无法解析某些属性的占位符

Question

我的数据库配置类：

@EnableTransactionManagement
public class DatabaseConfiguration {

    @Bean(name = "dbDataSource")
    @Profile("!development")
    public DataSource dataSource(@Value("${db.jndi}") String dbJndiName) {
        JndiDataSourceLookup lookup = new JndiDataSourceLookup();
        return lookup.getDataSource(dbJndiName);
    }

    @Profile("development")
    public DataSource dataSource(@Value("${development.db.driver}") String dbDriver,
            @Value("${development.db.url}") String dbUrl,
            @Value("${development.db.username}") String dbUsername,
            @Value("${development.db.password}") String dbPassword) {
        DriverManagerDataSource driverManagerDataSource = new DriverManagerDataSource(dbUrl);
        driverManagerDataSource.setDriverClassName(dbDriver);
        driverManagerDataSource.setUsername(dbUsername);
        driverManagerDataSource.setPassword(dbPassword);
        return driverManagerDataSource;
    }

}

和AppConfig：

@Import({DatabaseConfiguration.class, MailSenderConfiguration.class})
public class AppConfig {
@Bean
public PropertyPlaceholderConfigurer propertyPlaceholderConfigurer() {
    PropertyPlaceholderConfigurer propertyPlaceholderConfigurer = new PropertyPlaceholderConfigurer();
    propertyPlaceholderConfigurer.setLocation(new ClassPathResource("application.properties"));
    propertyPlaceholderConfigurer.setIgnoreUnresolvablePlaceholders(true);
    return propertyPlaceholderConfigurer;
}

}

嗨，我上面有个错误，我不知道怎么修复，你能帮我吗？在添加这个bean之前，我的项目运行良好：

@PropertySource("classpath:mail.properties")
public class MailSenderConfiguration {

@Value("${mail.smtp.host}")
private String mailHost;

@Value("${mail.smtp.port}")
private int mailPort;

@Value("${mail.username}")
private String mailUsername;

@Value("${mail.password}")
private String mailPassword;

@Value("${mail.protocol}")
private String mailProtocol;

@Value("${mail.smtp.auth}")
private boolean mailAuth;

@Value("${mail.smtp.starttls.enable}")
private String mailEnableTls;

@Value("${mail.smtp.debug}")
private boolean mailDebug;

@Bean
public JavaMailSender getMailSender() {
    JavaMailSenderImpl mailSender = new JavaMailSenderImpl();

    mailSender.setHost(mailHost);
    mailSender.setPort(mailPort);
    mailSender.setUsername(mailUsername);
    mailSender.setPassword(mailPassword);

    Properties mailProperties = new Properties();
    mailProperties.put("mail.transport.protocol", mailProtocol);
    mailProperties.put("mail.smtp.auth", mailAuth);
    mailProperties.put("mail.smtp.starttls.enable", mailEnableTls);
    mailProperties.put("mail.smtp.debug", mailDebug);
    mailSender.setJavaMailProperties(mailProperties);

    return mailSender;
}

@Bean
public PropertyPlaceholderConfigurer propertyPlaceholderConfigurer() {
    PropertyPlaceholderConfigurer propertyPlaceholderConfigurer = new PropertyPlaceholderConfigurer();
    propertyPlaceholderConfigurer.setLocation(new ClassPathResource("mail.properties"));
    propertyPlaceholderConfigurer.setIgnoreUnresolvablePlaceholders(true);
    return propertyPlaceholderConfigurer;
}

}

Answer 1

MailSenderConfiguration中的属性源配置似乎重写了AppConfig中的属性源配置。

您可以从MailSenderConfiguration中删除PropertyPlaceHolderConfigureer bean，并在AppConfig中为“mail.properties”设置附加位置（使用setLocations（）方法而不是setLocation（））：

@Import({DatabaseConfiguration.class, MailSenderConfiguration.class})
public class AppConfig {
@Bean
public PropertyPlaceholderConfigurer propertyPlaceholderConfigurer() {
    PropertyPlaceholderConfigurer propertyPlaceholderConfigurer = new PropertyPlaceholderConfigurer();
    propertyPlaceholderConfigurer.setLocations(new ClassPathResource("application.properties"), new ClassPathResource("mail.properties"));
    propertyPlaceholderConfigurer.setIgnoreUnresolvablePlaceholders(true);
    return propertyPlaceholderConfigurer;
}