HttpClient简单使用

本文介绍Apache HttpClient的使用方法,包括创建实例、模拟浏览器请求、获取响应内容及状态码等。此外,还介绍了如何设置代理和超时配置。

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简介

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。

官网 http://hc.apache.org/httpcomponents-client-4.5.x/index.html

简单实例

创建一个maven工程,添加httpclient依赖最新版为4.5.7

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<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.7</version>
</dependency>

创建一个httpclient实例

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import org.apache.http.HttpEntity;
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 java.io.IOException;

public class HttpClientDemo {
public static void main(String[] args) throws IOException{
//创建httpclient实例
CloseableHttpClient httpclient = HttpClients.createDefault();
// 创建httpget实例
HttpGet httpget = new HttpGet("https://www.cnblogs.com/");

CloseableHttpResponse response = httpclient.execute(httpget);
//返回实体
HttpEntity entity = response.getEntity();

String toString = EntityUtils.toString(entity, "utf-8");
System.out.println(toString);

//关闭流和释放系统资源
response.close();
httpclient.close();

}
}

> 成功获取并打印

httpclient

模拟浏览器

有的网站有限制比如请求 www.tuicool.com

不加请求头

返回

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<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<p>系统检测亲不是真人行为,因系统资源限制,我们只能拒绝你的请求。如果你有疑问,可以通过微博 http://weibo.com/tuicool2012/ 联系我们。</p>
</body>
</html>

设置请求头

通过设置 User-Agent 达到模拟请求
httpget.setHeader(“User-Agent”,”Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36”);

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import org.apache.http.HttpEntity;
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 java.io.IOException;

public class HttpClientDemo {
public static void main(String[] args) throws IOException {
//创建httpclient实例
CloseableHttpClient httpclient = HttpClients.createDefault();

// 创建httpget实例
HttpGet httpget = new HttpGet("https://www.tuicool.com/");

//设置请求头模拟浏览器
httpget.setHeader("User-Agent","Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36");

CloseableHttpResponse response = httpclient.execute(httpget);
//返回实体
HttpEntity entity = response.getEntity();

String toString = EntityUtils.toString(entity, "utf-8");
System.out.println(toString);

//关闭流和释放系统资源
response.close();
httpclient.close();

}
}

HttpClient

获取响应内容

HttpClient获取响应内容类型Content-Type

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import org.apache.http.Header;
import org.apache.http.HttpEntity;
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 java.io.IOException;

public class HttpClientDemo {
public static void main(String[] args) throws IOException {
//创建httpclient实例
CloseableHttpClient httpclient = HttpClients.createDefault();

// 创建httpget实例
HttpGet httpget = new HttpGet("https://www.tuicool.com/");

//设置请求头模拟浏览器
httpget.setHeader("User-Agent","Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36");

CloseableHttpResponse response = httpclient.execute(httpget);
//返回实体
HttpEntity entity = response.getEntity();

String toString = EntityUtils.toString(entity, "utf-8");
System.out.println(toString);

//获取响应内容类型Content-Type
Header contentType = entity.getContentType();

System.out.println(contentType);

//关闭流和释放系统资源
response.close();
httpclient.close();

}
}
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Content-Type: text/html; charset=utf-8

获取响应状态码

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import org.apache.http.Header;
import org.apache.http.HttpEntity;
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 java.io.IOException;

public class HttpClientDemo {
public static void main(String[] args) throws IOException {
//创建httpclient实例
CloseableHttpClient httpclient = HttpClients.createDefault();

// 创建httpget实例
HttpGet httpget = new HttpGet("https://www.tuicool.com/");

//设置请求头模拟浏览器
httpget.setHeader("User-Agent","Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36");

CloseableHttpResponse response = httpclient.execute(httpget);
//返回实体
HttpEntity entity = response.getEntity();

String toString = EntityUtils.toString(entity, "utf-8");
System.out.println(toString);

//获取响应内容类型Content-Type
Header contentType = entity.getContentType();

System.out.println(contentType);

//获取响应状态码
int statusCode = response.getStatusLine().getStatusCode();

System.out.println(statusCode);

//关闭流和释放系统资源
response.close();
httpclient.close();

}
}
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statusCode 200

设置代理

在爬取网页的时候,有的目标站点有反爬虫机制,对于频繁访问站点以及规则性访问站点的行为,会采集屏蔽IP措施。
使用代理可以使用。

代理ip获取 百度 代理ip
https://www.kuaidaili.com/free/

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import org.apache.http.Header;
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;

import java.io.IOException;

public class HttpClientDemo {
public static void main(String[] args) throws IOException {
//创建httpclient实例
CloseableHttpClient httpclient = HttpClients.createDefault();


// 创建httpget实例
HttpGet httpget = new HttpGet("https://www.tuicool.com/");

//设置请求头模拟浏览器
httpget.setHeader("User-Agent","Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36");

//使用代理IP
HttpHost proxy=new HttpHost("222.135.92.68", 38094);
RequestConfig requestConfig=RequestConfig.custom().setProxy(proxy).build();
httpget.setConfig(requestConfig);

CloseableHttpResponse response = httpclient.execute(httpget);
//返回实体
HttpEntity entity = response.getEntity();

String toString = EntityUtils.toString(entity, "utf-8");
System.out.println(toString);

//获取响应内容类型Content-Type
Header contentType = entity.getContentType();

System.out.println(contentType);

//获取响应状态码
int statusCode = response.getStatusLine().getStatusCode();

System.out.println(" statusCode "+statusCode);

//关闭流和释放系统资源
response.close();
httpclient.close();

}
}

设置超时

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import org.apache.http.Header;
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;

import java.io.IOException;

public class HttpClientDemo {
public static void main(String[] args) throws IOException {
//创建httpclient实例
CloseableHttpClient httpclient = HttpClients.createDefault();


// 创建httpget实例
HttpGet httpget = new HttpGet("https://www.cnblogs.com/");

//设置请求头模拟浏览器
httpget.setHeader("User-Agent","Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36");

//使用代理IP
HttpHost proxy=new HttpHost("101.89.132.131", 80);
RequestConfig requestConfig=RequestConfig.custom().
//设置连接超时和读取超时
setSocketTimeout(5000)
.setConnectTimeout(5000)
//设置代理
.setProxy(proxy)
.build();
httpget.setConfig(requestConfig);

CloseableHttpResponse response = httpclient.execute(httpget);
//返回实体
HttpEntity entity = response.getEntity();

String toString = EntityUtils.toString(entity, "utf-8");
System.out.println(toString);

//获取响应内容类型Content-Type
Header contentType = entity.getContentType();

System.out.println(contentType);

//获取响应状态码
int statusCode = response.getStatusLine().getStatusCode();

System.out.println(" statusCode "+statusCode);

//关闭流和释放系统资源
response.close();
httpclient.close();

}
}
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