cURL和HttpURLConnection - 发送JSON数据

Question

如何使用HttpURLConnection发布JSON数据？我正在尝试以下内容：

HttpURLConnection httpcon = (HttpURLConnection) ((new URL("a url").openConnection()));
httpcon.setDoOutput(true);
httpcon.setRequestProperty("Content-Type", "application/json");
httpcon.setRequestProperty("Accept", "application/json");
httpcon.setRequestMethod("POST");
httpcon.connect();

StringReader reader = new StringReader("{'value': 7.5}");
OutputStream os = httpcon.getOutputStream();

char[] buffer = new char[4096];
int bytes_read;    
while((bytes_read = reader.read(buffer)) != -1) {
    os.write(buffer, 0, bytes_read);// I am getting compilation error here
}
os.close();

我在第14行遇到编译错误。

cURL请求如下：

curl -H "Accept: application/json" \
-H "Content-Type: application/json" \
-d "{'value': 7.5}" \
"a URL"

这是处理cURL请求的正确方式吗？任何信息对我都非常有帮助。

谢谢。

- Tapas Bose

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你应该发布编译错误。 - ykaganovich

Answer 1

OutputStream期望处理字节，而您正在传递字符。请尝试以下方法：

HttpURLConnection httpcon = (HttpURLConnection) ((new URL("a url").openConnection()));
httpcon.setDoOutput(true);
httpcon.setRequestProperty("Content-Type", "application/json");
httpcon.setRequestProperty("Accept", "application/json");
httpcon.setRequestMethod("POST");
httpcon.connect();

byte[] outputBytes = "{'value': 7.5}".getBytes("UTF-8");
OutputStream os = httpcon.getOutputStream();
os.write(outputBytes);

os.close();

- ykaganovich

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通过这种方式发送复杂的JSON对象不可能吗？例如…“{"points":[{"point":{"latitude":40.8195085182092,"longitude":-73.75127574479318},"description":"test"},{"point":{"latitude":40.2195085182092,"longitude":-74.75127574479318},"description":"test2"}],"mode":"WALKING"}”这是我正在使用的方法发送的对象，但我收到了500的HTTP响应代码。 - crowmagnumb

@CrowMagnumb 你应该发布一个单独的问题。500 表示服务器在处理您的请求时出现内部错误。 - ykaganovich

好的，我已经在这里完成了（http://stackoverflow.com/questions/20452366/http-response-code-500-sending-complex-json-object-using-httpurlconnection）感谢您的建议。 - crowmagnumb

Answer 2

您可能需要使用OutputStreamWriter类。

final String toWriteOut = "{'value': 7.5}";
final OutputStreamWriter osw = new OutputStreamWriter(connection.getOutputStream());
osw.write(toWriteOut);
osw.close();

- Anthony Chuinard

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与OutputStream相比，有什么好处？ - Darpan