword(environment.getProperty("p4.company.password"));

    return dataSource;
  }

  @Primary
  @Bean
  public PlatformTransactionManager companyTransactionManager() {
    JpaTransactionManager transactionManager = new JpaTransactionManager();
    transactionManager.setEntityManagerFactory((companyEntityManagerFactory().getObject()));

    return transactionManager;
  }
}

注射

package com.ogl;

import org.crygier.graphql.GraphQLExecutor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

@Configuration
@ComponentScan
public class GraphQLJpaConfig {

  @PersistenceContext(unitName = "company")
  private EntityManager entityManager;

  @Bean
  public GraphQLExecutor graphQLExecutor() {
    return new GraphQLExecutor(entityManager);
  }
}

pom.xml

<?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>

    <groupId>com.ogl</groupId>
    <artifactId>jpa-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>jpa-demo</name>
    <description>Demo project for JPA</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.graphql-java</groupId>
            <artifactId>graphql-java</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>com.crygier</groupId>
            <artifactId>graphql-jpa</artifactId>
            <version>0.3</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Answer 1

您定义了两个EntityManager。现在你得告诉spring应该注射哪一种。为此，您可以使用@qualifier注释：

@PersistenceContext(unitName = "company")
@Qualifier(<Name of the entitimanager you want to use>)
private EntityManager entityManager;