HttpClient jar包使用详解分析

熊孩纸 阅读:261 2021-03-31 22:46:21 评论:0

Http协议的重要性相信不用我多说了,HttpClient相比传统JDK自带的URLConnection,增加了易用性和灵活性(具体区别,日后我们再讨论),它不仅是客户端发送Http请求变得容易,而且也方便了开发人员测试接口(基于Http协议的),即提高了开发的效率,也方便提高代码的健壮性。因此熟练掌握HttpClient是很重要的必修内容,掌握HttpClient后,相信对于Http协议的了解会更加深入。

一、简介

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。

下载地址: http://hc.apache.org/downloads.cgi

二、特性

1. 基于标准、纯净的java语言。实现了Http1.0和Http1.1

2. 以可扩展的面向对象的结构实现了Http全部的方法(GET, POST, PUT, DELETE, HEAD, OPTIONS, and TRACE)。

3. 支持HTTPS协议。

4. 通过Http代理建立透明的连接。

5. 利用CONNECT方法通过Http代理建立隧道的https连接。

6. Basic, Digest, NTLMv1, NTLMv2, NTLM2 Session, SNPNEGO/Kerberos认证方案。

7. 插件式的自定义认证方案。

8. 便携可靠的套接字工厂使它更容易的使用第三方解决方案。

9. 连接管理器支持多线程应用。支持设置最大连接数,同时支持设置每个主机的最大连接数,发现并关闭过期的连接。

10. 自动处理Set-Cookie中的Cookie。

11. 插件式的自定义Cookie策略。

12. Request的输出流可以避免流中内容直接缓冲socket服务器。

13. Response的输入流可以有效的从socket服务器直接读取相应内容。

14. 在http1.0和http1.1中利用KeepAlive保持持久连接。

15. 直接获取服务器发送的response code和 headers。

16. 设置连接超时的能力。

17. 实验性的支持http1.1 response caching。

18. 源代码基于Apache License 可免费获取。

三、使用方法

使用HttpClient发送请求、接收响应很简单,一般需要如下几步即可。

1. 创建HttpClient对象。

2. 创建请求方法的实例,并指定请求URL。如果需要发送GET请求,创建HttpGet对象;如果需要发送POST请求,创建HttpPost对象。

3. 如果需要发送请求参数,可调用HttpGet、HttpPost共同的setParams(HetpParams params)方法来添加请求参数;对于HttpPost对象而言,也可调用setEntity(HttpEntity entity)方法来设置请求参数。

4. 调用HttpClient对象的execute(HttpUriRequest request)发送请求,该方法返回一个HttpResponse。

5. 调用HttpResponse的getAllHeaders()、getHeaders(String name)等方法可获取服务器的响应头;调用HttpResponse的getEntity()方法可获取HttpEntity对象,该对象包装了服务器的响应内容。程序可通过该对象获取服务器的响应内容。

6. 释放连接。无论执行方法是否成功,都必须释放连接

四、实例

package com.test; 
 
import java.io.File; 
import java.io.FileInputStream; 
import java.io.IOException; 
import java.io.UnsupportedEncodingException; 
import java.security.KeyManagementException; 
import java.security.KeyStore; 
import java.security.KeyStoreException; 
import java.security.NoSuchAlgorithmException; 
import java.security.cert.CertificateException; 
import java.util.ArrayList; 
import java.util.List; 
 
import javax.net.ssl.SSLContext; 
 
import org.apache.http.HttpEntity; 
import org.apache.http.NameValuePair; 
import org.apache.http.ParseException; 
import org.apache.http.client.ClientProtocolException; 
import org.apache.http.client.entity.UrlEncodedFormEntity; 
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.conn.ssl.SSLConnectionSocketFactory; 
import org.apache.http.conn.ssl.SSLContexts; 
import org.apache.http.conn.ssl.TrustSelfSignedStrategy; 
import org.apache.http.entity.ContentType; 
import org.apache.http.entity.mime.MultipartEntityBuilder; 
import org.apache.http.entity.mime.content.FileBody; 
import org.apache.http.entity.mime.content.StringBody; 
import org.apache.http.impl.client.CloseableHttpClient; 
import org.apache.http.impl.client.HttpClients; 
import org.apache.http.message.BasicNameValuePair; 
import org.apache.http.util.EntityUtils; 
import org.junit.Test; 
 
public class HttpClientTest { 
 
	@Test 
	public void jUnitTest() { 
		get(); 
	} 
 
	/** 
	 * HttpClient连接SSL 
	 */ 
	public void ssl() { 
		CloseableHttpClient httpclient = null; 
		try { 
			KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType()); 
			FileInputStream instream = new FileInputStream(new File("d:\\tomcat.keystore")); 
			try { 
				// 加载keyStore d:\\tomcat.keystore   
				trustStore.load(instream, "123456".toCharArray()); 
			} catch (CertificateException e) { 
				e.printStackTrace(); 
			} finally { 
				try { 
					instream.close(); 
				} catch (Exception ignore) { 
				} 
			} 
			// 相信自己的CA和所有自签名的证书 
			SSLContext sslcontext = SSLContexts.custom().loadTrustMaterial(trustStore, new TrustSelfSignedStrategy()).build(); 
			// 只允许使用TLSv1协议 
			SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslcontext, new String[] { "TLSv1" }, null, 
					SSLConnectionSocketFactory.BROWSER_COMPATIBLE_HOSTNAME_VERIFIER); 
			httpclient = HttpClients.custom().setSSLSocketFactory(sslsf).build(); 
			// 创建http请求(get方式) 
			HttpGet httpget = new HttpGet("https://localhost:8443/myDemo/Ajax/serivceJ.action"); 
			System.out.println("executing request" + httpget.getRequestLine()); 
			CloseableHttpResponse response = httpclient.execute(httpget); 
			try { 
				HttpEntity entity = response.getEntity(); 
				System.out.println("----------------------------------------"); 
				System.out.println(response.getStatusLine()); 
				if (entity != null) { 
					System.out.println("Response content length: " + entity.getContentLength()); 
					System.out.println(EntityUtils.toString(entity)); 
					EntityUtils.consume(entity); 
				} 
			} finally { 
				response.close(); 
			} 
		} catch (ParseException e) { 
			e.printStackTrace(); 
		} catch (IOException e) { 
			e.printStackTrace(); 
		} catch (KeyManagementException e) { 
			e.printStackTrace(); 
		} catch (NoSuchAlgorithmException e) { 
			e.printStackTrace(); 
		} catch (KeyStoreException e) { 
			e.printStackTrace(); 
		} finally { 
			if (httpclient != null) { 
				try { 
					httpclient.close(); 
				} catch (IOException e) { 
					e.printStackTrace(); 
				} 
			} 
		} 
	} 
 
	/** 
	 * post方式提交表单(模拟用户登录请求) 
	 */ 
	public void postForm() { 
		// 创建默认的httpClient实例.   
		CloseableHttpClient httpclient = HttpClients.createDefault(); 
		// 创建httppost   
		HttpPost httppost = new HttpPost("http://localhost:8080/myDemo/Ajax/serivceJ.action"); 
		// 创建参数队列   
		List<namevaluepair> formparams = new ArrayList<namevaluepair>(); 
		formparams.add(new BasicNameValuePair("username", "admin")); 
		formparams.add(new BasicNameValuePair("password", "123456")); 
		UrlEncodedFormEntity uefEntity; 
		try { 
			uefEntity = new UrlEncodedFormEntity(formparams, "UTF-8"); 
			httppost.setEntity(uefEntity); 
			System.out.println("executing request " + httppost.getURI()); 
			CloseableHttpResponse response = httpclient.execute(httppost); 
			try { 
				HttpEntity entity = response.getEntity(); 
				if (entity != null) { 
					System.out.println("--------------------------------------"); 
					System.out.println("Response content: " + EntityUtils.toString(entity, "UTF-8")); 
					System.out.println("--------------------------------------"); 
				} 
			} finally { 
				response.close(); 
			} 
		} catch (ClientProtocolException e) { 
			e.printStackTrace(); 
		} catch (UnsupportedEncodingException e1) { 
			e1.printStackTrace(); 
		} catch (IOException e) { 
			e.printStackTrace(); 
		} finally { 
			// 关闭连接,释放资源   
			try { 
				httpclient.close(); 
			} catch (IOException e) { 
				e.printStackTrace(); 
			} 
		} 
	} 
 
	/** 
	 * 发送 post请求访问本地应用并根据传递参数不同返回不同结果 
	 */ 
	public void post() { 
		// 创建默认的httpClient实例.   
		CloseableHttpClient httpclient = HttpClients.createDefault(); 
		// 创建httppost   
		HttpPost httppost = new HttpPost("http://localhost:8080/myDemo/Ajax/serivceJ.action"); 
		// 创建参数队列   
		List<namevaluepair> formparams = new ArrayList<namevaluepair>(); 
		formparams.add(new BasicNameValuePair("type", "house")); 
		UrlEncodedFormEntity uefEntity; 
		try { 
			uefEntity = new UrlEncodedFormEntity(formparams, "UTF-8"); 
			httppost.setEntity(uefEntity); 
			System.out.println("executing request " + httppost.getURI()); 
			CloseableHttpResponse response = httpclient.execute(httppost); 
			try { 
				HttpEntity entity = response.getEntity(); 
				if (entity != null) { 
					System.out.println("--------------------------------------"); 
					System.out.println("Response content: " + EntityUtils.toString(entity, "UTF-8")); 
					System.out.println("--------------------------------------"); 
				} 
			} finally { 
				response.close(); 
			} 
		} catch (ClientProtocolException e) { 
			e.printStackTrace(); 
		} catch (UnsupportedEncodingException e1) { 
			e1.printStackTrace(); 
		} catch (IOException e) { 
			e.printStackTrace(); 
		} finally { 
			// 关闭连接,释放资源   
			try { 
				httpclient.close(); 
			} catch (IOException e) { 
				e.printStackTrace(); 
			} 
		} 
	} 
 
	/** 
	 * 发送 get请求 
	 */ 
	public void get() { 
		CloseableHttpClient httpclient = HttpClients.createDefault(); 
		try { 
			// 创建httpget.   
			HttpGet httpget = new HttpGet("http://www.baidu.com/"); 
			System.out.println("executing request " + httpget.getURI()); 
			// 执行get请求.   
			CloseableHttpResponse response = httpclient.execute(httpget); 
			try { 
				// 获取响应实体   
				HttpEntity entity = response.getEntity(); 
				System.out.println("--------------------------------------"); 
				// 打印响应状态   
				System.out.println(response.getStatusLine()); 
				if (entity != null) { 
					// 打印响应内容长度   
					System.out.println("Response content length: " + entity.getContentLength()); 
					// 打印响应内容   
					System.out.println("Response content: " + EntityUtils.toString(entity)); 
				} 
				System.out.println("------------------------------------"); 
			} finally { 
				response.close(); 
			} 
		} catch (ClientProtocolException e) { 
			e.printStackTrace(); 
		} catch (ParseException e) { 
			e.printStackTrace(); 
		} catch (IOException e) { 
			e.printStackTrace(); 
		} finally { 
			// 关闭连接,释放资源   
			try { 
				httpclient.close(); 
			} catch (IOException e) { 
				e.printStackTrace(); 
			} 
		} 
	} 
 
	/** 
	 * 上传文件 
	 */ 
	public void upload() { 
		CloseableHttpClient httpclient = HttpClients.createDefault(); 
		try { 
			HttpPost httppost = new HttpPost("http://localhost:8080/myDemo/Ajax/serivceFile.action"); 
 
			FileBody bin = new FileBody(new File("F:\\image\\sendpix0.jpg")); 
			StringBody comment = new StringBody("A binary file of some kind", ContentType.TEXT_PLAIN); 
 
			HttpEntity reqEntity = MultipartEntityBuilder.create().addPart("bin", bin).addPart("comment", comment).build(); 
 
			httppost.setEntity(reqEntity); 
 
			System.out.println("executing request " + httppost.getRequestLine()); 
			CloseableHttpResponse response = httpclient.execute(httppost); 
			try { 
				System.out.println("----------------------------------------"); 
				System.out.println(response.getStatusLine()); 
				HttpEntity resEntity = response.getEntity(); 
				if (resEntity != null) { 
					System.out.println("Response content length: " + resEntity.getContentLength()); 
				} 
				EntityUtils.consume(resEntity); 
			} finally { 
				response.close(); 
			} 
		} catch (ClientProtocolException e) { 
			e.printStackTrace(); 
		} catch (IOException e) { 
			e.printStackTrace(); 
		} finally { 
			try { 
				httpclient.close(); 
			} catch (IOException e) { 
				e.printStackTrace(); 
			} 
		} 
	} 
}
本实例是采用HttpClient4.3最新版本。该版本与之前的代码写法风格相差较大,大家多留意下。

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