使用HttpURLConnection连接http服务器，如何判断是否连接成功

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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;public class HttpURLConnectionTest {
public static void testConnect(String surl) throws IOException {
URL url = new URL(surl);
String userInfo = url.getUserInfo();
if (userInfo != null && userInfo.length() > 0) {
String string = surl.replace(userInfo, "");
url = new URL(string);
}
HttpURLConnection connection = (HttpURLConnection) url.openConnection(); if (userInfo != null && userInfo.length() > 0)
connection.setRequestProperty("Authorization", userInfo);
connection.connect();
System.out.println(connection.getResponseCode());//如果hhtp服务器不需要验证，输出200 }
public static void testConnect2(String surl) throws IOException {
URL url = new URL(surl);
String userInfo = url.getUserInfo();
if (userInfo != null && userInfo.length() > 0) {
String string = surl.replace(userInfo, "");
url = new URL(string);
}
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
StringBuffer sb = new StringBuffer();
sb.append("userName=" + "aaa");
sb.append("&password=" + "bbb");
//post信息
OutputStream os = connection.getOutputStream();
os.write(sb.toString().getBytes("GBK"));
os.close();
connection.connect();
System.out.println(connection.getResponseCode());//如果hhtp服务器需要验证时，输出401 }
public static void main(String args[]) throws IOException {
String url = "http://192.9.168.11:1122/";
testConnect(url);
//testConnect2(url);

}}如果没有密码时输出200，有密码时输出401，如何发送用户名和密码？

如果hhtp服务器需要验证时，输出401
改正：如果http服务器需要验证时，输出401

HttpURLConnection是如何发送用户名和密码的？

可以将用户名和密码写在URL中，用username= &password=

HttpURLConnection.HTTP_OK==httpConn.getResponseCode();
它们相等，就是成功连接！

试了"http://username=aa&[email protected]:1122/";不行，输出401

HttpURLConnection.HTTP_OK==httpConn.getResponseCode();
它们相等，就是成功连接！

这只是检测url和端口是否正确，如果有用户名和密码的如何连接，即如何发送用户名和密码？

调用connect方法，没有捕获到异常就是连接上了

这里再说明一下，可以参考一下7楼的代码，对于Http服务器(IIS或者Apache等)，如果url和端口正确，都会返回200，也就是说不管Http服务器是否需要用户认证，只要是http://url:端口正确，返回码都会是200.

因此想请教一下如果http服务器需要认证的，如何传递认证信息（用户名和密码），除了返回200，还会返回什么有用的信息（与不需要认证的区别信息）？

public static boolean isConnectedUrl(String url) {
HttpURLConnection con;
try {
HttpURLConnection.setFollowRedirects(false);
con = (HttpURLConnection) new URL(url)
.openConnection();
con.setRequestMethod("HEAD");
System.out.println("state code:" + con.getResponseCode());
if (con.getResponseCode() == HttpURLConnection.HTTP_OK) {
return true;
}
} catch (MalformedURLException e) {
e.printStackTrace();
return false;
} catch (IOException e) {
e.printStackTrace();
return false;
}
return false;
}

谢谢，这个方法用过，对于需要认证的Http服务器url格式是怎么样的？比如http://192.168.200.9:8002,用户名和密码为user/paswwd,试过这样的http://user:[email protected]:8002,但是返回了401，连接失败。不知道如何发送认证信息。

可以看下这个：
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.Authenticator;
import java.net.InetAddress;
import java.net.PasswordAuthentication;
import java.net.URL;public class Test {
  public static void main(String[] argv) throws Exception {
    Authenticator.setDefault(new MyAuthenticator());
    URL url = new URL("http://hostname:80/index.html");    BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
    String str;
    while ((str = in.readLine()) != null) {
      System.out.println(str);
    }
    in.close();
  }
}class MyAuthenticator extends Authenticator {

  protected PasswordAuthentication getPasswordAuthentication() {
    String promptString = getRequestingPrompt();
    System.out.println(promptString);
    String hostname = getRequestingHost();
    System.out.println(hostname);
    InetAddress ipaddr = getRequestingSite();
    System.out.println(ipaddr);
    int port = getRequestingPort();    String username = "name";
    String password = "password";
    return new PasswordAuthentication(username, password.toCharArray());
  }
}

这个可以，稍微修改一下就行，还有需要设置一下流的字符编码，html中带有汉字的连接显示乱码，因此需要根据不同的页面设置编码。import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.Authenticator;
import java.net.InetAddress;
import java.net.PasswordAuthentication;
import java.net.URL;
/**
* TODO javadoc for http.AuthenticatorTest
*
* @author wanghan
*/
public class AuthenticatorTest {
public static void main(String[] argv) throws Exception {
    Authenticator.setDefault(new MyAuthenticator("user","passwd"));
    URL url = new URL("http://192.168.200.10：8002");     BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream(),"UTF-8"));//这里根据服务器编码设置
    String str;
    while ((str = in.readLine()) != null) {
      System.out.println(str);
    }
    in.close();
  }
}
class MyAuthenticator extends Authenticator {
private String name;
private String passwd;
public MyAuthenticator(String name,String passwd){
this.name = name;
this.passwd = passwd;
}

  protected PasswordAuthentication getPasswordAuthentication() {
    String promptString = getRequestingPrompt();
    System.out.println(promptString);
    String hostname = getRequestingHost();
    System.out.println(hostname);
    InetAddress ipaddr = getRequestingSite();
    System.out.println(ipaddr);
    //int port = getRequestingPort();     String username = name;
    String password = passwd;
    return new PasswordAuthentication(username, password.toCharArray());
  }
}

谢谢35楼，用35楼的方法可以通过认证，我之前用HttpClient 认证一直没有成功。

System.out.println("state code:" + con.getResponseCode());
我这里直接出错。没打印出来

调试易

使用HttpURLConnection连接http服务器，如何判断是否连接成功

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