HttpClient基本功能的使用 Get方式
一、GET 方法
使用 HttpClient 需要以下 6 个步骤：
1. 创建 HttpClient 的实例
2. 创建某种连接方法的实例，在这里是 GetMethod。在 GetMethod 的构造函数中传入待连接的地址
3. 调用第一步中创建好的实例的 execute 方法来执行第二步中创建好的 method 实例
4. 读 response
5. 释放连接。无论执行方法是否成功，都必须释放连接
6. 对得到后的内容进行处理
根据以上步骤，我们来编写用GET方法取得某网页内容的代码。
1、大部分情况下 HttpClient 默认的构造函数已经足够使用。
HttpClient httpClient = new HttpClient();
2、创建GET方法的实例。
在GET方法的构造函数中传入待连接的地址即可。用GetMethod将会自动处理转发过程，如果想要把自动处理转发过程去掉的话，可以调用方法setFollowRedirects(false)。
GetMethod getMethod = new GetMethod( " http://www.ibm.com/ " );
3、调用 httpClient 的 executeMethod 方法来执行 getMethod。
由于是执行在网络上的程序，在运行executeMethod方法的时候，需要处理两个异常，分别是HttpException和 IOException。
HttpException：引起第一种异常的原因主要可能是在构造getMethod的时候传入的协议不对，比如将"http"写成了"htp"，或者服务 器端返回的内容不正常等，并且该异常发生是不可恢复的；
IOException：一般是由于网络原因引起的异常，对于这种异常 （IOException），HttpClient会根据你指定的恢复策略自动试着重新执行executeMethod方法。HttpClient的恢复 策略可以自定义（通过实现接口HttpMethodRetryHandler来实现）。通过httpClient的方法setParameter设置你实 现的恢复策略。
本例中使用的是系统提供的默认恢复策略，该策略在碰到第二类异常的时候将自动重试3次。executeMethod返回值是一个整数，表示 了执行该方法后服务器返回的状态码，该状态码能表示出该方法执行是否成功、需要认证或 者页面发生了跳转（默认状态下GetMethod的实例是自动处理跳 转的）等。
getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,new DefaultHttpMethodRetryHandler()); // 设置成了默认的恢复策略，在发生异常时候将自动重试3次，在这里你也可以设置成自定义的恢复策略
int statusCode = client.executeMethod(getMethod); // 执行getMethod
if (statusCode != HttpStatus.SC_OK) {
System.err.println( " Method failed: " + getMethod.getStatusLine());
}
4、在返回的状态码正确后，即可取得内容。
取得目标地址的内容有三种方法：
Ⅰ、getResponseBody，该方法返回的是目标的二进制的byte流；
Ⅱ、getResponseBodyAsString，这个方法返回的是String类型，值得注意的是该方法返回的String的编码是根据系统默认的编码方式，所以返回的String值可能编码类型有误；
Ⅲ、getResponseBodyAsStream，这个方法对于目标地址中有大量数据需要传输是最佳的。
在这里我们使用了最简单的 getResponseBody方法。
byte [] responseBody = method.getResponseBody();
5、释放连接。
无论执行方法是否成功，都必须释放连接。
method.releaseConnection();
6、处理内容。
在这一步中根据你的需要处理内容，本例中只是简单的将内容打印到控制台。System.out.println( new String(responseBody));
package com.asiainfo.hsop.common.utils; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.io.UnsupportedEncodingException; import java.nio.charset.Charset; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import com.alibaba.fastjson.JSONObject; import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler; import org.apache.commons.httpclient.HttpClient; import org.apache.commons.httpclient.HttpException; import org.apache.commons.httpclient.HttpStatus; import org.apache.commons.httpclient.MultiThreadedHttpConnectionManager; import org.apache.commons.httpclient.NameValuePair; import org.apache.commons.httpclient.methods.GetMethod; import org.apache.commons.httpclient.methods.PostMethod; import org.apache.commons.httpclient.params.HttpClientParams; import org.apache.commons.httpclient.params.HttpMethodParams; import org.apache.commons.httpclient.protocol.Protocol; import org.apache.commons.lang3.StringUtils; import org.apache.http.HttpEntity; 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.HttpPost; import org.apache.http.entity.ContentType; import org.apache.http.entity.StringEntity; import org.apache.http.entity.mime.HttpMultipartMode; import org.apache.http.entity.mime.MultipartEntityBuilder; import org.apache.http.entity.mime.content.FileBody; 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.apache.logging.log4j.LogManager; import org.apache.logging.log4j.Logger; /** * 处理http和https协议请求,根据请求url判断协议类型 * * @author yangxiaobing * @date 2017/9/6 */ public class HttpUtil { private static Logger logger = LogManager.getLogger(HttpUtil.class); private static final int HTTP_DEFAULT_TIMEOUT = 15000; //超时时间默认为15秒 private static final int HTTP_SOCKET_TIMEOUT = 30000; //连接状态下没有收到数据的话强制断时间为30秒 private static final int MAX_TOTAL_CONNECTIONS = 500; //最大连接数 private static final int CONN_MANAGER_TIMEOUT = 500; //该值就是连接不够用的时候等待超时时间，一定要设置，而且不能太大 private static MultiThreadedHttpConnectionManager httpConnectionManager = new MultiThreadedHttpConnectionManager(); //接口调用频繁，结果出现了很多ConnectTimeoutException 配置优化，共用HttpClient，减少开销 static { //每主机最大连接数和总共最大连接数，通过hosfConfiguration设置host来区分每个主机 //client.getHttpConnectionManager().getParams().setDefaultMaxConnectionsPerHost(8); httpConnectionManager.getParams().setMaxTotalConnections(MAX_TOTAL_CONNECTIONS); httpConnectionManager.getParams().setConnectionTimeout(HTTP_DEFAULT_TIMEOUT);//连接超时时间 httpConnectionManager.getParams().setSoTimeout(HTTP_SOCKET_TIMEOUT); //连接状态下没有收到数据的话强制断时间 httpConnectionManager.getParams().setLongParameter(HttpClientParams.CONNECTION_MANAGER_TIMEOUT, CONN_MANAGER_TIMEOUT); //是否计算节省带宽 httpConnectionManager.getParams().setTcpNoDelay(true); //延迟关闭时间 httpConnectionManager.getParams().setLinger(0); //失败的情况下会默认进行3次尝试,成功之后不会再尝试 ------关闭 httpConnectionManager.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler(0, false)); } /** * 构建 httpsclient 请求 * * @return */ private static HttpClient getHttpClient() { HttpClient httpClient = new HttpClient(httpConnectionManager); httpClient.getParams().setParameter(HttpMethodParams.HTTP_CONTENT_CHARSET, "UTF-8"); return httpClient; } /** * POST请求统一入口 */ public static String post(String url, Map<String, Object> paramMap) { logger.info("===>>>调用[post]接口开始...===>>> URL:" + url); Long beginTime = System.currentTimeMillis(); if (StringUtils.isEmpty(url)) { return null; } String result = null; if (startsWithIgnoreCase(url, "https")) { result = httpsPost(url, paramMap, "UTF-8"); } else if (startsWithIgnoreCase(url, "http")) { result = httpPost(url, paramMap, "UTF-8"); } else { logger.warn("http url format error!"); } logger.info("===>>>调用[post]接口结束 ===>>>URL:" + url + ",耗时:" + (System.currentTimeMillis() - beginTime) + "毫秒"); return result; } /** * GET请求统一入口 */ public static String get(String url) { logger.info("===>>>调用[get]接口开始...===>>> URL:" + url); Long beginTime = System.currentTimeMillis(); if (StringUtils.isEmpty(url)) { return null; } String result = null; if (startsWithIgnoreCase(url, "https")) { result = httpsGet(url, "UTF-8"); } else if (startsWithIgnoreCase(url, "http")) { result = httpGet(url, "UTF-8"); } else { logger.warn("http url format error!"); } logger.info("===>>>调用[get]接口结束 ===>>>URL:" + url + ",耗时:" + (System.currentTimeMillis() - beginTime) + "毫秒"); return result; } public static String httpPost(String url, Map<String, Object> paramMap, String encoding) { String content = null; if (paramMap == null) { paramMap = new HashMap<String, Object>(); } logger.info("http param:" + paramMap.toString()); HttpClient httpClient = getHttpClient(); PostMethod method = new PostMethod(url); if (!paramMap.isEmpty()) { for (Map.Entry<String, ?> entry : paramMap.entrySet()) { method.addParameter(new NameValuePair(entry.getKey(), entry.getValue().toString())); } } try { httpClient.executeMethod(method); logger.info("http status : " + method.getStatusLine().getStatusCode()); content = new String(method.getResponseBody(), encoding); logger.info("http response : [" + content + "]"); } catch (Exception e) { logger.error("发起http请求失败[" + url + "]" + ",param" + paramMap.toString(), e); } finally { method.releaseConnection(); httpClient.getHttpConnectionManager().closeIdleConnections(0); } return content; } public static String httpPost(String url, JSONObject param) { String content = null; CloseableHttpClient httpClient = HttpClients.createDefault(); HttpPost httpPost = new HttpPost(url); httpPost.setHeader("Content-Type", "application/json;charset=UTF-8"); StringEntity se = null; try { se = new StringEntity(JSONObject.toJSONString(param)); se.setContentType("text/json"); httpPost.setEntity(se); CloseableHttpResponse response = null; response = httpClient.execute(httpPost); HttpEntity httpEntity = response.getEntity(); content = EntityUtils.toString(httpEntity, "UTF-8"); } catch (IOException e) { e.printStackTrace(); } finally { if (httpClient != null) { try { httpClient.close(); } catch (IOException e) { e.printStackTrace(); } } } return content; } private static String httpsPost(String url, Map<String, Object> paramMap, String encoding) { String content = null; HttpClient httpsClient = getHttpClient(); Protocol myhttps = new Protocol("https", new MySSLProtocolSocketFactory(), 443); Protocol.registerProtocol("https", myhttps); PostMethod method = new PostMethod(url); if (paramMap != null && !paramMap.isEmpty()) { for (Map.Entry<String, Object> entry : paramMap.entrySet()) { if (null != entry.getValue()) { method.addParameter(new NameValuePair(entry.getKey(), entry.getValue().toString())); } } logger.info("https param : " + paramMap.toString()); } try { httpsClient.executeMethod(method); logger.info("https status :" + method.getStatusLine().getStatusCode()); if (method.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { content = new String(method.getResponseBody(), encoding); logger.info("https response : [" + content + "]"); } } catch (Exception e) { logger.error("https request failed. url : [" + url + "]" + ", param : [" + paramMap + "]", e); } finally { method.releaseConnection(); httpsClient.getHttpConnectionManager().closeIdleConnections(0); } return content; } private static String httpGet(String url, String encoding) { HttpClient httpClient = getHttpClient(); GetMethod method = new GetMethod(url); String result = null; try { httpClient.executeMethod(method); int status = method.getStatusCode(); if (status == HttpStatus.SC_OK) { result = method.getResponseBodyAsString(); } else { logger.error("Method failed: " + method.getStatusLine()); } } catch (HttpException e) { // 发生致命的异常，可能是协议不对或者返回的内容有问题 logger.error("Please check your provided http address!"); logger.error(e, e); } catch (IOException e) { // 发生网络异常 logger.error("发生网络异常！"); logger.error(e, e); } finally { // 释放连接 method.releaseConnection(); httpClient.getHttpConnectionManager().closeIdleConnections(0); } return result; } private static String httpsGet(String url, String encoding) { HttpClient httpsClient = getHttpClient();//HttpConnectionManager.alwaysClose=true Protocol myhttps = new Protocol("https", new MySSLProtocolSocketFactory(), 443); Protocol.registerProtocol("https", myhttps); GetMethod method = new GetMethod(url); String content = null; try { httpsClient.executeMethod(method); logger.info("https status : " + method.getStatusLine().getStatusCode()); if (method.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { content = new String(method.getResponseBody(), encoding); logger.info("https response : [" + content + "]"); } } catch (Exception e) { logger.error("https request failed. url : [" + url + "]", e.getCause()); } finally { method.releaseConnection(); httpsClient.getHttpConnectionManager().closeIdleConnections(0); } return content; } private static boolean startsWithIgnoreCase(String origin, String prefix) { int len = prefix.length(); if (len == 0 || origin.length() < len) { return false; } while (len-- > 0) { char a = origin.charAt(len); char b = prefix.charAt(len); if (a == b || Character.toUpperCase(a) == Character.toUpperCase(b)) { continue; } return false; } return true; } public static void main(String args[]) { // String url = "http://10.253.6.202:30001/dipic/api/auditControl/queryTraffic"; String url = "http://localhost:8180/comm/api/upload.do"; JSONObject Json = new JSONObject(); File file = new File("E:\\initParam.properties"); Map<String,String> map = new HashMap<>(); map.put("fileName","redis-64bit.rar"); System.out.println(HttpUtil.postFile(url, file)); } //文件上传，调用fastDFS方法封装层 public static String postFile(String url, File file){ CloseableHttpClient httpclient = HttpClients.createDefault(); CloseableHttpResponse response = null; String result = null; try { RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(3000) .setConnectTimeout(3000).setConnectionRequestTimeout(3000).build(); // if (params != null && !params.isEmpty()) { // List<BasicNameValuePair> pairs = new ArrayList<BasicNameValuePair>(params.size()); // for (Map.Entry<String, String> entry : params.entrySet()) { // String value = entry.getValue(); // if (value != null) { // pairs.add(new BasicNameValuePair(entry.getKey(), value)); // } // } // url += "?" + EntityUtils.toString(new UrlEncodedFormEntity(pairs, charset)); // } HttpPost httpPost = new HttpPost(url); httpPost.setConfig(requestConfig); // 将java.io.File对象添加到HttpEntity（org.apache.http.HttpEntity）对象中 MultipartEntityBuilder builder = MultipartEntityBuilder.create(); // 解决上传文件，文件名中文乱码问题 builder.setCharset(Charset.forName("utf-8")); builder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);// 设置浏览器兼容模式 builder.addPart("file", new FileBody(file)); httpPost.setEntity(builder.build()); response = httpclient.execute(httpPost); int statusCode = response.getStatusLine().getStatusCode(); if (statusCode == HttpStatus.SC_OK) { HttpEntity resEntity = response.getEntity(); result = EntityUtils.toString(resEntity); // 消耗掉response EntityUtils.consume(resEntity); } } catch (Exception e) { e.printStackTrace(); }finally { if(response!=null){ try { response.close(); } catch (IOException e) { e.printStackTrace(); } } if(httpclient!=null){ try { httpclient.close(); } catch (IOException e) { e.printStackTrace(); } } } return result; } }
package test; import java.io.IOException; import org.apache.commons.httpclient. * ; import org.apache.commons.httpclient.methods.GetMethod; import org.apache.commons.httpclient.params.HttpMethodParams; public class GetSample{ public static void main(String[] args) { // 构造HttpClient的实例 HttpClient httpClient = new HttpClient(); // 创建GET方法的实例 GetMethod getMethod = new GetMethod( " http://www.ibm.com " ); // 使用系统提供的默认的恢复策略 getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler()); try { // 执行getMethod int statusCode = httpClient.executeMethod(getMethod); if (statusCode != HttpStatus.SC_OK) { System.err.println( " Method failed: " + getMethod.getStatusLine()); } // 读取内容 byte [] responseBody = getMethod.getResponseBody(); // 处理内容 System.out.println( new String(responseBody)); } catch (HttpException e) { // 发生致命的异常，可能是协议不对或者返回的内容有问题 System.out.println( " Please check your provided http address! " ); e.printStackTrace(); } catch (IOException e) { // 发生网络异常 e.printStackTrace(); } finally { // 释放连接 getMethod.releaseConnection(); } } }
