我会给你看一些代码，然后我会问一个问题。
发送电子邮件.java
package com.goode;
import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
import org.springframework.core.io.ClassPathResource;
import org.springframework.stereotype.Component;
@Component
@NoArgsConstructor
@Data
@AllArgsConstructor
public class SendEmail {
@Value("${email.username}")
private String username;
@Value("${email.password}")
private String password;
@Value("${email.fullAddress}")
private String fullAddress;
@Value("${email.host}")
private String host;
@Value("${email.port}")
private String port;
public boolean send(String toEmail, String subject, String message){
Properties props = new Properties();
props.put("mail.smtp.auth", "true");
props.put("mail.smtp.starttls.enable", "true");
props.put("mail.smtp.host", host);
props.put("mail.smtp.port", port);
Session session = Session.getInstance(props,
new javax.mail.Authenticator() {
protected PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(username, password);
}
});
try {
Message createMessage = new MimeMessage(session);
createMessage.setFrom(new InternetAddress(fullAddress));
createMessage.setRecipients(Message.RecipientType.TO,
InternetAddress.parse(toEmail));
createMessage.setSubject(subject);
createMessage.setText(message);
Transport.send(createMessage);
return true;
} catch (MessagingException e) {
throw new RuntimeException(e);
}
}
@Bean
public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer()
{
PropertySourcesPlaceholderConfigurer o = new PropertySourcesPlaceholderConfigurer();
o.setLocation(new ClassPathResource("application.properties"));
return o;
}
}
根配置.java
package com.goode.config;
import java.util.Properties;
import javax.sql.DataSource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.PropertySource;
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 org.springframework.transaction.annotation.EnableTransactionManagement;
@Configuration
@EnableJpaRepositories( basePackages = {"com.goode.repository"})
@PropertySource(value = { "classpath:application.properties" })
@EnableTransactionManagement
@Import({ SecurityConfig.class })
@ComponentScan(basePackages = {"com.goode.service", "com.goode.repository", "com.goode.controller", "com.goode.business", "com.goode"})
public class RootConfig {
@Autowired
private Environment environment;
@Autowired
private DataSource dataSource;
@Bean
public DataSource dataSource() {
DriverManagerDataSource dataSource = new DriverManagerDataSource();
dataSource.setDriverClassName(environment.getRequiredProperty("jdbc.driverClassName"));
dataSource.setUrl(environment.getRequiredProperty("jdbc.url"));
dataSource.setUsername(environment.getRequiredProperty("jdbc.username"));
dataSource.setPassword(environment.getRequiredProperty("jdbc.password"));
return dataSource;
}
@Bean
public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
vendorAdapter.setDatabase(Database.POSTGRESQL);
vendorAdapter.setGenerateDdl(true);
vendorAdapter.setShowSql(true);
LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
factory.setJpaVendorAdapter(vendorAdapter);
factory.setPackagesToScan("com.goode.business");
factory.setDataSource(dataSource());
factory.setJpaProperties(jpaProperties());
return factory;
}
private Properties jpaProperties() {
Properties properties = new Properties();
properties.put("hibernate.dialect", environment.getRequiredProperty("hibernate.dialect"));
properties.put("hibernate.show_sql", environment.getRequiredProperty("hibernate.show_sql"));
properties.put("hibernate.format_sql", environment.getRequiredProperty("hibernate.format_sql"));
return properties;
}
@Bean
public PlatformTransactionManager transactionManager() {
JpaTransactionManager txManager = new JpaTransactionManager();
txManager.setEntityManagerFactory(entityManagerFactory().getObject());
return txManager;
}
}
应用程序属性
jdbc.driverClassName = org.postgresql.Driver
jdbc.url = jdbc:postgresql://localhost:5432/GoodE
jdbc.username = postgres
jdbc.password = postgres
hibernate.dialect = org.hibernate.dialect.PostgreSQLDialect
hibernate.show_sql = true
hibernate.format_sql = true
email.username = xx //I replce real data to xx just to this post
email.password = xx
email.fullAddress = xx@xx.com
email.host = xx
email.port = xx
当我尝试从SendEmail控制台调用发送方法时显示错误：
java.lang.NullPointerException： null
在行：
props.put("mail.smtp.host"， host(;
因此，注释@Value不会将任何值从 application.properties 注入 SendEmail 中的私有变量。为什么？
在RootConfig 中.java我使用了@Autowired、环境和@PropertySource但我在某处读到您只能在@Configuration类中使用@PropertySource所以我尝试寻找另一种方式 ->我找到了@Value，但我不知道为什么来自 application.properties 的数据没有注入到变量。 我把PropertySourcesPlaceholderConfigurer放在SendEmail中，因为我读到这是必要的。我不确定这是正确的地方，但将其放在另一个类中，例如 RootConfig 没有帮助。 您有什么建议，我应该在哪里搜索错误？
这一行：@PropertySource(value = { "classpath:application.properties" })是不必要的，因为默认情况下会选取application.properties中的所有值。话虽如此，您也不需要PropertySourcesPlaceholderConfigurer。
确保在调用send方法时，不要将SendEmail类实例化为new SendEmail()，因为这将不起作用，因为@Value仅在 spring 应用程序上下文中工作。
您必须执行@Autowired或构造函数注入(建议使用后者(。
还有这个：@ComponentScan(basePackages = {"com.goode.service", "com.goode.repository", "com.goode.controller", "com.goode.business", "com.goode"})可以替换为：@ComponentScan(basePackages = {"com.goode.*"})