使用 HttpURLConnection 设置自定义 header

Question

我只是使用 HttpURLConnection.

向 Rest API 发出 GET 请求

我需要添加一些自定义 headers 但我在尝试检索它们的值时得到 null。

代码：

URL url;
try {
    url = new URL("http://www.example.com/rest/");
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();

    // Set Headers
    conn.setRequestProperty("CustomHeader", "someValue");
    conn.setRequestProperty("accept", "application/json");

    // Output is null here <--------
    System.out.println(conn.getHeaderField("CustomHeader"));

    // Request not successful
    if (conn.getResponseCode() != HttpURLConnection.HTTP_OK) {
        throw new RuntimeException("Request Failed. HTTP Error Code: " + conn.getResponseCode());
    }

    // Read response
    BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
    StringBuffer jsonString = new StringBuffer();
    String line;
    while ((line = br.readLine()) != null) {
        jsonString.append(line);
    }
    br.close();
    conn.disconnect();
} catch (IOException e) {
    e.printStackTrace();
}

我错过了什么？

Answer 1

conn.getHeaderField("CustomHeader")return是响应header不是请求。

对return请求header使用：conn.getRequestProperty("CustomHeader")

Answer 2

发送是个好主意

conn.setRequestProperty("Content-Type", "application/json");
conn.setRequestProperty("CustomHeader", token);

而不是

// Set Headers
conn.setRequestProperty("CustomHeader", "someValue");
conn.setRequestProperty("accept", "application/json");

类型值和 header 都应该更改。它适用于我的情况。

使用 HttpURLConnection 设置自定义 header

Setting custom header using HttpURLConnection

java

rest

urlconnection

httpurlconnection

http-headers