filereader

问题 I have a requirement to convert an input image (blob) to base64 image. Im aware the size will increase by approx 1.37. However i have noticed when using the firereader.readAsDataUrl the size of the image is extremely large when compared to the built in base64 command line tool you have on macOS. https://developer.mozilla.org/en-US/docs/Web/API/FileReader/readAsDataURL Steps to reproduce: Download this free sample image https://wall.alphacoders.com/big.php?i=685897 make sure to click the

问题 I have a short JavaScript function which will take an uploaded file and display the hex equivalent of it. Comparing the original file and the output in a hex-editor shows that they are partially different but not completely. String.prototype.hexEncode = function(){ var hex, i; var result = ""; for (i = 0; i < this.length; i++) { hex = this.charCodeAt(i).toString(16); result += ("" + hex).slice(-4); } return result } function upload() { var file = document.getElementById("fileToUpload").files

问题 I have tried solutions from How to use FileReader in React? and gotten the same error as my code. I'm trying to use the FileReader() in a react component. class Home extends Component { onChange(e) { let files = e.target.files; console.log(files); let reader = new FileReader(); reader.readAsDataURL(files[0]); reader.onload = e => { console.log(e.target.result); }; } render() { return ( <div onSubmit={this.onFormSubmit}> <h1>Upload File Here</h1> <input type="file" name="file" onChange={e =>

问题 I am traing to load some images on client browser with this code: function addFiles() var input = document.querySelector("input[type='file']"); var files = input.files; var previewEl = document.getElementById("preview"); for (var i = 0; i < files.length; i++) { if (!files[i].type.match(/image.*/)) { alert("This is not image!"); continue; }; var divEnvelop = document.createElement('div'); divEnvelop.setAttribute('class','imgPrevEnvelop'); divEnvelop.setAttribute('id',"img"+i); previewEl

问题 In my springbatch+quartz setup, I am reading a CSV File using FlatFileItemReader. I want to set the cursor for the reader to start the next jobinstance with the given parameters for reader. Is it possible? <bean id="cvsFileItemReader" class="org.springframework.batch.item.file.FlatFileItemReader" scope="step"> <!-- Read a csv file --> <property name="resource" value="classpath:cvs/input/report.csv" /> <property name="lineMapper"> <bean class="org.springframework.batch.item.file.mapping

问题 I have a function that is loading a user selected file using the Javascript File API, but I want to limit the type of file that can be loaded. Is this possible and how do I go about doing it? So for example, I only want the user to be able to load a DAT file. Here's my function loading the file. function readFile(file){ var reader = new FileReader(); var holder; var holderArray = []; var fileArray = []; reader.readAsText(file, "UTF-8"); reader.onload = function(){ file = reader.result; file =

问题 I am using the HTML5 File API & FileReader. HTML: <div id="holder"></div> JS: <script> var holder = document.getElementById('holder'), state = document.getElementById('status'); if (typeof window.FileReader === 'undefined') { state.className = 'fail'; } else { state.className = 'success'; state.innerHTML = 'File API & FileReader available'; } holder.ondragover = function () { this.className = 'hover'; return false; }; holder.ondragend = function () { this.className = ''; return false; };

问题 I have a fixed length file and would like to read its data into class objects. These objects will be further used to insert/update data in Database. Although it can be done with StreamReader, I am looking for a more sophisticated solution. FileHelper is another solution but I do not want to use an open source code in my program. Is there any other option? In the below link, one user has answered this similar question but it is not elaborated: https://codereview.stackexchange.com/questions

问题 This prints base64 out to console: function getBase64(file) { var reader = new FileReader(); reader.readAsDataURL(file); reader.onload = function() { console.log(reader.result); }; reader.onerror = function(error) { console.log('Error: ', error); }; } var file = document.querySelector('#files > input[type="file"]').files[0]; getBase64(file); // prints the base64 string Source: https://stackoverflow.com/a/36281449/1063287 jsFiddle: jsFiddle demo of the above working code I want to be able to

问题 I have 40 MB file in server and i am downloading my file using HttpURLConnection c = (HttpURLConnection) u.openConnection(); c.setRequestMethod("GET"); c.setDoOutput(true); c.connect(); FileOutputStream f = new FileOutputStream(new File("trips.xml")); InputStream in = c.getInputStream(); byte[] buffer = new byte[1024]; int len1 = 0; while ( (len1 = in.read(buffer)) != -1 ) { f.write(buffer,0, len1); this code seems working fine but it is taking too long. is their any way I can make this