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cordova - Ionic V4（beta 11）文件插件似乎不适用于 V4

问题描述

我正在尝试通过 ionic V4 将图片从互联网下载到手机，然后使用 File 插件将下载的图片直接从本机文件系统显示到标签。

不幸的是，我无法让它在 V4 中工作......但它在 V3 中工作。我认为 V4 解释路径以将其绑定到 src 属性的方式可能存在问题（？）

我写了一个程序来测试它。

TS 文件：

import { Component, OnInit } from '@angular/core';
import { FileTransfer, FileTransferObject } from '@ionic-native/file-transfer/ngx';
import { File } from '@ionic-native/file/ngx'

@Component({
  selector: 'app-scratch2',
  templateUrl: './scratch2.page.html',
  styleUrls: ['./scratch2.page.scss'],
})
export class Scratch2Page implements OnInit {
  private address: string = null;
  private path: string = null;
  private fileNumber = 1;
  private latest = null;
  private toggle = false;

  constructor(
    private fileX: FileTransfer,
    private file: File
  ) { 
    this.path = this.file.dataDirectory + "files/";
  }

  ngOnInit() {
    let filename = this.nameFile()
    this.latest = this.nameFix(filename)
    console.log("1the filename that is returned is ********** ", filename)
  }

  nameFile(){
    let filename = this.path + "file" + this.fileNumber
    return filename
  }

  nameFix(filename){
    return filename.replace(/file:\/\//g, "")
  }

  downloadFile() {
    let filename = this.nameFile();
    console.log("2the filename that is returned is ********** ", filename)
    console.log("Entered download File with url: ", this.address)
    let url = this.address
    const fileTransfer: FileTransferObject = this.fileX.create();
    fileTransfer.download(url, filename).then((entry) => {
        console.log('fileTransfer.download data ** ** ** **:' + JSON.stringify(entry));
        this.fileNumber += 1;
        this.latest = this.nameFix(filename)
    }, (err) => {
      // handle error
      console.log("downloadfile() error: " + JSON.stringify(err));
    });
  }

  toggleToggle(){
    this.toggle = !this.toggle;

  }

}

这是 HTML 文件：

    <ion-header>
  <ion-toolbar>
      <ion-buttons slot="start">
          <ion-back-button defaultHref="/"></ion-back-button>
        </ion-buttons>
    <ion-title>scratch2</ion-title>
  </ion-toolbar>
  <ion-toolbar>{{latest}} {{toggle}}</ion-toolbar>
</ion-header>

<ion-content padding>
    <ion-item>
        <ion-label>Address</ion-label>
        <ion-input placeholder="Enter address" [(ngModel)]="address"></ion-input>
      </ion-item>
      <ion-button (click)="downloadFile()"> Download from address</ion-button>
      <ion-button (click)="toggleToggle()">Toggle</ion-button>

    <img *ngIf="toggle" [src]="latest"/>
</ion-content>

任何帮助，将不胜感激

标签： cordovaionic-framework

解决方案

在这里回答我自己的问题……这就是我发现的。

文件结构确实发生了变化，文件本身可以通过网络服务器而不是直接访问。这是在这个链接上讨论的：https ://ionicframework.com/docs/wkwebview/

归结为：当您想将文件下载到手机时，您使用以下两个路径进行操作，一个用于下载文件，另一个用于显示下载的文件：

this.downloadPath = this.file.dataDirectory + "filename.jpg"
this.showFilePath = normalizeURL(this.file.dataDirectory + "filename.jpg")

其中 normalizeURL 是通过以下方式导入的： import { normalizeURL } from “ionic-angular”；

所以，我重写了上面的代码，看起来像这样：

文件

import { Component, OnInit } from '@angular/core';
import { FileTransfer, FileTransferObject } from '@ionic-native/file-transfer/ngx';
import { File } from '@ionic-native/file/ngx'
import { normalizeURL } from "ionic-angular";

@Component({
  selector: 'app-scratch2',
  templateUrl: './scratch2.page.html',
  styleUrls: ['./scratch2.page.scss'],
})
export class Scratch2Page implements OnInit {
  private address: string = null;
  private path: string = null;
  private toggle = false;
  private showPath = null;
  private downloadPath = null

  constructor(
    private fileX: FileTransfer,
    private file: File
  ) {
    this.path = this.file.dataDirectory + "files/";
    this.downloadPath = this.path + "beer.jpg"
    this.showPath = normalizeURL(this.path + "beer.jpg")
  }
  ngOnInit() {
  }

  downloadFile() {
    console.log("Entered download File with url: ", this.address)
    let url = this.address
    const fileTransfer: FileTransferObject = this.fileX.create();
    fileTransfer.download(url, this.downloadPath).then((entry) => {
      console.log('fileTransfer.download data ** ** ** **:' + JSON.stringify(entry));
    }, (err) => {
      console.log("downloadfile() error: " + JSON.stringify(err));
    });
  }

  toggleToggle() {
    this.toggle = !this.toggle;
  }
}

文件

<ion-header>
  <ion-toolbar>
    <ion-buttons slot="start">
      <ion-back-button defaultHref="/"></ion-back-button>
    </ion-buttons>
    <ion-title>scratch2</ion-title>
  </ion-toolbar>
  <ion-toolbar>toggle:{{toggle}} <br><br> download path:<br>{{downloadPath}} <br><br> Show path:<br>{{showPath}}</ion-toolbar>
</ion-header>
<ion-content padding>
  <ion-item>
    <ion-label>http address of jpg:</ion-label>
    <ion-input placeholder="Enter address" [(ngModel)]="address"></ion-input>
  </ion-item>
  <ion-button (click)="downloadFile()"> download jpg</ion-button>
  <ion-button (click)="toggleToggle()">Toggle</ion-button>
  <img *ngIf="toggle" src="{{showPath}}" />
</ion-content>

在 iPhone 模拟器上，下载路径是这样开始的：

file:///Users/myUserName/Library/etc etc etc

显示文件路径如下所示：

http://localhost:8080/_file_/Users/myUserName/Library/etc etc etc

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