使用Expo ImagePicker API显示相机或相机胶卷，并获取有关所选图像的信息：

async function takeAndUploadPhotoAsync() {
  // Display the camera to the user and wait for them to take a photo or to cancel
  // the action
  let result = await ImagePicker.launchCameraAsync({
    allowsEditing: true,
    aspect: [4, 3],
  });

  if (result.cancelled) {
    return;
  }

  // ImagePicker saves the taken photo to disk and returns a local URI to it
  let localUri = result.uri;
  let filename = localUri.split('/').pop();

  // Infer the type of the image
  let match = /\.(\w+)$/.exec(filename);
  let type = match ? `image/${match[1]}` : `image`;

  // Upload the image using the fetch and FormData APIs
  let formData = new FormData();
  // Assume "photo" is the name of the form field the server expects
  formData.append('photo', { uri: localUri, name: filename, type });

  return await fetch(YOUR_SERVER_URL, {
    method: 'POST',
    body: formData,
    headers: {
      'content-type': 'multipart/form-data',
    },
  });
}

有关包含服务器代码的更全面的示例，请参阅下面的repo：https://github.com/expo/image-upload-example。

官方示例使用Node.js，以下是使用PHP的方式：

世博会

async function takePhotoAndUpload() {

  let result = await ImagePicker.launchCameraAsync({
    allowsEditing: false, // higher res on iOS
    aspect: [4, 3],
  });

  if (result.cancelled) {
    return;
  }

  let localUri = result.uri;
  let filename = localUri.split('/').pop();

  let match = /\.(\w+)$/.exec(filename);
  let type = match ? `image/${match[1]}` : `image`;

  let formData = new FormData();
  formData.append('photo', { uri: localUri, name: filename, type });

  return await fetch('http://example.com/upload.php', {
    method: 'POST',
    body: formData,
    header: {
      'content-type': 'multipart/form-data',
    },
  });
}

upload.php

<?php
    move_uploaded_file($_FILES['photo']['tmp_name'], './photos/' . $_FILES['photo']['name']);
?>

import React, { Component } from 'react';
import {
  ActivityIndicator,
  Button,
  Clipboard,
  Image,
  Share,
  StatusBar,
  StyleSheet,
  Text,
  TouchableOpacity,
  View,
} from 'react-native';
import { Constants } from 'expo';
import * as Permissions from 'expo-permissions';
import * as ImagePicker from 'expo-image-picker';
export default class App extends Component {
  state = {
    image: null,
    uploading: false,
  };

  render() {
    let {
      image
    } = this.state;

    return (
      <View style={styles.container}>
        <StatusBar barStyle="default" />

        <Text
          style={styles.exampleText}>
          Example: Upload ImagePicker result
        </Text>

        <Button
          onPress={this._pickImage}
          title="Pick an image from camera roll"
        />

        <Button onPress={this._takePhoto} title="Take a photo" />

        {this._maybeRenderImage()}
        {this._maybeRenderUploadingOverlay()}
      </View>
    );
  }

  _maybeRenderUploadingOverlay = () => {
    if (this.state.uploading) {
      return (
        <View
          style={[StyleSheet.absoluteFill, styles.maybeRenderUploading]}>
          <ActivityIndicator color="#fff" size="large" />
        </View>
      );
    }
  };

  _maybeRenderImage = () => {
    let {
      image
    } = this.state;

    if (!image) {
      return;
    }

    return (
      <View
        style={styles.maybeRenderContainer}>
        <View
          style={styles.maybeRenderImageContainer}>
          <Image source={{ uri: image }} style={styles.maybeRenderImage} />
        </View>

        <Text
          onPress={this._copyToClipboard}
          onLongPress={this._share}
          style={styles.maybeRenderImageText}>
          {image}
        </Text>
      </View>
    );
  };

  _share = () => {
    Share.share({
      message: this.state.image,
      title: 'Check out this photo',
      url: this.state.image,
    });
  };

  _copyToClipboard = () => {
    Clipboard.setString(this.state.image);
    alert('Copied image URL to clipboard');
  };

  _takePhoto = async () => {
    const {
      status: cameraPerm
    } = await Permissions.askAsync(Permissions.CAMERA);

    const {
      status: cameraRollPerm
    } = await Permissions.askAsync(Permissions.CAMERA_ROLL);

    // only if user allows permission to camera AND camera roll
    if (cameraPerm === 'granted' && cameraRollPerm === 'granted') {
      let pickerResult = await ImagePicker.launchCameraAsync({
        allowsEditing: true,
        aspect: [4, 3],
      });

      if (!pickerResult.cancelled) {
        this.setState({ image: pickerResult.uri });
      }

      this.uploadImageAsync(pickerResult.uri);
    }
  };

  _pickImage = async () => {
    const {
      status: cameraRollPerm
    } = await Permissions.askAsync(Permissions.CAMERA_ROLL);

    // only if user allows permission to camera roll
    if (cameraRollPerm === 'granted') {
      let pickerResult = await ImagePicker.launchImageLibraryAsync({
        allowsEditing: true,
        base64: true,
        aspect: [4, 3],
      });

      if (!pickerResult.cancelled) {
        this.setState({ image: pickerResult.uri});
      }

      this.uploadImageAsync(pickerResult.uri);
    }
  };

 uploadImageAsync(pictureuri) {
  let apiUrl = 'http://123.123.123.123/ABC';


    var data = new FormData();  
    data.append('file', {  
      uri: pictureuri,
      name: 'file',
      type: 'image/jpg'
    })

    fetch(apiUrl, {  
      headers: {
        'Accept': 'application/json',
        'Content-Type': 'multipart/form-data'
      },
      method: 'POST',
      body: data
    }).then(
      response => {
        console.log('succ ')
        console.log(response)
      }
      ).catch(err => {
      console.log('err ')
      console.log(err)
    } )



  }

}

const styles = StyleSheet.create({
  container: {
    alignItems: 'center',
    flex: 1,
    justifyContent: 'center',
  },
  exampleText: {
    fontSize: 20,
    marginBottom: 20,
    marginHorizontal: 15,
    textAlign: 'center',
  },
  maybeRenderUploading: {
    alignItems: 'center',
    backgroundColor: 'rgba(0,0,0,0.4)',
    justifyContent: 'center',
  },
  maybeRenderContainer: {
    borderRadius: 3,
    elevation: 2,
    marginTop: 30,
    shadowColor: 'rgba(0,0,0,1)',
    shadowOpacity: 0.2,
    shadowOffset: {
      height: 4,
      width: 4,
    },
    shadowRadius: 5,
    width: 250,
  },
  maybeRenderImageContainer: {
    borderTopLeftRadius: 3,
    borderTopRightRadius: 3,
    overflow: 'hidden',
  },
  maybeRenderImage: {
    height: 250,
    width: 250,
  },
  maybeRenderImageText: {
    paddingHorizontal: 10,
    paddingVertical: 10,
  }
});

对于Expo，除了使用Expo文件系统uploadAsync之外，没有什么对我有用

uploadImage = async ({ imageUri } }) => FileSystem.uploadAsync(
    apiUrl,
    imageUri,
    {
      headers: {
        // Auth etc
      },
      uploadType: FileSystem.FileSystemUploadType.MULTIPART,
      fieldName: 'files',
      mimeType: 'image/png',
    });

注意- imageUri格式为file：///mypath/to/image.png

由于所选的解决方案实际上对我不起作用，下面是我如何使用Expo和Django Rest Framework作为后端进行文件上传。

const blobToBase64 = blob => {
      const reader = new FileReader();
      reader.readAsDataURL(blob);
      return new Promise(resolve => {
        reader.onloadend = () => {
          resolve(reader.result);
        };
      });
    };

    const formData = new FormData();
    const base64 = await blobToBase64(blob);
    formData.append('file', base64);
    formData.append('data', JSON.stringify(payload));  // additional data (I parse the string as json in the backend to get my payload back)

    // same code as chosen answer, this was not part of the problem
    return await fetch(YOUR_SERVER_URL, {
      method: 'POST',
      body: formData,
      headers: {
        'content-type': 'multipart/form-data',
      },
    });

在Django中，我可以使用自定义解析器将base64字符串解码为字节，然后使用它创建一个SimpleUploadedFile对象。

class MultipartJsonParser(parsers.MultiPartParser):
      def parse(self, stream, media_type=None, parser_context=None):
        result = super().parse(
            stream,
            media_type=media_type,
            parser_context=parser_context
        )

        base64_file = result.data.get('file')
        file_parts = base64_file.split(',')
        mime_type = re.sub(r'^data:([\w\/]+);base64$', '\\1', file_parts[0])
        file = SimpleUploadedFile('file', base64.b64decode(file_parts[1]), mime_type)
        data = json.loads(result.data["data"]) or {}  # additional data sent by Expo app
        qdict = QueryDict('', mutable=True)
        qdict.update(data)
        return parsers.DataAndFiles(qdict, {'file': file})

    class MyUploadView(ModelViewSet):
      parser_classes = (MultipartJsonParser, parsers.JSONParser)

      def create(self, request, *args, **kwargs):
          # request.data should have a 'file' property with a SimpleUploadedFile object
          ...

对于那些没有找到或解决这个问题的人来说。我花了三天的时间来寻找解决方案，我得到了它。在我的例子中，它是数据对象的命名元素。Android版本10，Expo 4.11.0，

这里是前线

async function uploadImage(uploadFile){
    const data = new FormData()
    data.append('name',{
        name: image_name, {/* name your image whatever you want*/}
        type: 'image/jpeg', {/* type of image that you're uploading*/}
        uri: uploadFile {/*data, file or image from ImagePicker here you should pass uri data but not all data from ImagePicker*/}
    })
{/*names of data object should be like this: name, type, uri*/}
    const response = await fetch(my_upload_api.php,{
        method: 'POST',
        body: data,
        headers: {
            'Content-Type': 'multipart/form-data'
        }
    })
}

这是PHP的后台

if(!empty($_FILES['name']['name'])){
$target_dir = 'my folder where I put all images';
if(!file_exists($target_dir)){
    $data = array(
        (object)array(
            'code' => '400',
            'message' => 'Can\'t fined folder.'
        )
    );
    $json = json_encode($data);
    echo $json;
    die();
}
$target_file = $target_dir . basename($_FILES['name']['name']);
$image_file_type = pathinfo($target_file,PATHINFO_EXTENSION);
if(file_exists($target_file)){
    $data = array(
        (object)array(
            'code' => '400',
            'message' => 'Sorry. File already exists.'
        )
    );
    $json = json_encode($data);
    echo $json;
    die();
}
if($_FILES['name']['size'] > 50000000){
    $data = array(
        (object)array(
            'code' => '400',
            'message' => 'Sorry. Your file is too large.'
        )
    );
    $json = json_encode($data);
    echo $json;
    die();
}
if(move_uploaded_file($_FILES['name']['tmp_name'], $target_file)){
    $data = array(
        (object)array(
            'code' => '200',
            'message' => 'Successfuly your file has been uploaded.',
            'name' => $_FILES['name']
        )
    );
    $json = json_encode($data);
    echo $json;
    die();
}else{
    $data = array(
        (object)array(
            'code' => '400',
            'message' => 'Sorry. There was something wrong. Try it again.'
        )
    );
    $json = json_encode($data);
    echo $json;
    die();
}

}
这是我第一次尝试寻找解决方案的博客。如果解决方案在这里，我可能会花一天或更少的时间来解决这个问题。我希望我能帮助到某人。