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我用的是httpclient-4.5.1.jar,如果httpclient版本太低的话,此方法可能用不了,需要用手工设置cookie.那种方法,暂不讨论,主要思路就是通过登陆时获取返回的cookie,再讲coolie的值填到新的请求头中,不过这种方法一般不怎么遇到,基本上对面接口都会直接返回给你一个token,你下次访问直接将这个token作为参数传过去就能获取自己想要的数据.

package test;import java.util.Date;import java.util.HashMap;import java.util.Map;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.entity.StringEntity;import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.util.EntityUtils;import com.alibaba.fastjson.JSONArray;public class JKTest03 {	public static void main(String[] args) throws Exception {		long st=new Date().getTime();		CloseableHttpClient http = HttpClients.createDefault();		try {			String url = "post";			HashMap
   
     map = new HashMap
    
     ();			map.put("username", "admin");			map.put("password", "pass");			getlogin(http, map, url);//登陆验证			String url2 = "get";			String list = Get(http, url2);//获取数据			System.out.println(list);		} finally {			http.close();		}		long et=new Date().getTime();		System.out.println("共费时:"+(et-st));		// System.out.println("结束");	}	public static String getlogin(CloseableHttpClient client, Map
     
       map, String url) throws Exception {		String body = "";		String encoding = "utf-8";		// 创建post方式请求对象		HttpPost httpPost = new HttpPost(url);		// 装填参数,常规格式		/*		 * List
      
        nvps = new ArrayList
       
        (); if (map != null) {		 * for (Entry
        
          entry : map.entrySet()) { * //System.out.println(entry.getKey()+"=="+ entry.getValue()); nvps.add(new * BasicNameValuePair(entry.getKey(), entry.getValue())); } } // 设置参数到请求对象中 * httpPost.setEntity(new UrlEncodedFormEntity(nvps, encoding)); * // 设置参数到请求对象中 httpPost.setEntity(new UrlEncodedFormEntity(nvps, encoding)); */ //参数是json格式 httpPost.setEntity(new StringEntity(JSONArray.toJSONString(map))); // 设置header信息 // 指定报文头【Content-type】、【User-Agent】 //参数是json的需要将Content-type设为application/json httpPost.setHeader("Content-type", "application/json");//默认是:application/x-www-form-urlencoded httpPost.setHeader("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)"); // 执行请求操作，并拿到结果（同步阻塞） CloseableHttpResponse response = client.execute(httpPost); // response. // 获取结果实体 HttpEntity entity = response.getEntity(); if (entity != null) { // 按指定编码转换结果实体为String类型 body = EntityUtils.toString(entity, encoding); } // 释放链接 response.close(); return body; } public static String Get(CloseableHttpClient http, String url) throws Exception { HttpGet httpget = new HttpGet(url); String body = ""; CloseableHttpResponse response = http.execute(httpget); // response. // 获取结果实体 HttpEntity entity = response.getEntity(); if (entity != null) { // 按指定编码转换结果实体为String类型 body = EntityUtils.toString(entity, "utf-8"); } // 释放链接 response.close(); return body; }}