springBoot startup： Controller 的使用（二）

controller 及 url 映射

• @Controller 处理 http 请求
• @RestController,Spring4 之后新加的注释，返回原来的json 需要 @ResponseBody 配合 @Controller
• @RequestMapping 配置 url 映射

1. @Controller 和模板一起使用

@Controller 这个注解需要和模板一起使用。

1. 修改 IndexController 文件

@Controller
public class IndexController{
  
  @Autowired
  private myProperties prop;

  @RequestMapping(value = "/", method = RequestMethod.GET)
   public String say(){
    return prop.getBook();  
  }
}

2. pom.xml 中增加模板相关的插件。

            org.springframework.boot
            spring-boot-starter-thymeleaf

3. 在 templates 中添加 index.html 文件
   注意：生成的 meta 不是闭合标签，需要改为
4. 修改 IndexController 中相关的代码

@Controller
public class IndexController{
  @Autowired
  private myProperties prop;
    
  @RequestMapping(value = "/", method = RequestMethod.GET)
  public String say(){
    return "index";
    }
}  

2. @RestController = @Controller + @ResponseBody

@RestController = @Controller + @ResponseBody

@Controller
@ResponseBody
public class IndexController{
    @AutoWired
    private myProperties prop;

    @RequestMapping(value="/", method = RequestMethod.GET)
    public String say(){
        return prop.getBook();
    }
}

3. RequestMapping ，从 url 到 方法的映射

• 多网址指向同一个方法

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

• 给整个类注解路径

@RestController
@RequestMapping(value="/root", method= RequestMethod.GET)
public class IndexController{

  @AutoWired
  private myProperties prop;

  @RequestMapping(value = "/hi", method = RequestMethod.GET)
  public String say(){
      return prop.getBook();
  }
}

这样，两个地址拼接起来才能访问到，如 “http://localhost:8080/root/hi”

• 支持正则表达式 / 变量名

url 中的参数

• @PathVariable, 获取 url 中变量的值
• @RequestParam, 获取请求参数的值
• @GetMApping, 组合注解

1. @PathVariable 获取 url 中变量的值

修改 IndexController

@RestController
@RequestMapping(value = "/root/{id}", method = RequestMethod.GET)
public String say(@PathVariable("id") Integer id){
    return "ID: " + id
}

测试网址，http://localhost:8080/root/233

2. @RequestParam 获取url中传递的值

1. @RequestParam 获取 url 中传递值，

@RestController
public class HelloController{

    @RequestMapping(value = "/hello", method = RequestMethod.GET)
    public String say(RequestParam("local") String local
                                RequestParam("local") String time){
    return local + " : " + time;
    }
}

测试地址：http://localhost:8080/hello?local=Hangzhou&time=2018

2. @RequestParam 获取 url 中传递值，设置默认值及是否必须传值

@RestController
public class IndexController(){
    
    @RequestMapping("/hello", method = RequestMethod.GET)
    public say(@RequestParam(value="local", Required = false, defaultValue = "hangzhou" String local)){
    return local; 
    }    
}

3. @GetMapping, @RequestMapping 的简化写法

@RestController
public class IndexController(){
    
    @GetMapping("/hello")
    public say(@RequestParam(value = "local", required = false, defaultValue = "hangzhou" String local)){
    return local;
    }
}

同理还有，PostMapping / DeleteMapping