Java 验证码 图片验证码示例

package test.web.home.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.util.Random;
import javax.imageio.ImageIO;

public abstract class RandomGraphic
{
  private static int wordHeight = 10;
  private static int wordWidth = 15;

  private static int fontSize = 20;
  private static final int MAX_CHARCOUNT = 16;
  private static final int initypos = 5;
  private static final Color[] CHAR_COLOR = { Color.RED, Color.BLUE, Color.GREEN, Color.MAGENTA };

  public static String GRAPHIC_JPEG = "JPEG";

  public static String GRAPHIC_PNG = "PNG";

  public static String draw(String charValue, String graphicFormat, OutputStream out)
    throws Exception
  {
    int charCount = charValue.length();
    if ((charCount < 1) || (charCount > 16)) {
      throw new Exception("Invalid parameter charCount,charCount should between in 1 and 16");
    }

    int w = (charCount + 2) * wordWidth;
    int h = wordHeight * 3;

    BufferedImage bi = new BufferedImage(w, h, 5);
    Graphics2D g = bi.createGraphics();

    Color backColor = Color.WHITE;
    g.setBackground(backColor);
    g.fillRect(0, 0, w, h);

    g.setFont(new Font(null, 1, fontSize));

    for (int i = 0; i < charCount; i++) {
      String c = charValue.substring(i, i + 1);
      Color color = CHAR_COLOR[randomInt(0, CHAR_COLOR.length)];
      g.setColor(color);
      int xpos = (i + 1) * wordWidth;

      int ypos = randomInt(5 + wordHeight, 5 + wordHeight * 2);
      g.drawString(c, xpos, ypos);
    }
    g.dispose();
    bi.flush();

    ImageIO.write(bi, graphicFormat, out);

    out.close();
    return charValue;
  }

  public static String randNumber(int charCount)
  {
    String charValue = "";

    for (int i = 0; i < charCount; i++) {
      charValue = charValue + String.valueOf(randomInt(0, 10));
    }
    return charValue;
  }

  public static String randAlpha(int charCount) {
    String charValue = "";

    for (int i = 0; i < charCount; i++) {
      char c = (char)(randomInt(0, 26) + 97);
      charValue = charValue + String.valueOf(c);
    }
    return charValue;
  }

  protected static int randomInt(int from, int to)
  {
    Random r = new Random();
    return from + r.nextInt(to - from);
  }

  public static void main(String[] args)
    throws Exception
  {
    System.out.println(draw(randAlpha(4), GRAPHIC_PNG, new FileOutputStream("c:/myimg.png")));
  }
}

package test;

import test.LogProxy;
import java.io.IOException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import test.web.boot.api.ModuleBaseServlet;
import test.web.utils.http.ResultCode;
import test.web.utils.http.ResultProxy;

public class AuthCode extends ModuleBaseServlet
{
  private static final long serialVersionUID = 1L;
  private LogProxy logg = LogProxy.getProxy(getClass().getName());

  public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws IOException
  {
    try
    {
      String randomCode = RandomGraphic.randAlpha(4);
      this.logg.info("###> 【验证码】doGet==> randomCode:" + randomCode, new Object[0]);
      request.getSession().setAttribute("SESSION_KEY_AUTHCODE", randomCode);
      RandomGraphic.draw(randomCode, RandomGraphic.GRAPHIC_PNG, response.getOutputStream());
    } catch (Exception e) {
      e.printStackTrace();
      ResultProxy.getJSONResult().setCode(ResultCode.ERROR).send(response);
    }
  }
}