elementui上传text文件到java后端，前端的代码和后端的完整代码怎么写？

前端代码：

<template>
  <el-upload
    class="upload-demo"
    ref="upload"
    :action="uploadUrl"
    :on-change="handleChange"
    :auto-upload="false"
    :file-list="fileList"
    :headers="headers"
  >
    <el-button slot="trigger" size="small" type="primary">选择文件</el-button>
    <el-button
      style="margin-left: 10px;"
      size="small"
      type="success"
      @click="handleUpload"
      :disabled="fileList.length === 0"
    >
      上传到服务器
    </el-button>
  </el-upload>
</template>

<script>
export default {
  data() {
    return {
      fileList: [], // 文件列表
      uploadUrl: '', // 后端接口地址
      headers: {
        Authorization: 'Bearer ' + localStorage.getItem('token'), // 请求头中的 token
      },
    };
  },
  methods: {
    // 选择文件时触发
    handleChange(file) {
      this.fileList.push(file.raw);
    },
    // 点击上传按钮时触发
    handleUpload() {
      let formData = new FormData();
      this.fileList.forEach((file) => {
        formData.append('file', file);
      });
      this.$refs.upload.submit(formData);
    },
  },
};
</script>

后端代码（使用Spring Boot框架）：

@RestController
@RequestMapping("/api")
public class FileController {

    @PostMapping("/upload")
    public ResponseEntity<?> uploadFile(@RequestParam("file") MultipartFile file) {
        if (file.isEmpty()) {
            return new ResponseEntity<>("File is empty", HttpStatus.BAD_REQUEST);
        }

        String fileName = file.getOriginalFilename();
        byte[] bytes;
        try {
            bytes = file.getBytes();
        } catch (IOException e) {
            return new ResponseEntity<>("Failed to read file", HttpStatus.INTERNAL_SERVER_ERROR);
        }

        // save the file
        try {
            File newFile = new File(fileName);
            OutputStream os = new FileOutputStream(newFile);
            os.write(bytes);
            os.close();
        } catch (IOException e) {
            return new ResponseEntity<>("Failed to save file", HttpStatus.INTERNAL_SERVER_ERROR);
        }

        return new ResponseEntity<>("File uploaded successfully", HttpStatus.OK);
    }
}

以上代码仅供参考，实际应用中需要根据具体情况进行适当修改。