参考书 Using the HTML5 Filesystem API.pdf

用Chrome打开网站： www.baidu.com

打开其JavaScrip控制台，输入此js（以后称脚本一）查看当前本地存储使用状况:

window.webkitStorageInfo.queryUsageAndQuota(TEMPORARY, function(usage, quota) {  console.log('Using: ' + (usage / quota) * 100 + '% of temporary storage');}, function(e) {  console.log('Error', e);});

接着执行

var fileEn;function onFs(fs) {    fs.root.getFile('log.txt', {create: true, exclusive: true},        function(fileEntry) {            // fileEntry.isFile === true            // fileEntry.name == 'log.txt'            // fileEntry.fullPath == '/log.txt'            fileEn=fileEntry;            console.log('FileEntry Name: ' + fileEntry.name);            console.log('FileEntry FullPath: ' + fileEntry.fullPath);            //fileEntry.getMetaData(function(md) {            //    console.log(md.modificationTime.toDateString());            //}, onError);        },        onError    );}//FileError constantsfunction onError(err) {    var msg = 'Error: ';    switch (err.code) {        case FileError.NOT_FOUND_ERR:            msg += 'File or directory not found';            break;        case FileError.SECURITY_ERR:            msg += 'Insecure or disallowed operation';            break;        case FileError.ABORT_ERR:            msg += 'Operation aborted';            break;        case FileError.NOT_READABLE_ERR:            msg += 'File or directory not readable';            break;        case FileError.ENCODING_ERR:            msg += 'Invalid encoding';            break;        case FileError.NO_MODIFICATION_ALLOWED_ERR:            msg += 'Cannot modify file or directory';            break;        case FileError.INVALID_STATE_ERR:            msg += 'Invalid state';            break;        case FileError.SYNTAX_ERR:            msg += 'Invalid line-ending specifier';            break;        case FileError.INVALID_MODIFICATION_ERR:            msg += 'Invalid modification';            break;        case FileError.QUOTA_EXCEEDED_ERR:            msg += 'Storage quota exceeded';            break;        case FileError.TYPE_MISMATCH_ERR:            msg += 'Invalid filetype';            break;        case FileError.PATH_EXISTS_ERR:            msg += 'File or directory already exists at specified path';            break;        default:            msg += 'Unknown Error';            break;    };    console.log(msg);}window.webkitRequestFileSystem(TEMPORARY, 2*1024*1024 /*2MB*/, onFs, onError);

之后执行下列代码和 脚本一

console.dir(fileEn);

运行截图如下：

 

写入文件数据测试

var writeToFile=function(fileEntry) {    // Create a FileWriter object for our FileEntry.    fileEntry.createWriter(function(fileWriter) {      fileWriter.onwrite = function(e) {        console.log('Write completed.');      };      fileWriter.onerror = function(e) {        console.log('Write failed: ' + e.toString());      };      var bb = new WebKitBlobBuilder(); // Create a new Blob on-the-fly.      bb.append('Lorem Ipsum');      fileWriter.write(bb.getBlob('text/plain'));    }, onError);  }

输入 脚本一会发现占用的空间发生变化

 

读取文件

var reader;var readFromFile=function(fileEntry) {    // Obtain the File object representing the FileEntry.    // Use FileReader to read its contents.    fileEntry.file(function(file) {       reader = new FileReader();              reader.readAsText(file); // Read the file as plaintext.       console.log(reader.result);    }, onError);  }

执行查看reader对象情况

console.dir(reader)