我正在尝试向网站发出 POST 请求。作为对 POST 请求的响应，我需要一些 JSON 数据。
使用 Apache 的 HttpClient 库，我可以毫无问题地执行此操作。响应数据是 JSON，所以我只是解析它。
package com.mydomain.myapp;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
public class MyApp {
private static String extract(String patternString, String target) {
Pattern pattern = Pattern.compile(patternString);
Matcher matcher = pattern.matcher(target);
matcher.find();
return matcher.group(1);
}
private String getResponse(InputStream stream) throws Exception {
BufferedReader in = new BufferedReader(new InputStreamReader(stream));
String inputLine;
StringBuffer responseStringBuffer = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
responseStringBuffer.append(inputLine);
}
in.close();
return responseStringBuffer.toString();
}
private final static String BASE_URL = "https://www.volkswagen-car-net.com";
private final static String BASE_GUEST_URL = "/portal/en_GB/web/guest/home";
private void run() throws Exception {
CloseableHttpClient client = HttpClients.createDefault();
HttpGet httpGet = new HttpGet(BASE_URL + BASE_GUEST_URL);
CloseableHttpResponse getResponse = client.execute(httpGet);
HttpEntity responseEntity = getResponse.getEntity();
String data = getResponse(responseEntity.getContent());
EntityUtils.consume(responseEntity);
String csrf = extract("<meta name=\"_csrf\" content=\"(.*)\"/>", data);
System.out.println(csrf);
HttpPost post = new HttpPost(BASE_URL + "/portal/web/guest/home/-/csrftokenhandling/get-login-url");
post.setHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8");
post.setHeader("User-Agent'", "Mozilla/5.0 (Linux; Android 6.0.1; D5803 Build/23.5.A.1.291; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/63.0.3239.111 Mobile Safari/537.36");
post.setHeader("Referer", BASE_URL + "/portal");
post.setHeader("X-CSRF-Token", csrf);
CloseableHttpResponse postResponse = client.execute(post);
HttpEntity postResponseEntity = postResponse.getEntity();
String postData = getResponse(postResponseEntity.getContent());
System.out.println(postData);
EntityUtils.consume(postResponseEntity);
postResponse.close();
}
public static void main(String[] args) throws Exception {
MyApp myApp = new MyApp();
myApp.run();
}
}
但是我不能在我的项目中使用 HttpClient 库。我需要能够对“仅”HttpURLConnection 执行相同的操作。
但是 HttpClient 库有一些我无法理解的魔力。因为使用 HttpURLConnection 对我的 POST 请求的响应只是重定向到不同的网页。
有人能给我指出正确的方向吗？
这是我当前的 HttpURLConnection 尝试:
package com.mydomain.myapp;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class MyApp {
private static String extract(String patternString, String target) {
Pattern pattern = Pattern.compile(patternString);
Matcher matcher = pattern.matcher(target);
matcher.find();
return matcher.group(1);
}
private final static String BASE_URL = "https://www.volkswagen-car-net.com";
private final static String BASE_GUEST_URL = "/portal/en_GB/web/guest/home";
private String getResponse(InputStream stream) throws Exception {
BufferedReader in = new BufferedReader(new InputStreamReader(stream));
String inputLine;
StringBuffer responseStringBuffer = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
responseStringBuffer.append(inputLine);
}
in.close();
return responseStringBuffer.toString();
}
private String getResponse(HttpURLConnection connection) throws Exception {
return getResponse(connection.getInputStream());
}
private void run() throws Exception {
HttpURLConnection getConnection1;
URL url = new URL(BASE_URL + BASE_GUEST_URL);
getConnection1 = (HttpURLConnection) url.openConnection();
getConnection1.setRequestMethod("GET");
if (getConnection1.getResponseCode() != HttpURLConnection.HTTP_OK) {
throw new Exception("Request failed");
}
String response = getResponse(getConnection1);
getConnection1.disconnect();
String csrf = extract("<meta name=\"_csrf\" content=\"(.*)\"/>", response);
System.out.println(csrf);
HttpURLConnection postRequest;
URL url2 = new URL(BASE_URL + "/portal/web/guest/home/-/csrftokenhandling/get-login-url");
postRequest = (HttpURLConnection) url2.openConnection();
postRequest.setDoOutput(true);
postRequest.setRequestMethod("POST");
postRequest.setInstanceFollowRedirects(false);
postRequest.setRequestProperty("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8");
postRequest.setRequestProperty("User-Agent'", "Mozilla/5.0 (Linux; Android 6.0.1; D5803 Build/23.5.A.1.291; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/63.0.3239.111 Mobile Safari/537.36");
postRequest.setRequestProperty("Referer", BASE_URL + "/portal");
postRequest.setRequestProperty("X-CSRF-Token", csrf);
postRequest.disconnect();
}
public static void main(String[] args) throws Exception {
MyApp myApp = new MyApp();
myApp.run();
}
}
最佳答案
感谢优秀的程序员资源，例如MKYong(你知道你之前访问过他的网站 ;-))，我会回顾一下它的要点以防 link永远下降。
要点:
The HttpURLConnection‘s follow redirect is just an indicator, in fact it won’t help you to do the “real” http redirection, you still need to handle it manually.
If a server is redirected from the original URL to another URL, the response code should be 301: Moved Permanently or 302: Temporary Redirect. And you can get the new redirected url by reading the “Location” header of the HTTP response header.For example, access to the normal HTTP twitter website – http://www.twitter.com , it will auto redirect to the HTTPS twitter website – https://www.twitter.com.
示例代码
package com.mkyong.http;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class HttpRedirectExample {
public static void main(String[] args) {
try {
String url = "http://www.twitter.com";
URL obj = new URL(url);
HttpURLConnection conn = (HttpURLConnection) obj.openConnection();
conn.setReadTimeout(5000);
conn.addRequestProperty("Accept-Language", "en-US,en;q=0.8");
conn.addRequestProperty("User-Agent", "Mozilla");
conn.addRequestProperty("Referer", "google.com");
System.out.println("Request URL ... " + url);
boolean redirect = false;
// normally, 3xx is redirect
int status = conn.getResponseCode();
if (status != HttpURLConnection.HTTP_OK) {
if (status == HttpURLConnection.HTTP_MOVED_TEMP
|| status == HttpURLConnection.HTTP_MOVED_PERM
|| status == HttpURLConnection.HTTP_SEE_OTHER)
redirect = true;
}
System.out.println("Response Code ... " + status);
if (redirect) {
// get redirect url from "location" header field
String newUrl = conn.getHeaderField("Location");
// get the cookie if need, for login
String cookies = conn.getHeaderField("Set-Cookie");
// open the new connnection again
conn = (HttpURLConnection) new URL(newUrl).openConnection();
conn.setRequestProperty("Cookie", cookies);
conn.addRequestProperty("Accept-Language", "en-US,en;q=0.8");
conn.addRequestProperty("User-Agent", "Mozilla");
conn.addRequestProperty("Referer", "google.com");
System.out.println("Redirect to URL : " + newUrl);
}
BufferedReader in = new BufferedReader(
new InputStreamReader(conn.getInputStream()));
String inputLine;
StringBuffer html = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
html.append(inputLine);
}
in.close();
System.out.println("URL Content... \n" + html.toString());
System.out.println("Done");
} catch (Exception e) {
e.printStackTrace();
}
}
}
关于java - 如何使用 HttpURLConnection 以与 Apache HttpClient lib 相同的方式发出 POST 请求，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/53091231/