基于java流实现压缩图片过程解析

package test;
import java.io.*;
import java.util.Date;
import java.awt.*;
import java.awt.p_w_picpath.*;
import javax.p_w_picpathio.ImageIO;
import com.sun.p_w_picpath.codec.jpeg.*;
/** 
 * 图片压缩处理 
 * @author 崔素强 
 */
public class ImgCompress {
	private Image img;
	private int width;
	private int height;
	@SuppressWarnings("deprecation") 
	  public static void main(String[] args) throws Exception {
		System.out.println("开始：" + new Date().toLocaleString());
		ImgCompress imgCom = new ImgCompress("C:\temp\pic123.jpg");
		imgCom.resizeFix(400, 400);
		System.out.println("结束：" + new Date().toLocaleString());
	}
	/** 
   * 构造函数 
   */
	public ImgCompress(String fileName) throws IOException {
		File file = new File(fileName);
		// 读入文件 
		img = ImageIO.read(file);
		// 构造Image对象 
		width = img.getWidth(null);
		// 得到源图宽 
		height = img.getHeight(null);
		// 得到源图长
	}
	/** 
   * 按照宽度还是高度进行压缩 
   * @param w int 最大宽度 
   * @param h int 最大高度 
   */
	public void resizeFix(int w, int h) throws IOException {
		if (width / height > w / h) {
			resizeByWidth(w);
		} else {
			resizeByHeight(h);
		}
	}
	/** 
   * 以宽度为基准，等比例放缩图片 
   * @param w int 新宽度 
   */
	public void resizeByWidth(int w) throws IOException {
		int h = (int) (height * w / width);
		resize(w, h);
	}
	/** 
   * 以高度为基准，等比例缩放图片 
   * @param h int 新高度 
   */
	public void resizeByHeight(int h) throws IOException {
		int w = (int) (width * h / height);
		resize(w, h);
	}
	/** 
   * 强制压缩/放大图片到固定的大小 
   * @param w int 新宽度 
   * @param h int 新高度 
   */
	public void resize(int w, int h) throws IOException {
		// SCALE_SMOOTH 的缩略算法 生成缩略图片的平滑度的 优先级比速度高 生成的图片质量比较好 但速度慢 
		BufferedImage p_w_picpath = new BufferedImage(w, h,BufferedImage.TYPE_INT_RGB );
		p_w_picpath.getGraphics().drawImage(img, 0, 0, w, h, null);
		// 绘制缩小后的图 
		File destFile = new File("C:\temp\456.jpg");
		FileOutputStream out = new FileOutputStream(destFile);
		// 输出到文件流 
		// 可以正常实现bmp、png、gif转jpg 
		JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
		encoder.encode(p_w_picpath);
		// JPEG编码 
		out.close();
	}
}

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space 
  at java.awt.p_w_picpath.DataBufferByte.<init>(DataBufferByte.java:58) 
  at java.awt.p_w_picpath.ComponentSampleModel.createDataBuffer(ComponentSampleModel.java:397) 
  at java.awt.p_w_picpath.Raster.createWritableRaster(Raster.java:938) 
  at javax.p_w_picpathio.ImageTypeSpecifier.createBufferedImage(ImageTypeSpecifier.java:1169) 
  at javax.p_w_picpathio.ImageReader.getDestination(ImageReader.java:2879) 
  at com.sun.p_w_picpathio.plugins.jpeg.JPEGImageReader.readInternal(JPEGImageReader.java:943) 
  at com.sun.p_w_picpathio.plugins.jpeg.JPEGImageReader.read(JPEGImageReader.java:915) 
  at javax.p_w_picpathio.ImageIO.read(ImageIO.java:1422) 
  at javax.p_w_picpathio.ImageIO.read(ImageIO.java:1282) 
  at test.ImgCompress.<init>(ImgCompress.java:31) 
  at test.ImgCompress.main(ImgCompress.java:21)