HTTP协议，httpclient协议

深碍√TFBOYSˉ_ 2021-09-26 10:58 500阅读 0赞

> 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 plain copy
    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。

> 项目中自用的方法  
> urlStr：url  
> content:内容  
> encoding:编码格式  
> method:提交方式

public static String getResult(String urlStr, String content, String encoding,String method) {
              URL url = null;
              HttpURLConnection connection = null;
              try {
                 url = new URL(urlStr);
                 connection = (HttpURLConnection) url.openConnection();// 新建连接实例
                 connection.setConnectTimeout(10000);// 设置连接超时时间，单位毫秒
                 connection.setReadTimeout(10000);// 设置读取数据超时时间，单位毫秒
                 connection.setDoOutput(true);// 是否打开输出流 true|false
                 connection.setDoInput(true);// 是否打开输入流true|false
                 connection.setRequestMethod(method);// 提交方法POST|GET
                 connection.setUseCaches(false);// 是否缓存true|false
                 connection.connect();// 打开连接端口
                 DataOutputStream out = new DataOutputStream(connection.getOutputStream());// 打开输出流往对端服务器写数据
                 out.writeBytes(content);// 写数据,也就是提交你的表单 name=xxx&pwd=xxx
                 out.flush();// 刷新
                 out.close();// 关闭输出流
                 BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream(), encoding));
                 StringBuffer buffer = new StringBuffer();
                 String line = "";
                 while ((line = reader.readLine()) != null) {
                     buffer.append(line);
                 }
                 reader.close();
                 return buffer.toString();
             } catch (IOException e) {
                 e.printStackTrace();
             } finally {
                 if (connection != null) {
                     connection.disconnect();// 关闭连接
                 }
             }
             return null;
         }

》

> 自己用过的方法

public static String getAdd(String log, String lat ){ 
    	    //lat 小 log 大 
    	    //参数解释: 纬度,经度 type 001 (100代表道路，010代表POI，001代表门址，111可以同时显示前三项) 
    	    String urlString = "http://api.map.baidu.com/geocoder/v2/?address=北京市&output=json&ak=0GjzOTbAlqySzHYIudYG7V1WY3LLeD61&callback=showLocation"; 
    	    String res = "";   
    	    try {   
    	      URL url = new URL(urlString);  
    	      java.net.HttpURLConnection conn = (java.net.HttpURLConnection)url.openConnection();  
    	      conn.setDoOutput(true);  
    	      conn.setRequestMethod("POST");  
    	      java.io.BufferedReader in = new java.io.BufferedReader(new java.io.InputStreamReader(conn.getInputStream(),"UTF-8"));  
    	      String line;  
    	      while ((line = in.readLine()) != null) {  
    	        res += line+"\n";  
    	     }  
    	      in.close();  
    	    } catch (Exception e) {  
    	      System.out.println("error in wapaction,and e is " + e.getMessage());  
    	    }  
    	    System.out.println(res); 
    	    return res;  
    	  }

post请求

public static void post(String url,String param) throws IOException {
        CloseableHttpClient client = HttpClients.createDefault();
        UrlEncodedFormEntity entity = null;
        try {
    
            HttpPost put = new HttpPost(url);
            put.setHeader("Content-Type","application/x-www-form-urlencoded; charset=UTF-8");
            List<NameValuePair>list = new ArrayList<NameValuePair>();
            list.add(new BasicNameValuePair("param",param));
    
            entity = new UrlEncodedFormEntity(list,"UTF-8");
            put.setEntity(entity);
            CloseableHttpResponse response = client.execute(put);
            HttpEntity et = response.getEntity();
            InputStream in = et.getContent();
            int stat=  response.getStatusLine().getStatusCode();
    
        } catch (Exception e) {
    
            e.printStackTrace();
        }finally{
            client.close();
        }
    }

将参数分装成json请求http数据

public static String sendSmsByPost(String path, String postContent) { 
            URL url = null;
            try { 
                url = new URL(path);
                HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                httpURLConnection.setRequestMethod("POST");// 提交模式
                httpURLConnection.setConnectTimeout(10000);//连接超时 单位毫秒
                httpURLConnection.setReadTimeout(10000);//读取超时 单位毫秒
                // 发送POST请求必须设置如下两行
                httpURLConnection.setDoOutput(true);
                httpURLConnection.setDoInput(true);
                httpURLConnection.setRequestProperty("Charset", "UTF-8");
                httpURLConnection.setRequestProperty("Content-Type", "application/json");
    
    // PrintWriter printWriter = new PrintWriter(httpURLConnection.getOutputStream());
    // printWriter.write(postContent);
    // printWriter.flush();
    
                httpURLConnection.connect();
                OutputStream os=httpURLConnection.getOutputStream();
                os.write(postContent.getBytes("UTF-8"));
                os.flush();
    
                StringBuilder sb = new StringBuilder();
                int httpRspCode = httpURLConnection.getResponseCode();
                if (httpRspCode == HttpURLConnection.HTTP_OK) { 
                    // 开始获取数据
                    BufferedReader br = new BufferedReader(
                            new InputStreamReader(httpURLConnection.getInputStream(), "utf-8"));
                    String line = null;
                    while ((line = br.readLine()) != null) { 
                        sb.append(line);
                    }
                    br.close();
                    return sb.toString();
    
                }
    
            } catch (Exception e) { 
                e.printStackTrace();
            }
            return null;
        }

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