Question

如何在脚本中等待上传完成后再继续上传下一个文件？

我搜索了互联网，但只有setTimeout功能，等等！我的代码在这里：

function post(id){
   var formdata = new FormData();
   var id = f+1;
   var file = _("filestyle-"+id).files[0];
   formdata.append("file"+id, file);
   var title = _("title"+id).value;
   formdata.append("title"+id, title);
   document.getElementById("uploadname").innerHTML=title+"is uploading<br>";
   var ajax = new XMLHttpRequest();
   ajax.upload.addEventListener("progress", progressHandler, false);
   ajax.addEventListener("load", completeHandler, false);
   ajax.addEventListener("error", errorHandler, false);
   ajax.addEventListener("abort", abortHandler, false);
   ajax.open("POST", "../swupload.php");
   ajax.send(formdata);
}

在ajax.send(formdata);之后添加此代码：

ajax.onreadystatechange = function() {
    if (ajax.readyState==4 && ajax.status==200 && id < 4) {
        post(id + 1);
    }
}

不显示completHandler中的.target.responseText completeHandler：

function completeHandler(event){
     _("progressBar").innerHTML = event.target.responseText;
}

Answer 1

您可以将您想要在ajax请求的不同阶段执行的代码设置为： -

readyState保存XMLHttpRequest的状态。从0到4的变化：

0：请求未初始化
1：建立服务器连接
2：收到请求
3：处理请求
4：请求完成且响应准备就绪

但是，在您的情况下，您希望在完成上传后执行代码，可能会达到以下目的：

ajax.onreadystatechange=function()
{
     if (ajax.readyState==4 && ajax.status==200)
     {
          // code to execute after upload
     }
}

Answer 2

Ajax是异步的，因此您不能指望其他代码等待它。你可以做的是用一个函数替换你的循环，并从你的@Override public View onCreateView( LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.splash, container, false); //Initialize facebook FacebookSdk.sdkInitialize(getApplicationContext()); loginButton = (Button) view.findViewById(R.id.login_button); loginButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { //Login with facebook on clicking custom button LoginManager.getInstance().logInWithReadPermissions(this, Arrays.asList("public_profile", "user_friends")); } }); //Register a callback callbackManager = CallbackManager.Factory.create(); LoginManager.getInstance().registerCallback(callbackManager, new FacebookCallback<LoginResult>() { @Override public void onSuccess(LoginResult loginResult) { // login successful } @Override public void onCancel() { // login cancelled } @Override public void onError(FacebookException exception) { // login error } }); } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); callbackManager.onActivityResult(requestCode, resultCode, data); }回调中调用它。

completeHandler

如果必须在此函数范围之外定义post(1); function post(id) { var formdata = new FormData(); var file = _("filestyle-"+id).files[0]; formdata.append("file"+id, file); var title = _("title"+id).value; formdata.append("title"+id, title); document.getElementById("uploadname").innerHTML=title+"is uploading<br>"; var ajax = new XMLHttpRequest(); ajax.upload.addEventListener("progress", progressHandler, false); ajax.addEventListener("load", completeHandler, false); ajax.addEventListener("error", errorHandler, false); ajax.addEventListener("abort", abortHandler, false); ajax.open("POST", "../swupload.php"); ajax.send(formdata); function completeHandler() { if (id < 5) post(id + 1); } }，请保留id，如下所示：

completeHandler

ajax.id = id;

等到上传完成后再继续脚本

2 个答案: