语法错误：XMLHttpRequest.onLoad 处出现意外标记 < in JSON at position 0 at JSON.parse (<anonymous>)

Question

希望这不是一个愚蠢的问题。 连接 ionic 和 java springboot ，当应用程序在浏览器中实时服务并且数据正确显示时，没有错误消息。但得到了 SyntaxError: Unexpected token

< in JSON at position 0 at JSON.parse () error when testing on android device.

我搜索了一下，发现问题与 JSON 解析有关，但我不太明白为什么浏览器中没有报告错误消息。

我想在这里做什么： 我有一个包含姓名和电子邮件的用户表，我正在连接以在前端显示所有姓名。后端返回一个列表。

我还使用了 chrome CROS 扩展，但我认为这根本不相关。 任何人都可以帮忙解释一下吗？谢谢大家

   typescript
   ngOnInit() {
      this.surgeonList = [
      ];
      console.log(this.value);
      this.httpclient.get('http://localhost:8080/users'
      ).subscribe(
          data => {
              data = JSON.parse(JSON.stringify(data));
              for (var i  = 0 ; i < (<Array<any>>data).length; i++) {
                  this.surgeonList.push(
                      {
                          name: data[i].lastname,
                          icon: 'person'
                      }
                  );
              }
          }
      );
  }

JAVA spring controller

    @GetMapping("/users")
    public List getUsers(){
        List users = userRepository.findAll();
        return users;
    }

获取请求响应正确记录数据：

[
    {
        "id": 2,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "[email protected]",
        "password": "613387"
    },
    {
        "id": 3,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": null
    },
    {
        "id": 4,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": null
    },
    {
        "id": 5,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": null
    },
    {
        "id": 6,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": null
    },
    {
        "id": 7,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": "123333"
    },
    {
        "id": 8,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": "123333"
    },
    {
        "id": 9,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": "123333"
    },
    {
        "id": 10,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": "123333"
    },
    {
        "id": 11,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": "123333"
    },
    {
        "id": 12,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": "123333"
    },
    {
        "id": 13,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": "123333"
    },
    {
        "id": 14,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": "123333"
    },
    {
        "id": 15,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": "123333"
    },
    {
        "id": 16,
        "lastname": "Liu",
        "firstname": "Jerry",
        "email": "karen77777",
        "password": "123333"
    },
    {
        "id": 17,
        "lastname": "chenniuniu",
        "firstname": "Jerry",
        "email": "[email protected]",
        "password": "613387"
    },
    {
        "id": 18,
        "lastname": "chendada",
        "firstname": "Jerry",
        "email": "[email protected]",
        "password": "613387"
    },
    {
        "id": 19,
        "lastname": "chendada",
        "firstname": "Jerry",
        "email": "[email protected]",
        "password": "613387"
    },
    {
        "id": 20,
        "lastname": "VFVSD",
        "firstname": "Jerry",
        "email": "DSFSDF",
        "password": "FDSFSDFDS"
    },
    {
        "id": 22,
        "lastname": "zhaohua liu",
        "firstname": "Jerry",
        "email": "[email protected]",
        "password": "613387"
    },
    {
        "id": 23,
        "lastname": null,
        "firstname": null,
        "email": "[email protected]",
        "password": "613388"
    }
]

但是在 chrome 上远程检查时得到了这个

vendor.js:44729 ERROR 
HttpErrorResponse
error:
error: SyntaxError: Unexpected token < in JSON at position 0 at JSON.parse (<anonymous>) at XMLHttpRequest.onLoad

重新编辑：

谢谢你们的回复，我是社区的新人，你们是最棒的。

我发现这里出了什么问题：

当我在浏览器上提供服务时，我发现响应作为 json 是正确的，就像你们所有人所说的那样。

但是，当我部署应用程序并在设备上远程测试它时： 我得到了 index.html 作为响应：

Answer 1

您似乎正在取回一个 JSON 对象，然后重新字符串化并解析它。这可能就是为什么？

   ngOnInit() {
      this.surgeonList = [
      ];
      console.log(this.value);
      this.httpclient.get('http://localhost:8080/users'
      ).subscribe(
          data => {
          this.surgeonList = data.map(doc=>{
          return {
              doc.lastname,
              icon: 'person'
            }
          })
              
              
          }
      );
  }

Answer 2

执行以下操作： 将

@ResponseBody

 放在控制器上

@GetMapping("/users")
@ResponseBody
public List getUsers(){
    List users = userRepository.findAll();
    return users;
}

或

@GetMapping(value="/users",produces="application/json")
    @ResponseBody
    public List getUsers(){
        List users = userRepository.findAll();
        return users;
    }

或 用

@RestController

注释你的课程