HttpClient

阳光穿透心脏的1/2处 2024-03-31 16:27 61阅读 0赞

### 1、HttpClient简介 ###

在一般情况下，如果只是需要向Web站点的某个简单页面提交请求并获取服务器响应，HttpURLConnection完全可以胜任。但在绝大部分情况下，Web站点的网页可能没这么简单，这些页面并不是通过一个简单的URL就可访问的，可能需要用户登录而且具有相应的权限才可访问该页面。在这种情况下，就需要涉及Session、Cookie的处理了，如果打算使用HttpURLConnection来处理这些细节，当然也是可能实现的，只是处理起来难度就大了。

为了更好地处理向Web站点请求，包括处理Session、Cookie等细节问题，Apache开源组织提供了一个HttpClient项目，看它的名称就知道，它是一个简单的HTTP客户端（并不是浏览器），可以用于发送HTTP请求，接收HTTP响应。但不会缓存服务器的响应，不能执行HTML页面中嵌入的Javascript代码；也不会对页面内容进行任何解析、处理。

简单来说，HttpClient就是一个增强版的HttpURLConnection，HttpURLConnection可以做的事情HttpClient全部可以做；HttpURLConnection没有提供的有些功能，HttpClient也提供了，但它只是关注于如何发送请求、接收响应，以及管理HTTP连接。

###    2、**HttpClient的使用** ###

1.  创建HttpClient对象。
2.  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(HttpParams 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，执行该方法返回一个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。

### 3、**HttpClient的实例** ###

*  **httpGet**

package com.qf.client;
    
    import java.io.IOException;
    
    import org.apache.http.HttpEntity;
    import org.apache.http.client.ClientProtocolException;
    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.HttpClientBuilder;
    import org.apache.http.util.EntityUtils;
    
    /**
     * GET请求示例
     * 
     * @author 小明
     *
     */
    public class GetDemo {
    
        public static void main(String[] args) {
            // 1. 创建HttpClient对象
            CloseableHttpClient httpClient = HttpClientBuilder.create().build();
            // 2. 创建HttpGet对象
            HttpGet httpGet = new HttpGet(
                    "http://localhost:8080/Servlet/do_login.do?username=test&password=123456");
            CloseableHttpResponse response = null;
            try {
                // 3. 执行GET请求
                response = httpClient.execute(httpGet);
                System.out.println(response.getStatusLine());
                // 4. 获取响应实体
                HttpEntity entity = response.getEntity();
                // 5. 处理响应实体
                if (entity != null) {
                    System.out.println("长度：" + entity.getContentLength());
                    System.out.println("内容：" + EntityUtils.toString(entity));
                }
            } catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                // 6. 释放资源
                try {
                    response.close();
                    httpClient.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

*  **httpPost**

package com.qf.client;
    
    import java.io.IOException;
    import java.io.UnsupportedEncodingException;
    import java.util.ArrayList;
    import java.util.List;
    
    import org.apache.http.HttpEntity;
    import org.apache.http.NameValuePair;
    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.HttpPost;
    import org.apache.http.impl.client.CloseableHttpClient;
    import org.apache.http.impl.client.HttpClientBuilder;
    import org.apache.http.message.BasicNameValuePair;
    import org.apache.http.util.EntityUtils;
    
    /**
     * POST请求测试
     * 
     * @author 小明
     *
     */
    public class PostDemo {
    
        public static void main(String[] args) {
            // 1. 创建HttpClient对象
            CloseableHttpClient httpClient = HttpClientBuilder.create().build();
            // 2. 创建HttpPost对象
            HttpPost post = new HttpPost(
                    "http://localhost:8080/Servlet/do_login.do");
            // 3. 设置POST请求传递参数
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            params.add(new BasicNameValuePair("username", "test"));
            params.add(new BasicNameValuePair("password", "12356"));
            try {
                UrlEncodedFormEntity entity = new UrlEncodedFormEntity(params);
                post.setEntity(entity);
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
            // 4. 执行请求并处理响应
            try {
                CloseableHttpResponse response = httpClient.execute(post);
                HttpEntity entity = response.getEntity();
                if (entity != null){
                    System.out.println("响应内容：");
                    System.out.println(EntityUtils.toString(entity));
                }
                response.close();
            } catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                // 释放资源
                try {
                    httpClient.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

*  **httpClients工具类**

<dependency>
    		<groupId>com.alibaba</groupId>
    	<artifactId>fastjson</artifactId>
    	<version>1.2.78</version>
    </dependency>
    <dependency>
    	<groupId>org.apache.httpcomponents</groupId>
    	<artifactId>httpclient</artifactId>
    	<version>4.5.13</version>
    </dependency>

package com.sgcc.nrxt.nms.ios.util;
    import org.apache.http.HttpEntity;
    import org.apache.http.ParseException;
    import org.apache.http.client.ClientProtocolException;
    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.HttpClientBuilder;
    import org.apache.http.util.EntityUtils;
    import org.apache.log4j.Logger;
    
    import java.io.IOException;
    
    
    public class HttpClientUtil {
    	
    	private static Logger logger = Logger.getLogger(HttpClientUtil.class);
    
    	
    	private static final int connectionRequestTimeout = 5000;// ms毫秒,从池中获取链接超时时间  
    	private static final int connectTimeout = 5000;// ms毫秒,建立链接超时时间  
    	private static final int socketTimeout = 30000;// ms毫秒,读取超时时间 
    	
    	
    	/**
    	 * HttpClient get
    	 * @return
    	 */
    	public static String doGetData(String url) {
    		
    		logger.info("sms http请求开始");
    		
    		CloseableHttpClient httpClient = HttpClientBuilder.create().build();
     
    		HttpGet httpGet = new HttpGet(url);
    
    		CloseableHttpResponse response = null;
    
    		String resData = ""; //响应json数据
    		
    		try {
    			// 配置信息
    			RequestConfig requestConfig = RequestConfig.custom()
    					// 设置连接超时时间(单位毫秒)
    					.setConnectTimeout(connectTimeout)
    					// 设置请求超时时间(单位毫秒)
    					.setConnectionRequestTimeout(connectionRequestTimeout)
    					// socket读写超时时间(单位毫秒)
    					.setSocketTimeout(socketTimeout)
    					// 设置是否允许重定向(默认为true)
    					.setRedirectsEnabled(true).build();
     
    		
    			httpGet.setConfig(requestConfig);
     
    			response = httpClient.execute(httpGet);
     
    			HttpEntity responseEntity = response.getEntity();
    		
    			if (responseEntity != null) {
    				resData = EntityUtils.toString(responseEntity);
    			}
    			
    			logger.info("响应状态为:" + response.getStatusLine());
    			logger.info("响应内容为:" + resData);
    			
    			
    		} catch (ClientProtocolException e) {
    			e.printStackTrace();
    			logger.error(e.getMessage());
    			return null;
    		} catch (ParseException e) {
    			e.printStackTrace();
    			logger.error(e.getMessage());
    			return null;
    		} catch (IOException e) {
    			e.printStackTrace();
    			logger.error(e.getMessage());
    			return null;
    		} finally {
    			try {
    				if (response != null) {
    					response.close();
    				}
    				if (httpClient != null) {
    					httpClient.close();
    				}
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    		
    		logger.info("sms http请求结束");
    		
    		return resData;
    	}
    	
    	/**
    	 * HttpClient post
    	 * @return
    	 */
    	public static String doPostData(String url) {
    		
    		logger.info("sms http请求开始");
    		
    		CloseableHttpClient httpClient = HttpClientBuilder.create().build();
     
    		HttpPost httpPost  = new HttpPost (url);
    
    		CloseableHttpResponse response = null;
    
    		String resData = ""; //响应json数据
    		//定义接收数据
    		JSONObject result = new JSONObject();
    		
    		try {
    			// 配置信息
    			RequestConfig requestConfig = RequestConfig.custom()
    					// 设置连接超时时间(单位毫秒)
    					.setConnectTimeout(connectTimeout)
    					// 设置请求超时时间(单位毫秒)
    					.setConnectionRequestTimeout(connectionRequestTimeout)
    					// socket读写超时时间(单位毫秒)
    					.setSocketTimeout(socketTimeout)
    					// 设置是否允许重定向(默认为true)
    					.setRedirectsEnabled(true).build()
    					.setContentEncoding("UTF-8")
    					.setContentType("application/json").build();
     
    		
    			httpPost.setConfig(requestConfig);
     
    			response = httpClient.execute(httpPost);
     
    			HttpEntity responseEntity = response.getEntity();
    		
    			if (response.getStatusLine().getStatusCode() == 200) {
    				resData = EntityUtils.toString(responseEntity);
    				result = JSON.parseObject(EntityUtils.toString(response.getEntity(), "UTF-8"));
    
    			}
    			
    			logger.info("响应状态为:" + response.getStatusLine());
    			logger.info("响应内容为:" + resData);
    			
    			
    		} catch (ClientProtocolException e) {
    			e.printStackTrace();
    			logger.error(e.getMessage());
    			return null;
    		} catch (ParseException e) {
    			e.printStackTrace();
    			logger.error(e.getMessage());
    			return null;
    		} catch (IOException e) {
    			e.printStackTrace();
    			logger.error(e.getMessage());
    			return null;
    		} finally {
    			try {
    				if (response != null) {
    					response.close();
    				}
    				if (httpClient != null) {
    					httpClient.close();
    				}
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    		
    		logger.info("sms http请求结束");
    		
    		return resData;
    	}
    }