Servlet与Jsp学习笔记--2、POST HTTP Request
Problem
POST request.
Solution
Use the ServletRequest.getParameter(String name), getParameterMap( ), getParameterNames( ), or getParameterValues(String name) methods in the servlet's doPost method
Code(servlet)
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Map;
import java.util.Iterator;
import java.util.Map.Entry;
public class FirstServlet extends HttpServlet {
public void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException,
java.io.IOException {
//set the MIME type of the response, "text/html"
response.setContentType("text/html");
//use a PrintWriter to send text data to the client who has requested the
//servlet
java.io.PrintWriter out = response.getWriter( );
//Begin assembling the HTML content
out.println("<html><head>");
out.println("<title>Help Page</title></head><body>");
out.println("<h2>Please submit your information</h2>");
//make sure method="post" so that the servlet service method
//calls doPost in the response to this form submit
out.println(
"<form method=""post"" action =""" + request.getContextPath( ) +
"/firstservlet"" >");
out.println("<table border=""0""><tr><td valign=""top"">");
out.println("Your username: </td> <td valign=""top"">");
out.println("<input type=""text"" name=""username"" size=""20"">");
out.println("</td></tr><tr><td valign=""top"">");
out.println("Your department: </td> <td valign=""top"">");
out.println("<input type=""text"" name=""department"" size=""20"">");
out.println("</td></tr><tr><td valign=""top"">");
out.println("Your email: </td> <td valign=""top"">");
out.println("<input type=""text"" name=""email"" size=""20"">");
out.println("</td></tr><tr><td valign=""top"">");
out.println("<input type=""submit"" value=""Submit Info""></td></tr>");
out.println("</table></form>");
out.println("</body></html>");
}//doGet
public void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException,
java.io.IOException {
//display the parameter names and values
Enumeration paramNames = request.getParameterNames( );
String parName;//this will hold the name of the parameter
boolean emptyEnum = false;
if (! paramNames.hasMoreElements( ))
emptyEnum = true;
//set the MIME type of the response, "text/html"
response.setContentType("text/html");
//use a PrintWriter to send text data to the client
java.io.PrintWriter out = response.getWriter( );
//Begin assembling the HTML content
out.println("<html><head>");
out.println("<title>Submitted Parameters</title></head><body>");
if (emptyEnum){
out.println(
"<h2>Sorry, the request does not contain any parameters</h2>");
} else {
out.println(
"<h2>Here are the submitted parameter values</h2>");
}
while(paramNames.hasMoreElements( )){
parName = (String) paramNames.nextElement( );
out.println(
"<strong>" + parName + "</strong> : " +
request.getParameter(parName));
out.println("<br />");
}//while
String name = request.getParameter("username");
String depart = request.getParameter("department");
String email = request.getParameter("email");
out.println(
"Your name is: " + ( (name == null || name.equals("")) ?
"Unknown" : name));
out.println("<br><br>");
out.println(
"Your department is: " + ( (depart == null || depart.equals("")) ?
"Unknown" : depart));
out.println("<br><br>");
out.println(
"Your email address is: " + ( (email == null ||
email.equals("")) ? "Unknown" : email));
Map param_map = request.getParameterMap( );
if (param_map == null)
throw new ServletException(
"getParameterMap returned null in: " +
getClass( ).getName( ));
Iterator iterator = param_map.entrySet( ).iterator( );
while(iterator.hasNext( )){
Map.Entry me = (Map.Entry)iterator.next( );
out.println(me.getKey( ) + ": ");
String[] arr = (String[]) me.getValue( );
for(int i=0;i<arr.length;i++){
out.println(arr[i]);
//print commas after multiple values,
//except for the last one
if (i > 0 && i != arr.length-1)
out.println(", ");
}//end for
out.println("<br><br>");
}//end while
out.println("</body></html>");
}// doPost
}
Code(单一jsp)
<%@page contentType="text/html"%>
<%@ taglib uri="http://java.sun.com/jstl/core" prefix="c" %>
<html>
<head><title>Post Data Viewer</title></head>
<body>
<h2>Here is your posted data</h2>
<FORM METHOD=POST ACTION="">
<INPUT TYPE="text" NAME="name">
<INPUT TYPE="text" NAME="department"><INPUT TYPE="submit">
</FORM>
<c:forEach var="map_entry" items="${param}">
<strong><c:out value="${map_entry.key}" /></strong>:
<c:out value="${map_entry.value}" /><br><br>
</c:forEach>
</body>
</html>
Code(Bean和jsp)
package pk;
public class UserBean implements java.io.Serializable{
String username;
String email;
String department;
public UserBean( ){}
public void setUsername(String _username){
if(_username != null && _username.length( ) > 0)
username = _username;
else
username = "Unknown";
}
public String getUsername( ){
if(username != null)
return username;
else
return "Unknown";}
public void setEmail(String _email){
if(_email != null && _email.length( ) > 0)
email = _email;
else
email = "Unknown";
}
public String getEmail( ){
if(email != null)
return email;
else
return "Unknown";}
public void setDepartment(String _department){
if(_department != null && _department.length( ) > 0)
department = _department;
else
department = "Unknown";
}
public String getDepartment( ){
if(department != null)
return department;
else
return "Unknown"; }
}
部署到"WEB-INF"classes"pk
javac -d WEB-INF/classes UserBean.java
jsp:
<%@page contentType="text/html"%>
<%@ taglib uri="http://java.sun.com/jstl/core" prefix="c" %>
<%@page import="pk.*"%>
<jsp:useBean id="userB" class="UserBean" >
<jsp:setProperty name="userB" property="*" />
</jsp:useBean>
<html>
<head><title>Post Data Viewer</title></head>
<body>
<FORM METHOD=POST ACTION="">
<INPUT TYPE="text" NAME="username">
<INPUT TYPE="text" NAME="department">
<INPUT TYPE="text" NAME="email">
<INPUT TYPE="submit">
</FORM>
<h2>Here is your posted data</h2>
<strong>User name</strong>:
<c:out value="${userB.username}" /><br><br>
<strong>Department</strong>:
<c:out value="${userB.department}" /><br><br>
<strong>Email</strong>:
<c:out value="${userB.email}" />
</body>
</html>