图片工具类， 图片水印，文字水印，缩放，补白等

import java.awt.AlphaComposite;
 import java.awt.Color;
 import java.awt.Font;
 import java.awt.Graphics2D;
 import java.awt.Image;
 import java.awt.geom.AffineTransform;
 import java.awt.image.AffineTransformOp;
 import java.awt.image.BufferedImage;
 import java.io.File;
 import java.io.IOException;
 
 import javax.imageio.ImageIO;
 
 /**
  * 图片工具类， 图片水印，文字水印，缩放，补白等
  */
 public final class ImageUtils {
     
     
     /**图片格式：JPG*/
     private static final String PICTRUE_FORMATE_JPG = "jpg";
     
     private ImageUtils(){}
     /**
      * 添加图片水印
      * @param targetImg 目标图片路径，如：C://myPictrue//1.jpg
      * @param waterImg  水印图片路径，如：C://myPictrue//logo.png
      * @param x 水印图片距离目标图片左侧的偏移量，如果x<0, 则在正中间
      * @param y 水印图片距离目标图片上侧的偏移量，如果y<0, 则在正中间
      * @param alpha 透明度(0.0 -- 1.0, 0.0为完全透明，1.0为完全不透明)
 */
     public final static void pressImage(String targetImg, String waterImg, int x, int y, float alpha) {
             try {
                 File file = new File(targetImg);
                 Image image = ImageIO.read(file);
                 int width = image.getWidth(null);
                 int height = image.getHeight(null);
                 BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
                 Graphics2D g = bufferedImage.createGraphics();
                 g.drawImage(image, 0, 0, width, height, null);
             
                 Image waterImage = ImageIO.read(new File(waterImg));    // 水印文件
                 int width_1 = waterImage.getWidth(null);
                 int height_1 = waterImage.getHeight(null);
                 g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));
                 
                 int widthDiff = width - width_1;
                 int heightDiff = height - height_1;
                 if(x < 0){
                     x = widthDiff / 2;
                 }else if(x > widthDiff){
                     x = widthDiff;
                 }
                 if(y < 0){
                     y = heightDiff / 2;
                 }else if(y > heightDiff){
                     y = heightDiff;
                 }
                 g.drawImage(waterImage, x, y, width_1, height_1, null); // 水印文件结束
                 g.dispose();
                 ImageIO.write(bufferedImage, PICTRUE_FORMATE_JPG, file);
             } catch (IOException e) {
                 e.printStackTrace();
             }
     }
 
     /**
      * 添加文字水印
      * @param targetImg 目标图片路径，如：C://myPictrue//1.jpg
      * @param pressText 水印文字， 如：中国证券网
      * @param fontName 字体名称，    如：宋体
      * @param fontStyle 字体样式，如：粗体和斜体(Font.BOLD|Font.ITALIC)
      * @param fontSize 字体大小，单位为像素
      * @param color 字体颜色
      * @param x 水印文字距离目标图片左侧的偏移量，如果x<0, 则在正中间
      * @param y 水印文字距离目标图片上侧的偏移量，如果y<0, 则在正中间
      * @param alpha 透明度(0.0 -- 1.0, 0.0为完全透明，1.0为完全不透明)
 */
     public static void pressText(String targetImg, String pressText, String fontName, int fontStyle, int fontSize, Color color, int x, int y, float alpha) {
         try {
             File file = new File(targetImg);
             
             Image image = ImageIO.read(file);
             int width = image.getWidth(null);
             int height = image.getHeight(null);
             BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
             Graphics2D g = bufferedImage.createGraphics();
             g.drawImage(image, 0, 0, width, height, null);
             g.setFont(new Font(fontName, fontStyle, fontSize));
             g.setColor(color);
             g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));
             
             int width_1 = fontSize * getLength(pressText);
             int height_1 = fontSize;
             int widthDiff = width - width_1;
             int heightDiff = height - height_1;
             if(x < 0){
                 x = widthDiff / 2;
             }else if(x > widthDiff){
                 x = widthDiff;
             }
             if(y < 0){
                 y = heightDiff / 2;
             }else if(y > heightDiff){
                 y = heightDiff;
             }
             
             g.drawString(pressText, x, y + height_1);
             g.dispose();
             ImageIO.write(bufferedImage, PICTRUE_FORMATE_JPG, file);
         } catch (Exception e) {
             e.printStackTrace();
         }
     }
     
     /**
      * 获取字符长度，一个汉字作为 1 个字符, 一个英文字母作为 0.5 个字符
      * @param text
      * @return 字符长度，如：text="中国",返回 2；text="test",返回 2；text="中国ABC",返回 4.
 */
     public static int getLength(String text) {
         int textLength = text.length();
         int length = textLength;
         for (int i = 0; i < textLength; i++) {
             if (String.valueOf(text.charAt(i)).getBytes().length > 1) {
                 length++;
             }
         }
         return (length % 2 == 0) ? length / 2 : length / 2 + 1;
     }
 
     /**
      * 图片缩放
      * @param filePath 图片路径
      * @param height 高度
      * @param width 宽度
      * @param bb 比例不对时是否需要补白
 */
     public static void resize(String filePath, int height, int width, boolean bb) {
         try {
             double ratio = 0; //缩放比例    
             File f = new File(filePath);   
             BufferedImage bi = ImageIO.read(f);   
             Image itemp = bi.getScaledInstance(width, height, BufferedImage.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) {   
                 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, "jpg", f);   
         } catch (IOException e) {
             e.printStackTrace();
         }
     }
 
     public static void main(String[] args) throws IOException {
       //添加文字水印
       //pressText("D:/1.jpg", "test", "宋体", Font.BOLD, 24, Color.red, 50, 50, 0.3f);
       //图片缩放
       resize("D:/1.jpg", 100, 600, false);
       System.out.println("处理完毕！");
     }
     
 }