如何限制上传图片的尺寸？

只做过服务端的验证，客户端的验证不知道能否实现
参考：http://download.csdn.net/source/2874743 http://download.csdn.net/source/2530273

JavaScript验证的代码
<HTML>
<HEAD>
<SCRIPT>
function getImageDimension (imgURL, loadHandler) {
　var img = new Image();
　img.onload = loadHandler;
　if (document.layers
　　　&& location.protocol.toLowerCase() != 'file:'
　　　&& navigator.javaEnabled())
　　netscape.security.PrivilegeManager.enablePrivilege(
　　　'UniversalFileRead'
　　);
　img.src = imgURL;
}
function getFileSize (fileName) {
　if (document.layers) {
　　if (navigator.javaEnabled()) {
　　　var file = new java.io.File(fileName);
　　　if (location.protocol.toLowerCase() != 'file:')
　　　　netscape.security.PrivilegeManager.enablePrivilege(
　　　　'UniversalFileRead'
　　　　);
　　　return file.length();
　　}
　　else return -1;
　}
　else if (document.all) {
　　window.oldOnError = window.onerror;
　　window.onerror = function (err) {
　　　if (err.indexOf('utomation') != -1) {
　　　　alert('file access not possible');
　　　　return true;
　　　}
　　　else
　　　　return false;
　　};
　　var fso = new ActiveXObject('Scripting.FileSystemObject');
　　var file = fso.GetFile(fileName);
　　window.onerror = window.oldOnError;
　　return file.Size;
　}
}
function showImageDimensions () {
　alert(this.width + 'x' + this.height);
}
</SCRIPT>
<SCRIPT>
function checkImageDimensions (fileName) {
　var imgURL = 'file:///' + fileName;
　getImageDimension(imgURL, showImageDimensions);
}
</SCRIPT>
</HEAD>
<BODY>
<FORM NAME="formName">
<INPUT TYPE="file" NAME="fileName">
<BR>
<INPUT TYPE="button" VALUE="check file size"
　　　 ONCLICK="alert(getFileSize(this.form.fileName.value))"
>
<BR>
<INPUT TYPE="button" VALUE="check image dimensions"
　　　 ONCLICK="checkImageDimensions(this.form.fileName.value)"
>
</FORM>
</BODY>
</HTML>

相关的类似百度空间 qq空间都有点击ie9的工具--->f12开发人员工具查看源代码，当然你要是觉得查看完了打开再来检查即可

import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import java.awt.image.ConvolveOp;
import java.awt.image.Kernel;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;import javax.imageio.ImageIO;
import javax.swing.ImageIcon;import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGEncodeParam;
import com.sun.image.codec.jpeg.JPEGImageEncoder;/**
* 图像压缩工具
* @author [email protected]
*
*/
public class ImageSizer {
    public static final MediaTracker tracker = new MediaTracker(new Component() {
        private static final long serialVersionUID = 1234162663955668507L;}
    );
    /**
     * @param originalFile 原图像
     * @param resizedFile 压缩后的图像
     * @param width 图像宽
     * @param format 图片格式 jpg, png, gif(非动画)
     * @throws IOException
     */
    public static void resize(File originalFile, File resizedFile, int width, String format) throws IOException {
        if(format!=null && "gif".equals(format.toLowerCase())){
         resize(originalFile, resizedFile, width, 1);
         return;
        }
        FileInputStream fis = new FileInputStream(originalFile);
        ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
        int readLength = -1;
        int bufferSize = 1024;
        byte bytes[] = new byte[bufferSize];
        while ((readLength = fis.read(bytes, 0, bufferSize)) != -1) {
            byteStream.write(bytes, 0, readLength);
        }
        byte[] in = byteStream.toByteArray();
        fis.close();
        byteStream.close();

     Image inputImage = Toolkit.getDefaultToolkit().createImage( in );
        waitForImage( inputImage );
        int imageWidth = inputImage.getWidth( null );
        if ( imageWidth < 1 )
           throw new IllegalArgumentException( "image width " + imageWidth + " is out of range" );
        int imageHeight = inputImage.getHeight( null );
        if ( imageHeight < 1 )
           throw new IllegalArgumentException( "image height " + imageHeight + " is out of range" );

        // Create output image.
        int height = -1;
        double scaleW = (double) imageWidth / (double) width;
        double scaleY = (double) imageHeight / (double) height;
        if (scaleW >= 0 && scaleY >=0) {
            if (scaleW > scaleY) {
                height = -1;
            } else {
                width = -1;
            }
        }
        Image outputImage = inputImage.getScaledInstance( width, height, java.awt.Image.SCALE_DEFAULT);
        checkImage( outputImage );
        encode(new FileOutputStream(resizedFile), outputImage, format);
    }        /** Checks the given image for valid width and height. */
    private static void checkImage( Image image ) {
       waitForImage( image );
       int imageWidth = image.getWidth( null );
       if ( imageWidth < 1 )
          throw new IllegalArgumentException( "image width " + imageWidth + " is out of range" );
       int imageHeight = image.getHeight( null );
       if ( imageHeight < 1 )
          throw new IllegalArgumentException( "image height " + imageHeight + " is out of range" );
    }    /** Waits for given image to load. Use before querying image height/width/colors. */
    private static void waitForImage( Image image ) {
       try {
          tracker.addImage( image, 0 );
          tracker.waitForID( 0 );
          tracker.removeImage(image, 0);
       } catch( InterruptedException e ) { e.printStackTrace(); }
    }     /** Encodes the given image at the given quality to the output stream. */
    private static void encode( OutputStream outputStream, Image outputImage, String format )
       throws java.io.IOException {
       int outputWidth  = outputImage.getWidth( null );
       if ( outputWidth < 1 )
          throw new IllegalArgumentException( "output image width " + outputWidth + " is out of range" );
       int outputHeight = outputImage.getHeight( null );
       if ( outputHeight < 1 )
          throw new IllegalArgumentException( "output image height " + outputHeight + " is out of range" );       // Get a buffered image from the image.
       BufferedImage bi = new BufferedImage( outputWidth, outputHeight,
          BufferedImage.TYPE_INT_RGB );
       Graphics2D biContext = bi.createGraphics();
       biContext.drawImage( outputImage, 0, 0, null );
       ImageIO.write(bi, format, outputStream);
       outputStream.flush();
    }

/**
* 缩放gif图片
* @param originalFile 原图片
* @param resizedFile 缩放后的图片
* @param newWidth 宽度
* @param quality 缩放比例 (等比例)
* @throws IOException
*/
    private static void resize(File originalFile, File resizedFile, int newWidth, float quality) throws IOException {
        if (quality < 0 || quality > 1) {
            throw new IllegalArgumentException("Quality has to be between 0 and 1");
        }
        ImageIcon ii = new ImageIcon(originalFile.getCanonicalPath());
        Image i = ii.getImage();
        Image resizedImage = null;
        int iWidth = i.getWidth(null);
        int iHeight = i.getHeight(null);
        if (iWidth > iHeight) {
            resizedImage = i.getScaledInstance(newWidth, (newWidth * iHeight) / iWidth, Image.SCALE_SMOOTH);
        } else {
            resizedImage = i.getScaledInstance((newWidth * iWidth) / iHeight, newWidth, Image.SCALE_SMOOTH);
        }
        // This code ensures that all the pixels in the image are loaded.
        Image temp = new ImageIcon(resizedImage).getImage();
        // Create the buffered image.
        BufferedImage bufferedImage = new BufferedImage(temp.getWidth(null), temp.getHeight(null),
                                                        BufferedImage.TYPE_INT_RGB);
        // Copy image to buffered image.
        Graphics g = bufferedImage.createGraphics();
        // Clear background and paint the image.
        g.setColor(Color.white);
        g.fillRect(0, 0, temp.getWidth(null), temp.getHeight(null));
        g.drawImage(temp, 0, 0, null);
        g.dispose();
        // Soften.
        float softenFactor = 0.05f;
        float[] softenArray = {0, softenFactor, 0, softenFactor, 1-(softenFactor*4), softenFactor, 0, softenFactor, 0};
        Kernel kernel = new Kernel(3, 3, softenArray);
        ConvolveOp cOp = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);
        bufferedImage = cOp.filter(bufferedImage, null);
        // Write the jpeg to a file.
        FileOutputStream out = new FileOutputStream(resizedFile);
        // Encodes image as a JPEG data stream
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
        JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(bufferedImage);
        param.setQuality(quality, true);
        encoder.setJPEGEncodeParam(param);
        encoder.encode(bufferedImage);
    }
}可能会有点错误，楼主自己改一下

比较老的办法是上传到服务器端，在那里进行验证大小，或者做缩略图。但现在基本上使用flex或者silverlight来直接在客户端来搞。

可以用JS加Flash上传文件，你可以查找Jquery 上传文件，可以作到在客户端判断大小，
另外，图片压缩，很少自己写程序，
在Linxu下，可以用ImageMagick的Convert命令实现，速度快，任何格式都支持。
功能无限。
如果你是windows平台，可以装个cygwin+ImageMagick试试。

用到jquery了、、自己去弄一个、想要多大的自己设置就可以了！ <script type="text/javascript" src="jquery.min.js"></script>
  <script type="text/javascript">
  function changePic(obj) {
        var img    = new Image();
        img.src    = obj.value;
var width  = img.width;
        var height = img.height;
                 if(width>500||height>500){
alert('图片太大');
$(obj).after($(obj).clone($(obj)));
$(obj).remove();
}
}
  </script>

<input type="file" name="img" id="img"  onchange="changePic(this);">

再给你个后台的缩放图片package com.huang.test;import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import javax.imageio.ImageIO;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;public class lessenImg { public static void main(String[] args) {
File file=new File("D://1.jpg");
try {
Image src=ImageIO.read(file);
BufferedImage bufferedImage=new BufferedImage(200,200,BufferedImage.TYPE_INT_RGB);
bufferedImage.getGraphics().drawImage(src,0,0,200,200,null);//绘制缩小后的图,两个一致...
OutputStream os=new FileOutputStream("D://aa.jpg");
JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(os);
encoder.encode(bufferedImage);
os.close();
System.out.println("完成");
} catch (IOException e) {
e.printStackTrace();
}
}
}有俩对宽和高、、你只需要设置成一样就可以了！！！

调试易

如何限制上传图片的尺寸？

解决方案 »