HttpClient的使用

17-08-22 来源：[db:作者]
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HttpClient的使用：

1）httpClient的简单使用：

	import java.net.URI;
	import java.util.ArrayList;
	import java.util.List;

	import org.apache.http.NameValuePair;
	import org.apache.http.client.config.RequestConfig;
	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.client.utils.URIBuilder;
	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;

	public class HttpClientDemo {

		public static void main(String[] args) throws Exception {

			// 1.创建Httpclient对象
			CloseableHttpClient httpclient = HttpClients.createDefault();

			// 2.1创建http GET请求，并设置参数
			String url = "http://www.jxn.com/";
			URI uri = new URIBuilder(url).setParameter("name", "jack").setParameter("age", "1").build();
			HttpGet httpGet = new HttpGet(uri);

			// 2.2创建http POST请求，并设置参数
			HttpPost httpPost = new HttpPost(url);
			List parameters = new ArrayList();
			parameters.add(new BasicNameValuePair("name", "jack"));
			parameters.add(new BasicNameValuePair("age", "1"));
			UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(parameters);
			httpPost.setEntity(formEntity);
					
			// 3.构建请求配置信息
			RequestConfig config = RequestConfig.custom().setConnectTimeout(1000) // 创建连接的最长时间
					.setConnectionRequestTimeout(500) // 从连接池中获取到连接的最长时间
					.setSocketTimeout(10 * 1000) // 数据传输的最长时间
					.setStaleConnectionCheckEnabled(true) // 提交请求前测试连接是否可用
					.build();
			httpGet.setConfig(config);
			httpPost.setConfig(config);

			CloseableHttpResponse response = null;
			try {
				// 4.执行请求
				response = httpclient.execute(httpGet);
	//            response = httpclient.execute(httpPost);
							
				if (response.getStatusLine().getStatusCode() == 200) { // 判断返回状态是否为200
					String content = EntityUtils.toString(response.getEntity(), "UTF-8");
					System.out.println(content);
				}	
			} finally {
				if (response != null) {
					response.close();
				}
				httpclient.close();
			}
		}
	}

2）使用httpClient连接池：
	
	import org.apache.http.client.methods.CloseableHttpResponse;
	import org.apache.http.client.methods.HttpGet;
	import org.apache.http.conn.HttpClientConnectionManager;
	import org.apache.http.impl.client.CloseableHttpClient;
	import org.apache.http.impl.client.HttpClients;
	import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
	import org.apache.http.util.EntityUtils;

	public class HttpClientConnectionManagerDemo {

		public static void main(String[] args) throws Exception {
			PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager();
			connectionManager.setMaxTotal(200); 			// 设置最大连接数
			connectionManager.setDefaultMaxPerRoute(20); 	// 设置每个主机地址的并发数

			// 执行一次get请求
			doGet(connectionManager);
		}

		public static void doGet(HttpClientConnectionManager connectionManager) throws Exception {
			CloseableHttpClient httpClient = HttpClients.custom().setConnectionManager(connectionManager).build();

			String url = "http://www.jxn.com/";
			HttpGet httpGet = new HttpGet(url);

			CloseableHttpResponse response = null;
			try {
				response = httpClient.execute(httpGet);
				if (response.getStatusLine().getStatusCode() == 200) {
					String content = EntityUtils.toString(response.getEntity(), "UTF-8");
					System.out.println(content);
				}
			} finally {
				if (response != null) {
					response.close();
				}
				// 此处不能关闭httpClient！如果把httpClient关闭掉，则连接池也会被销毁
				// httpClient.close();
			}
		}
	}

		
3）HttpClient与Spring整合：

【1】pom.xml文件：
  	
  		org.apache.httpcomponents
  		httpclient
  		4.3.5
  	


【2】spirng配置文件applicationContext-httpclient.xml：

	
	
		
		
	

	
	
		
	

	
	
	

	
	
		
		
		
		
		
		
		
		
	

	
	

	
	
		
	
	
	属性配置文件httpclient.properties：
		http.maxTotal=200
		http.defaultMaxPerRoute=50
		http.connectTimeout=1000
		http.connectionRequestTimeout=500
		http.socketTimeout=10000
		http.staleConnectionCheckEnabled=true

【3】封装成Service：

	import java.io.IOException;
	import java.net.URISyntaxException;
	import java.util.ArrayList;
	import java.util.List;
	import java.util.Map;
	import org.apache.http.NameValuePair;
	import org.apache.http.client.ClientProtocolException;
	import org.apache.http.client.config.RequestConfig;
	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.client.utils.URIBuilder;
	import org.apache.http.entity.ContentType;
	import org.apache.http.entity.StringEntity;
	import org.apache.http.impl.client.CloseableHttpClient;
	import org.apache.http.message.BasicNameValuePair;
	import org.apache.http.util.EntityUtils;
	import org.springframework.beans.BeansException;
	import org.springframework.beans.factory.BeanFactory;
	import org.springframework.beans.factory.BeanFactoryAware;
	import org.springframework.beans.factory.annotation.Autowired;
	import org.springframework.stereotype.Service;
	import com.jxn.common.httpclient.HttpResult;

	@Service
	public class ApiService implements BeanFactoryAware {

		private BeanFactory beanFactory;

		@Autowired(required = false)
		private RequestConfig requestConfig;
		
		
		@Override
		public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
			this.beanFactory = beanFactory;
		}

		private CloseableHttpClient getHttpClient() {
			return this.beanFactory.getBean(CloseableHttpClient.class);
		}
		
		// 执行GET请求
		public String doGet(String url) throws ClientProtocolException, IOException {

			HttpGet httpGet = new HttpGet(url);
			httpGet.setConfig(requestConfig);
			CloseableHttpResponse response = null;
			try {
				// 执行请求
				response = getHttpClient().execute(httpGet);
				// 判断返回状态是否为200
				if (response.getStatusLine().getStatusCode() == 200) {
					return EntityUtils.toString(response.getEntity(), "UTF-8");
				}
			} finally {
				if (response != null) {
					response.close();
				}
			}
			return null;
		}

		// 带有参数的GET请求
		public String doGet(String url, Map params) throws ClientProtocolException, IOException,
				URISyntaxException {
			URIBuilder builder = new URIBuilder(url);
			for (Map.Entry entry : params.entrySet()) {
				builder.setParameter(entry.getKey(), entry.getValue());
			}
			return doGet(builder.build().toString());
		}

		// 执行post请求
		public HttpResult doPost(String url, Map params) throws IOException {
			// 创建http POST请求
			HttpPost httpPost = new HttpPost(url);
			httpPost.setConfig(requestConfig);
			if (null != params) {
				List parameters = new ArrayList(0);
				for (Map.Entry entry : params.entrySet()) {
					parameters.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));
				}
				// 构造一个form表单式的实体
				UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(parameters, "UTF-8");
				httpPost.setEntity(formEntity);
			}

			CloseableHttpResponse response = null;
			try {
				response = getHttpClient().execute(httpPost);
				return new HttpResult(response.getStatusLine().getStatusCode(), EntityUtils.toString(
						response.getEntity(), "UTF-8"));
			} finally {
				if (response != null) {
					response.close();
				}
			}
		}

		// 执行post请求，发送json数据
		public HttpResult doPostJson(String url, String json) throws IOException {
			// 创建http POST请求
			HttpPost httpPost = new HttpPost(url);
			httpPost.setConfig(requestConfig);
			if (null != json) {
				// 构造一个字符串的实体
				StringEntity stringEntity = new StringEntity(json, ContentType.APPLICATION_JSON);
				httpPost.setEntity(stringEntity);
			}

			CloseableHttpResponse response = null;
			try {
				response = getHttpClient().execute(httpPost);
				return new HttpResult(response.getStatusLine().getStatusCode(), EntityUtils.toString(
						response.getEntity(), "UTF-8"));
			} finally {
				if (response != null) {
					response.close();
				}
			}
		}
	}
	
	// 返回的结果
	public class HttpResult {

		private Integer code;
		private String data;

		public HttpResult() {
		}
		public HttpResult(Integer code, String data) {
			this.code = code;
			this.data = data;
		}
		public Integer getCode() {
			return code;
		}
		public void setCode(Integer code) {
			this.code = code;
		}
		public String getData() {
			return data;
		}
		public void setData(String data) {
			this.data = data;
		}
	}

		
【4】实现定期关闭无效的连接：

	import org.apache.http.conn.HttpClientConnectionManager;

	public class IdleConnectionEvictor extends Thread {

		private final HttpClientConnectionManager connectionManager;

		private volatile boolean shutdown;

		// 创建IdleConnectionEvictor对象的时候，启动线程
		public IdleConnectionEvictor(HttpClientConnectionManager connectionManager) {
			this.connectionManager = connectionManager;
			this.start();
		}

		@Override
		public void run() {
			try {
				while (!shutdown) {
					synchronized (this) {
						wait(5000);
						// 关闭失效的连接(每隔5秒检查一次)
						connectionManager.closeExpiredConnections();
					}
				}
			} catch (InterruptedException ex) {
				// 结束
			}
		}

		public void shutdown() {
			shutdown = true;
			synchronized (this) {
				notifyAll();
			}
		}
	}
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