JAVA Http Basic auth

一、Http Base Auth 方式

当访问一个Http Basic Auth 网站的时候需要提供用户名，密码，否则会返回401 (without authoration)。

Http Basic Authentication认证有2种方式：

1、请求头部Authorization 中添加用户名/密码的base64 编码字符串。

2、url中拼用户名和密码。

市面上大部分浏览器支持url拼用户名，密码的方式访问，

代码不支持这种url 拼用户名，密码。

二、Http Basic Auth 原理

在HTTP协议进行通信的过程中，HTTP协议定义了基本认证过程以允许HTTP服务器对WEB浏览器进行用户身份认证的方法，当一个客户端向HTTP服务器进行数据请求时，

如果客户端未被认证，则HTTP服务器将通过基本认证过程对客户端的用户名及密码进行验证，以决定用户是否合法。

客户端在接收到HTTP服务器的身份认证要求后，会提示用户输入用户名及密码，用户输入后，

客户端将用户名和密码中间用“：”分隔合并，并将合并后的字符串用BASE64编码，在每次请求数据时，将密文附加于请求头（Request Header）Authorization: Basic XXXXXXX中。

HTTP服务器在每次收到请求包后，根据协议取得客户端附加的用户信息（BASE64编码的用户名和密码），解开请求包，对用户名及密码进行验证，

如果用户名及密码正确，则根据客户端请求，返回客户端所需要的数据;否则，返回错误代码或重新要求客户端提供用户名及密码。

三、Basic Auth 的优缺点

优点：提供简单的用户验证功能，其认证过程简单明了，适合于对安全性要求不高的系统或设备中。

缺点：输入的用户名，密码 base64编码后会出现在Authorization里，很容易被解析出来。


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package org.apache.http.examples.client;

import org.apache.http.HttpHost;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.AuthCache;
import org.apache.http.client.CredentialsProvider;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.protocol.HttpClientContext;
import org.apache.http.impl.auth.BasicScheme;
import org.apache.http.impl.client.BasicAuthCache;
import org.apache.http.impl.client.BasicCredentialsProvider;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

/**
 * An example of HttpClient can be customized to authenticate
 * preemptively using BASIC scheme.
 * <b>
 * Generally, preemptive authentication can be considered less
 * secure than a response to an authentication challenge
 * and therefore discouraged.
 */
public class ClientPreemptiveBasicAuthentication {

    public static void main(String[] args) throws Exception {
        HttpHost target = new HttpHost("httpbin.org", 80, "http");
        CredentialsProvider credsProvider = new BasicCredentialsProvider();
        credsProvider.setCredentials(
                new AuthScope(target.getHostName(), target.getPort()),
                new UsernamePasswordCredentials("user", "passwd"));
        CloseableHttpClient httpclient = HttpClients.custom()
                .setDefaultCredentialsProvider(credsProvider).build();
        try {

            // Create AuthCache instance
            AuthCache authCache = new BasicAuthCache();
            // Generate BASIC scheme object and add it to the local
            // auth cache
            BasicScheme basicAuth = new BasicScheme();
            authCache.put(target, basicAuth);

            // Add AuthCache to the execution context
            HttpClientContext localContext = HttpClientContext.create();
            localContext.setAuthCache(authCache);

            HttpGet httpget = new HttpGet("http://httpbin.org/hidden-basic-auth/user/passwd");

            System.out.println("Executing request " + httpget.getRequestLine() + " to target " + target);
            for (int i = 0; i < 3; i++) {
                CloseableHttpResponse response = httpclient.execute(target, httpget, localContext);
                try {
                    System.out.println("----------------------------------------");
                    System.out.println(response.getStatusLine());
                    System.out.println(EntityUtils.toString(response.getEntity()));
                } finally {
                    response.close();
                }
            }
        } finally {
            httpclient.close();
        }
    }

}