生成圖片驗證碼（VerifyCode）

package cn.itcast.image;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import javax.imageio.ImageIO;

import org.junit.Test;

/**
 * 動態生成圖片
 * @author HP
 *
 */
public class Demo {
    @Test
    public void fun() throws FileNotFoundException, IOException{
        /**
         * 1.創建圖片緩沖區
         * 2.設置其寬高
         * 3.得到這個圖片的繪制環境（得到畫筆）
         * 4.保存起來
         * 
         */
        BufferedImage bi = new BufferedImage(70,35,BufferedImage.TYPE_INT_RGB);
        Graphics g = bi.getGraphics();//得到繪制環境
        g.setColor(Color.WHITE);//把環境設置為紅色
        g.fillRect(0,0,70,35);//填充矩形；從0,0開始，寬70，高35，即整個圖片，即為圖片設置背景色
        g.setColor(Color.RED);//把環境設置為紅色
        g.drawString("Hello", 2, 35-2);//向圖片上寫入字符串，其中2,2表示x，y軸的坐標
        
        ImageIO.write(bi, "JPEG",new FileOutputStream("F://xxx.jpg"));
    }
    @Test
    public void fun2() throws FileNotFoundException, IOException{
        VerifyCode vc = new VerifyCode();
        BufferedImage bi = vc.getImage();
        VerifyCode.output(bi,new FileOutputStream("F:/xxx.jpg"));
        
        System.out.println(vc.getText());
    }
}

以上是Demo類，下面我們寫VerifyCode類

package cn.itcast.image;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.imageio.ImageIO;

public class VerifyCode {
    private int w = 70;
    private int h = 35;
    private Random r = new Random();
    //("宋體“，”華文楷體“，”黑體“，”華文新魏“，”華文隸書“，”微軟雅黑”，“楷體_GB2312")
    private String[] fontNames = {"宋體","華文楷書","黑體","微軟雅黑","楷體_GB2312"};
    //可選的字符
    private String codes = "23456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    //背景色
    private Color bgColor = new Color(255,255,255);
    //驗證碼上的文本
    private String text;
    //生成隨機的顏色
    private Color randomColor(){
        int red = r.nextInt(150);
        int green = r.nextInt(150);
        int blue = r.nextInt(150);
        return new Color(red,green,blue);
    }
    //生成隨機字體
    private Font randomFont(){
        int index = r.nextInt(fontNames.length);
        String fontName = fontNames(index); //生成隨機的字體名稱
        int style = r.nextInt(4);//生成隨機的樣式，0（無樣式），1（粗體），2（斜體），3（粗體+斜體）
        int size = r.nextInt(5)+24;//生成隨機字號 24-28
        return new Font(fontName,style,size);
        
    }
    

    private String fontNames(int index) {
        // TODO Auto-generated method stub
        return null;
    }
    //畫干擾線
    private void drawLine(BufferedImage image){
        int num = 3;//一共畫三條
        Graphics2D g2 = (Graphics2D)image.getGraphics();
        for(int i=0;i<num;i++){//生成兩個點的坐標，即4個值
            int x1 = r.nextInt(w);
            int y1 = r.nextInt(h);
            int x2 = r.nextInt(w);
            int y2 = r.nextInt(h);
            g2.setStroke(new BasicStroke(1.5F));
            g2.setColor(Color.BLUE);//干擾線是藍色
            g2.drawLine(x1,y1,x2,y2); //划線
        }
    }
        //隨機生成一個字符
        private char randomChar(){
            int index = r.nextInt(codes.length());
            return codes.charAt(index);
        }
        private BufferedImage createImage(){
            BufferedImage image = new BufferedImage(w,h,BufferedImage.TYPE_INT_RGB);
            Graphics2D g2 = (Graphics2D)image.getGraphics();
            g2.setColor(this.bgColor);
            g2.fillRect(0, 0, w, h);
            return image;
        }
        //調用這個方法得到驗證碼
    public BufferedImage getImage(){
        BufferedImage image = createImage();//創建圖片緩沖區
        Graphics2D g2 = (Graphics2D) image.getGraphics();//得到繪制環境
        StringBuilder sb = new StringBuilder();//用來裝載生成的驗證文本
        //向圖片中畫4個字符
        for(int i= 0;i<4;i++){//循環四次
            String s = randomChar()+"";//隨機生成一個字符
            sb.append(s);//把字母添加到sb中
            float x = i*1.0F * w/4;//設置當前字符的x軸坐標
            g2.setFont(randomFont());//設置隨機字體
            g2.setColor(randomColor());//設置隨機顏色
            g2.drawString(s,x,h-5);//畫圖
        }
        this.text = sb.toString();//把生成的字符串賦給了this.text
        drawLine(image);//添加干擾線
        return image;
    }
    //返回驗證碼圖片上的文本
    public String getText(){
        return text;
    }
    
    //保存圖片到指定的輸出流
    public static void output(BufferedImage image,OutputStream out) throws IOException{
        ImageIO.write(image, "JPEG", out);
    }
    

}