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Spring RESTful Routing & Static Files

Spring RequestMapping

1. @RequestMapping Basics

@RequestMapping — by Path

  • Define the Request URI to access the REST Endpoints
@RequestMapping(value = "/ex/foos", method = RequestMethod.GET)
@ResponseBody
public String getFoosBySimplePath() {
    return "Get some Foos";
}

@RequestMapping — the HTTP Method

  • The HTTP method parameter has no default
@RequestMapping(value = "/ex/foos", method = POST)
@ResponseBody
public String postFoos() {
    return "Post some Foos";
}

2. RequestMapping and HTTP Headers

@RequestMapping With the headers Attribute

  • The mapping can be narrowed even further by specifying a header for the request:
@RequestMapping(value = "/ex/foos", headers = "key=val", method = GET)
@ResponseBody
public String getFoosWithHeader() {
    return "Get some Foos with Header";
}

@RequestMapping Consumes and Produce

@RequestMapping(
  value = "/ex/foos", 
  method = GET, 
  headers = "Accept=application/json")
@ResponseBody
public String getFoosAsJsonFromBrowser() {
    return "Get some Foos with Header Old";
}

3. RequestMapping With Path Variables

  • Parts of the mapping URI can be bound to variables via the @PathVariable annotation.
    • Single @PathVariable
    • Multiple @PathVariable
    • @PathVariable With Regex

4. @RequestMapping With Request Parameters

  • allows easy mapping of URL parameters with the @RequestParam annotation.
  • @RequestMapping allows easy mapping of URL parameters with the @RequestParam annotation.
@RequestMapping(value = "/ex/bars", method = GET)
@ResponseBody
public String getBarBySimplePathWithRequestParam(
  @RequestParam("id") long id) {
    return "Get a specific Bar with id=" + id;
}

5. RequestMapping Corner Cases

  • @RequestMapping — Multiple Paths Mapped to the Same Controller Method :is usually used for a single controller method

  • @RequestMapping — Multiple HTTP Request Methods to the Same Controller Method

  • @RequestMapping — a Fallback for All Requests

Multiple requests using different HTTP verbs can be mapped to the same controller method.

To implement a simple fallback for all requests using a particular HTTP method

Ambiguous Mapping Error

  • The ambiguous mapping error occurs when Spring evaluates two or more request mappings to be the same for different controller methods. A request mapping is the same when it has the same HTTP method, URL, parameters, headers, and media type.

Accessing Data with JPA

These notes fro how to build an application that stores Customer POJOs (Plain Old Java Objects) in a memory-based database.

  • To generate a new project with the required dependencies (Spring Data JPA and H2 H2 Database).for Gradle users, visit the Spring Initializr

  • The class is annotated with @Entity, indicating that it is a JPA entity. (Because no @Table annotation exists, it is assumed that this entity is mapped to a table of the class name.)

Create an Application Class

  • @SpringBootApplication : it is convenience annotation that use to auto-configuration, component scan and be able to define extra configuration on application class.

  • @EnableAutoConfiguration : Tells Spring Boot to start adding beans based on classpath settings, other beans, and various property settings.

  • @Configuration : Allow to register extra beans in the context or import additional configuration classes.

  • @ComponentScan : Enable @Component scan on the package where the application is located.