Thymeleaf不会将所有图标附加到模板

Question

当我试图在模板上生成带有图标的电子邮件时，我遇到了Thymeleaf的问题。我已经按照留档建议的步骤进行了操作，请参见第4.3部分，但在电子邮件中，只显示了3个图标中的2个。

首先我加载图标：

private byte[] loadImage(String path, String extension) {
    byte[] image = new byte[0];

    try {
        URL file = getClass().getClassLoader().getResource(path);
        BufferedImage buffer = ImageIO.read(file);
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        ImageIO.write(buffer, extension, outputStream);
        image = outputStream.toByteArray();
    } catch (IOException exception) {
        log.debug(exception.getLocalizedMessage());
    }

然后我将图标添加到mimessagehelper：

private void attachIcons(MimeMessageHelper message) {
    try {
        byte[] logoIconInBytes = loadImage(LOGO_ICON_PATH, "png");
        InputStreamSource logoImageSource = new ByteArrayResource(logoIconInBytes);
        message.addInline(LOGO_IMAGE_RESOURCE, logoImageSource, IMAGE_CONTENT_TYPE);
        byte[] phoneIconInBytes = loadImage(PHONE_ICON_PATH, "png");
        InputStreamSource phoneImageSource = new ByteArrayResource(phoneIconInBytes);
        message.addInline(PHONE_IMAGE_RESOURCE, phoneImageSource, IMAGE_CONTENT_TYPE);
        byte[] emailIconInBytes = loadImage(EMAIL_ICON_PATH, "png");
        InputStreamSource emailImageSource = new ByteArrayResource(emailIconInBytes);
        message.addInline(EMAIL_IMAGE_RESOURCE, emailImageSource, IMAGE_CONTENT_TYPE);
    } catch (MessagingException exception) {
        log.debug(exception.getLocalizedMessage());
    }
}

在哪里：

private static final String LOGO_ICON_PATH = "data" + File.separator + "logo_example.png";
private static final String PHONE_ICON_PATH = "data" + File.separator + "phone.png";
private static final String EMAIL_ICON_PATH = "data" + File.separator + "email.png";
private static final String IMAGE_CONTENT_TYPE = "image/png";

然后，在发送电子邮件之前，我在上下文中设置变量：

......
context.setVariable(LOGO_IMAGE_RESOURCE, LOGO_IMAGE_RESOURCE);
context.setVariable(PHONE_IMAGE_RESOURCE, PHONE_IMAGE_RESOURCE);
context.setVariable(EMAIL_IMAGE_RESOURCE, EMAIL_IMAGE_RESOURCE);
String content = templateEngine.process(templateName, context);
......

在模板上，我分别调用

....
<img class="resize" th:src="|cid:${logoIcon}|" alt="Test">
....
<td class="someCssClass"> <img th:src="|cid:${phoneIcon}|" alt="phone"> </td>
<td class="someCssClass"> <img th:src="|cid:${emailIcon}|" alt="email"> </td>
....

但是电子邮件图标没有显示，我用Firefox开发工具检查DOM时发现：

您可以看到徽标和手机图标已附加，但电子邮件图标未附加。

我改变了我的想法，认为可能是文件被破坏了，但没有改变。

问题出在哪里？

当做




Answer 1

嗯，我偶然发现了这个问题。我不知道这是一个bug还是因为我不知道如何使用API，但这是发生的奇怪事情：

当我添加图标时：

byte[] logoIconInBytes = loadImage(LOGO_ICON_PATH, "png");
InputStreamSource logoImageSource = new ByteArrayResource(logoIconInBytes);
message.addInline(LOGO_IMAGE_RESOURCE, logoImageSource, IMAGE_CONTENT_TYPE);
byte[] phoneIconInBytes = loadImage(PHONE_ICON_PATH, "png");
InputStreamSource phoneImageSource = new ByteArrayResource(phoneIconInBytes);
message.addInline(PHONE_IMAGE_RESOURCE, phoneImageSource, IMAGE_CONTENT_TYPE);
byte[] emailIconInBytes = loadImage(EMAIL_ICON_PATH, "png");
InputStreamSource emailImageSource = new ByteArrayResource(emailIconInBytes);
message.addInline(EMAIL_IMAGE_RESOURCE, emailImageSource, IMAGE_CONTENT_TYPE);

我删除了电子邮件代码行，以便再次编写它们，以防出现任何错误。

byte[] logoIconInBytes = loadImage(LOGO_ICON_PATH, "png");
InputStreamSource logoImageSource = new ByteArrayResource(logoIconInBytes);
message.addInline(LOGO_IMAGE_RESOURCE, logoImageSource, IMAGE_CONTENT_TYPE);
byte[] phoneIconInBytes = loadImage(PHONE_ICON_PATH, "png");
InputStreamSource phoneImageSource = new ByteArrayResource(phoneIconInBytes);
message.addInline(PHONE_IMAGE_RESOURCE, phoneImageSource, IMAGE_CONTENT_TYPE);

我无意中运行了应用程序并生成了电子邮件，我注意到手机图标没有显示出来。我删除了手机图标，只加载了徽标，这次电子邮件上没有显示任何图标。

所以，解决方案是在加载所有图标后添加一个虚拟内容，以便显示。

byte[] logoIconInBytes = loadImage(LOGO_ICON_PATH, "png");
InputStreamSource logoImageSource = new ByteArrayResource(logoIconInBytes);
message.addInline(LOGO_IMAGE_RESOURCE, logoImageSource, IMAGE_CONTENT_TYPE);
byte[] phoneIconInBytes = loadImage(PHONE_ICON_PATH, "png");
InputStreamSource phoneImageSource = new ByteArrayResource(phoneIconInBytes);
message.addInline(PHONE_IMAGE_RESOURCE, phoneImageSource, IMAGE_CONTENT_TYPE);
byte[] emailIconInBytes = loadImage(EMAIL_ICON_PATH, "png");
InputStreamSource emailImageSource = new ByteArrayResource(emailIconInBytes);
message.addInline(EMAIL_IMAGE_RESOURCE, emailImageSource, IMAGE_CONTENT_TYPE);
// Dummy content that won't be displayed to make all previous icons visible on the email
message.addInline("emptyIcon", new ByteArrayResource(new byte[0]), IMAGE_CONTENT_TYPE);