Guide to the Spring WebUtils and ServletRequestUtils (#1184)

* rest with spark java

* 4

* Update Application.java

* indentation changes

* spring @requestmapping shortcuts

* removing spring requestmapping and pushing spring-mvc-java

* Joining/Splitting Strings with Java and Stream API

* adding more join/split functionality

* changing package name

* testcase change

* adding webutils

spring-boot/src/main/java/com/baeldung/utils/Application.java

@@ -0,0 +1,18 @@
+package com.baeldung.utils;
+
+import javax.annotation.security.RolesAllowed;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.ComponentScan;
+
+@SpringBootApplication
+@ComponentScan(basePackages="com.baeldung.utils")
+public class Application {
+
+	@RolesAllowed("*")
+	public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+	}
+
+}

spring-boot/src/main/java/com/baeldung/utils/controller/UtilsController.java

@@ -0,0 +1,49 @@
+package com.baeldung.utils.controller;
+
+import javax.servlet.http.HttpServletRequest;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.ui.Model;
+import org.springframework.web.bind.ServletRequestBindingException;
+import org.springframework.web.bind.ServletRequestUtils;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.util.WebUtils;
+
+@Controller
+public class UtilsController {
+
+	@GetMapping("/utils")
+	public String webUtils(Model model) {
+		return "utils";
+	}
+	
+	@PostMapping("/setParam")
+	public String post(HttpServletRequest request, Model model) {
+		String param = ServletRequestUtils.getStringParameter(request, "param", "DEFAULT");
+		
+//		Long param = ServletRequestUtils.getLongParameter(request, "param",1L);
+//		boolean param = ServletRequestUtils.getBooleanParameter(request, "param", true);
+//		double param = ServletRequestUtils.getDoubleParameter(request, "param", 1000);
+//		float param = ServletRequestUtils.getFloatParameter(request, "param", (float) 1.00);
+//		int param = ServletRequestUtils.getIntParameter(request, "param", 100);
+		
+//		try {
+//			ServletRequestUtils.getRequiredStringParameter(request, "param");
+//		} catch (ServletRequestBindingException e) {
+//			e.printStackTrace();
+//		}
+		
+		WebUtils.setSessionAttribute(request, "parameter", param);
+        model.addAttribute("parameter", "You set: "+(String) WebUtils.getSessionAttribute(request, "parameter"));
+		return "utils";
+	}
+	
+	@GetMapping("/other")
+	public String other(HttpServletRequest request, Model model) {
+		String param = (String) WebUtils.getSessionAttribute(request, "parameter");
+		model.addAttribute("parameter", param);
+		return "other";
+	}
+	
+}