spring-mvc中controller，前端傳過來的參數,用數組，列表，Map來接受參數的方式

僅使用get方法來進行演示，其他請求方法(POST,DELETE,PUT)接受參數的形式都是一樣的。

• 用數組接受參數

  import org.springframework.stereotype.Controller;
  import org.springframework.web.bind.annotation.RequestMapping;
  import org.springframework.web.bind.annotation.ResponseBody;
  
  @Controller
  public class CIsBestController {
  
      // 訪問路徑 http://localhost:8080/array?strings="貂蟬學python","小喬學java","魯班學C++"
      // 瀏覽器顯示的結果：響應數據："貂蟬學python","小喬學java","魯班學C ",
      @RequestMapping("/array")
      @ResponseBody
      public String resp(String[] strings) {
          String str = "";
          for(String s:strings){
              System.out.println("接受的參數是：" + s);
              str += s+",";
          }
  
          return "響應數據：" + str;
      }
  }
  

• 用List接受參數

  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 {
  
      // 訪問路徑 http://localhost:8080/list?array_list="貂蟬學python","小喬學java","魯班學C++"
      // 瀏覽器顯示的結果：響應數據："貂蟬學python","小喬學java","魯班學C ",
      @RequestMapping("/list")
      @ResponseBody
      public String resp(@RequestParam("array_list") ArrayList<String> arrayList) {
          String str = "";
          for(String s:arrayList){
              System.out.println("接受的參數是：" + s);
              str += s+",";
          }
  
          return "響應數據：" + str;
      }
  }
  

• 用Map接受參數

  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 {
  
      // 訪問路徑 http://localhost:8080/map?name=貂蟬&age=18&sex=女
      // 瀏覽器顯示的結果：響應數據：{name=貂蟬, age=18, sex=女}
      @RequestMapping("/map")
      @ResponseBody
      public String resp(@RequestParam Map map) {
          System.out.println(map);
  
          return "響應數據：" + map;
      }
  }
  

  關於用Map接受參數有個小坑，用Map接受參數必須要在參數前添加 @RequestParam 注解。

  Map不能用來接受復合參數。對於前端來說，Map只能接受

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

  這種形式的參數。如果前端傳的是

  {
      name : "貂蟬",
      age : 18,
      sex : "女",
      spouse : {
          name : "呂布",
          age: 25,
          sex: "男"
      }
  }
  

  Map 是拿不到 spouse 里面的參數信息的。

  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 {
  
      // 訪問路徑 http://localhost:8080/map?name=貂蟬&age=18&sex=女&spouse.name=呂布&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 "響應數據：" + spouse.toString();
      }
  }
  

  訪問地址http://localhost:8080/map?name=貂蟬&age=18&sex=女&spouse.name=呂布&spouse.age=25&spouse.sex=男，會報java.lang.NullPointerException的異常。