Cordova FileEntry.file（）返回大小0

Question

我遇到了一個問題，當我將jpg保存爲Windows上的八位字節流時​​，隨後的讀取將返回一個大小爲0的文件。我可以看到該文件我的硬盤，文件看起來不錯，但讀取文件失敗。

下面的代碼是我用來與文件系統進行交互的，有些黑客試圖解決這個問題。

function downloadFileFromUrl(url, localPath, contentType, successCallback, failureCallback) { 
    var xhr = new XMLHttpRequest(); 
    xhr.open('GET', url, true); 
    xhr.responseType = 'blob'; 

    xhr.onload = function() { 
     if (this.status == 200) { 
      localPath = encodeURI(localPath); 
      writePersistantFile(localPath, this.response, true, contentType, 
       function (fileEntry) { 
        if (successCallback != undefined) { 
         successCallback(fileEntry); 
        } 
       }, 
       function (error) { 
        if (failureCallback != undefined) { 
         failureCallback(error); 
        } 
       }); 
     } 
    }; 
    xhr.send(); 
} 

function createDirectoryRecursively(path, parentDir, callback, errorCallback) { 
    if (path == null || path.length == 0) { 
     callback(parentDir); 
     return; 
    } 
    var index = path.indexOf('/'); 
    var dirName = null; 
    var remainder = null; 
    if (index <= 0) { 
     dirName = path; 
    } else { 
     dirName = path.substring(0, index); 
     remainder = path.substring(index + 1); 
    } 

    parentDir.getDirectory(dirName, { create: true, exclusive: true }, function (dirEntry) { 
     self.createDirectoryRecursively(remainder, dirEntry, callback, errorCallback); 
    }, function (error) { 
     if (error.code == 12) { 
      parentDir.getDirectory(dirName, { create: false }, function (dirEntry) { 
       self.createDirectoryRecursively(remainder, dirEntry, callback, errorCallback); 
      }, function (error2) { 
       errorCallback(error); 
      }); 
      return; 
     } 
     errorCallback(error); 
    }); 
} 

function getFile(fileName, parentDir, callback, errorCallback) { 
    if (parentDir == null) { 
     window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, 
      function (fs) { 
       getFile(fileName, fs.root, callback, errorCallback); 
      }, 
      function (error) { 

      }); 
     return; 
    } 
    if (fileName.indexOf('/') >= 0) { 
     var dirName = fileName.substring(0, fileName.lastIndexOf('/')); 
     createDirectoryRecursively(dirName, parentDir, 
      function (directory) { 
       var name = fileName.substring(fileName.lastIndexOf('/') + 1); 
       getFile(name, directory, callback, errorCallback); 
      }, errorCallback); 
     return; 
    } 
    parentDir.getFile(fileName, { create: true }, 
     function (fileEntry) { 
      console.log('obtained file'); 
      callback(fileEntry); 
     }, 
     function (error) { 
      if (error.code == 1) { 
       parentDir.getFile(fileName, { create: false }, 
        function (fileEntry) { 
         console.log('obtained file'); 
         callback(fileEntry); 
        }, 
        function (error) { 
         if (error.code == 12) { 
          return; 
         } 
         errorCallback(error); 
        }); 
       return; 
      } 
      errorCallback(error); 
     }); 
} 

function readPersistantFile(filePath, successCallback, errorCallback) { 
    getFile(filePath, null, 
     function (fileEntry) { 
      console.log('obtained file'); 
      fileEntry.file(function (file) { 
       console.log('file size: ' + file.size); 
       var reader = new FileReader(); 

       reader.onloadend = function() { 
        console.log("Successful file read"); 
        if (successCallback != undefined) { 
         successCallback(this.result); 
        } 
       }; 

       var extension = filePath.substring(filePath.lastIndexOf('.') + 1); 
       if (extension == 'json') { 
        reader.readAsText(file); 
       } else { 
        reader.readAsDataURL(file); 
       } 
      }); 

     }, 
     function (error) { 
      console.log('An error occured while getting the file'); 
      console.error(error); 
      if (errorCallback != undefined) { 
       errorCallback(error); 
      } 
     }); 
} 

function writePersistantFile(filePath, data, isBinary, contentType, successCallback, errorCallback) { 
    var dataSize = (data.length != undefined) ? data.length : (data.size != undefined)? data.size : 5 * 1024 * 1024; 
    window.requestFileSystem(LocalFileSystem.PERSISTENT, dataSize, function (fs) { 
     console.log('file system opened: ' + fs.name); 

     var lastIndex = filePath.lastIndexOf('/'); 
     var directory = filePath.substring(0, lastIndex); 
     createDirectoryRecursively(directory, fs.root, function (parentDir) { 
      console.log('Directory created'); 
      var fileName = filePath.substring(lastIndex + 1); 
      getFile(fileName, parentDir, 
       function (fileEntry) { 
        console.log('obtained file'); 
        fileEntry.createWriter(function (fileWriter) { 
         console.log('created writer'); 
         if (typeof (data) == 'string') { 
          fileWriter.write(new Blob([data], { type: contentType })); 
         } else { 
          fileWriter.write(data); 
         } 

         if (successCallback != undefined) { 
          successCallback(fileEntry); 
         } 
        }); 
       }, 
       function (error) { 
        console.log('An error occured while getting the file'); 
        console.error(error); 
        if (errorCallback != undefined) { 
         errorCallback(error); 
        } 
       }); 

     }, function (error) { 
      console.log('An error occured while saving the file'); 
      console.error(error); 
      if (errorCallback != undefined) { 
       errorCallback(error); 
      } 
     }); 
    }); 
} 

Answer 1

它似乎不是上面的代碼，其可容易地最優化，而是文件夾的長度/數中被傳遞。

正在寫入的相同的文件具有36個字符的長度，並且4個子文件夾。將它改爲只有一個文件名，例如'page-1.jpg'沒有問題。