在 mimemessage 中添加“addinline”函数时出现 NullPointerException答案

【问题标题】：NullPointerException while adding "addinline" function in mimemessage在 mimemessage 中添加“addinline”函数时出现 NullPointerException
【发布时间】：2015-12-15 08:47:49
【问题描述】：

500 错误 - 嵌套异常是 org.springframework.mail.MailPreparationException：无法准备邮件；嵌套异常是 java.lang.NullPointerException

我正在尝试使用 smtp 服务器生成电子邮件。我能够在不添加 inlne 图像的情况下生成电子邮件，而当我添加“addinline”功能时，我在输出屏幕中收到空指针错误并且无法生成电子邮件，图像不是已从系统中获取。当我尝试发送附件时，我遇到了同样的错误。Thnaks 提前。

在dao实现中

@Autowired
private JavaMailSender mailSender;


mailSender.send(new MimeMessagePreparator() {
        public void prepare(MimeMessage mimeMessage) throws MessagingException, IOException {
    MimeMessageHelper message = new MimeMessageHelper(mimeMessage, true, "UTF-8");
    message.setFrom(from);
    message.setTo(recipientAddress);
    message.setSubject("Subject");
        message.setText("<html><body><img src=\"cid:identifier1234\"/></body></html>", true);
        FileSystemResource res = new FileSystemResource(new File("D:\images\photo.svg.png"));
            message.addInline("identifier1234", res);
     }
    });

xml中的Bean类

<bean id="mailSender" class="org.springframework.mail.javamail.JavaMailSenderImpl">
    <property name="host" value="smtp.com" />
    <property name="port" value="25" />

     <property name="username" value="Sender.email@abc.com" /> 
    <property name="password" value="password@123" />
    <property name="javaMailProperties">
        <props>
            <prop key="mail.transport.protocol">smtp</prop>
            <prop key="mail.smtp.auth">true</prop>
            <prop key="mail.smtp.starttls.enable">true</prop>
        </props>
    </property>
</bean>

输出窗口出错

SEVERE: Servlet.service() for servlet [welcome] in context with path [/registrationForm] threw exception [Request processing failed; nested exception is org.springframework.mail.MailPreparationException: Could not prepare mail; nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException
at javax.mail.internet.MimeUtility.getEncoding(MimeUtility.java:226)
at javax.mail.internet.MimeUtility.getEncoding(MimeUtility.java:299)
at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1375)
at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1021)
at javax.mail.internet.MimeMultipart.updateHeaders(MimeMultipart.java:419)
at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1354)
at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1021)
at javax.mail.internet.MimeMultipart.updateHeaders(MimeMultipart.java:419)
at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1354)
at javax.mail.internet.MimeMessage.updateHeaders(MimeMessage.java:2107)
at javax.mail.internet.MimeMessage.saveChanges(MimeMessage.java:2075)
at org.springframework.mail.javamail.JavaMailSenderImpl.doSend(JavaMailSenderImpl.java:411)
at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:340)
at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:355)
at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:344)
at com.registrationForm.dao.DocumentDaoImpl.generateEmail(DocumentDaoImpl.java:182)
at com.registrationForm.service.DocumentServiceImpl.generateEmail(DocumentServiceImpl.java:45)
at com.registrationForm.controller.DocumentController.saveForm(DocumentController.java:84)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)

【问题讨论】：

"D:\images\photo.svg.png"，这是真实的文件路径吗？

标签： java spring email nullpointerexception email-attachments

【解决方案1】：

在您的 DAO 实现中，哪一行是 182？我猜是 FileSystemResource 声明。尝试像这样拆分该行：

File file = new File(/* your file path*/);
if(!file.exists())System.out.println("File doesn't exist");
else { 
  //do stuff
}

如果您在控制台中看到消息，则说明您的文件路径错误。

【讨论】：