我有一个如下的jsp表单，
<form action="../Registration" enctype="multipart/form-data">
<label> First Name:</label>
<input type="text" class="large-field" name="firstname">
<label> Last Name:</label>
<input type="text" class="large-field" name="lastname">
<label> Gender:</label>
<label class="radio">
<input type="radio" name="gender" value="Male">
Male
</label>
<label class="radio">
<input type="radio" name="gender" value="Female">
FeMale
</label>
<label> Address :</label>
<input type="text" class="large-field" name="address">
<label> City:</label>
<input type="text" class="large-field" name="city">
<label> College:</label>
<select class="large-field" name="college">
<option value=""> --- Please Select --- </option>
<option value="XYZ">XYZ</option>
</select>
<label> Branch:</label>
<select class="large-field" name="branch">
<option value=""> --- Please Select --- </option>
<option value="ABC">ABC</option>
</select>
<br />
<label> Mobile Number:</label>
<input type="text" class="large-field" name="mobilenumber">
<br />
<label> Email_ID:</label>
<input type="text" class="large-field" name="email">
<br />
<label> Password:</label>
<input type="password" class="large-field" name="password">
<br />
<label> Re-Enter Password:</label>
<input type="password" class="large-field" name="repassword">
<br />
<label> Profile Picture:</label>
<input type="file" name="file">
<br />
<button class="btn btn-primary">Continue</button>
</form>
然后调用我的servlet，编码如下：
package Client_Controller;
import CommonData.ComData;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.tomcat.util.http.fileupload.FileItemFactory;
import org.apache.tomcat.util.http.fileupload.disk.DiskFileItemFactory;
import org.apache.tomcat.util.http.fileupload.servlet.ServletFileUpload;
import java.util.*;
import java.sql.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.servlet.RequestDispatcher;
import org.apache.tomcat.util.http.fileupload.FileItem;
import org.apache.tomcat.util.http.fileupload.FileUploadException;
public class Registration extends HttpServlet {
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
String f_name = request.getParameter("firstname");
String l_name = request.getParameter("lastname");
String gender = request.getParameter("gender");
String address = request.getParameter("address");
String city = request.getParameter("city");
String college = request.getParameter("college");
String branch = request.getParameter("branch");
String mobile = request.getParameter("mobilenumber");
String email = request.getParameter("email");
String password = request.getParameter("password");
String filePath = request.getParameter("file").toString();
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/table", "root", "root");
s = con.createStatement();
s.execute("insert into tblmembers(first_name,last_name,sex,address,city,college_name,branch,mobile,email_id,password) " +
"values('" + f_name + "','" + l_name + "','" + gender + "','" + address + "','" + city + "','" + college + "','" + branch + "','" + mobile + "'," + email + ",'" + password + "')");
out.write("Suceess");
} catch (Exception e) {
out.write("" + e);
} finally {
out.close();
}
}
// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
public String getServletInfo() {
return "Short description";
}// </editor-fold>
}
插入数据时，所有值都为空。我尝试过很多东西，但没有工作，所以需要一些帮助。我使用bootstrap作为前端。
答案 0 :(得分：11)
使用enctype="multipart/form-data"时，无法使用普通request.getParameter检索参数。看起来您正在使用Servlet 2.5或更早版本，因此您需要使用第三方库来解析请求，该第三方库通过了解enctype来处理它。这可以使用Apache Common FileUpload库轻松完成。
请注意，如果使用Servlet 3.0或更新版本，则不应出现此问题。
更多信息：
此外，您必须在当前表单中添加method="POST"才能使其正常运行。您无法使用GET请求上传文件。
答案 1 :(得分：1)
不知道为什么，但当我为输入文字提供'name'属性时，它对我有用。
我的旧代码在Servlet中返回null：
<input id="closure" type="text" size="25"><a
href="javascript:NewCal('closure','ddmmyyyy')"><img
src="drawables/cal.gif" width="16" height="16" border="0"
alt="Pick a date"></a>
只需将 name =“closure”为我工作。现在它完美地将此输入文本的值返回到servlet中。
<input id="closure" name="closure" type="text" size="25"><a
href="javascript:NewCal('closure','ddmmyyyy')"><img
src="drawables/cal.gif" width="16" height="16" border="0"
alt="Pick a date"></a>
我在Servlet中获得这个输入文本的价值如下：
String closure = request.getParameter("closure");
答案 2 :(得分：0)
使用下面的一个来访问文件数据
public static Hashtable getParamsFromMultipartForm(HttpServletRequest req) throws FileUploadException {
Hashtable ret = new Hashtable();
List items = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(req);
for (FileItem item : items) {
if (item.isFormField()) {
ret.put(item.getFieldName(), item.getString());
}
}
return ret;
}
然后，每当我需要任何params的值时，只需写下如下
/在servlet的开头
Hashtable multipartParams = TheClassWhereIPutThatMethod.getParamsFromMultipartForm(req);
String myParamFromForm = multipartParams.get("myParamFromForm");
答案 3 :(得分：-1)
更改以下按钮以输入提交，然后重试。我的猜测是你的按钮没有提交表格。
<button type="submit" class="btn btn-primary">Continue</button>