如何上传世博会照片？

Question

我正在制作一个带有Expo的应用程序,并希望让用户拍照或从相机胶卷中选择一个并将其上传到我的服务器.我该怎么做呢？

Answer 1

使用Expo ImagePickerAPI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,
    header: {
      'content-type': 'multipart/form-data',
    },
  });
}

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

Answer 2

官方示例使用Node.js，以下是使用PHP的方法：

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']);
?>

Answer 3

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,
  }
});

Answer 4

对于 Expo，除了使用 Expo FileSystem 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