spring-boot 属性注入在自定义 @Configuration 类中不起作用 [英] spring-boot property injection not working in custom @Configuration class

问题描述

我想创建一个 DatabaseConfig 类来设置我的数据库相关内容(EntityManager、DataSource、TransactionManager)并获取我使用 @Value("${property.name}") 的属性String 字段

I wanted to make a DatabaseConfig class to setup my database related stuff (EntityManager, DataSource, TransactionManager) and to get the properties I use @Value("${property.name}") on String fields

喜欢

@Configuration
public class DataBaseConfig {
    @Value("${hibernate.connection.username}")
    private String hibernateConnectionUsername;
    @Value("${hibernate.connection.password}")
    private String hibernateConnectionPassword;
    @Value("${hibernate.connection.driver_class}")
    private String hibernateConnectionDriverClass;
    @Value("${hibernate.connection.url}")
    private String hibernateConnectionUrl;
    @Value("${hibernate.dialect}")
    private String hibernateDialect;
    @Value("${hibernate.showSql}")
    private String hibernateShowSql;
    @Value("${hibernate.generateDdl}")
    private String hibernateGenerateDdl;

// All my @Beans
}

问题是，所有这些字符串都是 NULL，而不是我的属性文件的值.

The Problem is, that all those Strings are NULL instead of the values of my properties file.

如果我将代码放入我的 Application 类(具有 main 并在 SpringApplication.run(Application.class, args) 中引用的那个类);) 值注入有效

if I put the code into my Application class (the one that has the main and is referenced in SpringApplication.run(Application.class, args);) the value injection works

简而言之，@Value 在我的 Application 类中有效，但在我的自定义 @Configuration 类中无效:(

In short, @Value works in my Application class, but not in my custom @Configuration classes :(

可能有什么问题?还是需要更多信息?

What could be wrong? Or are more informations needed?

更新:更多代码

方法 1，我的 Application.java 中的 DB Config 和 @Value 可以使用和不使用 PropertySourcesPlaceholderConfigurer

Way 1, DB Config and @Value in my Application.java works with and without the PropertySourcesPlaceholderConfigurer

import java.beans.PropertyVetoException;

import javax.persistence.EntityManagerFactory;
import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;

import com.mchange.v2.c3p0.ComboPooledDataSource;

@Configuration
@ComponentScan
@EnableJpaRepositories
@EnableAutoConfiguration(exclude = HibernateJpaAutoConfiguration.class)
public class Application {
    public static void main(String[] args) throws Throwable {
        SpringApplication.run(Application.class, args);
    }

    // @Bean
    // public static PropertySourcesPlaceholderConfigurer properties() {
    // PropertySourcesPlaceholderConfigurer pspc = new PropertySourcesPlaceholderConfigurer();
    // pspc.setLocations(new Resource[] { new ClassPathResource("application.properties") });
    // return pspc;
    // }

    /*****************************/
    @Value("${hibernate.connection.username}")
    private String hibernateConnectionUsername;

    @Value("${hibernate.connection.password}")
    private String hibernateConnectionPassword;

    @Value("${hibernate.connection.driver_class}")
    private String hibernateConnectionDriverClass;

    @Value("${hibernate.connection.url}")
    private String hibernateConnectionUrl;

    @Value("${hibernate.dialect}")
    private String hibernateDialect;
    @Value("${hibernate.showSql}")
    private String hibernateShowSql;
    @Value("${hibernate.generateDdl}")
    private String hibernateGenerateDdl;

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        vendorAdapter.setDatabasePlatform(hibernateDialect);
        boolean generateDdl = Boolean.parseBoolean(hibernateGenerateDdl);
        boolean showSql = Boolean.parseBoolean(hibernateShowSql);
        vendorAdapter.setGenerateDdl(generateDdl);
        vendorAdapter.setShowSql(showSql);

        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setJpaVendorAdapter(vendorAdapter);
        factory.setDataSource(dataSource());
        factory.setPackagesToScan("xxx");

        return factory;
    }

    @Bean
    public DataSource dataSource() {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setUser(hibernateConnectionUsername);
        dataSource.setPassword(hibernateConnectionPassword);
        try {
            dataSource.setDriverClass(hibernateConnectionDriverClass);
        } catch (PropertyVetoException e) {
            throw new IllegalArgumentException("Wrong driver class");
        }

        dataSource.setJdbcUrl(hibernateConnectionUrl);
        return dataSource;
    }

    @Bean
    public PlatformTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
        return new JpaTransactionManager(entityManagerFactory);
    }
}

方式 2(我想要的)，DB Stuff 在它自己的文件 (DatabaseConfing.java) 中不起作用，不管我在哪里有 PropertySourcesPlaceholderConfigurer(Application 或 DatabaseConfig)，因为它总是在 DatabaseConfig 中的 @Beans 之后调用 :(

Way 2 (what i want to have), DB Stuff in its own file (DatabaseConfing.java) does not work regardles of where i have the PropertySourcesPlaceholderConfigurer (Application or DatabaseConfig) as it is always called AFTER the @Beans inside the DatabaseConfig :(

import java.beans.PropertyVetoException;
import java.util.ArrayList;
import java.util.List;

import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.springframework.core.type.filter.AnnotationTypeFilter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;

import com.mchange.v2.c3p0.ComboPooledDataSource;


@Configuration
public class DatabaseConfig {
    @Value("${hibernate.connection.username}")
    private String hibernateConnectionUsername;
    @Value("${hibernate.connection.password}")
    private String hibernateConnectionPassword;
    @Value("${hibernate.connection.driver_class}")
    private String hibernateConnectionDriverClass;
    @Value("${hibernate.connection.url}")
    private String hibernateConnectionUrl;
    @Value("${hibernate.dialect")
    private String hibernateDialect;
    @Value("${hibernate.showSql}")
    private String hibernateShowSql;
    @Value("${hibernate.generateDdl}")
    private String hibernateGenerateDdl;

        // @Bean
        // public static PropertySourcesPlaceholderConfigurer properties() {
        // PropertySourcesPlaceholderConfigurer pspc = new PropertySourcesPlaceholderConfigurer();
        // pspc.setLocations(new Resource[] { new ClassPathResource("application.properties") });
        // return pspc;
        // }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        vendorAdapter.setDatabasePlatform(hibernateDialect);
        boolean generateDdl = Boolean.parseBoolean(hibernateGenerateDdl);
        boolean showSql = Boolean.parseBoolean(hibernateShowSql);
        vendorAdapter.setGenerateDdl(generateDdl);
        vendorAdapter.setShowSql(showSql);

        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setJpaVendorAdapter(vendorAdapter);
        factory.setDataSource(dataSource());
        factory.setPackagesToScan("xxx");

        return factory;
    }

    @Bean
    public DataSource dataSource() {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setUser(hibernateConnectionUsername);
        dataSource.setPassword(hibernateConnectionPassword);
        try {
            dataSource.setDriverClass(hibernateConnectionDriverClass);
        } catch (PropertyVetoException e) {
            throw new IllegalArgumentException("Wrong driver class");
        }
        System.err.println(hibernateConnectionUrl);
        dataSource.setJdbcUrl(hibernateConnectionUrl);
        return dataSource;
    }
}

推荐答案

在 src/main/resources 中添加以下 application.properties 代替你的 DatabaseConfig(从而删除您的 DatabaseConfig 类)

Instead of your DatabaseConfig add the following application.properties to src/main/resources (and thus remove your DatabaseConfig class)

#DataSource configuration
spring.datasource.driverClassName=<hibernateConnectionDriverClass>
spring.datasource.url=<hibernateConnectionUrl>
spring.datasource.username=<hibernateConnectionUsername>
spring.datasource.password=<hibernateConnectionPassword>

#JPA/HIbernate
spring.jpa.database-platform=<dialect-class>
spring.jpa.generate-ddl=<hibernateGenerateDdl>
spring.jpa.show-sql=<hibernateShowSql>

替换<占位符 > 与实际值和 spring-boot 会照顾到这一点.

Replace the < placeholder > with the actual value and spring-boot will take care of this.

提示删除 C3P0 依赖项，因为 Spring 将为您(默认)提供 tomcat 连接池(它更新且维护得更积极，尽管该名称在没有 Tomcat 的情况下/在 Tomcat 之外也完全可用).

Tip remove the C3P0 dependency as Spring will provide you (default) with the tomcat connection pool (which is newer and more activly maintained and despite the name is perfectly usable without/outside Tomcat).

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