如何使用 HttpURLConnection 在请求正文中发送数据？答案

【问题标题】：How do you send data in a Request body using HttpURLConnection?如何使用 HttpURLConnection 在请求正文中发送数据？
【发布时间】：2017-11-02 11:21:38
【问题描述】：

我正在使用HttpURLConnection 向本地部署并使用 JAVA Spark 创建的本地服务发出 POST 请求。 当我使用HttpURLConnection 进行 POST 调用时，我想在请求正文中发送一些数据，但每次 JAVA Spark 中的请求正文为空。以下是我为此使用的代码 p>

Java Spark POST 服务处理程序

post("/", (req, res) -> {
    System.out.println("Request Body: " + req.body());
    return "Hello!!!!";
});

HTTPClass 发出 POST 调用

public class HTTPClassExample{
    public static void main(String[] args) {
        try{
            URL url = new URL("http://localhost:4567/");
            HttpURLConnection httpCon = (HttpURLConnection) url.openConnection();
            httpCon.setDoOutput(true);
            httpCon.setRequestMethod("POST");
            httpCon.connect();
            OutputStream os = httpCon.getOutputStream();
            OutputStreamWriter osw = new OutputStreamWriter(os, "UTF-8");    
            osw.write("Just Some Text");
            System.out.println(httpCon.getResponseCode());
            System.out.println(httpCon.getResponseMessage());
            osw.flush();
            osw.close();  
        } catch(Exception ex){
            ex.printStackTrace();
        }
    }
}

【问题讨论】：

标签： java web-services httpurlconnection microservices spark-java

【解决方案1】：

您应该只在将参数写入正文之后而不是之前调用httpCon.connect();。您的代码应如下所示：

URL url = new URL("http://localhost:4567/");
HttpURLConnection httpCon = (HttpURLConnection) url.openConnection();
httpCon.setDoOutput(true);
httpCon.setRequestMethod("POST");
OutputStream os = httpCon.getOutputStream();
OutputStreamWriter osw = new OutputStreamWriter(os, "UTF-8");    
osw.write("Just Some Text");
osw.flush();
osw.close();
os.close();  //don't forget to close the OutputStream
httpCon.connect();

//read the inputstream and print it
String result;
BufferedInputStream bis = new BufferedInputStream(httpCon.getInputStream());
ByteArrayOutputStream buf = new ByteArrayOutputStream();
int result2 = bis.read();
while(result2 != -1) {
    buf.write((byte) result2);
    result2 = bis.read();
}
result = buf.toString();
System.out.println(result);

【讨论】：

看来这不是真的。打电话给getOutputStream 打电话给connect。如果要显式连接，请在getOutputStream 之前调用connect。要测试自己，请禁用您的互联网，当连接失败时，您会看到名为 connect 的 getOutputStream 失败。

【解决方案2】：

我以 XML 格式发布了请求的数据，代码如下所示。您还应该添加请求属性 Accept 和 Content-Type。

URL url = new URL("....");
HttpURLConnection httpConnection = (HttpURLConnection) url.openConnection();

httpConnection.setRequestMethod("POST");
httpConnection.setRequestProperty("Accept", "application/xml");
httpConnection.setRequestProperty("Content-Type", "application/xml");

httpConnection.setDoOutput(true);
OutputStream outStream = httpConnection.getOutputStream();
OutputStreamWriter outStreamWriter = new OutputStreamWriter(outStream, "UTF-8");
outStreamWriter.write(requestedXml);
outStreamWriter.flush();
outStreamWriter.close();
outStream.close();

System.out.println(httpConnection.getResponseCode());
System.out.println(httpConnection.getResponseMessage());

InputStream xml = httpConnection.getInputStream();

【讨论】：