HttpClient总结

HttpClient不是浏览器，但可以模拟浏览器发送请求，主要作用：

爬取网页（Http,Https）内容使用get/post方式发送请求，post可以是表单提交或json提交

依赖的jar包

<dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.5.7</version> </dependency> <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpcore</artifactId> <version>4.4.7</version> </dependency>

使用httpClient的步骤为:

创建httpClient对象-->创建httpGet-->执行get/post请求-->返回HTTPEntity-->通过EntityUtil取出响应内容。

1、get方式

//get方式请求 public static String get(String url) throws IOException { // CloseableHttpClient httpClient = HttpClients.createDefault(); //建造者模式 CloseableHttpClient httpClient = HttpClientBuilder.create().build(); HttpGet httpGet = new HttpGet(url); CloseableHttpResponse response = null; response = httpClient.execute(httpGet); HttpEntity entity = response.getEntity(); String html = EntityUtils.toString(entity); response.close(); httpClient.close(); return html; } //请求方式 get("http://www.chery.cn/vehicles/tiggo8#page-1");

2、表单提交

/** * 表单提交 * * @param url * @return */ public static String post(String url) throws Exception { //和上面一样，也可以通过build创建 CloseableHttpClient httpClient = HttpClients.createDefault(); HttpPost httpPost = new HttpPost(url); CloseableHttpResponse response = null; List<NameValuePair> list = Lists.newArrayList(); list.add(new BasicNameValuePair("name", "张三")); list.add(new BasicNameValuePair("pwd", "123321")); log.info(JSONObject.toJSONString(list)); //需要把表单包装到entity中 StringEntity formEntity = new UrlEncodedFormEntity(list, "UTF-8"); httpPost.setEntity(formEntity); //设置请求和传输超时时间 RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(3000).setConnectTimeout(3000).build(); httpPost.setConfig(requestConfig); response = httpClient.execute(httpPost); HttpEntity entity = response.getEntity(); String result = EntityUtils.toString(entity, "UTF-8"); response.close(); httpClient.close(); return result; }

3、json方式发送post请求

/** * json参数提交 * * @param url * @return * @throws Exception */ public static String httpPostWithJSON(String url) throws Exception { CloseableHttpClient client = HttpClients.createDefault(); HttpPost httpPost = new HttpPost(url); String respContent = null; //封装json参数 //{"endpoint":"abd.cn-beijing.abc.com","reportData":{"metricName":"test","groupId":"101","values":{"value":10.5},"dimensions":{"sampleName1":"value1","sampleName2":"value2"}},"acckey":"something","secret":"something"} JSONObject jsonParam = new JSONObject(); jsonParam.put("endpoint", "abd.cn-beijing.abc.com"); jsonParam.put("acckey", "something"); jsonParam.put("secret", "something"); JSONObject paramVar = new JSONObject(); paramVar.put("groupId", "101"); paramVar.put("metricName", "test"); paramVar.put("groupId", "101"); JSONObject dimensions = new JSONObject(); dimensions.put("sampleName1", "value1"); dimensions.put("sampleName2", "value2"); paramVar.put("dimensions", dimensions); JSONObject values = new JSONObject(); values.put("value", 10.5); paramVar.put("values", values); jsonParam.put("reportData", paramVar); //解决中文乱码问题 StringEntity entity = new StringEntity(jsonParam.toString(), "UTF-8"); entity.setContentType("application/json"); httpPost.setEntity(entity); log.info(JSONObject.toJSONString(jsonParam)); HttpResponse resp = client.execute(httpPost); if (resp.getStatusLine().getStatusCode() == 200) { HttpEntity he = resp.getEntity(); respContent = EntityUtils.toString(he, "UTF-8"); } return respContent; }