springBoot 入门（三）—— 使用 RestController

一.常用注解说明 https://blog.csdn.net/uniquewonderq/article/details/79971433?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-6.channel_param&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-6.channel_param

• @Controller 处理http请求
• @RestController Spring框架4版本之后出来的注解,之前版本返回json数据需要@ResponseBody配合@Controller
• @RequestMapping 配置url映射关系
• @PathVariable 获取url中的数据
• @RequestParam 获取请求参数的值
• @GetMapping 组合注解

二.@RestController 使用

package HelloWord;
import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.annotation.Value;

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

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

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

public class HelloController {
<span class="hljs-annotation">@Value</span>(<span class="hljs-string">"${cupSize}"</span>)<span class="hljs-comment">//注意写法,获取配置文件中的cupSize</span>
<span class="hljs-keyword">private</span> String cpuSize;

<span class="hljs-annotation">@Value</span>(<span class="hljs-string">"${age}"</span>)
<span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> age;

<span class="hljs-annotation">@Value</span>(<span class="hljs-string">"${content}"</span>)
<span class="hljs-keyword">private</span> String content; 


<span class="hljs-annotation">@RequestMapping</span>(value=<span class="hljs-string">"/hello"</span>,method= RequestMethod.GET)<span class="hljs-comment">//写法与springMVC有点相似</span>
<span class="hljs-keyword">public</span> String <span class="hljs-title">say</span>(){
    <span class="hljs-keyword">return</span> <span class="hljs-string">"Hello Spring Boot!"</span>+cpuSize+<span class="hljs-string">" "</span>+age+<span class="hljs-string">" "</span>+content;
}

}
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application-prd.properties文件：

#模拟生产变量
curvar=prd.curvar
cupSize = 16g
age = 24
content = HelloWord-prd
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启动spring boot后，在浏览器中输入：
localhost:8889/hello

注解@RestController标记在类上,表示该类处理http请求,并且返回json数据

三.@RequestMapping注解使用(与SpringMVC中的使用相同)

如上面代码中的一样,可以作用于方法上,但是也可以作用于类上,作用于类上就相当于给所有的方法添加了一个前缀。再次访问之前的会报错

加上前缀后，则可以访问

四.@PathVariable注解使用

package HelloWord;
import org.springframework.beans.factory.annotation.Value;

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

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

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

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

@RequestMapping("/demo")

public class HelloController {
<span class="hljs-annotation">@Value</span>(<span class="hljs-string">"${cupSize}"</span>)<span class="hljs-comment">//注意写法,获取配置文件中的cupSize</span>
<span class="hljs-keyword">private</span> String cpuSize;

<span class="hljs-annotation">@Value</span>(<span class="hljs-string">"${age}"</span>)
<span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> age;

<span class="hljs-annotation">@Value</span>(<span class="hljs-string">"${content}"</span>)
<span class="hljs-keyword">private</span> String content;


<span class="hljs-annotation">@RequestMapping</span>(value=<span class="hljs-string">"/hello/{name}"</span>,method=RequestMethod.GET)<span class="hljs-comment">//这里也可以写成/{name}/hello</span>
<span class="hljs-keyword">public</span> String <span class="hljs-title">say</span>(@<span class="hljs-title">PathVariable</span>("name") String name){
    <span class="hljs-keyword">return</span> <span class="hljs-string">"Hello :"</span>+name;
}

}
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注意观察,注解@PathVariable使用需要在url中添加一个大括号对，中间是名字,方法参数里面@PathVariable(“name”)，中间的name必须与url的一致
写好后，重启

在浏览器中：

地址说明:最后的zhang为传递的参数

五.@RequestParam注解使用

package HelloWord;
    <span class="hljs-keyword">import</span> org.springframework.beans.factory.annotation.Value;
    <span class="hljs-keyword">import</span> org.springframework.web.bind.annotation.*;

@RestController

@RequestMapping("/demo")

public class HelloController {
<span class="hljs-annotation">@Value</span>(<span class="hljs-string">"${cupSize}"</span>)<span class="hljs-comment">//注意写法,获取配置文件中的cupSize</span>
<span class="hljs-keyword">private</span> String cpuSize;

<span class="hljs-annotation">@Value</span>(<span class="hljs-string">"${age}"</span>)
<span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> age;

<span class="hljs-annotation">@Value</span>(<span class="hljs-string">"${content}"</span>)
<span class="hljs-keyword">private</span> String content;


<span class="hljs-annotation">@RequestMapping</span>(value=<span class="hljs-string">"/hello"</span>,method=RequestMethod.GET)
<span class="hljs-keyword">public</span> String <span class="hljs-title">say</span>(@<span class="hljs-title">RequestParam</span>("name") String myName){
    <span class="hljs-keyword">return</span> <span class="hljs-string">"Hello :"</span>+myName;
}

}
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访问地址

访问地址中的参数名name一定要和@RequestParam(“name”)注解中的name一致,后面的参数myName可以不与前面一致

六.@GetMapping注解使用

注解@GetMapping,主要是简化@RequestMapping,@GetMapping等同于@RequestMapping设置method=RequestMethod.GET

package HelloWord;
    <span class="hljs-keyword">import</span> org.springframework.beans.factory.annotation.Value;
    <span class="hljs-keyword">import</span> org.springframework.web.bind.annotation.*;

@RestController

@RequestMapping("/demo")

public class HelloController {
<span class="hljs-annotation">@Value</span>(<span class="hljs-string">"${cupSize}"</span>)<span class="hljs-comment">//注意写法,获取配置文件中的cupSize</span>
<span class="hljs-keyword">private</span> String cpuSize;

<span class="hljs-annotation">@Value</span>(<span class="hljs-string">"${age}"</span>)
<span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> age;

<span class="hljs-annotation">@Value</span>(<span class="hljs-string">"${content}"</span>)
<span class="hljs-keyword">private</span> String content;

//    @RequestMapping(value="/hello",method=RequestMethod.GET)

@GetMapping(value="/hello")

public String say(@RequestParam("name") String myName){

return "Hello :"+myName;

}

}
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改后重启，同样可以访问,当然同理还有其他方式的mapping