HttpClient实战

HttpClient 是 Apache Jakarta Common 下的子项目，可以用来提供高效的、最新的、功能丰富的支持 HTTP 协议的客户端编程工具包，并且它支持 HTTP 协议最新的版本和建议。

HTTP 协议可能是现在 Internet 上使用得最多、最重要的协议了，越来越多的 Java 应用程序需要直接通过 HTTP 协议来访问网络资源。虽然在 JDK 的 java net包中已经提供了访问 HTTP 协议的基本功能，但是对于大部分应用程序来说，JDK 库本身提供的功能还不够丰富和灵活。HttpClient 是 Apache Jakarta Common 下的子项目，用来提供高效的、最新的、功能丰富的支持 HTTP 协议的客户端编程工具包，并且它支持 HTTP 协议最新的版本和建议。HttpClient 已经应用在很多的项目中，比如 Apache Jakarta 上很著名的另外两个开源项目 Cactus 和 HTMLUnit 都使用了 HttpClient。现在HttpClient最新版本为 HttpClient 4.5 (GA) 

---------------------------------------------------------------doget-------------------------------------------------------

public static String doGet(String url, Map<String, String> param) {

// 创建Httpclient对象
CloseableHttpClient httpclient = HttpClients.createDefault();


String resultString = "";
CloseableHttpResponse response = null;
try {
// 创建uri
URIBuilder builder = new URIBuilder(url); //URIBuilder包含：协议，主机名，端口（可选），资源路径，和多个参数（可选）
if (param != null) {
for (String key : param.keySet()) {
builder.addParameter(key, param.get(key));
}
}
URI uri = builder.build();


// 创建http GET请求
HttpGet httpGet = new HttpGet(uri);


// 执行请求
response = httpclient.execute(httpGet);
// 判断返回状态是否为200
if (response.getStatusLine().getStatusCode() == 200) {
resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (response != null) {
response.close();
}
httpclient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;

}

------------------------------------------------------------------------doPost-----------------------------------------------

public static String doPost(String url, Map<String, String> param) {
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
// 创建参数列表
if (param != null) {
List<NameValuePair> paramList = new ArrayList<>();
for (String key : param.keySet()) {
paramList.add(new BasicNameValuePair(key, param.get(key)));
}
// 模拟表单
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);
httpPost.setEntity(entity);
}
// 执行http请求
response = httpClient.execute(httpPost);
resultString = EntityUtils.toString(response.getEntity(), "utf-8");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
response.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}


return resultString;
}

---------------------------------------------------------------------------- ----------------------------------------------

package com.dt.httpclient;


import org.apache.http.HttpEntity;
import org.apache.http.HttpHost;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;


public class HttpClientDemo {


public static void main(String[] args) throws Exception {
CloseableHttpClient httpClient = HttpClients.createDefault(); // 创建httpClient实例

 //使用代理  关于代理IP的话 也分几种 透明代理、匿名代理、混淆代理、高匿代理 
//----》使用高匿代理  http://www.xicidaili.com/
 HttpHost proxy=new HttpHost("219.145.232.204", 8118); 
     RequestConfig requestConfig=RequestConfig.custom()
     .setConnectTimeout(5000)  //设置连接超时
     .setSocketTimeout(5000)
     .setProxy(proxy)
     .build();
       
 HttpGet httpGet = new HttpGet("http://www.xicidaili.com/"); // 创建httpget实例
 httpGet.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:50.0) Gecko/20100101 Firefox/50.0");// 设置请求头消息User-Agent
 httpGet.setConfig(requestConfig);  //设置代理服务器
 
 CloseableHttpResponse response = httpClient.execute(httpGet); // 执行http get请求

//服务器内部报错 返回500,  比如这个请求地址不存在 返回404 ,正常情况 执行成功 返回200状态码，
System.out.println("Status:"+response.getStatusLine().getStatusCode());
HttpEntity entity = response.getEntity(); // 获取返回实体

System.out.println("Content-Type:"+entity.getContentType().getValue());
System.out.println("网页内容：" + EntityUtils.toString(entity, "utf-8")); // 获取网页内容
System.out.println("-------"+entity.getContent());

response.close(); // response关闭
httpClient.close(); // httpClient关闭


}


}