如何/我可以在 Jasper 报告模板中使用 base64 作为图像源吗?

2022-01-21 00:00:00 image base64 java jasper-reports

所以在我的 jrxml 文件中，我有以下内容:

<参数名="smileyfaceimage" class="java.lang.String"/>

然后我引用它:

这不正确吗?

base64 有无我都试过了:

data:image/png;base64,

这是我正在使用的图像

然后我使用

重要提示:smileyfaceimage需无:data:image/png;base64,

EDIT:OP(评论)的问题是，对于旧的 jasper 报告库(3.0)，您需要在 imageExpression 中指定类 @see class="java.io.InputStream" 该帖子因此已更新，因为这也适用于 6.0.

So in my jrxml file I have the following:

<parameter name="smileyfaceimage" class="java.lang.String"/>

Then I reference it in:

<image scaleImage="FillFrame" onErrorType="Blank">
    <reportElement x="167" y="62" width="363" height="171" backcolor="#333333"/>
    <imageExpression class="java.lang.String"><![CDATA[$P{smileyfaceimage}]]></imageExpression>
</image>

Is this not correct?

I've tried the base64 both with and without:

data:image/png;base64,

Here's the image im working with

Then I used https://www.base64-image.de/ or any random site to get the base64 string. I tested the string it produces and it's valid.

Now in my code;

  • set the value of a variable to the based64 string
  • on the template
    • set the parameter: <parameter name="smileyfaceimage" class="java.lang.String"/>

  • then add the image data to the page:

    • <image scaleImage="FillFrame" onErrorType="Blank">
    <reportElement x="167" y="62" width="363" height="171" backcolor="#333333"/>
    <imageExpression><![CDATA[new java.io.ByteArrayInputStream(org.apache.commons.codec.binary.Base64.decodeBase64($P{smileyfaceimage}.getBytes()))]]></imageExpression>
</image>

Am I missing a step?

解决方案

Passing parameter as String makes jasper report believe its a absolute file path, so you need another class. The most obvious would be java.awt.Image or java.io.InputStream.

I choose java.io.InputStream since this will require less code, so the first thing we need to do now is to decode the base64 image String.

There are several Base64 class that will do the job, I choose the org.apache.commons.codec.binary.Base64 since apache commons-codec.jar is already distributed with jasper report (dependencies). The decode will give us a byte array byte[], so now we need only to add a ByteArrayInputStream

The java code would be:

InputStream stream = new ByteArrayInputStream(Base64.decodeBase64(smileyfaceimage.getBytes()));

Time to pass it into the jasper report imageExpression

<image scaleImage="FillFrame" onErrorType="Blank">
<reportElement x="167" y="62" width="363" height="171" backcolor="#333333"/>
    <imageExpression class="java.io.InputStream"><![CDATA[new java.io.ByteArrayInputStream(org.apache.commons.codec.binary.Base64.decodeBase64($P{smileyfaceimage}.getBytes()))]]></imageExpression>
</image>

Hope for the best and press the preview:

Important notice: The smileyfaceimage needs to be without:data:image/png;base64,

EDIT: The problem of the OP (comments) was that with old jasper report lib (3.0) you need to specify the class in the imageExpression @see class="java.io.InputStream" the post has been update consequently since this works also in 6.0.

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