Spring boot controller

Template

If you only use @Controller instead of @RestController, then you have to use a template like Thymeleaf.

1. In pom,xml, import thymeleaf

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>

1. Create a html file in template folder, for example, say “Hello World” in a <h1> tag.

2. In controller java class, @Controller and return the name of that html file.

@Controller
public class HelloController {

    @Autowired
    private LimitConfig limitConfig;


    @GetMapping("/hello")
    public String say(){
//        return "Description: " + limitConfig.getDescription();
        return "index";
    }
}

@Controller + @ResponseBody = @RestController

If you want to return both html and String/Json data, then you can @Controller on the class level, and @ResponseBody on the method level. However, this approach is not recommended. Nowadays, we usually separate back-end and front-end.

url

Multiply url for a same method

@GetMapping({"/hello", "/hi"})
public String say(){
    return "Description: " + limitConfig.getDescription();
}

url chain

@RestController
@RequestMapping("/hello")
public class HelloController {

    @Autowired
    private LimitConfig limitConfig;

    @GetMapping("/say")
    public String say(){
        return "Description: " + limitConfig.getDescription();
    }
}

POST and GET

It is better to Specify the request method, either GetMapping or PostMapping. It is not recommended to use RequestMapping both a method, which means both will work.

Request Parameters

• @PathVariable

@GetMapping("/say/{id}")
public String say(@PathVariable("id") Integer id){
    return "id: " + id;
}

• @RequestParam

@GetMapping("/say")
public String say(@RequestParam("id") Integer id){
    return "id: " + id;
}

• Optional parameters

@GetMapping("/say")
public String say(@RequestParam(value = "id", required = false, defaultValue = "0") Integer id){
    return "id: " + id;
}

• postman

To send a Post request with parameters, use postman, and choose Body, then choose x-www-form-urlencoded