Spring Boot - 5. Controller 的使用

1. @Controller ：处理 http 请求；
2. @RestController ：Spring4 之后新加的注解，原来返回 json 需要 @ResponseBody 配合 @Controller；

import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {
}

3. @RequsetMapping ：配置 url 映射；

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@RequestMapping(value = "/hello", method = RequestMethod.GET)
public String sayHello() {
    return "Hello";
}

4. @PathVariable ：获取 URL 中的数据；

import org.springframework.web.bind.annotation.PathVariable;

@RequestMapping(value = "/{id}/hello", method = RequestMethod.GET)
public String sayHello(@PathVariable("id") Integer id) {
    return "id is " + id;
}

// 访问 http://localhost:8081/cme/23/hello

屏幕快照 2018-01-18 15.58.51.png

5. @RequestParam ：获取请求参数的值；

import org.springframework.web.bind.annotation.RequestParam;

@RequestMapping(value = "/hello", method = RequestMethod.GET)
public String sayHello(@RequestParam("id") Integer myId) {
    return "id is " + myId;
}

// 访问 http://localhost:8081/cme/hello?id=100

屏幕快照 2018-01-18 16.05.54.png

• 设置默认值

@RequestMapping(value = "/hello", method = RequestMethod.GET)
public String sayHello(@RequestParam(value = "id", required = false, defaultValue = "0") Integer myId) {
    return "id is " + myId;
}

// 访问 http://localhost:8081/cme/hello

屏幕快照 2018-01-18 16.11.44.png

6. @GetMapping @PostMapping ... ：组合注解；