出于某种原因，我在 doGet 方法中附加到 StringBuffer (sb) 的代码 HTML 没有在其他 servlet 中被拾取。
这是我附加到 StringBuffer sb 的 HTML 代码:
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletContext context = request.getSession().getServletContext();
List<Course> courses = (List<Course>) context.getAttribute("COURSES");
StringBuffer sb = new StringBuffer();
sb.append(getHeader());
sb.append("<form action=\"/Assignment_2/addCourse\">");
sb.append("<table border=\"2\">");
//sb.append("<tr><td>");
//sb.append("</tr></td>");
sb.append("<select>"
+ "<option value = book>Book</option>"
+ "<option value=tablet>Tablet</option>"
/*+ "<option value=xxxxxx>XXXXXXX</option>"
+ "<option value=yyyyy>YYYYY</option>"*/
+ "/select>");
sb.append("<tr><td>Type</td><td><input type=\"text\" name=\"type\" value=\"\" /></td></tr>");
sb.append("<tr><td>Name</td><td><input type=\"text\" name=\"name\" value=\"\" /></td></tr>");
sb.append("<tr><td>Additional Info</td><td><input type=\"text\" info=\"Additional Info\" value=\"\" /></td></tr>");
sb.append("<tr><td># of Copies</td><td><input type=\"text\" name=\"# of Copies\" value=\"\" /></td></tr>");
/*for (Course course : courses) {
sb.append("<input type=\"checkbox\" name=\"prerequisite\" value=\"" + course.getCode() + "\">" + course.getCode() + "</input> <br />");
}*/
sb.append("</td></tr><tr><td><input type=\"submit\" value=\"Add\" /></td></tr></table></form>");
sb.append("</body></html>");
PrintWriter out = response.getWriter();
out.println(sb.toString());
}
public String getHeader() {
StringBuffer sb = new StringBuffer();
sb.append("<html>");
sb.append("<head><title>Department Library</title></head><body>");
return sb.toString();
}
因此，在用户单击“提交”后，代码将显示在此处:
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletContext context = request.getSession().getServletContext();
List<Course> courses = (List<Course>) context.getAttribute("COURSES");
for (Course course : courses) {
System.out.println(course);
}
StringBuffer sb = new StringBuffer();
sb.append(getHeader());
sb.append("<table border=\"2\"><tr>"
+ "<td>ID</td>"
+ "<td>Type</td>"
+ "<td>Name</td>"
+ "<td>Additional Info</td>"
+ "<td>Available</td>"
+ "<td>Operation</td></tr>");
for (Course course : courses) {
sb.append("<tr><td>");
sb.append(course.getMyId() + "</td><td>" + course.getType() + "</td>");
/*sb.append("<td>");
for (String str : course.getPrerequisites()) {
sb.append(str + " ");
}*/
sb.append("</td><td>"
+ course.getName());
sb.append("</td><td>"
+ course.getAdditionalInfo());
sb.append("</td><td>"
+ course.getAvailable());
sb.append("</td><td><a href=\"edit?code="+course.getCode() +"\">Edit</a></td>");//</tr>");
}
sb.append("</table><a href=\"add\">Add Items</a></body></html>");
PrintWriter out = response.getWriter();
out.println(sb.toString());
}
public String getHeader() {
StringBuffer sb = new StringBuffer();
sb.append("<html>");
sb.append("<head><title>Department Library</title></head><body>");
return sb.toString();
}
这一行:
for (Course course : courses) {
System.out.println(course);
}
告诉我我的数据很好...Servlet 发生了什么？
****************编辑****************
添加以下内容时(在我原始帖子的第一种方法中):
sb.append("<tr><td>Available</td><td><input type=\"text\" name=\"available\" value=\"\" /> </td></tr>");
到 doGet 我在表中收到了该数据!但由于某种原因(在同一文件中):
sb.append("<tr><td>Additional Info</td><td><input type=\"text\" name=\"info\" value=\"\" /> </td></tr>");
未被读取，例如，它在我的表中读取为“null”。我没有在输入中键入“null”(只是为了澄清)。
此外..单击下一步/提交/添加任何内容以提交表单操作输入后，我的数据/输入将在 URL 中可见。
最佳答案
in first method...
/*for (Course course : courses) {
sb.append("<input type=\"checkbox\" name=\"prerequisite\" value=\"" + course.getCode() + "\">" + course.getCode() + "</input> <br />");
}*/
in second method
String [] temp=request.getparameterbyValues("prerequisite");
for (i=0;i<=temp.length;i++) {
System.out.println(temp[i]);
}
关于java - 附加到 StringBuffer (Java Servlet) 未作为 Servlet 中的属性获取，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/26191135/