缩放在Java中存储为字节[]的图像

Question

我上传带有struts表单的文件。我有图像作为一个字节[]，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来做到这一点？

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"); 
     } 
    } 

如果像我这样用完了tomcat中的Java Heap Space，请增加tomcat使用的堆空间。如果您使用的是tomcat Eclipse插件，接下来应该适用于：

在Eclipse中，选择Window> 首选项>的Tomcat> JVM设置

添加以下到JVM 参数部分

-Xms256m -Xmx512m

Answer 1

看到这个：

Java 2D - How to convert byte[] to BufferedImage

然后看到：

How can I resize an image using Java?

Answer 2

取决于数据格式。

但是，如果您使用的是JPEG，GIF，PNG或BMP之类的东西，则可以使用ImageIO类。

喜欢的东西：

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"); 
     } 
    }