验证码功能实现

使用google的kaptcha包实现，可预定义验证码内容。

pom.xml:

<dependency>
            <groupId>com.google.code.kaptcha</groupId>
            <artifactId>kaptcha</artifactId>
            <version>2.3</version>
            <!--Kaptcha针对1.5和1.4提供了不同的分发包，这里使用classifier来区分-->
            <classifier>jdk15</classifier>
        </dependency>

CaptchaService:

package net.deniro.captcha;

import java.util.List;

/**
 * 验证码
 *
 * @author deniro
 *         15-2-24上午10:49
 */
public interface CaptchaService {
    /**
     * 生成随机验证码主键
     *
     * @return
     * @throws CaptchaException
     */
    String generateCaptchaKey() throws CaptchaException;

    /**
     * 生成验证码图片
     *
     * @param captchaKey
     * @return
     * @throws CaptchaException
     */
    byte[] generateCaptchaImage(String captchaKey) throws CaptchaException;

    /**
     * 验证用户返回的主键和值
     *
     * @param captchaKey
     * @param captchaValue
     * @return
     * @throws CaptchaException
     */
    boolean validateCaptcha(String captchaKey, String captchaValue) throws CaptchaException;

    /**
     * 获取 预定义验证码图片的内容
     *
     * @return
     */
    List<String> getPreDefinedTexts();

    /**
     * 设置 预定义验证码图片的内容
     *
     * 提高可测试性
     *
     * @param preDefinedTexts
     */
    void setPreDefinedTexts(List<String> preDefinedTexts);
}

CaptchaServiceImpl:

package net.deniro.captcha;

import com.google.code.kaptcha.impl.DefaultKaptcha;
import com.google.code.kaptcha.util.Config;
import org.springframework.beans.factory.InitializingBean;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;

/**
 * 验证码实现
 *
 * @author deniro
 *         15-2-24上午11:05
 */
public class CaptchaServiceImpl implements CaptchaService, InitializingBean {
    /**
     * 验证码生成器
     */
    private DefaultKaptcha producer;
    private Map<String, String> captchaMap = new HashMap<String, String>();
    /**
     * 预定义验证码内容列表
     */
    private List<String> preDefinedTexts;
    /**
     * 预定义验证码内容列表索引
     */
    private int textCount = 0;

    /**
     * 生成随机验证码
     *
     * @return
     * @throws CaptchaException
     */
    @Override
    public String generateCaptchaKey() throws CaptchaException {
        String key = RandomGenerator.getRandomString();//主键的目的仅是标识验证码图片，本身没有实际意义
        String value = getCaptchaText();
        captchaMap.put(key, value);
        return key;
    }

    /**
     * 生成验证码字符串
     *
     * @return
     */
    private String getCaptchaText() {
        if (preDefinedTexts != null && !preDefinedTexts.isEmpty()) {//顺序循环字符串列表读取值
            String text = preDefinedTexts.get(textCount);
            textCount = (textCount + 1) % preDefinedTexts.size();
            return text;
        } else {//创建随机字符串
            return producer.createText();
        }
    }

    /**
     * 生成验证码图片
     *
     * @param captchaKey
     * @return
     * @throws CaptchaException
     */
    @Override
    public byte[] generateCaptchaImage(String captchaKey) throws CaptchaException {
        String text = captchaMap.get(captchaKey);
        if (text == null) {
            throw new CaptchaException("验证码' " + captchaKey + " ' 未找到。");
        }

        BufferedImage image = producer.createImage(text);
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        try {
            ImageIO.write(image, "jpg", out);
        } catch (Exception e) {
            throw new CaptchaException("无法生成验证码流。");
        }

        return out.toByteArray();
    }

    /**
     * 验证
     *
     * @param captchaKey
     * @param captchaValue
     * @return
     * @throws CaptchaException
     */
    @Override
    public boolean validateCaptcha(String captchaKey, String captchaValue) throws CaptchaException {
        String text = captchaMap.get(captchaKey);
        if (text == null) {
            throw new CaptchaException("验证码主键' " + captchaKey + " '不存在！");
        }

        if (text.equals(captchaValue)) {
            captchaMap.remove(captchaKey);
            return true;
        } else {
            return false;
        }
    }

    @Override
    public List<String> getPreDefinedTexts() {
        return preDefinedTexts;
    }

    @Override
    public void setPreDefinedTexts(List<String> preDefinedTexts) {
        this.preDefinedTexts = preDefinedTexts;
    }

    /**
     * 初始化验证码生成器，并提供默认配置
     * <p/>
     * Spring初始化对象时调用
     *
     * @throws Exception
     */
    @Override
    public void afterPropertiesSet() throws Exception {
        producer = new DefaultKaptcha();
        producer.setConfig(new Config(new Properties()));
    }
}

RandomGenerator:

package net.deniro.captcha;

import java.util.Random;

/**
 * 随机码生成器
 *
 * @author deniro
 *         15-2-24上午10:59
 */
public class RandomGenerator {
    /**
     * 字符范围
     */
    private static String range="0123456789abcdefghijklmnopqrstuvwxyz";

    /**
     * 获取随机字符串
     *
     * 静态、线程安全
     * @return
     */
    public static synchronized String getRandomString(){
        Random random=new Random();
        StringBuilder result=new StringBuilder();
        for (int i = 0; i < 8; i++) {
            result.append(range.charAt(random.nextInt(range.length())));
        }
        return result.toString();
    }
}

CaptchaException:

package net.deniro.captcha;

/**
 * 验证码异常
 *
 * @author deniro
 *         15-2-24上午10:51
 */
public class CaptchaException extends Exception {

    public CaptchaException(String message) {
        super(message);
    }

    public CaptchaException(String message, Throwable throwable) {
        super(message, throwable);
    }
}

captcha.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="CaptchaService" class="net.deniro.captcha.CaptchaServiceImpl"></bean>

</beans>

CaptchaServiceTest:

package captcha;

import net.deniro.captcha.CaptchaService;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;

/**
 * @author deniro
 *         15-2-24下午11:24
 */
public class CaptchaServiceTest {

    private CaptchaService service;

    @Before
    public void prepare() throws Exception {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("captcha.xml");
        service = (CaptchaService) ctx.getBean("CaptchaService");
    }

    @Test
    public void testGenerateCaptcha() throws Exception {
        List<String> preDefinedTexts = new ArrayList<String>();
        preDefinedTexts.add("12345");
        preDefinedTexts.add("abcde");
        service.setPreDefinedTexts(preDefinedTexts);

        for (int i = 0; i < preDefinedTexts.size(); i++) {

            String captchaKey = service.generateCaptchaKey();
            assertNotNull(captchaKey);

            byte[] captchaImage = service.generateCaptchaImage(captchaKey);
            assertTrue(captchaImage.length > 0);

            File image = new File("target/" + captchaKey + ".jpg");
            OutputStream output = null;
            try {
                output = new FileOutputStream(image);
                output.write(captchaImage);
            } finally {
                if (output != null) {
                    output.close();
                }
            }
            assertTrue(image.exists() && image.length() > 0);
        }

    }

    @Test
    public void testValidateCaptchaCorrect() throws Exception {

        List<String> preDefinedTexts = new ArrayList<String>();
        preDefinedTexts.add("12345");
        preDefinedTexts.add("abcde");
        service.setPreDefinedTexts(preDefinedTexts);

        String captchaKey = service.generateCaptchaKey();
        service.generateCaptchaImage(captchaKey);
        assertTrue(service.validateCaptcha(captchaKey, "12345"));

        captchaKey = service.generateCaptchaKey();
        service.generateCaptchaImage(captchaKey);
        assertTrue(service.validateCaptcha(captchaKey, "abcde"));
    }
}

生成的验证码图片：