JavaでHTTP応答ヘッダーを取得する方法
この例は、JavaでHttp応答ヘッダー値を取得する方法を示しています。
1. 標準JDKの例。
URL obj = new URL("/");
URLConnection conn = obj.openConnection();
//get all headers
Map> map = conn.getHeaderFields();
for (Map.Entry> entry : map.entrySet()) {
System.out.println("Key : " + entry.getKey() +
" ,Value : " + entry.getValue());
}
//get header by 'key'
String server = conn.getHeaderField("Server");
2. Apache HttpClientの例。
HttpClient client = HttpClientBuilder.create().build();
HttpGet request = new HttpGet("/");
HttpResponse response = client.execute(request);
//get all headers
Header[] headers = response.getAllHeaders();
for (Header header : headers) {
System.out.println("Key : " + header.getName()
+ " ,Value : " + header.getValue());
}
//get header by 'key'
String server = response.getFirstHeader("Server").getValue();
1. URLConnectionの例
URLConnectionを介して応答ヘッダー値を取得する完全な例を参照してください。
ResponseHeaderUtil.java
package com.example;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;
public class ResponseHeaderUtil {
public static void main(String[] args) {
try {
URL obj = new URL("/");
URLConnection conn = obj.openConnection();
Map> map = conn.getHeaderFields();
System.out.println("Printing Response Header...\n");
for (Map.Entry> entry : map.entrySet()) {
System.out.println("Key : " + entry.getKey()
+ " ,Value : " + entry.getValue());
}
System.out.println("\nGet Response Header By Key ...\n");
String server = conn.getHeaderField("Server");
if (server == null) {
System.out.println("Key 'Server' is not found!");
} else {
System.out.println("Server - " + server);
}
System.out.println("\n Done");
} catch (Exception e) {
e.printStackTrace();
}
}
}
出力
Printing Response Header... Key : null ,Value : [HTTP/1.1 200 OK] Key : ETag ,Value : ["713cd-9b82-4dd6d789447c0"] Key : Content-Length ,Value : [39810] Key : Expires ,Value : [Fri, 24 May 2013 03:22:31 GMT] Key : Last-Modified ,Value : [Fri, 24 May 2013 02:22:31 GMT] Key : Connection ,Value : [Keep-Alive] Key : X-Powered-By ,Value : [W3 Total Cache/0.9.2.9] Key : Server ,Value : [Apache/2.2.22 (Unix) mod_ssl/2.2.22 OpenSSL/1.0.0-fips mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635] Key : Pragma ,Value : [public] Key : Cache-Control ,Value : [public] Key : Date ,Value : [Fri, 24 May 2013 02:22:37 GMT] Key : Vary ,Value : [Accept-Encoding,Cookie] Key : Keep-Alive ,Value : [timeout=2, max=100] Key : Content-Type ,Value : [text/html] Key : Accept-Ranges ,Value : [bytes] Get Response Header By Key ... Server - Apache/2.2.22 (Unix) mod_ssl/2.2.22 OpenSSL/1.0.0-fips mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635 Done
2. Apache HttpClientの例
これは同等の例ですが、Apache HttpClientを使用しています。
ResponseHeaderUtil.java
package com.example;
import org.apache.http.Header;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.HttpClientBuilder;
public class ResponseHeaderUtil {
public static void main(String[] args) {
try {
HttpClient client = HttpClientBuilder.create().build();
HttpGet request = new HttpGet("/");
HttpResponse response = client.execute(request);
System.out.println("Printing Response Header...\n");
Header[] headers = response.getAllHeaders();
for (Header header : headers) {
System.out.println("Key : " + header.getName()
+ " ,Value : " + header.getValue());
}
System.out.println("\nGet Response Header By Key ...\n");
String server = response.getFirstHeader("Server").getValue();
if (server == null) {
System.out.println("Key 'Server' is not found!");
} else {
System.out.println("Server - " + server);
}
System.out.println("\n Done");
} catch (Exception e) {
e.printStackTrace();
}
}
}