生成验证码的Java类库：Cage

特性

• it is open source, Apache v2 licensed so it can be used in enterprise/proprietary projects too
• it supports maven (available from the central maven repository)
• it is fast (on the test pc 3-5 msec / image)
• it is small (a single, small jar, no external dependencies, only Java 1.5 or newer is needed)
• supports a wide variety of effects (symbol crowding, rotating, ripple - waving, outline shadowing and blurring)
• has two predefined templates that mimics those captchas used by large email providers. See Templates for more info.
• it is simple to use and integrate. See QuickStart for a fast start.

public class QuickStart {    public static void main(String[] args) throws IOException {      Cage cage = new GCage();        OutputStream os = new FileOutputStream("captcha.jpg", false);      try {        cage.draw(cage.getTokenGenerator().next(), os);      } finally {        os.close();      }    }  }