1. General way to get request parameters: the following methods can be used to get request parameters in both get and post request modes
1. String getParameter(String name): get the parameter value according to the parameter name. Username = ZS & password = 123
2. String[] getParameterValues(String name): get the array of parameter values according to the parameter name. Hobby = XX & Hobby = game
3. Enumeration < string > getparameternames(): get the parameter names of all requests
4. Map < string, string [] > getparametermap(): get the map set of all parameters
regist2.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Registration page</title>
</head>
<body>
<form action="/day14/requestDemo6" method="post">
<input type="text" placeholder="enter one user name" name="username"><br>
<input type="text" placeholder="Please input a password" name="password"><br>
<input type="checkbox" name="hobby" value="game">Game
<input type="checkbox" name="hobby" value="study">Study
<br>
<input type="submit" value="register">
</form>
</body>
</html>RequestDemo6.java
package cn.itcast.web.request;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Map;
import java.util.Set;
@WebServlet("/requestDemo6")
public class RequestDemo6 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//post get request parameters
//Get parameter value according to parameter name
/* String username = request.getParameter("username");
System.out.println(username);*/
/*//Get an array of parameter values according to the parameter name
String[] hobbies = request.getParameterValues("hobby");
for (String hobby : hobbies) {
System.out.println(hobby);
}*/
//Get parameter names for all requests
/*Enumeration<String> parameterNames = request.getParameterNames();
while(parameterNames.hasMoreElements()){
String name = parameterNames.nextElement();
System.out.println(name);
String value = request.getParameter(name);
System.out.println(value);
System.out.println("----------------");
}*/
// Get the map set of all parameters
Map<String, String[]> parameterMap = request.getParameterMap();
//ergodic
Set<String> keyset = parameterMap.keySet();
for (String name : keyset) {
//Get key get value
String[] values = parameterMap.get(name);
System.out.println(name);
for (String value : values) {
System.out.println(value);
}
System.out.println("-----------------");
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//Get get request parameters
//Get parameter value according to parameter name
/* String username = request.getParameter("username");
System.out.println("get");
System.out.println(username);*/
this.doPost(request,response);
}
}
Chinese code scrambling:
* get method: tomcat 8 has solved the problem of getting method scrambling
* post mode: random code
* solution: before obtaining parameters, set the encoding request.setCharacterEncoding("utf-8") of request;
2. Request forwarding: a way of resource jump within the server
1. Steps:
1. Get the request forwarder object through the request object: RequestDispatcher getRequestDispatcher(String path)
2. Use RequestDispatcher object to forward: forward(ServletRequest request, ServletResponse response)
2. Features:
1. The browser address bar path does not change
2. It can only be forwarded to the internal resources of the current server.
3. Forwarding is a request
Shared data:
* domain object: a scoped object that can share data within the scope
* request domain: represents the scope of a request, which is generally used to share data among multiple resources for request forwarding
* method:
1. void setAttribute(String name,Object obj): store data
2. Object getattribute (string name): get value by key
3. Void removeaattribute (string name): remove key value pair through key
