Java 如何 取得http 網頁的 檔頭
How to get HTTP Response Header in Java
By mkyongmkyong | March 10, 2013 | Updated : January 8, 2014
This example shows you how to get the Http response header values in Java.
1. Standard JDK example.
URL obj = new URL("http://mkyong.com");
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 example.
HttpClient client = HttpClientBuilder.create().build();
HttpGet request = new HttpGet("http://mkyong.com");
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 Example
See a full example to get response headers value via URLConnection.
ResponseHeaderUtil.java
package com.mkyong;
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("http://mkyong.com");
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();
}
}
}
其他
Not quite sure what you really want to do. But to see what is posted to the server you would have to post it to your own and read the data you receive there.
If you want to see all the REQUEST headers you could:
for (String header : conn.getRequestProperties().keySet()) {
if (header != null) {
for (String value : conn.getRequestProperties().get(header)) {
System.out.println(header + ":" + value);
}
}
}
Or after connecting you can print out the RESPONSE headers:
for (String header : conn.getHeaderFields().keySet()) {
if (header != null) {
for (String value : conn.getHeaderFields().get(header)) {
System.out.println(header + ":" + value);
}
}
}
21個範例
/**
Copyright (C) 2004 Juho Vh-Herttua
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
import java.io.*;
import java.util.*;
import java.text.*;
import java.net.URLDecoder;
public class HttpParser {
private static final String[][] HttpReplies = {{"100", "Continue"},
{"101", "Switching Protocols"},
{"200", "OK"},
{"201", "Created"},
{"202", "Accepted"},
{"203", "Non-Authoritative Information"},
{"204", "No Content"},
{"205", "Reset Content"},
{"206", "Partial Content"},
{"300", "Multiple Choices"},
{"301", "Moved Permanently"},
{"302", "Found"},
{"303", "See Other"},
{"304", "Not Modified"},
{"305", "Use Proxy"},
{"306", "(Unused)"},
{"307", "Temporary Redirect"},
{"400", "Bad Request"},
{"401", "Unauthorized"},
{"402", "Payment Required"},
{"403", "Forbidden"},
{"404", "Not Found"},
{"405", "Method Not Allowed"},
{"406", "Not Acceptable"},
{"407", "Proxy Authentication Required"},
{"408", "Request Timeout"},
{"409", "Conflict"},
{"410", "Gone"},
{"411", "Length Required"},
{"412", "Precondition Failed"},
{"413", "Request Entity Too Large"},
{"414", "Request-URI Too Long"},
{"415", "Unsupported Media Type"},
{"416", "Requested Range Not Satisfiable"},
{"417", "Expectation Failed"},
{"500", "Internal Server Error"},
{"501", "Not Implemented"},
{"502", "Bad Gateway"},
{"503", "Service Unavailable"},
{"504", "Gateway Timeout"},
{"505", "HTTP Version Not Supported"}};
private BufferedReader reader;
private String method, url;
private Hashtable headers, params;
private int[] ver;
public HttpParser(InputStream is) {
reader = new BufferedReader(new InputStreamReader(is));
method = "";
url = "";
headers = new Hashtable();
params = new Hashtable();
ver = new int[2];
}
public int parseRequest() throws IOException {
String initial, prms[], cmd[], temp[];
int ret, idx, i;
ret = 200; // default is OK now
initial = reader.readLine();
if (initial == null || initial.length() == 0) return 0;
if (Character.isWhitespace(initial.charAt(0))) {
// starting whitespace, return bad request
return 400;
}
cmd = initial.split("\\s");
if (cmd.length != 3) {
return 400;
}
if (cmd[2].indexOf("HTTP/") == 0 && cmd[2].indexOf('.') > 5) {
temp = cmd[2].substring(5).split("\\.");
try {
ver[0] = Integer.parseInt(temp[0]);
ver[1] = Integer.parseInt(temp[1]);
} catch (NumberFormatException nfe) {
ret = 400;
}
}
else ret = 400;
if (cmd[0].equals("GET") || cmd[0].equals("HEAD")) {
method = cmd[0];
idx = cmd[1].indexOf('?');
if (idx < 0) url = cmd[1];
else {
url = URLDecoder.decode(cmd[1].substring(0, idx), "ISO-8859-1");
prms = cmd[1].substring(idx+1).split("&");
params = new Hashtable();
for (i=0; i
temp = prms[i].split("=");
if (temp.length == 2) {
// we use ISO-8859-1 as temporary charset and then
// String.getBytes("ISO-8859-1") to get the data
params.put(URLDecoder.decode(temp[0], "ISO-8859-1"),
URLDecoder.decode(temp[1], "ISO-8859-1"));
}
else if(temp.length == 1 && prms[i].indexOf('=') == prms[i].length()-1) {
// handle empty string separatedly
params.put(URLDecoder.decode(temp[0], "ISO-8859-1"), "");
}
}
}
parseHeaders();
if (headers == null) ret = 400;
}
else if (cmd[0].equals("POST")) {
ret = 501; // not implemented
}
else if (ver[0] == 1 && ver[1] >= 1) {
if (cmd[0].equals("OPTIONS") ||
cmd[0].equals("PUT") ||
cmd[0].equals("DELETE") ||
cmd[0].equals("TRACE") ||
cmd[0].equals("CONNECT")) {
ret = 501; // not implemented
}
}
else {
// meh not understand, bad request
ret = 400;
}
if (ver[0] == 1 && ver[1] >= 1 && getHeader("Host") == null) {
ret = 400;
}
return ret;
}
private void parseHeaders() throws IOException {
String line;
int idx;
// that fscking rfc822 allows multiple lines, we don't care now
line = reader.readLine();
while (!line.equals("")) {
idx = line.indexOf(':');
if (idx < 0) {
headers = null;
break;
}
else {
headers.put(line.substring(0, idx).toLowerCase(), line.substring(idx+1).trim());
}
line = reader.readLine();
}
}
public String getMethod() {
return method;
}
public String getHeader(String key) {
if (headers != null)
return (String) headers.get(key.toLowerCase());
else return null;
}
public Hashtable getHeaders() {
return headers;
}
public String getRequestURL() {
return url;
}
public String getParam(String key) {
return (String) params.get(key);
}
public Hashtable getParams() {
return params;
}
public String getVersion() {
return ver[0] + "." + ver[1];
}
public int compareVersion(int major, int minor) {
if (major < ver[0]) return -1;
else if (major > ver[0]) return 1;
else if (minor < ver[1]) return -1;
else if (minor > ver[1]) return 1;
else return 0;
}
public static String getHttpReply(int codevalue) {
String key, ret;
int i;
ret = null;
key = "" + codevalue;
for (i=0; i
if (HttpReplies[i][0].equals(key)) {
ret = codevalue + " " + HttpReplies[i][1];
break;
}
}
return ret;
}
public static String getDateHeader() {
SimpleDateFormat format;
String ret;
format = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss", Locale.US);
format.setTimeZone(TimeZone.getTimeZone("GMT"));
ret = "Date: " + format.format(new Date()) + " GMT";
return ret;
}
}
