java处理图片缩放

public static boolean compressImage(File file, String directoryFileName,
			int width, int height, boolean proportion) {
		boolean ret = false;
		FileOutputStream fileOutputStream = null;
		try {
			if (file == null || directoryFileName == null) {
				return ret;
			}

			fileOutputStream = new FileOutputStream(new File(directoryFileName));
			Image image = ImageIO.read(file);
			if (image.getWidth(null) == -1) {
				return ret;
			}

			int newWidth = 0;
			int newHeight = 0;

			if (image.getWidth(null) > width || image.getHeight(null) > height) {
				if (proportion) {
					int rate1 = image.getWidth(null) / width;
					int rate2 = image.getHeight(null) / height;
					int rate = rate1 > rate2 ? rate1 : rate2;
					newWidth = image.getWidth(null) / rate;
					newHeight = image.getHeight(null) / rate;
				} else {
					newWidth = width;
					newHeight = height;
				}
			} else {
				newWidth = image.getWidth(null);
				newHeight = image.getHeight(null);
			}

			BufferedImage bufferedImage = new BufferedImage(newWidth,
					newHeight, BufferedImage.TYPE_INT_RGB);

			bufferedImage.getGraphics().drawImage(
					image.getScaledInstance(newWidth, newHeight,
							image.SCALE_SMOOTH), 0, 0, null);

			JPEGImageEncoder encoder = JPEGCodec
					.createJPEGEncoder(fileOutputStream);
			encoder.encode(bufferedImage);
			fileOutputStream.close();

			ret = true;

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (fileOutputStream != null) {
				try {
					fileOutputStream.close();
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		}
		return ret;
	}

 正在的改版的网站需要增加一个功能，对会员用户上传的图片选择一部分进行首页处理，虽然在用户上传图片时候已经对上传图片大小进行了限制，但限制的大小，如果提交到首页显示，很影响首页打开的速度，所以，需要将选择进行首页显示的图片重新进行缩放处理，以适合首页显示。

 

网上找了很多资料，但不知道为什么只对jpeg格式的图片处理有效，其他的都会报格式异常错误，终于找到这个类，对基本的格式图片都可以进行处理：

package com.common.helper;

import java.io.*;
import java.util.*;
import com.sun.image.codec.jpeg.*;
import java.awt.image.*;
import java.awt.*;
import java.net.*;
import java.applet.*;
import java.sql.*;
//缩略图类，
//本java类能将jpg图片文件，进行等比或非等比的大小转换。
//具体使用方法
//s_pic(大图片路径,生成小图片路径,大图片文件名,生成小图片文名,生成小图片宽度,生成小图片高度,是否等比缩放(默认为true))
public class DwindlePic {

    String InputDir; //输入图路径
    String OutputDir; //输出图路径
    String InputFileName; //输入图文件名
    String OutputFileName; //输出图文件名
    int OutputWidth = 80; //默认输出图片宽
    int OutputHeight = 80; //默认输出图片高
    int rate = 0;
    boolean proportion = true; //是否等比缩放标记(默认为等比缩放)

    public DwindlePic() {
        //初始化变量
        InputDir = "";
        OutputDir = "";
        InputFileName = "";
        OutputFileName = "";
        OutputWidth = 80;
        OutputHeight = 80;
        rate = 0;
    }

    public boolean s_pic() {
//        BufferedImage image;
//        String NewFileName;
//建立输出文件对象
        File file = new File(OutputDir + OutputFileName);
        FileOutputStream tempout = null;
        try {
            tempout = new FileOutputStream(file);
        } catch (Exception ex) {
            System.out.println(ex.toString());
        }
        Image img = null;
        Toolkit tk = Toolkit.getDefaultToolkit();
        Applet app = new Applet();
        MediaTracker mt = new MediaTracker(app);
        try {
            img = tk.getImage(InputDir + InputFileName);
            mt.addImage(img, 0);
            mt.waitForID(0);
        } catch (Exception e) {
            e.printStackTrace();
        }

        if (img.getWidth(null) == -1) {
//            System.out.println(" can't read,retry!" + "<BR>");
            return false;
        } else {
            int new_w;
            int new_h;
            if (this.proportion == true) { //判断是否是等比缩放.
//为等比缩放计算输出的图片宽度及高度
                double rate1 = ((double) img.getWidth(null)) / (double) OutputWidth +
                        0.1;
                double rate2 = ((double) img.getHeight(null)) / (double) OutputHeight +
                        0.1;
                double rate = rate1 > rate2 ? rate1 : rate2;
                new_w = (int) (((double) img.getWidth(null)) / rate);
                new_h = (int) (((double) img.getHeight(null)) / rate);
            } else {
                new_w = OutputWidth; //输出的图片宽度
                new_h = OutputHeight; //输出的图片高度
            }
            BufferedImage buffImg = new BufferedImage(new_w, new_h,
                    BufferedImage.TYPE_INT_RGB);

            Graphics g = buffImg.createGraphics();

            g.setColor(Color.white);
            g.fillRect(0, 0, new_w, new_h);

            g.drawImage(img, 0, 0, new_w, new_h, null);
            g.dispose();

            JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(tempout);
            try {
                encoder.encode(buffImg);
                tempout.close();
            } catch (IOException ex) {
                System.out.println(ex.toString());
            }
        }
        return true;
    }

    public boolean s_pic(String InputDir, String OutputDir, String InputFileName,
            String OutputFileName) {
//输入图路径
        this.InputDir = InputDir;
//输出图路径
        this.OutputDir = OutputDir;
//输入图文件名
        this.InputFileName = InputFileName;
//输出图文件名
        this.OutputFileName = OutputFileName;
        return s_pic();
    }

    public boolean s_pic(String InputDir, String OutputDir, String InputFileName,
            String OutputFileName, int width, int height, boolean gp) {
//输入图路径
        this.InputDir = InputDir;
//输出图路径
        this.OutputDir = OutputDir;
//输入图文件名
        this.InputFileName = InputFileName;
//输出图文件名
        this.OutputFileName = OutputFileName;
//设置图片长宽
        setW_H(width, height);
//是否是等比缩放 标记
        this.proportion = gp;
        return s_pic();
    }

    public void setInputDir(String InputDir) {
        this.InputDir = InputDir;
    }

    public void setOutputDir(String OutputDir) {
        this.OutputDir = OutputDir;
    }

    public void setInputFileName(String InputFileName) {
        this.InputFileName = InputFileName;
    }

    public void setOutputFileName(String OutputFileName) {
        this.OutputFileName = OutputFileName;
    }

    public void setOutputWidth(int OutputWidth) {
        this.OutputWidth = OutputWidth;
    }

    public void setOutputHeight(int OutputHeight) {
        this.OutputHeight = OutputHeight;
    }

    public void setW_H(int width, int height) {
        this.OutputWidth = width;
        this.OutputHeight = height;
    }

    public static void main(String[] a) {
        //s_pic(大图片路径,生成小图片路径,大图片文件名,生成小图片文名,生成小图片宽度,生成小图片高度)
        DwindlePic mypic = new DwindlePic();
        System.out.println(
                mypic.s_pic("c:/",
                "d:/",
                "aa.bmp", "wwww.jpg", 120, 80, true));
    }
}

 

在使用时将用户上传的图片进行压缩处理，再转存到首页的图片目录中。over！

评论

4 楼 Shmily奕蝶 2012-02-17  

直接用这段代码就可以啦？？

3 楼 east_java 2009-10-09  

缩放后 怎么变模糊了。

2 楼 liuwei1981 2008-07-22  

什么意思？

1 楼 zhongxun20 2008-07-21  

   都显示不了[color=red][/color][b][/b][img][/img]