缩放在Java中以byte []格式存储的图像

Question

我上传了一个带有struts表单的文件.我将图像作为byte [],我想缩放它.

FormFile file = (FormFile) dynaform.get("file");
byte[] fileData = file.getFileData(); 
fileData = scale(fileData,200,200);

public byte[] scale(byte[] fileData, int width, int height) {
// TODO 
}

任何人都知道一个简单的功能吗？

public byte[] scale(byte[] fileData, int width, int height) {
        ByteArrayInputStream in = new ByteArrayInputStream(fileData);
        try {
            BufferedImage img = ImageIO.read(in);
            if(height == 0) {
                height = (width * img.getHeight())/ img.getWidth(); 
            }
            if(width == 0) {
                width = (height * img.getWidth())/ img.getHeight();
            }
            Image scaledImage = img.getScaledInstance(width, height, Image.SCALE_SMOOTH);
            BufferedImage imageBuff = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            imageBuff.getGraphics().drawImage(scaledImage, 0, 0, new Color(0,0,0), null);

            ByteArrayOutputStream buffer = new ByteArrayOutputStream();

            ImageIO.write(imageBuff, "jpg", buffer);

            return buffer.toByteArray();
        } catch (IOException e) {
            throw new ApplicationException("IOException in scale");
        }
    }

如果你像我一样用尽tomcat中的Java堆空间,请增加tomcat使用的堆空间.如果你使用Eclipse的tomcat插件,接下来应该适用:

在Eclipse中,选择Window> Preferences> Tomcat> JVM Settings

将以下内容添加到JVM Parameters部分

-Xms256m -Xmx512m

Answer 1

取决于数据格式.

但是,如果您使用的是JPEG,GIF,PNG或BMP,则可以使用ImageIO类.

就像是:

public byte[] scale(byte[] fileData, int width, int height) {
    ByteArrayInputStream in = new ByteArrayInputStream(fileData);
    try {
        BufferedImage img = ImageIO.read(in);
        if(height == 0) {
            height = (width * img.getHeight())/ img.getWidth(); 
        }
        if(width == 0) {
            width = (height * img.getWidth())/ img.getHeight();
        }
        Image scaledImage = img.getScaledInstance(width, height, Image.SCALE_SMOOTH);
        BufferedImage imageBuff = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        imageBuff.getGraphics().drawImage(scaledImage, 0, 0, new Color(0,0,0), null);

        ByteArrayOutputStream buffer = new ByteArrayOutputStream();

        ImageIO.write(imageBuff, "jpg", buffer);

        return buffer.toByteArray();
    } catch (IOException e) {
        throw new ApplicationException("IOException in scale");
    }
}

Answer 2

看看这个：

Java 2D - 如何将 byte[] 转换为 BufferedImage

然后看这个：

如何使用 Java 调整图像大小？