用于java邮件api的NoSuchProviderException

Question

我在eclipse中创建了一个简单的maven项目，以便用一个个人gmail帐户发送一些电子邮件。在日食中，邮件被成功发送。然后，我将项目构建到一个带有依赖项的可执行jar中。但是，当我从命令行运行jar时，它会引发以下异常：

Exception in thread "main" java.lang.RuntimeException: javax.mail.NoSuchProviderException: smtp
    at EmailSender.send(EmailSender.java:75)
    at EmailSender.createNewAccount(EmailSender.java:33)
    at EmailSender.main(EmailSender.java:18)
Caused by: javax.mail.NoSuchProviderException: smtp
    at javax.mail.Session.getService(Session.java:792)
    at javax.mail.Session.getTransport(Session.java:728)
    at javax.mail.Session.getTransport(Session.java:668)
    at javax.mail.Session.getTransport(Session.java:648)
    at javax.mail.Session.getTransport(Session.java:705)
    at javax.mail.Transport.send0(Transport.java:248)
    at javax.mail.Transport.send(Transport.java:124)
    at EmailSender.send(EmailSender.java:73)
    ... 2 more

有人知道在Eclipse中执行程序和在外部执行jar有什么区别吗？非常感谢!

Answer 1

我通过修改pom.xml来解决这个问题，这样它就可以导出所有的依赖项。诀窍是去掉这条线

<minimizeJar>true</minimizeJar>

在以下代码中

<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>*******</groupId>
    <artifactId>**********</artifactId>
    <version>1</version>
    <dependencies>
        <dependency>
            <groupId>javax.mail</groupId>
            <artifactId>mail</artifactId>
            <version>1.5.0-b01</version>
        </dependency>
        <dependency>
            <groupId>javaee</groupId>
            <artifactId>javaee-api</artifactId>
            <version>5</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>1.6</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${project.build.directory}/shaded</outputDirectory>
                            <finalName>d2si-mailsender</finalName>
                            <minimizeJar>true</minimizeJar>
                            <transformers>
                                <transformer
                                    implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                    <mainClass>EmailSender</mainClass>
                                </transformer>
                            </transformers>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

Answer 2

您应该在META文件夹中有一个包含所有提供程序文件的服务文件夹，并且应该将它们导出到jar。默认情况下，eclipse包括它们，但是导出的jar不是