如何使用google kaptcha生成驗證碼

1.首先，咱們要引入kaptcha的jar包，或者在pom.xml中引入

<dependency>
	<groupId>com.google.code</groupId>
	<artifactId>kaptcha</artifactId>
	<version>2.3.2</version>
</dependency>

2.其次，咱們在spring的配置文件中配置參數，如在spring.xml中。

<bean id="captchaProducer" class="com.google.code.kaptcha.impl.DefaultKaptcha">
		<property name="config">
			<bean class="com.google.code.kaptcha.util.Config">
				<constructor-arg>
					<props>
						<prop key="kaptcha.border">no</prop>
						<prop key="kaptcha.textproducer.font.color">red</prop>
						<prop key="kaptcha.textproducer.char.string">1234567890</prop>
						<prop key="kaptcha.textproducer.char.space">5</prop>
						<prop key="kaptcha.image.width">160</prop>
						<prop key="kaptcha.textproducer.font.size">60</prop>
						<prop key="kaptcha.image.height">100</prop>
						<prop key="kaptcha.session.key">code</prop>
						<prop key="kaptcha.textproducer.char.length">4</prop>
					</props>
				</constructor-arg>
			</bean>
		</property>
	</bean>

這樣就能夠在java中使用captchaProducer。 3.建立一個生成驗證碼的Controller

@Controller
@RequestMapping("/main/captchaImage")
public class CaptchaImageCreateController {
    @Resource
    private Producer  captchaProducer;

    @RequestMapping("/vc.jpg")
    public void handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {

        response.setDateHeader("Expires", 0);
        // Set standard HTTP/1.1 no-cache headers.
        response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
        // Set IE extended HTTP/1.1 no-cache headers (use addHeader).
        response.addHeader("Cache-Control", "post-check=0, pre-check=0");
        // Set standard HTTP/1.0 no-cache header.
        response.setHeader("Pragma", "no-cache");
        // return a jpeg
        response.setContentType("image/jpeg");
        // create the text for the image
        String capText = captchaProducer.createText();
        // store the text in the session
        request.getSession().setAttribute(Constants.KAPTCHA_SESSION_KEY, capText);
        // create the image with the text
        BufferedImage bi = captchaProducer.createImage(capText);
        ServletOutputStream out = response.getOutputStream();
        // write the data out
        ImageIO.write(bi, "jpg", out);
        try {
            out.flush();
        } finally {
            out.close();
        }
    }
}

其中resource標籤就是能夠將在配置文件中配置的bean注入到實體類中。該方法即生成了驗證碼，並將驗證碼返回。 4.在jsp中咱們能夠調用這個方法. 方式一：img標籤直接請求

<img
	id="imgCode"
	src="<%=request.getContextPath()%>/main/captchaImage/vc.jpg"
	class="inline-block vm codeimg" alt="" width="90"  height="42">

方式二：刷新按鈕，按鈕直接調用方法，並將返回值注入img標籤中

function reloadValidCode() {
		$("#imgCode").attr('src', '${ctx}/main/captchaImage/vc.jpg?' + Math.random());
	}