Spring MVC Tutorial
Core Spring MVC
Spring MVC - Annotation
Spring MVC - Form Handling
Spring MVC with JSTL
Spring MVC with REST API
Spring MVC with Database
In Spring MVC, the @RequestParam annotation is used to capture request parameters from the query string of a URL. It can be used in the methods of Spring controllers to extract values from the query string and pass them as method parameters.
Here's a breakdown of how to capture data using the @RequestParam annotation:
@RequestMapping("/greet")
public String greet(@RequestParam String name) {
return "Hello, " + name + "!";
}
If you access the URL /greet?name=John, the response will be Hello, John!.
If you want to provide a default value for a parameter in case it's not present in the query string:
@RequestMapping("/greet")
public String greet(@RequestParam(defaultValue = "Guest") String name) {
return "Hello, " + name + "!";
}
If the name parameter is not provided (/greet), the response will be Hello, Guest!.
@RequestParam Optional:By default, @RequestParam considers the parameter as required. If the parameter is missing in the request, Spring will throw an exception. To make it optional:
@RequestMapping("/greet")
public String greet(@RequestParam(required = false) String name) {
if (name == null) {
return "Hello, Guest!";
}
return "Hello, " + name + "!";
}
If the method parameter name is different from the query string parameter name, you can specify the exact name using value or directly:
@RequestMapping("/greet")
public String greet(@RequestParam(value = "username") String name) {
return "Hello, " + name + "!";
}
Now, you can use the URL /greet?username=John.
You can use multiple @RequestParam annotations in a single method to capture multiple parameters:
@RequestMapping("/add")
public String add(@RequestParam int num1, @RequestParam int num2) {
int result = num1 + num2;
return "Result: " + result;
}
Accessing /add?num1=5&num2=3 will return Result: 8.
You can capture all request parameters as a Map:
@RequestMapping("/params")
public String getParams(@RequestParam Map<String, String> params) {
return params.toString();
}
For the URL /params?name=John&age=30, the response will be {name=John, age=30}.
The @RequestParam annotation is a powerful tool in Spring MVC that provides flexibility in capturing request parameters from URLs. By understanding its various attributes and usages, developers can effectively extract and handle data sent by clients.
How to use @RequestParam in Spring MVC:
Description: @RequestParam is an annotation in Spring MVC used to bind request parameters to method parameters in your controller. It is commonly used for extracting values from query parameters in the URL.
Code snippet (Java):
@Controller
@RequestMapping("/example")
public class ExampleController {
@GetMapping("/process")
public String processRequest(@RequestParam String parameter) {
// Use the value of the 'parameter' query parameter
// ...
return "result";
}
}
Capture data with @RequestParam in Spring:
Description: This example demonstrates capturing data from a request parameter using @RequestParam in a Spring MVC controller method.
Code snippet (Java):
@Controller
@RequestMapping("/data")
public class DataController {
@GetMapping("/capture")
public String captureData(@RequestParam String data) {
// Process the 'data' request parameter
// ...
return "result";
}
}
Working with request parameters in Spring using @RequestParam:
Description: This snippet illustrates how to work with request parameters using @RequestParam in a Spring MVC controller method.
Code snippet (Java):
@Controller
@RequestMapping("/process")
public class ProcessController {
@GetMapping("/handle")
public String handleRequest(@RequestParam String param1, @RequestParam int param2) {
// Process 'param1' and 'param2' request parameters
// ...
return "result";
}
}
@RequestParam example in Spring MVC:
Description: An example demonstrating the usage of @RequestParam in a Spring MVC controller method to extract values from request parameters.
Code snippet (Java):
@Controller
@RequestMapping("/example")
public class ExampleController {
@GetMapping("/process")
public String processRequest(@RequestParam String param1, @RequestParam int param2) {
// Process 'param1' and 'param2' request parameters
// ...
return "result";
}
}
Request parameter binding in Spring with @RequestParam:
Description: This code shows how to bind request parameters to method parameters using @RequestParam in a Spring MVC controller.
Code snippet (Java):
@Controller
@RequestMapping("/binding")
public class BindingController {
@GetMapping("/bind")
public String bindParameters(@RequestParam("id") long productId, @RequestParam("name") String productName) {
// Bind 'id' and 'name' request parameters to method parameters
// ...
return "result";
}
}
Using @RequestParam for query parameters in Spring:
Description: Demonstrates using @RequestParam to handle query parameters in a Spring MVC controller method.
Code snippet (Java):
@Controller
@RequestMapping("/query")
public class QueryController {
@GetMapping("/process")
public String processQueryParams(@RequestParam String param1, @RequestParam(defaultValue = "default") String param2) {
// Process 'param1' and 'param2' query parameters
// ...
return "result";
}
}
Spring MVC URL parameters with @RequestParam:
Description: Illustrates how to use @RequestParam to handle URL parameters in a Spring MVC controller.
Code snippet (Java):
@Controller
@RequestMapping("/url")
public class URLController {
@GetMapping("/handle")
public String handleURLParams(@RequestParam String username, @RequestParam int age) {
// Handle 'username' and 'age' URL parameters
// ...
return "result";
}
}
Handling form data with @RequestParam in Spring:
Description: This example showcases how to handle form data using @RequestParam in a Spring MVC controller method.
Code snippet (Java):
@Controller
@RequestMapping("/form")
public class FormController {
@PostMapping("/submit")
public String submitForm(@RequestParam String username, @RequestParam String password) {
// Handle form data with 'username' and 'password' parameters
// ...
return "result";
}
}