HttpClient详解

其他 2018-09-02 06:14:43 阅读次数: 0

JAVA的第三方库HttpClient使用详解

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。
 

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到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。根据请求方式选择请求对象，GET请求，创建HttpGet对象；POST请求，创建HttpPost对象。
  3. 若有请求参数，可以使用HttpGet、HttpPost共同的setParams(HetpParams params)方法来添加参数；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，返回结果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。根据响应码进行处理响应体。
  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 TestGet() {get();}

/**

* HttpClient连接SSL

*/

public void sslClient() {

CloseableHttpClient httpclient = null;

try {

KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType());

FileInputStream instream = new FileInputStream(new File("f:\\tomcat.keystore"));

try {

// 加载keyStore f:\\tomcat.keystore

trustStore.load(instream, "888888".toCharArray());

} catch (CertificateException e) {

e.printStackTrace();

} finally {

try {

instream.close();

} catch (Exception ignore) {

}

}

// CA和自签名证书

SSLContext sslcontext = SSLContexts.custom().loadTrustMaterial(trustStore, new TrustSelfSignedStrategy()).build();

// 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:8123/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

*/

public void postForm() {

// 创建默认的httpClient实例.

CloseableHttpClient httpclient = HttpClients.createDefault();

// 创建httppost

HttpPost httppost = new HttpPost("http://localhost:8123/test/Ajax/testPost.action");

// 创建参数队列

List formparams = new ArrayList();

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:8123/test/Ajax/testPost.action");

// 创建参数队列

List formparams = new ArrayList();

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();

}

}

}

/**get请求带参*/

public void getHaveParam() {

CloseableHttpClient httpclient = HttpClients.createDefault();

try {

// 创建httpget

List<NameValuePair> params = Lists.newArrayList();  

 params.add(new BasicNameValuePair("city", "beijing"));  

String str = "";  

// 执行get请求.

try {

//转换为键值对

str = EntityUtils.toString(new UrlEncodedFormEntity(params, Consts.UTF_8));    

HttpGet httpget = new HttpGet("http://www.jd.com/"+str);

System.out.println("executing request " + httpget.getURI());

//执行请求

CloseableHttpResponse response = httpclient.execute(httpget);

// 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();

}

}

}

/**

* get请求

*/

public void get() {

CloseableHttpClient httpclient = HttpClients.createDefault();

try {

// 创建httpget.

HttpGet httpget = new HttpGet("http://www.jd.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:8123/test/Ajax/testGet.action");

FileBody bin = new FileBody(new File("F:\\image\\get.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();

}

}

}

}



 

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