spring-mvc中controller，前端传过来的参数,用数组，列表，Map来接受参数的方式

仅使用get方法来进行演示，其他请求方法(POST,DELETE,PUT)接受参数的形式都是一样的。

• 用数组接受参数

  import org.springframework.stereotype.Controller;
  import org.springframework.web.bind.annotation.RequestMapping;
  import org.springframework.web.bind.annotation.ResponseBody;
  
  @Controller
  public class CIsBestController {
  
      // 访问路径 http://localhost:8080/array?strings="貂蝉学python","小乔学java","鲁班学C++"
      // 浏览器显示的结果：响应数据："貂蝉学python","小乔学java","鲁班学C ",
      @RequestMapping("/array")
      @ResponseBody
      public String resp(String[] strings) {
          String str = "";
          for(String s:strings){
              System.out.println("接受的参数是：" + s);
              str += s+",";
          }
  
          return "响应数据：" + str;
      }
  }
  

• 用List接受参数

  import org.springframework.stereotype.Controller;
  import org.springframework.web.bind.annotation.RequestMapping;
  import org.springframework.web.bind.annotation.RequestParam;
  import org.springframework.web.bind.annotation.ResponseBody;
  
  import java.util.ArrayList;
  
  @Controller
  public class CIsBestController {
  
      // 访问路径 http://localhost:8080/list?array_list="貂蝉学python","小乔学java","鲁班学C++"
      // 浏览器显示的结果：响应数据："貂蝉学python","小乔学java","鲁班学C ",
      @RequestMapping("/list")
      @ResponseBody
      public String resp(@RequestParam("array_list") ArrayList<String> arrayList) {
          String str = "";
          for(String s:arrayList){
              System.out.println("接受的参数是：" + s);
              str += s+",";
          }
  
          return "响应数据：" + str;
      }
  }
  

• 用Map接受参数

  import org.springframework.stereotype.Controller;
  import org.springframework.web.bind.annotation.RequestMapping;
  import org.springframework.web.bind.annotation.RequestParam;
  import org.springframework.web.bind.annotation.ResponseBody;
  
  import java.util.Map;
  
  @Controller
  public class CIsBestController {
  
      // 访问路径 http://localhost:8080/map?name=貂蝉&age=18&sex=女
      // 浏览器显示的结果：响应数据：{name=貂蝉, age=18, sex=女}
      @RequestMapping("/map")
      @ResponseBody
      public String resp(@RequestParam Map map) {
          System.out.println(map);
  
          return "响应数据：" + map;
      }
  }
  

  关于用Map接受参数有个小坑，用Map接受参数必须要在参数前添加 @RequestParam 注解。

  Map不能用来接受复合参数。对于前端来说，Map只能接受

  {
      name : "貂蝉",
      age : 18,
      sex : "女"
  }
  

  这种形式的参数。如果前端传的是

  {
      name : "貂蝉",
      age : 18,
      sex : "女",
      spouse : {
          name : "吕布",
          age: 25,
          sex: "男"
      }
  }
  

  Map 是拿不到 spouse 里面的参数信息的。

  import lombok.Data;
  import org.springframework.stereotype.Controller;
  import org.springframework.web.bind.annotation.RequestMapping;
  import org.springframework.web.bind.annotation.RequestParam;
  import org.springframework.web.bind.annotation.ResponseBody;
  
  import java.util.Map;
  
  @Data
  class Spouse{
      private String name;
      private String age;
      private String sex;
  }
  
  @Controller
  public class CIsBestController {
  
      // 访问路径 http://localhost:8080/map?name=貂蝉&age=18&sex=女&spouse.name=吕布&spouse.age=25&spouse.sex=男
      @RequestMapping("/map")
      @ResponseBody
      public String resp(@RequestParam Map map) {
  
          System.out.println(map);
          String name = (String) map.get("name");
          System.out.println(name);
          Spouse spouse = (Spouse) map.get("spouse");
          System.out.println(spouse.getName());
          return "响应数据：" + spouse.toString();
      }
  }
  

  访问地址http://localhost:8080/map?name=貂蝉&age=18&sex=女&spouse.name=吕布&spouse.age=25&spouse.sex=男，会报java.lang.NullPointerException的异常。