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This tutorial shows how to "virtually" add HTTP Request Parameters by
● creating new Request (that extends HttpServletRequestWrapper)
● overriding Methods that return HTTP Request Parameters (getParameterNames, getParameterValues)
Then we will load HTTP Request Parameters into PersonDTO Properties to cnfirm that they are visible to Controller.
Application Schema [Results]
Spring Boot Starters
GROUP
DEPENDENCY
DESCRIPTION
Web
Spring Web
Enables: Controller Annotations, Tomcat Server
MyFilter
http://localhost:8080/Hello?name=John
hello()
PersonDTO
MyController
MyHttpServlet
RequestWrapper
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Create Project: springboot_filter_addrequestparameters (add Spring Boot Starters from the table)
Create Package: DTO (inside main package)
– Create Class: PersonDTO.java (inside DTO package)
Create Package: controllers (inside main package)
– Create Class: MyController.java (inside controllers package)
Create Package: filters (inside main package)
– Create Class: MyHttpServletRequestWrapper.java (inside filters package)
– Create Class: MyFilter.java (inside filters package)
PersonDTO.java
package com.ivornline.springboot_filter_addrequestparameters.DTO;
public class PersonDTO {
//PROPERTIES
public String name; //EXISTING REQUEST PARAMETER
public String age; //ADDED REQUEST PARAMETER
//SETTERS (Used for Deserialization)
public void setName(String name) { this.name = name; }
public void setAge (String age ) { this.age = age; }
}
MyController.java
package com.ivornline.springboot_filter_addrequestparameters.controllers;
import com.ivornline.springboot_filter_addrequestparameters.DTO.PersonDTO;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
public class MyController {
@ResponseBody
@RequestMapping("/Hello")
public String hello(PersonDTO personDTO) {
return personDTO.name + " is " + personDTO.age + " years old";
}
}
MyHttpServletRequestWrapper.java
package com.ivornline.springboot_filter_addrequestparameters.filters;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
public class MyHttpServletRequestWrapper extends HttpServletRequestWrapper {
//PARAMETER MAP WITH ORIGINAL AND ADDITIONAL REQUEST PARAMETERS
Map<String, String[]> extendedParameterMap = new HashMap<>();
//===============================================================
// CONSTRUCTOR
//===============================================================
public MyHttpServletRequestWrapper(HttpServletRequest request) {
super(request);
//CREATE ADDITIONAL REQUEST PARAMETERS
String[] age = {"20"};
//ADD ADDITIONAL REQUEST PARAMETERS TO NEW MAP
extendedParameterMap.put("age", age);
//ADD EXISTING REQUEST PARAMETERS TO NEW MAP
extendedParameterMap.putAll(request.getParameterMap());
}
//===============================================================
// GET PARAMETER NAMES
//===============================================================
@Override
public Enumeration<String> getParameterNames() {
return Collections.enumeration(extendedParameterMap.keySet());
}
//===============================================================
// GET PARAMETER VALUES
//===============================================================
@Override
public String[] getParameterValues(String name) {
return extendedParameterMap.get(name);
}
}
MyFilter.java
package com.ivornline.springboot_filter_addrequestparameters.filters;
import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;
@Component
public class MyFilter extends OncePerRequestFilter {
@Override
public void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
throws IOException, ServletException {
//CREATE REPLACEMENT REQUEST
HttpServletRequest myHttpServletRequestWrapper = new MyHttpServletRequestWrapper(request);
//FORWARD REPLACEMENT REQUEST (With additional Request Parameters)
chain.doFilter(myHttpServletRequestWrapper, response);
}
}
