httpclient封装工具类

##前言##
在日常开发中，我们经常需要通过http协议去调用网络内容，虽然java自身提供了net相关工具包，但是其灵活性和功能总是不如人意，于是有人专门搞出一个httpclient类库，来方便进行Http操作。对于httpcore的源码研究，我们可能并没有达到这种层次，在日常开发中也只是需要的时候，在网上百度一下，然后进行调用就行。在项目中对于这个工具类库也许没有进行很好的封装。在哪里使用就写在哪些，很多地方用到，就在多个地方写。反正是复制粘贴，很方便，但是这样就会导致项目中代码冗余。所以这里简单的对httpcient的简单操作封装成一个工具类，统一放在项目的工具包中，在使用的时候直接从工具包中调用，不需要写冗余代码。

httpclient操作实例

首先需要在注意的一点是，这是基于httpclient4.5版本的，我们在使用的时候需要引入具体对应jar。下面是具体代码示例

import java.io.IOException;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import javax.net.ssl.SSLContext;

import org.apache.commons.lang3.StringUtils;
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.ParseException;
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.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.ssl.SSLContextBuilder;
import org.apache.http.ssl.TrustStrategy;
import org.apache.http.util.EntityUtils;

/**
 * 基于 httpclient 4.5版本的 http工具类
 * 
 * @author 爱琴孩
 * 
 */
public class HttpClientTool {

	private static final CloseableHttpClient httpClient;
	public static final String CHARSET = "UTF-8";
	// 采用静态代码块，初始化超时时间配置，再根据配置生成默认httpClient对象
	static {
		RequestConfig config = RequestConfig.custom().setConnectTimeout(60000).setSocketTimeout(15000).build();
		httpClient = HttpClientBuilder.create().setDefaultRequestConfig(config).build();
	}

	public static String doGet(String url, Map params) {
		return doGet(url, params, CHARSET);
	}

	public static String doGetSSL(String url, Map params) {
		return doGetSSL(url, params, CHARSET);
	}

	public static String doPost(String url, Map params) throws IOException {
		return doPost(url, params, CHARSET);
	}

	/**
	 * HTTP Get 获取内容
	 * @param url 请求的url地址 ?之前的地址
	 * @param params 请求的参数
	 * @param charset 编码格式
	 * @return 页面内容
	 */
	public static String doGet(String url, Map params, String charset) {
		if (StringUtils.isBlank(url)) {
			return null;
		}
		try {
			if (params != null && !params.isEmpty()) {
				List pairs = new ArrayList(params.size());
				for (Map.Entry entry : params.entrySet()) {
					String value = entry.getValue();
					if (value != null) {
						pairs.add(new BasicNameValuePair(entry.getKey(), value));
					}
				}
				// 将请求参数和url进行拼接
				url += "?" + EntityUtils.toString(new UrlEncodedFormEntity(pairs, charset));
			}
			HttpGet httpGet = new HttpGet(url);
			CloseableHttpResponse response = httpClient.execute(httpGet);
			int statusCode = response.getStatusLine().getStatusCode();
			if (statusCode != 200) {
				httpGet.abort();
				throw new RuntimeException("HttpClient,error status code :" + statusCode);
			}
			HttpEntity entity = response.getEntity();
			String result = null;
			if (entity != null) {
				result = EntityUtils.toString(entity, "utf-8");
			}
			EntityUtils.consume(entity);
			response.close();
			return result;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * HTTP Post 获取内容
	 * @param url 请求的url地址 ?之前的地址
	 * @param params 请求的参数
	 * @param charset 编码格式
	 * @return 页面内容
	 * @throws IOException
	 */
	public static String doPost(String url, Map params, String charset) 
			throws IOException {
		if (StringUtils.isBlank(url)) {
			return null;
		}
		List pairs = null;
		if (params != null && !params.isEmpty()) {
			pairs = new ArrayList(params.size());
			for (Map.Entry entry : params.entrySet()) {
				String value = entry.getValue();
				if (value != null) {
					pairs.add(new BasicNameValuePair(entry.getKey(), value));
				}
			}
		}
		HttpPost httpPost = new HttpPost(url);
		if (pairs != null && pairs.size() > 0) {
			httpPost.setEntity(new UrlEncodedFormEntity(pairs, CHARSET));
		}
		CloseableHttpResponse response = null;
		try {
			response = httpClient.execute(httpPost);
			int statusCode = response.getStatusLine().getStatusCode();
			if (statusCode != 200) {
				httpPost.abort();
				throw new RuntimeException("HttpClient,error status code :" + statusCode);
			}
			HttpEntity entity = response.getEntity();
			String result = null;
			if (entity != null) {
				result = EntityUtils.toString(entity, "utf-8");
			}
			EntityUtils.consume(entity);
			return result;
		} catch (ParseException e) {
			e.printStackTrace();
		} finally {
			if (response != null)
				response.close();
		}
		return null;
	}

	/**
	 * HTTPS Get 获取内容
	 * @param url 请求的url地址 ?之前的地址
	 * @param params 请求的参数
	 * @param charset  编码格式
	 * @return 页面内容
	 */
	public static String doGetSSL(String url, Map params, String charset) {
		if (StringUtils.isBlank(url)) {
			return null;
		}
		try {
			if (params != null && !params.isEmpty()) {
				List pairs = new ArrayList(params.size());
				for (Map.Entry entry : params.entrySet()) {
					String value = entry.getValue();
					if (value != null) {
						pairs.add(new BasicNameValuePair(entry.getKey(), value));
					}
				}
				url += "?" + EntityUtils.toString(new UrlEncodedFormEntity(pairs, charset));
			}
			HttpGet httpGet = new HttpGet(url);

			// https  注意这里获取https内容，使用了忽略证书的方式，当然还有其他的方式来获取https内容
			CloseableHttpClient httpsClient = HttpClientTool.createSSLClientDefault();
			CloseableHttpResponse response = httpsClient.execute(httpGet);
			int statusCode = response.getStatusLine().getStatusCode();
			if (statusCode != 200) {
				httpGet.abort();
				throw new RuntimeException("HttpClient,error status code :" + statusCode);
			}
			HttpEntity entity = response.getEntity();
			String result = null;
			if (entity != null) {
				result = EntityUtils.toString(entity, "utf-8");
			}
			EntityUtils.consume(entity);
			response.close();
			return result;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}
	
	/**
	 * 这里创建了忽略整数验证的CloseableHttpClient对象
	 * @return
	 */
	public static CloseableHttpClient createSSLClientDefault() {
		try {
			SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, new TrustStrategy() {
				// 信任所有
				public boolean isTrusted(X509Certificate[] chain, String authType) throws CertificateException {
					return true;
				}
			}).build();
			SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslContext);
			return HttpClients.custom().setSSLSocketFactory(sslsf).build();
		} catch (KeyManagementException e) {
			e.printStackTrace();
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (KeyStoreException e) {
			e.printStackTrace();
		}
		return HttpClients.createDefault();
	}
}

总结

上面就是对于httpclient的简单工具类，对于httpclient，还有很多知识点需要仔细研究，后面再和大家一起来总结学习！