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) （2015-09-11）
总结:在Java代码中发起Http请求，之后解析返回结果即可
特点:Http请求协议中 参数类型:string 结果:html/json
<httpclient.version>4.3.5</httpclient.version>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>${httpclient.version}</version>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpmime</artifactId>
<version>4.3.1</version>
</dependency>
package com.jt.test.httpclient;
import java.io.IOException;
import org.apache.http.HttpEntity;
import org.apache.http.client.ClientProtocolException;
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;
import org.junit.Test;
public class TestHttpClient {
//get方法
@Test
public void doGet() throws ClientProtocolException, IOException{
//1.实例化httpClient对象
CloseableHttpClient client = HttpClients.createDefault();
//2.定义url
String url="https://www.baidu.com";
//3.定义请求类型
HttpGet get=new HttpGet(url);
String method=get.getRequestLine().getMethod();
System.out.println("获取请求类型:"+method);
String http = get.getRequestLine().getProtocolVersion().toString();
System.out.println("获取请求协议:"+http);
//4.发起http请求
CloseableHttpResponse response = client.execute(get);
//5.判断状态信息是否正确200
if(response.getStatusLine().getStatusCode()==200)
{
HttpEntity entity = response.getEntity();
String result = EntityUtils.toString(entity);
System.out.println(result);
}
}
}
运行结果
获取请求类型:GET
获取请求协议:HTTP/1.1
log4j:WARN No appenders could be found for logger (org.apache.http.client.protocol.RequestAddCookies).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
<!DOCTYPE html>
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