Java进阶之走进RESTful接口

restful认为,每个资源都有自己唯一的资源定位符(URI),

   每个URI都代表了一种资源,以一张图片为例:图片有自己的路径,

   所以图片也是一种资源. 所以URI中不用动词,只用名词.

   一般数据库的表都是记录同种的集合,所以为名词为复数

   这就是为什么请求路径中的操作资源要加 s ,

   可以不遵循这个规范(看自己喜欢或者公司规范)

新增 :从无到有

更新:从某个状态变成另一个状态

删除 :从有到无

员工列表查询与员工单个查询,使用相同映射路径" /employees 和相同请求方法:RequestMethod.GET,

导致请求路径(路径+请求方法)一样,报错

restful提供解决方案:使用参数路径方法

     参数路径:将参数作为请求路径的一部分  /employee/{id}      

     还要加上注解 @PathVariable ,将id拿到

浏览器/postman发起请求时使用:

    http: //localhost:8080/employee/1 其中1是id参数值,同时也是请求路径的一部分

   另外,请求映射方法必须使用 @PathVariable 进行参数读取

  注意: 如果路径参数标记与请求参数名不一致时 ,怎么办?

         可以使用 @PathVariable ( "eid" ) value属性指定

@Controller

public class EmployeeController {

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

     @ResponseBody

     public List<Employee> list(){

         List<Employee> employees = Arrays.asList( new Employee(1L, "小罗" , 22 ), new Employee(2L, "小轩" , 18 ));

         return   employees;

     }

     @RequestMapping (value = "employees/{id}" ,method = RequestMethod.GET)

     @ResponseBody

     public Employee get( @PathVariable Long id){

         List<Employee> employees = Arrays.asList( new Employee(1L, "xxx" , 22 ), new Employee(2L, "qqq" , 22 ));

         return employees.get(( int ) (id- 1 ));

     }

     @RequestMapping (value = "employees" ,method = RequestMethod.POST)

     @ResponseBody

     public Employee save(Employee employee){

         employee.setId(1L);

         return employee ;

     }

     @RequestMapping (value = "employees" ,method = RequestMethod.DELETE)

     @ResponseBody

     public JsonResult delete(Long id){

         return new JsonResult( true , "删除成功" );

     }

     @RequestMapping (value = "employees" ,method = RequestMethod.PUT)

     @ResponseBody

     public JsonResult update(Long id){

         return new JsonResult( true , "更新成功" );

     }

}

参数路径方式:

    优点:可以隐藏参数,避免暴露参数,相对安全

    缺点:如果参数较多,url过长 不建议使用           

    参数较少选用参数路径方法

Accept：application/json :代表客户端希望接受得数据类型是json类型,后台返回json数据

Content-Type：application/json:代表发送端发送数据格式是json,后台要以这种格式类接收前端的数据

删除,更新操作

     $.ajax({

         url:  路径   ,

         type:  类型  ,

         data: 参数{id: 111 },

         success:(回调函数)function(data){

         }

     })

<script>

         $(function () {

             //查全部

             $( "#btn1" ).click(function () {

                 $.get( "/employees" ,function (data) {

                     console.log(data);

                 })

             });

             //查单个

             $( "#btn2" ).click(function () {

                 $.get( "/employees/1" ,function (data) {

                     console.log(data);

                 })

             });

             //新增

             $( "#btn4" ).click(function () {

                 $.post( "/employees" ,{name: "xiao" ,age: 18 },function (data) {

                     console.log(data);

                 })

             });

             //删除

             $( "#btn3" ).click(function () {

                 $.ajax({

                     url: "/employees" ,

                     type: "DELETE" ,

                     data:{id: 1 },

                     success:function (data) {

                         console.log(data);

                     }

                 })

             });

             //更新

             $( "#btn5" ).click(function () {

                 $.ajax({

                     url: "/employees" ,

                     type: "PUT" ,

                     data:{id: 1 },

                     success:function (data) {

                         console.log(data);

                     }

                 })

             })

         })

     </script>

<filter>

     <filter-name>httpPutFormContentFilter</filter-name>

     <filter- class >org.springframework.web.filter.HttpPutFormContentFilter</filter- class >

</filter>

<filter-mapping>

     <filter-name>httpPutFormContentFilter</filter-name>

     <servlet-name>springMVC</servlet-name>

</filter-mapping>

等价于 method =RequestMethod.GET|POST|DELETE|PUT

等价于 @Controller + @ResponseBody

params :要求请求中必须携带指定名称的参数   

           params= "name" :必须携带name参数

           params= "name=xuan" :必须携带name参数,并且name=xuan

  headers :请求头，限定要处理请求的请求头信息，只有匹配才会被方法处理

consume :等价于Content-Type 

value/path：映射路径

method：限定请求的方式  

@RestController

@RequestMapping ( "employees" )

public class EmployeeController {

     @GetMapping

     public List<Employee> list(){

         List<Employee> employees = Arrays.asList( new Employee(1L, "小罗" , 22 ), new Employee(2L, "小轩" , 18 ));

         return   employees;

     }

     @GetMapping (value = "/{id}" )

     public Employee get( @PathVariable Long id){

         List<Employee> employees = Arrays.asList( new Employee(1L, "xxx" , 22 ), new Employee(2L, "qqq" , 22 ));

         return employees.get(( int ) (id- 1 ));

     }

     @PostMapping

     public Employee save(Employee employee){

         employee.setId(1L);

         return employee ;

     }

     @DeleteMapping

     public JsonResult delete(Long id){

         return new JsonResult( true , "删除成功" );

     }

     @PutMapping

     public JsonResult update(Long id){

         return new JsonResult( true , "更新成功" );

     }

}