HttpClient获取重定向之后的信息

HttpClient缺省会自动处理客户端重定向

即访问网页AA后，假设被重定向到了BB网页，那么HttpClient将自动返回BB网页的内容

若想取得BB网页的地址，就需要借助HttpContext对象，它是客户端用来在多次请求响应的交互中，保持状态信息的

我们也可以利用HttpContext来存放一些我们需要的信息，以便下次请求的时候能够取出这些信息来使用

示例代码如下

package com.xuanyuv.httpclient;
import org.apache.http.HttpEntity;
import org.apache.http.HttpHost;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.entity.ContentType;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.ExecutionContext;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.EntityUtils;

public class HttpClientRedirectDemo {
    public static void getRedirectInfo(){
        HttpClient httpClient = new DefaultHttpClient();
        HttpContext httpContext = new BasicHttpContext();
        HttpGet httpGet = new HttpGet("http://127.0.0.1:8088/blog/main.jsp");
        try {
            //将HttpContext对象作为参数传给execute()方法
            //则HttpClient会把请求响应交互过程中的状态信息存储在HttpContext中
            HttpResponse response = httpClient.execute(httpGet, httpContext);
            //获取重定向之后的主机地址信息，即"http://127.0.0.1:8088"
            HttpHost targetHost = (HttpHost)httpContext.getAttribute(ExecutionContext.HTTP_TARGET_HOST);
            //获取实际的请求对象的URI，即重定向之后的"/blog/admin/login.jsp"
            HttpUriRequest realRequest = (HttpUriRequest)httpContext.getAttribute(ExecutionContext.HTTP_REQUEST);
            System.out.println("主机地址:" + targetHost);
            System.out.println("URI信息:" + realRequest.getURI());
            HttpEntity entity = response.getEntity();
            if(null != entity){
                System.out.println("响应内容:" + EntityUtils.toString(entity, ContentType.getOrDefault(entity).getCharset()));
                EntityUtils.consume(entity);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            httpClient.getConnectionManager().shutdown();
        }
    }
}