Java 的 HttpURLConnection 不支持 REPORT/PROPFIND - 我该怎么办？

Question

HttpURLConnection 仅支持 GET、POST 和 HEAD - 但不支持 REPORT/PROPFIND。我要实现一个 CalDAV 客户端，但没有这些操作（如果我想使用它们，我会得到一个 ProtocolException）我必须编写/交付一个完整的、巨大的 HTTP 库和 auth 等等。

“矫枉过正”。

如何使用 PROPFIND 和 REPORT 发送请求？

Answer 1

我在 WebDav 上遇到了 PROPFIND 方法的类似问题。

通过实施此解决方案解决了问题： https://java.net/jira/browse/JERSEY-639

    try {
            httpURLConnection.setRequestMethod(method);
        } catch (final ProtocolException pe) {
            try {
                final Class<?> httpURLConnectionClass = httpURLConnection
                        .getClass();
                final Class<?> parentClass = httpURLConnectionClass
                        .getSuperclass();
                final Field methodField;
                // If the implementation class is an HTTPS URL Connection, we
                // need to go up one level higher in the heirarchy to modify the
                // 'method' field.
                if (parentClass == HttpsURLConnection.class) {
                    methodField = parentClass.getSuperclass().getDeclaredField(
                            "method");
                } else {
                    methodField = parentClass.getDeclaredField("method");
                }
                methodField.setAccessible(true);
                methodField.set(httpURLConnection, method);
            } catch (final Exception e) {
                throw new RuntimeException(e);

            }
     }

Answer 2

您可能希望为此查找 WebDAV 库，而不是 HTTP 库。

也许看看Apache Jackrabbit。

Answer 3

你可以使用https://github.com/square/okhttp

示例代码

    // using OkHttp
    public class PropFindExample {        
    private final OkHttpClient client = new OkHttpClient();
    String run(String url) throws IOException {
        String credential = Credentials.basic(userName, password);
        // body
        String body = "<d:propfind xmlns:d=\"DAV:\" xmlns:cs=\"http://calendarserver.org/ns/\">\n" +
                "  <d:prop>\n" +
                "     <d:displayname />\n" +
                "     <d:getetag />\n" +
                "  </d:prop>\n" +
                "</d:propfind>";
        Request request = new Request.Builder()
                .url(url)
                .method("PROPFIND", RequestBody.create(MediaType.parse(body), body))
                .header("DEPTH", "1")
                .header("Authorization", credential)
                .header("Content-Type", "text/xml")
                .build();

        Response response = client.newCall(request).execute();
        return response.body().string();
    }
 }

或者玩 Sockets

示例代码

String host = "example.com";
int port = 443;
String path = "/placeholder";
String userName = "username";
String password = "password";

SSLSocketFactory ssf = (SSLSocketFactory) SSLSocketFactory.getDefault();
Socket socket = ssf.createSocket(host, port);
PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())));

// xml data to be sent in body
String xmlData = "<?xml version=\"1.0\"?> <d:propfind xmlns:d=\"DAV:\" xmlns:cs=\"http://calendarserver.org/ns/\"> <d:prop> <d:displayname /> <d:getetag /> </d:prop> </d:propfind>";
// append headers
out.println("PROPFIND path HTTP/1.1");
out.println("Host: "+host);
String userCredentials = username+":"+password;
String basicAuth = "Basic " + new String(Base64.encode(userCredentials.getBytes(), Base64.DEFAULT));
String authorization = "Authorization: " + basicAuth;
out.println(authorization.trim());
out.println("Content-Length: "+ xmlData.length());
out.println("Content-Type: text/xml");
out.println("Depth: 1");
out.println();
// append body
out.println(xmlData);
out.flush();

// get response
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String inputLine;

System.out.println("--------------------------------------------------------");
System.out.println("---------------Printing response--------------------------");
System.out.println("--------------------------------------------------------");
while ((inputLine = in.readLine()) != null) {
    System.out.println(inputLine);
}

in.close();

Answer 4

您可以尝试使用另一个 HTTP 库，例如 Apache HTTP client 并扩展其 HttpRequestBase（例如，参见 HttpGet 和 HttpPost）。

或者，您可以直接使用 WebDAV 客户端库。

Answer 5

考虑使用Caldav4j

它支持：

• 轻松生成报告请求
• 基于httpclient 3.0
• 安卓应用
• 目前正在迁移到jackrabbit

Answer 6

private static void setRequestMethod(HttpURLConnection conn, String method) throws Throwable {
    try {
        conn.setRequestMethod(method);
    } catch (ProtocolException e) {
        Class<?> c = conn.getClass();
        Field methodField = null;
        Field delegateField = null;
        try {
            delegateField = c.getDeclaredField("delegate");
        } catch (NoSuchFieldException nsfe) {

        }
        while (c != null && methodField == null) {
            try {
                methodField = c.getDeclaredField("method");
            } catch (NoSuchFieldException nsfe) {

            }
            if (methodField == null) {
                c = c.getSuperclass();
            }
        }
        if (methodField != null) {
            methodField.setAccessible(true);
            methodField.set(conn, method);
        }

        if (delegateField != null) {
            delegateField.setAccessible(true);
            HttpURLConnection delegate = (HttpURLConnection) delegateField.get(conn);
            setRequestMethod(delegate, method);
        }
    }
}

Answer 7

"方法PROPFIND不能有请求体。执行此代码时发生此异常。"

Answer 8

"方法PROPFIND不能有请求体。执行上面示例代码3的代码时会发生此异常。