5
誰能解釋如下:HTTP與請求體刪除發出
package com.foo.bar;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.ProtocolException;
import java.net.URL;
import org.springframework.util.FileCopyUtils;
public class ATest {
public static void main(String[] args) throws Exception {
try {
final String payload = "{\"parentExecutor\":\"foo1233\"}";
URL url = new URL("http://localhost/notes");
final HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("DELETE");
connection.setRequestProperty("Accept", "application/json");
connection.setRequestProperty("Content-Type", "application/json");
FileCopyUtils.copy(payload.getBytes(), connection.getOutputStream());
connection.connect();
final InputStream is = connection.getInputStream();
int b = is.read();
String result = "";
while (b != -1) {
result += (char) b;
b = is.read();
}
System.out.println(connection.getResponseCode());
System.out.println(result);
is.close();
}
catch (final ProtocolException e) {
e.printStackTrace();
}
}
}
上面的例子拋出以下異常:
java.net.ProtocolException: cannot write to a URLConnection if doOutput=false - call setDoOutput(true)
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:995)
at com.foo.bar.ATest.main(ATest.java:24)
但是,如果我添加了一個調用setDoOutput(真) ,拋出以下例外:
java.net.ProtocolException: HTTP method DELETE doesn't support output
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1004)
at com.foo.bar.ATest.main(ATest.java:25)
那麼,如果我改變e從http到https的協議不會引發任何異常,並且從服務器獲取預期的響應代碼和內容。我查看了源代碼並可以跟蹤調用並跟蹤發生異常的位置,但爲什麼可以通過HTTPS而不是HTTP來發出此類請求?