服務端為什麼不能直接傳大檔案？跟php.ini裡面的幾個配置有關
upload_max_filesize = 2M //PHP最大能接受的檔案大小post_max_size = 8M //PHP能收到的最大POST值'memory_limit = 128M //記憶體上限max_execution_time = 30 //最大執行時間
當然不能簡單粗暴的把上面幾個值調大，否則伺服器記憶體資源吃光是遲早的問題。
解決思路
好在HTML5開放了新的FILE API，也可以直接操作二進位對象，我們可以直接在瀏覽器端實現檔案切割，按照以前的做法就得用Flash的方案，實現起來會麻煩很多。
JS思路
1.監聽上傳按鈕的onchange事件
2.擷取檔案的FILE對象
3.把檔案的FILE對象進行切割，並且附加到FORMDATA對象中
4.把FORMDATA對象通過AJAX發送到伺服器
5.重複3、4步驟，直到檔案發送完。
PHP思路
1.建立上傳檔案夾
2.把檔案從上傳臨時目錄移動到上傳檔案夾
3.所有的檔案塊上傳完成後，進行檔案合成
4.刪除檔案夾
5.返回上傳後的檔案路徑
DEMO代碼
前端部分代碼
<!doctype html><html lang="en"><head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> <style> #progress{ width: 300px; height: 20px; background-color:#f7f7f7; box-shadow:inset 0 1px 2px rgba(0,0,0,0.1); border-radius:4px; background-image:linear-gradient(to bottom,#f5f5f5,#f9f9f9); } #finish{ background-color: #149bdf; background-image:linear-gradient(45deg,rgba(255,255,255,0.15) 25%,transparent 25%,transparent 50%,rgba(255,255,255,0.15) 50%,rgba(255,255,255,0.15) 75%,transparent 75%,transparent); background-size:40px 40px; height: 100%; } form{ margin-top: 50px; } </style></head><body><p id="progress"> <p id="finish" style="width: 0%;" progress="0"></p></p><form action="./upload.php"> <input type="file" name="file" id="file"> <input type="button" value="停止" id="stop"></form><script> var fileForm = document.getElementById("file"); var stopBtn = document.getElementById('stop'); var upload = new Upload(); fileForm.onchange = function(){ upload.addFileAndSend(this); } stopBtn.onclick = function(){ this.value = "停止中"; upload.stop(); this.value = "已停止"; } function Upload(){ var xhr = new XMLHttpRequest(); var form_data = new FormData(); const LENGTH = 1024 * 1024; var start = 0; var end = start + LENGTH; var blob; var blob_num = 1; var is_stop = 0 //對外方法，傳入檔案對象 this.addFileAndSend = function(that){ var file = that.files[0]; blob = cutFile(file); sendFile(blob,file); blob_num += 1; } //停止檔案上傳 this.stop = function(){ xhr.abort(); is_stop = 1; } //切割檔案 function cutFile(file){ var file_blob = file.slice(start,end); start = end; end = start + LENGTH; return file_blob; }; //傳送檔案 function sendFile(blob,file){ var total_blob_num = Math.ceil(file.size / LENGTH); form_data.append('file',blob); form_data.append('blob_num',blob_num); form_data.append('total_blob_num',total_blob_num); form_data.append('file_name',file.name); xhr.open('POST','./upload.php',false); xhr.onreadystatechange = function () { var progress; var progressObj = document.getElementById('finish'); if(total_blob_num == 1){ progress = '100%'; }else{ progress = Math.min(100,(blob_num/total_blob_num)* 100 ) +'%'; } progressObj.style.width = progress; var t = setTimeout(function(){ if(start < file.size && is_stop === 0){ blob = cutFile(file); sendFile(blob,file); blob_num += 1; }else{ setTimeout(t); } },1000); } xhr.send(form_data); } }</script></body></html>
PHP部分代碼
<?phpclass Upload{ private $filepath = './upload'; //上傳目錄 private $tmpPath; //PHP檔案臨時目錄 private $blobNum; //第幾個檔案塊 private $totalBlobNum; //檔案塊總數 private $fileName; //檔案名稱 public function __construct($tmpPath,$blobNum,$totalBlobNum,$fileName){ $this->tmpPath = $tmpPath; $this->blobNum = $blobNum; $this->totalBlobNum = $totalBlobNum; $this->fileName = $fileName; $this->moveFile(); $this->fileMerge(); } //判斷是否是最後一塊，如果是則進行檔案合成並且刪除檔案塊 private function fileMerge(){ if($this->blobNum == $this->totalBlobNum){ $blob = ''; for($i=1; $i<= $this->totalBlobNum; $i++){ $blob .= file_get_contents($this->filepath.'/'. $this->fileName.'__'.$i); } file_put_contents($this->filepath.'/'. $this->fileName,$blob); $this->deleteFileBlob(); } } //刪除檔案塊 private function deleteFileBlob(){ for($i=1; $i<= $this->totalBlobNum; $i++){ @unlink($this->filepath.'/'. $this->fileName.'__'.$i); } } //移動檔案 private function moveFile(){ $this->touchDir(); $filename = $this->filepath.'/'. $this->fileName.'__'.$this->blobNum; move_uploaded_file($this->tmpPath,$filename); } //API返回資料 public function apiReturn(){ if($this->blobNum == $this->totalBlobNum){ if(file_exists($this->filepath.'/'. $this->fileName)){ $data['code'] = 2; $data['msg'] = 'success'; $data['file_path'] = 'http://'.$_SERVER['HTTP_HOST'].dirname($_SERVER['DOCUMENT_URI']).str_replace('.','',$this->filepath).'/'. $this->fileName; } }else{ if(file_exists($this->filepath.'/'. $this->fileName.'__'.$this->blobNum)){ $data['code'] = 1; $data['msg'] = 'waiting for all'; $data['file_path'] = ''; } } header('Content-type: application/json'); echo json_encode($data); } //建立上傳檔案夾 private function touchDir(){ if(!file_exists($this->filepath)){ return mkdir($this->filepath); } }}//執行個體化並擷取系統變數傳參$upload = new Upload($_FILES['file']['tmp_name'],$_POST['blob_num'],$_POST['total_blob_num'],$_POST['file_name']);//調用方法，返回結果$upload->apiReturn();
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