Java – Check If URL Contains Query String or not
In this post, we show you two ways how to check if URL contains query string or not in Java Web: using HttpServletRequest.getQueryString()
and using HttpServletRequest.getParameterMap()
.
1. Using HttpServletRequest.getQueryString()
Example1Servlet.java
package com.bytenota;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet(name = "Example1Servlet", urlPatterns = {"/example1"})
public class Example1Servlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
if (request.getQueryString() == null) {
out.write("The URL does not contain query string.");
}
}
}
In the above code, we simply check whether request.getQueryString()
is null
or not. If it returns null
, the current URL does not contain query string and vice versa.
2. Using HttpServletRequest.getParameterMap()
Example2Servlet.java
package com.bytenota;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet(name = "Example2Servlet", urlPatterns = {"/example2"})
public class Example2Servlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
if (request.getParameterMap().isEmpty()) {
out.write("The URL does not contain query string.");
}
}
}
In the above code, we simply check whether request.getParameterMap()
is empty or not. If it is empty, the current URL does not contain query string and vice versa.