java成神之——HttpURLConnection訪問api

• HttpURLConnection
  • 訪問get資源
  • 訪問post資源
  • 訪問Delete資源
  • 獲取狀態碼
• 結語

HttpURLConnection

訪問get資源

HttpURLConnection connection = (HttpURLConnection)new URL("http://ip/test").openConnection();
int responseCode = connection.getResponseCode();
InputStream inputStream;
if (200 <= responseCode && responseCode <= 299) {
    inputStream = connection.getInputStream();
} else {
    inputStream = connection.getErrorStream();
}
BufferedReader in = new BufferedReader( new InputStreamReader(inputStream));
StringBuilder response = new StringBuilder();
String currentLine;
while ((currentLine = in.readLine()) != null) response.append(currentLine);
in.close();
response.toString();

訪問post資源

HttpURLConnection connection = (HttpURLConnection)new URL("http://ip/test").openConnection();
connection.setRequestProperty("Content-Type", "application/json");
connection.setDoOutput(true);

OutputStream out = connection.getOutputStream();
out.write("post傳遞的數據".getBytes());
out.close();

InputStream in = connection.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
String line = null;
while ((line = reader.readLine()) != null) {
    System.out.println(line);
}
in.close();

if (connection != null) connection.disconnect();
if (out != null) out.close();
if (in != null) in.close();

訪問Delete資源

HttpURLConnection connection = (HttpURLConnection)new URL("http://ip/test").openConnection();
connection.setRequestProperty("Content-Type", "application/json");
connection.setRequestMethod("DELETE");
connection.setDoInput(true);

Map<String, List<String>> map = connection.getHeaderFields();
StringBuilder sb = new StringBuilder();
Iterator<Map.Entry<String, List<String>>> iterator = map.entrySet().iterator();
while(iterator.hasNext()) {
    Map.Entry<String, List<String>> entry = iterator.next();
    sb.append(entry.getKey());
    sb.append('=').append('"');
    sb.append(entry.getValue());
    sb.append('"');
    if(iterator.hasNext()){
        sb.append(',').append(' ');
    }
}
System.out.println(sb.toString());
if (connection != null) connection.disconnect();

獲取狀態碼

HttpURLConnection connection = (HttpURLConnection)new URL("http://ip/test").openConnection();
connection.setRequestMethod("HEAD");
int code = connection.getResponseCode();
connection.disconnect();

結語

本文章是java成神的系列文章之一

如果你想知道，但是本文沒有的，請下方留言

我會第一時間總結出來並發布填充到本文