Java 实现生成水印,生成验证码,读取图片尺寸的方法,在Android项目开发中,如果要实现瀑布流类似的布局,不得不进行提前获取图片尺寸。
另外图片水印和验证码也有很多用处,验证码和水印的原理类似,无非就是图形的绘制,这里只说说验证码即可
--------实现图片尺寸的读取--------
/** * */package com.b510;import java.awt.image.BufferedImage;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.util.Date;import java.util.Iterator;import javax.imageio.ImageIO;import javax.imageio.ImageReader;import javax.imageio.stream.ImageInputStream;public class ImageUtil { /** * 源图片路径名称如:c:/1.jpg */ private String srcpath = "e:/pool.jpg"; public ImageUtil() { } public static void main(String[] args) throws Exception { ImageUtil util = new ImageUtil(); util.getImageSizeByImageReader(util.getSrcpath()); util.getImageSizeByBufferedImage(util.getSrcpath()); } /** * 使用ImageReader获取图片尺寸 * * @param src * 源图片路径 */ public void getImageSizeByImageReader(String src) { long beginTime = new Date().getTime(); File file = new File(src); try { Iteratorreaders = ImageIO.getImageReadersByFormatName("jpg"); ImageReader reader = (ImageReader) readers.next(); ImageInputStream iis = ImageIO.createImageInputStream(file); reader.setInput(iis, true); System.out.println("width:" + reader.getWidth(0)); System.out.println("height:" + reader.getHeight(0)); } catch (IOException e) { e.printStackTrace(); } long endTime = new Date().getTime(); System.out.println("使用[ImageReader]获取图片尺寸耗时:[" + (endTime - beginTime)+"]ms"); } /** * 使用BufferedImage获取图片尺寸 * * @param src * 源图片路径 */ public void getImageSizeByBufferedImage(String src) { long beginTime = new Date().getTime(); File file = new File(src); FileInputStream is = null; try { is = new FileInputStream(file); } catch (FileNotFoundException e2) { e2.printStackTrace(); } BufferedImage sourceImg = null; try { sourceImg = javax.imageio.ImageIO.read(is); System.out.println("width:" + sourceImg.getWidth()); System.out.println("height:" + sourceImg.getHeight()); } catch (IOException e1) { e1.printStackTrace(); } long endTime = new Date().getTime(); System.out.println("使用[BufferedImage]获取图片尺寸耗时:[" + (endTime - beginTime)+"]ms"); } public String getSrcpath() { return srcpath; } public void setSrcpath(String srcpath) { this.srcpath = srcpath; }}
------实现验证码-------
public class RandomValidateCode { public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";//放到session中的key private Random random = new Random(); private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生的字符串 private int width = 80;//图片宽 private int height = 26;//图片高 private int lineSize = 40;//干扰线数量 private int stringNum = 4;//随机产生字符数量 /* * 获得字体 */ private Font getFont(){ return new Font("Fixedsys",Font.CENTER_BASELINE,18); } /* * 获得颜色 */ private Color getRandColor(int fc,int bc){ if(fc > 255) fc = 255; if(bc > 255) bc = 255; int r = fc + random.nextInt(bc-fc-16); int g = fc + random.nextInt(bc-fc-14); int b = fc + random.nextInt(bc-fc-18); return new Color(r,g,b); } /** * 生成随机图片 */ public void getRandcode(HttpServletRequest request, HttpServletResponse response) { HttpSession session = request.getSession(); //BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类 BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR); Graphics g = image.getGraphics();//产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作 g.fillRect(0, 0, width, height); g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,18)); g.setColor(getRandColor(110, 133)); //绘制干扰线 for(int i=0;i<=lineSize;i++){ drowLine(g); } //绘制随机字符 String randomString = ""; for(int i=1;i<=stringNum;i++){ randomString=drowString(g,randomString,i); } session.removeAttribute(RANDOMCODEKEY); session.setAttribute(RANDOMCODEKEY, randomString); System.out.println(randomString); g.dispose(); try { ImageIO.write(image, "JPEG", response.getOutputStream());//将内存中的图片通过流动形式输出到客户端 } catch (Exception e) { e.printStackTrace(); } } /* * 绘制字符串 */ private String drowString(Graphics g,String randomString,int i){ g.setFont(getFont()); g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121))); String rand = String.valueOf(getRandomString(random.nextInt(randString.length()))); randomString +=rand; g.translate(random.nextInt(3), random.nextInt(3)); g.drawString(rand, 13*i, 16); return randomString; } /* * 绘制干扰线 */ private void drowLine(Graphics g){ int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(13); int yl = random.nextInt(15); g.drawLine(x, y, x+xl, y+yl); } /* * 获取随机的字符 */ public String getRandomString(int num){ return String.valueOf(randString.charAt(num)); }}