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angular - 语法错误：JSON.parse 中位置 0 的 JSON 中的意外标记 <) 在 XMLHttpRequest.onLoad

问题描述

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。但是在 android 设备上测试时出现 SyntaxError: Unexpected token < in JSON at JSON.parse () 位置 0 错误。

我四处搜索并意识到这个问题与 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。

我在这里尝试做什么：我有一个带有名称和电子邮件的表用户，并且我正在连接以在前端显示所有名称。后端返回一个列表。

我也使用了 chrome CROS 扩展，但我认为这根本不相关。谁能帮忙解释一下？谢谢

   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": "karen698698@gmail.com",
        "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": "chenniuniu@gmail.com",
        "password": "613387"
    },
    {
        "id": 18,
        "lastname": "chendada",
        "firstname": "Jerry",
        "email": "chendaada@bobo.com",
        "password": "613387"
    },
    {
        "id": 19,
        "lastname": "chendada",
        "firstname": "Jerry",
        "email": "chendaada@bobo.com",
        "password": "613387"
    },
    {
        "id": 20,
        "lastname": "VFVSD",
        "firstname": "Jerry",
        "email": "DSFSDF",
        "password": "FDSFSDFDS"
    },
    {
        "id": 22,
        "lastname": "zhaohua liu",
        "firstname": "Jerry",
        "email": "zliu633@uwo.ca",
        "password": "613387"
    },
    {
        "id": 23,
        "lastname": null,
        "firstname": null,
        "email": "yche98@uwo.ca",
        "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手，你们是最好的。

我在这里找出问题所在：

当我在浏览器上服务时，我发现响应是正确的 json ，就像你们所有人所说的那样。 在浏览器上服务时的响应

但是，当我部署应用程序并在设备上对其进行远程测试时：我得到了 index.html 作为响应： 在此处输入图像描述

标签： angularspring-bootionic4

解决方案

执行以下操作：戴上@ResponseBody控制器

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

或者

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

或 Annonate 你的班级@RestController

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