HTML5文件系统API和资料整理

2024-04-27 14:10:37

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HTML5文件系统API和资料整理

　　来着火狐开发网络的官方文档：点我打开；

　　W3C的官方文档: 点我打开；

　　园友的博客: 点我打开；

　　浏览器兼容性，好了就Chrome支持，我刚刚更新的火狐37也不支持， nice，太nice了：

　　如果我们在http://localhost/下使用文件系统api创建了虚拟文件，那么通过一下地址可以访问文件系统：filesystem:http://localhos1/persistent/;

　　如果没有文件系统没有本地文件，那么应该是一个错误界面：

　　就chrome支持本地文件系统，所以兼容完全不用管那么多了，我们先通过 requestFileSystem获取文件句柄，第一个参数为临时文件系统，还是永久文件系统；第二个参数为请求的空间大小；第三个是回调函数；　

            //window.TEMPORARY 是 0 ， window.PERSISTENT是1;            storeType = storeType === 0 ? window.TEMPORARY : window.PERSISTENT;            window.requestFileSystem = window.requestFileSystem || window.webkitRequestFileSystem;            window.requestFileSystem(storeType, 5 * 1024 * 1024, function (fs) {                console.log(fs);//文件系统根目录句柄(root);            }, errorHandler);

　　上面回调函数会返回一个参数fs，这个参数“fs”很重要， fs下面有很多方法，主要是操作文件或者目录：

　　getDirectory是在对象上面的方法，这个主要是处理目录，比如打开目录，或者新建目录：

Parameter	Type	Nullable	Optional	Description
path	`DOMString`	?	?	Either an absolute path or a relative path from this DirectoryEntry to the directory to be looked up or created. It is an error to attempt to create a directory whose immediate parent does not yet exist.
options	`Flags`	?	?	If `create` and `exclusive` are both true and the path already exists, getDirectory MUST fail. If `create` is true, the path doesn't exist, and no other error occurs, getDirectory MUST create and return a corresponding DirectoryEntry. If `create` is not true and the path doesn't exist, getDirectory MUST fail. If `create` is not true and the path exists, but is a file, getDirectory MUST fail. Otherwise, if no other error occurs, getDirectory MUST return a DirectoryEntry corresponding to path.
successCallback	`EntryCallback`	?	?	A callback that is called to return the DirectoryEntry selected or created.
errorCallback	`ErrorCallback`	?	?	A callback that is called when errors happen.

　　getFile这个是获取文件，作用是打开文件或者新建文件；

Parameter	Type	Nullable	Optional	Description
path	`DOMString`	?	?	Either an absolute path or a relative path from this DirectoryEntry to the file to be looked up or created. It is an error to attempt to create a file whose immediate parent does not yet exist.
options	`Flags`	?	?	If `create` and `exclusive` are both true, and the path already exists, getFile MUST fail. If `create` is true, the path doesn't exist, and no other error occurs, getFile MUST create it as a zero-length file and return a corresponding FileEntry. If `create` is not true and the path doesn't exist, getFile MUST fail. If `create` is not true and the path exists, but is a directory, getFile MUST fail. Otherwise, if no other error occurs, getFile MUST return a FileEntry corresponding to path.
successCallback	`EntryCallback`	?	?	A callback that is called to return the File selected or created.
errorCallback	`ErrorCallback`	?	?	A callback that is called when errors happen.

　　　　通过上面的方法，我们就获取到了文件句柄啦，那么可以通过FileReader对象读取文件， 通过Blob对象创建二进制流，把数据保存到文件，以及FileWriter也很重要；

　　　　FileReader的API；

　　　　Blob的API；

　　　　FileWriter的API；

　　通过getFile可以获取到fileEntry对象，fileEntry就是这个文件的对象，我们可以操作文件了哦，方法如下：createWriter，file：

　　通过createWriter这个的回调参数我们可以得到操作这个二进制文件的方法：

　　createWriter

Creates a new FileWriter associated with the file that this FileEntry rePResents.

Parameter	Type	Nullable	Optional	Description
successCallback	`FileWriterCallback`	?	?	A callback that is called with the new FileWriter.
errorCallback	`ErrorCallback`	?	?	A callback that is called when errors happen.