将表单提交给 Servlet 后，如何在 JSP 中保留 HTML 表单字段值? [英] How can I retain HTML form field values in JSP after submitting form to Servlet?

问题描述

提交 HTML 中的数据后，servlet 将这些数据添加到我的数据库，并将结果消息转发到 JSP 页面.我想在转发后保留表单中最初提交的值.

After submitting data in the HTML from, a servlet adds these data to my DB and forwards a result message to a JSP page. I want to retain the initially submitted values in the form after the forward.

在 servlet 中创建一个对象并添加我收到的所有参数并将其与请求一起发送给 JSP 是否明智?还有其他更好的方法吗?

Is it sensible to make an object in a servlet and add all the parameters I receive and send it with a request to JSP? Is there another better way?

推荐答案

您可以通过 ${param} 访问单值请求参数.

You could access single-value request parameters by ${param}.

<%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %>
...
<input name="foo" value="${fn:escapeXml(param.foo)}">
<textarea name="bar">${fn:escapeXml(param.bar)}</textarea>
...
<input type="radio" name="faz" value="a" ${param.faz == 'a' ? 'checked' : ''} />
<input type="radio" name="faz" value="b" ${param.faz == 'b' ? 'checked' : ''} />
<input type="radio" name="faz" value="c" ${param.faz == 'c' ? 'checked' : ''} />
...
<select name="baz">
    <option value="a" ${param.baz == 'a' ? 'selected' : ''}>label a</option>
    <option value="b" ${param.baz == 'b' ? 'selected' : ''}>label b</option>
    <option value="c" ${param.baz == 'c' ? 'selected' : ''}>label c</option>
</select>

请注意，JSTL 的 fn:escapeXml() 是防止 XSS 攻击所必需的.另请参阅JSP/Servlet Web 应用程序中的 XSS 预防.

Do note that JSTL's fn:escapeXml() is necessary in order to prevent XSS attacks. See also XSS prevention in JSP/Servlet web application.

您可以通过 ${paramValues} 和 EL 3.0 流访问多值请求参数.

You could access multi-value request parameters by ${paramValues} and EL 3.0 streams.

<input type="checkbox" name="far" value="a" ${paramValues.far.stream().anyMatch(v->v == 'a').get() ? 'checked' : ''} />
<input type="checkbox" name="far" value="b" ${paramValues.far.stream().anyMatch(v->v == 'b').get() ? 'checked' : ''} />
<input type="checkbox" name="far" value="c" ${paramValues.far.stream().anyMatch(v->v == 'c').get() ? 'checked' : ''} />
...
<select name="boo" multiple>
    <option value="a" ${paramValues.boo.stream().anyMatch(v->v == 'a').get() ? 'selected' : ''}>label a</option>
    <option value="b" ${paramValues.boo.stream().anyMatch(v->v == 'b').get() ? 'selected' : ''}>label b</option>
    <option value="c" ${paramValues.boo.stream().anyMatch(v->v == 'c').get() ? 'selected' : ''}>label c</option>
</select>

这篇关于将表单提交给 Servlet 后，如何在 JSP 中保留 HTML 表单字段值?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！