Controller中註解的使用:

@Controller
●該註解用來響應頁面，必須配合模板來使用

關於模板的使用，下一節會說到。

@RestController

●該註解可以直接響應字符串，返回的類型為JSON格式

 1 package com.example.demo.controller;
 2 
 3 import org.springframework.web.bind.annotation.RequestMapping;
 4 import org.springframework.web.bind.annotation.RestController;
 
 5 
 6 @RestController
 7 public class HelloWorldController {
 8 
 9    @RequestMapping("/")    
10    public String index() {
11         return "Hello World";
12     }
13 }

啟動程序，訪問http://localhost:8080/，返回Hello World

@RequestMapping

●指定URL訪問中的前綴

 1 package com.example.demo;
 2 
 3 import org.springframework.boot.SpringApplication;
 
 4 import org.springframework.boot.autoconfigure.SpringBootApplication;
 5 
 6 @SpringBootApplication
 7 public class DemoApplication {
 8 
 9     public static void main(String[] args) {
10         SpringApplication.run(DemoApplication.class, args);
11     }
12 }

訪問http://localhost:8080/hello，返回Hello World

@RequestParam

●獲取請求URL中參數的變量

 1 package com.example.demo.controller;
 2 
 3 import org.springframework.web.bind.annotation.RequestMapping;
 4 import org.springframework.web.bind.annotation.RequestMethod;
 5 import org.springframework.web.bind.annotation.RequestParam;
 6 import org.springframework.web.bind.annotation.RestController;
 7 
 8 @RestController
 9 public class HelloWorldController {
10 
11    @RequestMapping(value="/hello",method=RequestMethod.GET)    
12    public String index(@RequestParam("name")String name) {
13         return "Hello World:"+name;
14     }
15 }

訪問http://localhost:8080/hello?name=張三，返回Hello World：張三

@PathVariable

●獲取請求URL中路徑的變量

 1 package com.example.demo.controller;
 2 
 3 import org.springframework.web.bind.annotation.PathVariable;
 4 import org.springframework.web.bind.annotation.RequestMapping;
 5 import org.springframework.web.bind.annotation.RequestMethod;
 6 import org.springframework.web.bind.annotation.RestController;
 7 
 8 @RestController
 9 public class HelloWorldController {
10 
11    @RequestMapping(value="/hello/{name}",method=RequestMethod.GET)    
12    public String index(@PathVariable("name")String name) {
13         return "Hello World:"+name;
14     }
15 }

訪問http://localhost:8080/hello/張三，返回Hello World：張三

@GetMapping/@PostMapping
●與RequestMapping類似，不同的是指定了請求的方式(get/post)

 1 package com.example.demo.controller;
 2 
 3 import org.springframework.web.bind.annotation.GetMapping;
 4 import org.springframework.web.bind.annotation.RestController;
 5 
 6 @RestController
 7 public class HelloWorldController {
 8 
 9    @GetMapping(value="/hello")    
10    public String index() {
11         return "Hello World";
12     }
13 }

總結

Controller是SpringBoot裏比較常用的組件，通過匹配客戶端提交的請求，分配不同的處理方法，然後向客戶端返回結果。

SpringBoot入門(二):Controller的使用