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问在Struts 2表单中显示SimpleCaptcha
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Stack Overflow用户

提问于 2014-11-16 06:46:09

回答 2查看 4.7K关注 0票数 1

我正在尝试用Struts 2实现SimpleCaptcha，到目前为止图像正在显示。但是，它显示在<s:form>的顶部。

register.jsp:

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib prefix="s" uri="/struts-tags"%>

<head>
...
<s:head />
</head>

<body>
  <b>REGISTER</b>
  <p>Please fill up the form below.</p>
  <s:form action="register" method="post">
    <s:textfield label="Enter username" key="userId" maxlength="25"
      size="30" />
    <s:textfield label="Enter email" key="userEmail1" type="email"
      placeholder="someone@domain.com" size="30" />
    <s:textfield label="Re-enter email" key="userEmail2" type="email"
      placeholder="someone@domain.com" size="30" />
    <s:password label="Enter password" key="userPassword1" size="30" />
    <s:password label="Re-enter password" key="userPassword2"
      size="30" />
    <img src="<c:url value='simple-captcha.png' />" />
    <br />
    Cannot read? Refresh page for new CAPTCHA.                      
    <s:textfield label="Enter CAPTCHA" key="captchaAnswer" size="30" />
    <s:submit value="Register" />
  </s:form>
</body>

如何使图像显示在代码中指定的Enter CAPTCHA文本字段之上？

java

jsp

struts2

captcha

simplecaptcha

回答 2

Stack Overflow用户

回答已采纳

发布于 2014-11-16 12:57:00

图像应该由captcha操作生成。然后，在<img>标记中提供此操作的URL。要在项目中实现captcha，请执行以下步骤

将jar添加到web项目类路径：simplecaptcha-1.2.1.jar。通常在web-inf/lib文件夹中。
添加新的操作类RegisterAction

注意:下面的代码使用约定插件映射操作，为了简单起见，在提交表单时使用DMI调用操作类的某些方法。要打开DMI，请在struts.xml中使用常量

<constant name="struts.enable.DynamicMethodInvocation" value="true"/>

RegisterAction.java**:**

public class RegisterAction extends ActionSupport {
  private String userId;
  private String userEmail1;
  private String userEmail2;
  private String userPassword1;
  private String userPassword2;

  private String captchaResponse;
  private InputStream inputStream;

  //getters and setters

  public String create() {
    //RegisterAction is the form bean of the current action and captchaResponse is the field of user input

    String answer = (String) ActionContext.getContext().getSession().get("CorrectAnswer");
    if (answer == null || getCaptchaResponse()==null || !answer.equals(getCaptchaResponse())){
      addFieldError("captchaResponse", getText("error.captcha"));
    }
    return SUCCESS;
  }

  @Action(value = "captcha", results = {@Result(type="stream", params = {"contentType", "image/jpeg"})})
  public String captcha() {
    try {
      Captcha captcha = new Captcha.Builder(200, 50).addText(new DefaultTextProducer()).gimp(new DropShadowGimpyRenderer()).build();
      ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
      //write the image
      CaptchaServletUtil.writeImage(outputStream, captcha.getImage());
      //store the answer for this in session
      ActionContext.getContext().getSession().put("CorrectAnswer", captcha.getAnswer());
      //return image
      inputStream = new ByteArrayInputStream(outputStream.toByteArray());
      return SUCCESS;
    } catch (Exception e) {
      e.printStackTrace();
      throw e;
    }

  }

}

RegisterAction.properties包含错误键的以下值：

RegisterAction.properties**:**

error.captcha=Invalid value of shown text!

因此，我们要么检查pass成功，要么添加与captcha有关的错误。

在register.jsp中添加典型的web-inf\content

register.jsp**:**

<!DOCTYPE html>
<%@ taglib prefix="s" uri="/struts-tags"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head>
  <meta charset="UTF-8">
  <title>Register</title>
</head>
<body>
<b>REGISTER</b>
<p>Please fill up the form below.</p>
<s:form action="register" method="post">
  <s:textfield label="Enter username" key="userId" maxlength="25"
               size="30" />
  <s:textfield label="Enter email" key="userEmail1" type="email"
               placeholder="someone@domain.com" size="30" />
  <s:textfield label="Re-enter email" key="userEmail2" type="email"
               placeholder="someone@domain.com" size="30" />
  <s:password label="Enter password" key="userPassword1" size="30" />
  <s:password label="Re-enter password" key="userPassword2"
              size="30" />
  <tr><td>
  <img id="captchaImg" src="<s:url action='captcha'/>" alt="Captcha Image" height="45">
  <img src="<c:url value='/images/reload.jpg' />" alt="Reload" onclick="document.forms[0].captchaImg.src='<s:url action='captcha'/>'+'?id='+Math.random();" style="cursor:pointer"/>
  <s:textfield label="Enter CAPTCHA" key="captchaResponse" size="30" requiredLabel="*"/>
  <tr><td>
  Cannot read? Refresh page for new CAPTCHA.
  </td></tr>
  <s:submit method="create" value="Register" />
</s:form>

</body>
</html>

这将构造Captcha和text字段，以输入value和Struts错误消息，以显示captchaResponse字段中的错误，以及刷新图标。

注意:我们这里使用的一个很好的技巧是javascript Math.random()函数，这样可以防止像Firefox这样的浏览器缓存该URL并继续发布相同的Captcha图像，这样可以使它无需付出任何努力就可以获得新的值。

以下是它的样子：

有关更多详细信息，请参阅网站：SimpleCaptcha

票数 1

Stack Overflow用户

发布于 2014-11-17 06:46:45

这只是为了说明我是如何解决这个问题的。我不知道你能把<tr><td>放进<s:form>里。多亏了Roman ，我才能在我想要的地方显示CAPTCHA的图像。

register.jsp:

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib prefix="s" uri="/struts-tags"%>

<head>
...
<s:head />
</head>

<body>
    <b>REGISTER</b>
    <p>Please fill up the form below.</p>
    <s:form action="register" method="post">
        <s:textfield label="Enter username" key="userId" maxlength="25"
            placeholder="someone" size="30" />
        <s:textfield label="Enter email" key="userEmail1"
            placeholder="someone@domain.com" size="30" />
        <s:textfield label="Confirm email" key="userEmail2"
            placeholder="someone@domain.com" size="30" />
        <s:password label="Enter password" key="userPassword1" size="30" />
        <s:password label="Confirm password" key="userPassword2"
            size="30" />
        <tr>
            <td></td>
            <td>
                <img src="<c:url value='simple-captcha.png' />" />
                <br />
                Cannot read? Press F5 to refresh.
            </td>
        </tr>
        <s:textfield label="Enter code" key="captchaAnswer" size="30" />
        <s:submit value="Register" />
    </s:form>
</body>

RegisterAction.java:

import nl.captcha.Captcha;
...

public class RegisterAction extends ActionSupport implements SessionAware, Message {
    private static final long serialVersionUID = 1L;

    private Map<String, Object> session;

    private String userId;
    private String userEmail1;
    private String userEmail2;
    private String userPassword1;
    private String userPassword2;
    private String captchaAnswer;

    @Override
    public String execute() throws Exception {      
        // business logic to insert user into database

        return SUCCESS;
    }

    @Override
    public void validate() {
        Captcha captcha = (Captcha) session.get(Captcha.NAME);

        if(!captcha.isCorrect(getCaptchaAnswer())) {
            addFieldError("captchaAnswer", INCORRECT_CAPTCHA);
        }

        // other validations
    }

    @Override
    public void setSession(Map<String, Object> session) {
        this.session = session;
    }

    // getters and setters
}

struts.xml:

<struts>
    <constant name="struts.devMode" value="true" />
    <package name="default" extends="struts-default">
        <action name="register" class="com.mypackage.action.RegisterAction">
            <result name="success">/login.jsp</result>
            <result name="input">/register.jsp</result>
        </action>

        <!-- other actions -->
    </package>
</struts>

web.xml:

( <init-param>是可选的。)

<servlet>
    <servlet-name>SimpleCaptcha</servlet-name>
    <servlet-class>nl.captcha.servlet.SimpleCaptchaServlet</servlet-class>
    <init-param>
        <param-name>captcha-width</param-name>
        <param-value>200</param-value>
    </init-param>
    <init-param>
        <param-name>captcha-height</param-name>
        <param-value>50</param-value>
    </init-param>
</servlet>

<servlet-mapping>
    <servlet-name>SimpleCaptcha</servlet-name>
    <url-pattern>/simple-captcha.png</url-pattern>
</servlet-mapping>

<filter>
    <filter-name>struts2</filter-name>
    <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>

<filter-mapping>
    <filter-name>struts2</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

输出：

票数 0

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/26954594

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