一个用于图片处理的工具类

其中包括图片与字节流的相互转换，获取图片类型，图片大小，图片长宽等：

import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Iterator;

import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;

import org.apache.commons.codec.binary.Base64;

/**
 * This utility class is used for HTTP access operation, like URL encoding.
 *
 * @author Leo.zhou
 *
 */
public class CommonUtils {

    /**
     * Convert byte stream base on base64 format to file
     * 
     * @param stream, byte stream base on base64
     * @return file convert from byte stream
     * @throws IOException 
     */
    public static File convertToFileFromBase64(String stream, String path) throws IOException {
        byte[] bytes = stream.getBytes("ASCII");
        byte[] decoded = Base64.decodeBase64(bytes);
        File file = new File(path);
        File parent = file.getParentFile();
        if (parent != null && !parent.exists()) {
            parent.mkdirs();
        }
        file.createNewFile();
        OutputStream os = new FileOutputStream(file);
        try {
            ByteArrayInputStream buffer = new ByteArrayInputStream(decoded);
            byte[] barr = new byte[1024];
            while(true) {
                int r = buffer.read(barr);
                if(r <= 0) {
                    break;
                }
                os.write(barr, 0, r);
            }
        } finally {
            os.close();
        }
        return file;
    }

    /**
     * Convert file to byte stream base on base64 format
     * 
     * @param file file in file system
     * @return byte stream convert from file
     * @throws IOException
     */
    public static String convertToBase64FromFile(File file) throws IOException {
        InputStream in = new FileInputStream(file);
        byte[] bytes = null;
        try {
            ByteArrayOutputStream buffer = new ByteArrayOutputStream();
            byte[] barr = new byte[1024];
            while (true) {
                int r = in.read(barr);
                if (r <= 0) {
                    break;
                }
                buffer.write(barr, 0, r);
            }
            bytes = buffer.toByteArray();
        } finally {
            in.close();
        }
        //All chars in encoded are guaranteed to be 7-bit ASCII
        byte[] encoded = Base64.encodeBase64(bytes);
        return new String(encoded, "ASCII");
    }

    /**
     * Get image file format type
     * 
     * @param imageFile image file
     * @return image type
     * @throws IOException
     */
    public static String getImageFormatName(File imageFile) throws IOException {
        ImageInputStream iis = null;
        try {
            iis= ImageIO.createImageInputStream(imageFile);
            // Find all image readers that recognize the image format
            Iterator<ImageReader> iter = ImageIO.getImageReaders(iis);
            if(iter == null || !iter.hasNext()) {
                throw new IOException("image format error");
            }
            ImageReader reader = iter.next();
            // Return the format name
            return reader.getFormatName().toUpperCase();
        } finally {
            if(iis != null) {
                iis.close();
            }
        }
    }

    /**
     * Get image dimension
     * 
     * @param imageFile image file
     * @return image dimension
     * @throws IOException
     */
    public static String getImageDimension(File imageFile) throws IOException {
        FileInputStream fis = null;
        try {
            fis = new FileInputStream(imageFile);
            BufferedImage sourceImg = ImageIO.read(fis);
            if(sourceImg == null) {
                throw new IOException("image format error");
            }
            String dimension = sourceImg.getWidth() + "*" + sourceImg.getHeight();
            return dimension;
        } finally {
            if(fis != null) {
                fis.close();
            }
        }
    }

    /**
     * Get file size
     * 
     * @param File file
     * @return file size
     * @throws IOException
     */
    public static Integer getFileSize(File file) throws IOException {
        FileInputStream fis = null;
        try {
            fis = new FileInputStream(file);
            return fis.available();
        } finally {
            if(fis != null) {
                fis.close();
            }
        }
    }
}