如何在 javascript/jquery 中发出 ajax 请求

Posted 2023-03-14

【中文标题】如何在 javascript/jquery 中发出 ajax 请求

【英文标题】：how to make a ajax request in javascript/jquery

【发布时间】：2014-03-27 04:59:59

【问题描述】：

我是 javascript 和 jQuery 的新手。我想将图像发送到 RTTI 服务器。我在本机 ios 中完成了相同的任务，如下所示。

NSData *checkData = [NSData dataWithBytes:[self getImageFileBuffer]length:self.imageFileBufferSize];
NSString *extractionURLString = [[NSUserDefaults standardUserDefaults] valueForKey:@"serverAddress"];
NSURL *checkExtractionServerURL = [NSURL URLWithString:[NSString stringWithFormat:@"%@/mobilesdk/api/CheckDeposit",extractionURLString]];<br/>
NSMutableURLRequest  *urlRequest = [NSMutableURLRequest requestWithURL:checkExtractionServerURL cachePolicy:NSURLRequestReloadRevalidatingCacheData timeoutInterval:30];
[urlRequest setHTTPMethod:@"PUT"];
[urlRequest setValue:@"application/json" forHTTPHeaderField:@"Accept"];
[urlRequest setValue:@"image/tiff" forHTTPHeaderField:@"Content-Type"];
[urlRequest setHTTPBody:checkData];<br/>
NSURLConnection *checkConn = [[NSURLConnection alloc] initWithRequest:urlRequest delegate:self startImmediately:NO];
[checkConn scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
[checkConn start];

我必须在 JavaScript/jQuery 中完成上述任务。我尝试了很多，但没有得到解决方案。我的 JavaScript 代码如下。

var xhr4 = new XMLHttpRequest();
xhr4.open("POST", URL4, true);
xhr4.setRequestHeader('Content-Type', 'image/tiff');
xhr4.setRequestHeader('Accept','application/json');
xhr4.setRequestHeader('Content-Length',imageObjectData.length);
xhr4.onload = function (e4) 
    alert(e4.target.responseText);
;
xhr4.send(imageObjectData);

请任何人帮助我。 提前致谢。

【参考方案1】：

使用onreadystatechange 代替onload 之类的，

var xhr4 = new XMLHttpRequest();
xhr4.open("POST", URL4, true);
xhr4.setRequestHeader('Content-Type', 'image/tiff'); 
xhr4.setRequestHeader('Accept','application/json');
xhr4.setRequestHeader('Content-Length',imageObjectData.length);
xhr4.onreadystatechange = function ()  // use onreadystatechange 
     alert(xh4.responseText); // use xh4.responseText
;
xhr4.send(imageObjectData);

【参考方案2】：

使用beforeSend 设置jquery Ajax 中的标头。

$.ajax(
        beforeSend: function(xhrObj)
                xhrObj.setRequestHeader("Content-Type","image/tiff");
                xhrObj.setRequestHeader("Accept","application/json");
        
        type: "PUT",
        url: URL4,
        processData: false,
        data: jsonData,
        dataType: "json",
        success: function(json)
               // do something with response `json`...
        
);