如何使用TagLib将字节数组（Blob）渲染为图像

Question

如何使用自定义标记渲染存储在数据库中的图像文件（Blob），我曾用于渲染徽标，但图像正在崩溃，输出是字节数组。

这就是我的尝试：

def logo = { attrs, body ->
    if(session?.companyId && session?.companyId != 'null'){
        Company company = Company.findById(session?.companyId)
        if (!company || !company?.logo) {
            println "No response..."
            out <<"<img src='/cdc/static/images/logo.png' width='150' height='70' />"
        }
        else{
            println "Writing..."
            out << "<img src='"
            out << company?.logo
            out << "' width='150' height='70' />"
        }
    }
    else{
        println "No response..."
        //out <<"<img src='/cdc/static/images/logo.png' width='150' height='70' />"
    }
}

输出如下：

如何将公司？.logo 呈现为图片而不是字节数组？

Answer 1

听起来你想提供一个data URI，基本上。为此你需要像：

src="data:img/png;base64,xxx"

其中“xxx”是base64格式的数据。

例如，使用this public domain base64 library：

out << "<img src='data:img/png;base64,"
out << Base64.encode(company?.logo)
out << "' width='150' height='70' />"

Answer 2

我试图在Grails 3.0.11中做同样的事情，而Base64.encode行给了我一个错误。这是我想出的结果taglib，对我来说很有用：

/** imgFromByteArray
 *
 * Print a byte array as an image tag.
 *
 * attrs:
 *      1. String imageType         Example: image/jpeg
 *      2. byte[] imageContent
 *      #. Any additional attrs will be included in the <img /> tag
 */
def imgFromByteArray = { attrs ->

    //Get image content and type from attrs
    byte[] imageContent = attrs.imageBytes
    String imageType = attrs.imageType

    //Remove attributes that should not be printed in the img tag
    ['imageBytes', 'imageType'].each{
        if(attrs.containsKey(it)){ attrs.remove(it) }
    }

    //Print the image tag with image content
    out << """<img src='data:${imageType};base64,${imageContent?.encodeBase64()}'"""

    //Include any other tags given
    attrs.each { attrLabel, attrValue ->
        out << " ${attrLabel}=\"${attrValue}\""
    }

    //Close the image tag
    out<< "/>"
}