Spring boot（二）

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1.Controller的使用

常用注解
这里写图片描述

1.1.@Controller

需要配合模版使用
在pom.xml中加入依赖

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

在resource下面创建templates文件夹，创建index.html
直接在controller中写如下格式：

@Controllerpublic class HelloController {    @RequestMapping(value = "/hello", method = RequestMethod.GET)    public String say() {        return "index";    }}

即可跳转到index页面
对于目前前后端分离的开发趋势，不建议采用thymeleaf的依赖形势，会影响性能。

1.2.@RestController

@RestController = @Controller+@ResponseBody

@Controller@ResponseBodypublic class HelloController {    @Autowired    private DbConfig dbConfig;    @RequestMapping(value = "/hello", method = RequestMethod.GET)    public String say() {        return "Hello Spring Boot" + dbConfig.getUrl();    }}

为了简洁常采用@RestController

1.3.@RequestMapping

对于多映射多访问url，采用如下格式

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

也可以在类上面写@RequestMapping
格式如下：

@RestController@RequestMapping(value = "/hello")public class HelloController {   @Autowired    private DbConfig dbConfig;    @RequestMapping(value = "/say", method = RequestMethod.GET)    public String say() {        return "Hello Spring Boot" + dbConfig.getUrl();    }}

Url中参数的注解

1.4.@PathVariable

获取url中的数据

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

访问地址：
http://localhost:8081/molly/hello/say/34

1.5.@RequestParam

获取请求参数的值

@RestController@RequestMapping(value = "/hello")public class HelloController {    @RequestMapping(value = "/say", method = RequestMethod.GET)    public String say(@RequestParam("id") Integer myid) {        return "id:" + myid;    }}

访问地址：
http://localhost:8081/molly/hello/say?id=39

id也可以不传入，格式如下

@RestController@RequestMapping(value = "/hello")public class HelloController {    @RequestMapping(value = "/say", method = RequestMethod.GET)    public String say(@RequestParam(value = "id",required = false,defaultValue = "0") Integer id) {        return "id:" + id;    }}

required必填标志，defaultValue默认值

1.6.@GetMapping

组合注解
简化mapping注解

@RequestMapping(value = "/say", method = RequestMethod.GET)等同于@GetMapping(value = "/say")同理还有@PostMapping(value = "/say")

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