使用SendGrid发送带附件邮件时抛出NoHttpResponseException求助

使用SendGrid 4.9.3、commons-codec 1.15和httpclient5 5.2.1版本发送带附件邮件时，抛出org.apache.http.NoHttpResponseException: api.sendgrid.com failed to respond异常，以下是相关代码及堆栈跟踪：

参考代码 #

public synchronized void sendEmail() {
    try {
        Email from = new Email("qa-automation@revmedia.my");
        String subject = "Buletin TV3 Test Automation Report";
        Email to = new Email("nicholaswkc34@gmail.com");
        Content content = new Content("text/plain", "Dear Stakeholders, please find the test automation report from attachment");
        Mail mail = new Mail(from, subject, to, content);

        Path reportFilePath = Paths.get(".//report//TestReport-Spark.html");
        Attachments attachments = new Attachments();
        attachments.setFilename("TestReport-Spark.html");
        attachments.setType("text/html");
        attachments.setDisposition("attachment");

        byte[] attachBytes = Files.readAllBytes(reportFilePath);
        String attachContent = Base64.getMimeEncoder().encodeToString(attachBytes);
        String s = Base64.getEncoder().encodeToString(attachBytes);
        attachments.setContent(s);
        mail.addAttachments(attachments);

        SendGrid sg = new SendGrid("API_Keys");
        Request request = new Request();

        request.setMethod(Method.POST);
        request.setEndpoint("mail/send");
        request.setBody(mail.build());
        Response response = sg.api(request);

        System.out.println(response.getStatusCode());
        System.out.println(response.getBody());
        System.out.println(response.getHeaders());
    } catch (IOException ex) {
        ex.printStackTrace();
    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

堆栈跟踪信息 #

org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:57)
org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:259)
org.apache.http.impl.DefaultBHttpClientConnection.receiveResponseHeader(DefaultBHttpClientConnection.java:163)
org.apache.http.impl.conn.CPoolProxy.receiveResponseHeader(CPoolProxy.java:167)
org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:273)
org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:125)
org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:271)
org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:184)
org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:88)
org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110)
org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:107)
com.sendgrid.Client.executeApiCall(Client.java:377)
com.sendgrid.Client.post(Client.java:249)
com.sendgrid.Client.api(Client.java:407)
com.sendgrid.BaseInterface.makeCall(BaseInterface.java:253)

排查及解决方案 #

1. 版本兼容性问题 #

SendGrid 4.9.3依赖的是Apache HttpClient 4.5.x版本，而你使用的HttpClient5 5.2.1是完全重构的大版本，API和内部实现与4.x不兼容，会导致连接处理逻辑异常。

• 解决方案：将httpclient5替换为SendGrid官方依赖的HttpClient版本（如4.5.13），移除httpclient5相关依赖，确保版本匹配。

2. 附件Base64编码格式错误 #

SendGrid要求附件内容使用MIME兼容的Base64编码（自动添加换行符分割长内容），但你的代码中使用了普通的Base64.getEncoder()，生成的无换行长字符串可能触发服务端异常处理，导致连接被关闭。

• 解决方案：替换为Base64.getMimeEncoder().encodeToString(attachBytes)设置附件内容：

  byte[] attachBytes = Files.readAllBytes(reportFilePath);
  String attachContent = Base64.getMimeEncoder().encodeToString(attachBytes);
  attachments.setContent(attachContent);
  

3. 网络连通性与拦截 #

• 检查服务器是否能正常访问api.sendgrid.com，可以用telnet api.sendgrid.com 443或curl -v https://api.sendgrid.com/v3/mail/send测试连通性。
• 确认是否有防火墙、代理服务器拦截了HTTPS请求，必要时配置代理参数到SendGrid客户端。

4. 客户端超时与重试配置 #

默认的SendGrid客户端超时时间较短，且重试策略不足，网络波动时易出现无响应异常。可以手动配置客户端参数：

SendGrid sg = new SendGrid("API_Keys");
Client client = sg.getClient();
client.setConnectTimeout(30000); // 30秒连接超时
client.setReadTimeout(60000); // 60秒读取超时
client.setRetryOnConnectionFailure(true); // 开启连接失败重试

5. API密钥验证 #

确认你的SendGrid API密钥是否有效，且拥有mail.send权限。可以在SendGrid控制台生成新的测试密钥，替换后再次尝试。

内容的提问来源于stack exchange，提问作者Ivan