java图片处理类(图片水印，图片缩放)(2)_JSP教程

推荐：jsp switch语句的用法
如果希望选择执行若干代码块中的一个，你可以使用switch语句： 语法： switch(n) { case 1: 执行代码块 1 break case 2: 执行代码块 2 break default: 如果n即不是1也不是2，则执行此代码 } 工作原理：switch后面的(n)可以是表达式，也可以（并通常）是变量。然后表达

    /**
     * 缩放图像（按高度和宽度缩放）
     * @param srcImageFile 源图像文件地址
     * @param result 缩放后的图像地址
     * @param height 缩放后的高度
     * @param width 缩放后的宽度
     * @param bb 比例不对时是否需要补白：true为补白; false为不补白;
     */
    public final static void scale2(String srcImageFile, String result, int height, int width, boolean bb) {
        try {
            double ratio = 0.0; // 缩放比例
            File f = new File(srcImageFile);
            BufferedImage bi = ImageIO.read(f);
            Image itemp = bi.getScaledInstance(width, height, bi.SCALE_SMOOTH);
            // 计算比例
            if ((bi.getHeight() > height) || (bi.getWidth() > width)) {
                if (bi.getHeight() > bi.getWidth()) {
                    ratio = (new Integer(height)).doubleValue()
                            / bi.getHeight();
                } else {
                    ratio = (new Integer(width)).doubleValue() / bi.getWidth();
                }
                AffineTransformOp op = new AffineTransformOp(AffineTransform
                        .getScaleInstance(ratio, ratio), null);
                itemp = op.filter(bi, null);
            }
            if (bb) {//补白
                BufferedImage image = new BufferedImage(width, height,
                        BufferedImage.TYPE_INT_RGB);
                Graphics2D g = image.createGraphics();
                g.setColor(Color.white);
                g.fillRect(0, 0, width, height);
                if (width == itemp.getWidth(null))
                    g.drawImage(itemp, 0, (height - itemp.getHeight(null)) / 2,
                            itemp.getWidth(null), itemp.getHeight(null),
                            Color.white, null);
                else
                    g.drawImage(itemp, (width - itemp.getWidth(null)) / 2, 0,
                            itemp.getWidth(null), itemp.getHeight(null),
                            Color.white, null);
                g.dispose();
                itemp = image;
            }
            ImageIO.write((BufferedImage) itemp, "JPEG", new File(result));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
   
    /**
     * 图像切割(按指定起点坐标和宽高切割)
     * @param srcImageFile 源图像地址
     * @param result 切片后的图像地址
     * @param x 目标切片起点坐标X
     * @param y 目标切片起点坐标Y
     * @param width 目标切片宽度
     * @param height 目标切片高度
     */
    public final static void cut(String srcImageFile, String result,
            int x, int y, int width, int height) {
        try {
            // 读取源图像
            BufferedImage bi = ImageIO.read(new File(srcImageFile));
            int srcWidth = bi.getHeight(); // 源图宽度
            int srcHeight = bi.getWidth(); // 源图高度
            if (srcWidth > 0 && srcHeight > 0) {
                Image image = bi.getScaledInstance(srcWidth, srcHeight,
                        Image.SCALE_DEFAULT);
                // 四个参数分别为图像起点坐标和宽高
                // 即: CropImageFilter(int x,int y,int width,int height)
                ImageFilter cropFilter = new CropImageFilter(x, y, width, height);
                Image img = Toolkit.getDefaultToolkit().createImage(
                        new FilteredImageSource(image.getSource(),
                                cropFilter));
                BufferedImage tag = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
                Graphics g = tag.getGraphics();
                g.drawImage(img, 0, 0, width, height, null); // 绘制切割后的图
                g.dispose();
                // 输出为文件
                ImageIO.write(tag, "JPEG", new File(result));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
   
    /**
     * 图像切割（指定切片的行数和列数）
     * @param srcImageFile 源图像地址
     * @param descDir 切片目标文件夹
     * @param rows 目标切片行数。默认2，必须是范围 [1, 20] 之内
     * @param cols 目标切片列数。默认2，必须是范围 [1, 20] 之内
     */
    public final static void cut2(String srcImageFile, String descDir,
            int rows, int cols) {
        try {
            if(rows<=0||rows>20) rows = 2; // 切片行数
            if(cols<=0||cols>20) cols = 2; // 切片列数
            // 读取源图像
            BufferedImage bi = ImageIO.read(new File(srcImageFile));
            int srcWidth = bi.getHeight(); // 源图宽度
            int srcHeight = bi.getWidth(); // 源图高度
            if (srcWidth > 0 && srcHeight > 0) {
                Image img;
                ImageFilter cropFilter;
                Image image = bi.getScaledInstance(srcWidth, srcHeight, Image.SCALE_DEFAULT);
                int destWidth = srcWidth; // 每张切片的宽度
                int destHeight = srcHeight; // 每张切片的高度
                // 计算切片的宽度和高度
                if (srcWidth % cols == 0) {
                    destWidth = srcWidth / cols;
                } else {
                    destWidth = (int) Math.floor(srcWidth / cols) + 1;
                }
                if (srcHeight % rows == 0) {
                    destHeight = srcHeight / rows;
                } else {
                    destHeight = (int) Math.floor(srcWidth / rows) + 1;
                }
                // 循环建立切片
                // 改进的想法:是否可用多线程加快切割速度
                for (int i = 0; i < rows; i++) {
                    for (int j = 0; j < cols; j++) {
                        // 四个参数分别为图像起点坐标和宽高
                        // 即: CropImageFilter(int x,int y,int width,int height)
                        cropFilter = new CropImageFilter(j * destWidth, i * destHeight,
                                destWidth, destHeight);
                        img = Toolkit.getDefaultToolkit().createImage(
                                new FilteredImageSource(image.getSource(),
                                        cropFilter));
                        BufferedImage tag = new BufferedImage(destWidth,
                                destHeight, BufferedImage.TYPE_INT_RGB);
                        Graphics g = tag.getGraphics();
                        g.drawImage(img, 0, 0, null); // 绘制缩小后的图
                        g.dispose();
                        // 输出为文件
                        ImageIO.write(tag, "JPEG", new File(descDir
                                + "_r" + i + "_c" + j + ".jpg"));
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

分享：jsp if else语句使用方法
if else在大部份编程语言中都是这样使用的，我们今天来简单的介绍一下关于jsp教程 中的if else 与多重条件判断。 HTML HEAD TITLEUsing the if Statement/TITLE /HEAD BODY H1Using the if Statement/H1 % int value = 10; if(value 0) out.println(Absolute value of