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  • HttpClient特性

    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。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
    [java] view plaincopy在CODE上查看代码片派生到我的代码片
    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();
    }
    }
    }
    }

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  • 原文地址:https://www.cnblogs.com/lhfyy/p/4238293.html
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