Fegin参数使用总结

注解：

@RequestParam：前端传值时要在URL后面拼接 参数名+参数值
用法：@RequestParam(value="nnn",required=false)，Post和Get都可以使用
@RequestBody：从请求体中获取数据
用法：支持Post
@PathVariable：前端传值时，不需要参数名，直接在URL后面拼接参数值即可，url/typeId，用来获取url中的动态参数
用法：只支持Get
get和post请求中对于传递单个引用类型的参数，比如String，Integer....用@RequestParam()，括号中一定要有值(参数的别名)。调用方需要加注解，被调用方不需要加。当然加上也不会出错。被调用方的参数名和调用方的别名保持一致即可。
 
post请求中对于javaBean，map，list类型的参数的传递，用@RequestBody，调用方不需要加注解，被调用方加注解即可。 注：get请求中使用@RequestBody会出错，同时也不能传递javaBean，map，list类型的参数。

参考文章：http://www.javashuo.com/article/p-parfdzuq-mg.html

（1）无参请求

Post和Get没有区别，均只需要修改RequestMethod请求类型就可以

/**
 * 调用过程代码
 */
public Result<?> queryParticipantsList(){
   System.out.println(iSysBaseAPI.feignTestDemo());
   return new Result<>().ok(null);
}

/** 
  * 在Feign的Api接口和实现类的代码如下
  * @Description Feign调用测试 get和post无参调用
  */
@RequestMapping(value = "/sys/api/feignTestDemo",method = RequestMethod.GET)
public String feignTestDemo();
@RequestMapping(value = "/feignTestDemo",method = RequestMethod.GET)
public String feignTestDemo(){
    return "Get调用测试";
}

@RequestMapping(value = "/sys/api/feignTestDemo",method = RequestMethod.POST)
public String feignTestDemo();
@RequestMapping(value = "/feignTestDemo",method = RequestMethod.POST)
public String feignTestDemo(){
    return "Post无参调用测试";
}

@RequestMapping(value = "/sys/api/feignTestDemo",method = RequestMethod.POST)
public List<SysUser> feignTestDemo();
@RequestMapping(value = "/feignTestDemo",method = RequestMethod.POST)
public List<SysUser> feignTestDemo(){
    List<SysUser> list=new ArrayList<>();
    SysUser sysUser=new SysUser();
    sysUser.setId("110");
    sysUser.setUsername("Post无参调用测试");
    list.add(sysUser);
    return list;
}

@RequestMapping(value = "/sys/api/feignTestDemo",method = RequestMethod.GET)
public List<SysUser> feignTestDemo();
@RequestMapping(value = "/feignTestDemo",method = RequestMethod.GET)
public List<SysUser> feignTestDemo(){
    List<SysUser> list=new ArrayList<>();
    SysUser sysUser=new SysUser();
    sysUser.setId("110");
    sysUser.setUsername("Post无参调用测试");
    list.add(sysUser);
    return list;
}

（2）有参请求

get请求

第一种Get请求，没有使用任何注解，结果会提示错误
public Result<?> queryParticipantsList(){
   String title="String参数,Get请求,没有使用注解";
   System.out.println(iSysBaseAPI.feignTestDemo(title));
   return new Result<>().ok(null);
}
@RequestMapping(value = "/sys/api/feignTestDemo",method = RequestMethod.GET)
public String feignTestDemo(String title);
@RequestMapping(value = "/feignTestDemo",method = RequestMethod.GET)
public String feignTestDemo(String title){
    return title;
}
错误信息如下：
org.springframework.web.HttpRequestMethodNotSupportedException: Request method 'POST' not supported

第二种情况 使用@RequestParam("title")，正常没有任何问题
public Result<?> queryParticipantsList(){
   String title="String参数,Get请求,使用@RequestParam(\"title\")";
   System.out.println(iSysBaseAPI.feignTestDemo(title));
   return new Result<>().ok(null);
}
@RequestMapping(value = "/sys/api/feignTestDemo",method = RequestMethod.GET)
public String feignTestDemo(@RequestParam("title") String title);
 @RequestMapping(value = "/feignTestDemo",method = RequestMethod.GET)
public String feignTestDemo(@RequestParam("title")String title){
    return title;
}

第三种情况：当传递的参数是List<String>和List<T>的时候，当时List<String>正常调用，没有任何问题
public Result<?> queryParticipantsList(){
   String title="String参数,Post请求,使用@RequestParam(\"title\")";
   List<String> titles=new ArrayList<>();
   titles.add(title);
   System.out.println(iSysBaseAPI.feignTestDemo(titles));
   return new Result<>().ok(null);
}
@RequestMapping(value = "/sys/api/feignTestDemo",method = RequestMethod.GET)
public List<String> feignTestDemo(@RequestParam(name = "titles") List<String> titles);
@RequestMapping(value = "/feignTestDemo",method = RequestMethod.GET)
public List<String> feignTestDemo(@RequestParam(name = "titles")List<String> titles){
    return titles;
}
当传递的是List<实体的时候，会出现错误>，错误信息如下
public Result<?> queryParticipantsList(){
   SysUser sysUser=new SysUser();
   sysUser.setUsername("get请求，传送List<SysUser>参数");
   sysUser.setId("110");
   ArrayList<SysUser> titles=new ArrayList<>();
   titles.add(sysUser);

   System.out.println(iSysBaseAPI.feignTestDemo(titles));
   return new Result<>().ok(null);
}
@RequestMapping(value = "/sys/api/feignTestDemo",method = RequestMethod.GET)
public List<SysUser> feignTestDemo(@RequestParam(name = "titles") ArrayList<SysUser> titles);
2021-12-16 15:56:54.372 [http-nio-7001-exec-7] ERROR o.jeecg.common.exception.JeecgBootExceptionHandler:69 - Failed to convert value of type 'java.lang.String' to required type 'java.util.ArrayList'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'java.util.ArrayList': no matching editors or conversion strategy found
@RequestMapping(value = "/feignTestDemo",method = RequestMethod.GET)
public List<SysUser> feignTestDemo(@RequestParam(name = "titles")ArrayList<SysUser> titles){
    return titles;
}

第四种情况 使用@PathVariable("title")，错误
错误原因：无法在url中拼接参数，后期需要询问讨论一下。
public Result<?> queryParticipantsList(){
   String title="String参数,Get请求,使用@PathVariable(\"title\")";
   System.out.println(iSysBaseAPI.feignTestDemo(title));
   return new Result<>().ok(null);
}
@RequestMapping(value = "/sys/api/feignTestDemo/{title)}",method = RequestMethod.GET)
public String feignTestDemo(@PathVariable(value = "title") String title);
@RequestMapping(value = "/feignTestDemo/{title)}",method = RequestMethod.GET)
public String feignTestDemo(@PathVariable(value = "title") String title){
    return title;
}
错误信息如下：
org.springframework.web.HttpRequestMethodNotSupportedException: Request method 'POST' not supported

post请求

第一种，单参数，使用@RequestParam传递，没问题
public Result<?> queryParticipantsList(){
   String title="String参数,Post请求,使用@RequestParam(\"title\")";
   System.out.println(iSysBaseAPI.feignTestDemo(title));
   return new Result<>().ok(null);
}
@RequestMapping(value = "/sys/api/feignTestDemo",method = RequestMethod.POST)
public String feignTestDemo(@RequestParam(name = "title") String title);
@RequestMapping(value = "/feignTestDemo",method = RequestMethod.POST)
public String feignTestDemo(@RequestParam(name = "title") String title){
    return title;
}

第二种传递实体的时候，使用@RequestParam和@RequestBody两种方式进行测试
采用@RequestParam注解的，失败
public Result<?> queryParticipantsList(){
   SysUser sysUser=new SysUser();
   sysUser.setUsername("Post请求，传送List<SysUser>参数");
   sysUser.setId("110");
   ArrayList<SysUser> titles=new ArrayList<>();
   titles.add(sysUser);

   System.out.println(iSysBaseAPI.feignTestDemo(titles));
   return new Result<>().ok(null);
}
@RequestMapping(value = "/sys/api/feignTestDemo",method = RequestMethod.POST)
public List<SysUser> feignTestDemo(@RequestParam(name = "titles")ArrayList<SysUser> titles);
@RequestMapping(value = "/feignTestDemo",method = RequestMethod.POST)
public List<SysUser> feignTestDemo(@RequestParam(name = "titles")ArrayList<SysUser> titles){
    return titles;
}
错误信息如下：
2021-12-16 16:11:58.725 [http-nio-7001-exec-7] ERROR o.jeecg.common.exception.JeecgBootExceptionHandler:69 - Failed to convert value of type 'java.lang.String' to required type 'java.util.ArrayList'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'java.util.ArrayList': no matching editors or conversion strategy found

采用@RequestBody注解的，成功
public Result<?> queryParticipantsList(){
   SysUser sysUser=new SysUser();
   sysUser.setUsername("Post请求，传送List<SysUser>参数");
   sysUser.setId("110");
   ArrayList<SysUser> titles=new ArrayList<>();
   titles.add(sysUser);

   System.out.println(iSysBaseAPI.feignTestDemo(titles));
   return new Result<>().ok(null);
}
@RequestMapping(value = "/sys/api/feignTestDemo",method = RequestMethod.POST)
public List<SysUser> feignTestDemo(@RequestBody ArrayList<SysUser> titles);
@RequestMapping(value = "/feignTestDemo",method = RequestMethod.POST)
public List<SysUser> feignTestDemo(@RequestBody ArrayList<SysUser> titles){
    return titles;
}
第三种传递多种参数，使用@RequestParam和@RequestBody进行混合使用，没问题
public Result<?> queryParticipantsList(){
   SysUser sysUser=new SysUser();
   sysUser.setUsername("Post请求，传送List<SysUser>参数");
   sysUser.setId("110");
   ArrayList<SysUser> titles=new ArrayList<>();
   titles.add(sysUser);

   String name="Post，多参数测试";

   System.out.println(iSysBaseAPI.feignTestDemo(titles,name));
   return new Result<>().ok(null);
}
@RequestMapping(value = "/sys/api/feignTestDemo",method = RequestMethod.POST)
public List<SysUser> feignTestDemo(@RequestBody ArrayList<SysUser> titles,@RequestParam(name = "name")String name);
@RequestMapping(value = "/feignTestDemo",method = RequestMethod.POST)
public List<SysUser> feignTestDemo(@RequestBody ArrayList<SysUser> titles,@RequestParam(name = "name") String name){
    return titles;
}