java成神之——HttpURLConnection访问api

Posted 2021-01-11 叶家伟的博客

• HttpURLConnection
  • 访问get资源
  • 访问post资源
  • 访问Delete资源
  • 获取状态码
• 结语

HttpURLConnection

访问get资源

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();

访问post资源

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传递的数据".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();

访问Delete资源

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();

获取状态码

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

结语

本文章是java成神的系列文章之一

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