Java 在Struts 2表单中显示SimpleCaptcha

我正在尝试用Struts 2实现

SimpleCaptcha

，到目前为止，图像已经显示出来了。但是，它显示在

的顶部

register.jsp:

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

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;
    }

  }

}

error.captcha=Invalid value of shown text!

...
登记
请填写下面的表格

" />


无法读取？刷新页面以获取新的验证码。

---

如何使图像显示在代码中指定的“输入验证码”文本字段上方？

图像应通过验证码操作生成。然后在

“alt=”验证码图像“height=”45“>
“alt=”Reload“onclick=”document.forms[0]。captchaImg.src=''+'？id=''+Math.random（）；“style=”光标：指针“/>
无法读取？刷新页面以获取新的验证码。

这将构造Captcha和文本字段以输入值，Struts错误消息以显示

captchaResponse

字段中的错误，以及刷新图标

注意：我们在这里使用的一个很好的技巧是javascript

Math.random（）

函数，这种方法可以防止某些浏览器（如Firefox）缓存URL并不断发布相同的验证码图像，这样就可以在不做任何努力的情况下强制执行它以获取新值

下面是它的样子：

---

有关更多详细信息，请访问网站：

这只是为了说明我是如何解决问题的。我不知道您可以将

放在

中。多亏了Roman C，我获得了验证码图像，并将其显示在我想要的位置

register.jsp:

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

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;
    }

  }

}

error.captcha=Invalid value of shown text!

...
登记
请填写下面的表格

" />


不识字？按F5刷新。

RegisterAction.java:

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

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;
    }

  }

}

error.captcha=Invalid value of shown text!

导入nl.captcha.captcha；
...
公共类RegisterAction扩展ActionSupport实现SessionAware、消息{
私有静态最终长serialVersionUID=1L；
私人Map会议；
私有字符串用户标识；
私有字符串userEmail1；
私有字符串userEmail2；
私有字符串userPassword1；
私有字符串userPassword2；
私有字符串；
@凌驾
公共字符串execute（）引发异常{
//将用户插入数据库的业务逻辑
回归成功；
}
@凌驾
public void validate（）{
Captcha Captcha=（Captcha）session.get（Captcha.NAME）；
如果（！captcha.isCorrect（GetCaptchAnswer（）））{
addFieldError（“验证码应答”，不正确的验证码）；
}
//其他验证
}
@凌驾
公共无效设置会话（映射会话）{
this.session=会话；
}
//接球手和接球手
}

struts.xml:

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

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;
    }

  }

}

error.captcha=Invalid value of shown text!

/login.jsp
/register.jsp

web.xml:
（

是可选的。）

SimpleCaptcha
nl.captcha.servlet.SimpleCaptchaServlet
验证码宽度
200
验证码高度
50
SimpleCaptcha
/simple-captcha.png
支柱2
org.apache.struts2.dispatcher.ng.filter.strutspreadexecutefilter
支柱2
/*

输出：

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

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;
    }

  }

}

error.captcha=Invalid value of shown text!

---

感谢您在回答问题之外的其他问题。这肯定会对每个人都有帮助。我还根据上面链接的SimpleCaptcha的sourceforge J2EE示例发布了一个答案。