java web 图片水印设置

先将最基本的功能代码写出来
package com.mjp.images;
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;


public final class ImageUtils {
/**
* 图片水印
* @param pressImg 水印图片
* @param targetImg 目标图片
* @param x 修正值 默认在中间
* @param y 修正值 默认在中间
* @param alpha 透明度
*/
public final static void pressImage(String pressImg, String targetImg, int x, int y, float alpha) {
try {
File img = new File(targetImg);
Image src = ImageIO.read(img);
int wideth = src.getWidth(null);
int height = src.getHeight(null);
BufferedImage image = new BufferedImage(wideth, height, BufferedImage.TYPE_INT_RGB);
Graphics2D g = image.createGraphics();
g.drawImage(src, 0, 0, wideth, height, null);
//水印文件
Image src_biao = ImageIO.read(new File(pressImg));
int wideth_biao = src_biao.getWidth(null);
int height_biao = src_biao.getHeight(null);
g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));
g.drawImage(src_biao, (wideth - wideth_biao) / 2, (height - height_biao) / 2, wideth_biao, height_biao, null);
//水印文件结束
g.dispose();
ImageIO.write((BufferedImage) image, "jpg", img);
} catch (Exception e) {
e.printStackTrace();
}
}

/**
* 文字水印
* @param pressText 水印文字
* @param targetImg 目标图片
* @param fontName 字体名称
* @param fontStyle 字体样式
* @param color 字体颜色
* @param fontSize 字体大小
* @param x 修正值
* @param y 修正值
* @param alpha 透明度
*/
public static void pressText(String pressText, String targetImg, String fontName, int fontStyle, Color color, int fontSize, int x, int y, float alpha) {
try {
File img = new File(targetImg);
Image src = ImageIO.read(img);
int width = src.getWidth(null);
int height = src.getHeight(null);
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics2D g = image.createGraphics();
g.drawImage(src, 0, 0, width, height, null);
g.setColor(color);
g.setFont(new Font(fontName, fontStyle, fontSize));
g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));
g.drawString(pressText, (width - (getLength(pressText) * fontSize)) / 2 + x, (height - fontSize) / 2 + y);
g.dispose();
ImageIO.write((BufferedImage) image, "jpg", img);
} catch (Exception e) {
e.printStackTrace();
}
}

/**
* 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 = 0.0; //缩放比例
File f = new File(filePath);
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) {
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 {
pressImage("d:\\imgtest\\sy.jpg", "d:\\imgtest\\test1.jpg", 0, 0, 0.5f);
pressText("水印文字", "d:\\imgtest\\test1.jpg", "黑体", 12, Color.white, 80, 0, 0, 0.3f);
resize("d:\\imgtest\\test1.jpg", 500, 500, true);
}

public static int getLength(String text) {
int length = 0;
for (int i = 0; i < text.length(); i++) {
if (new String(text.charAt(i) + "").getBytes().length > 1) {
length += 2;
} else {
length += 1;
}
}
return length / 2;
}
}
==============================
后续再写一个web应用 使用过滤的方式来处理