java實現http請求的方法常用有兩種，一種則是通過java自帶的標準類HttpURLConnection去實現，另一種是通過apache的httpclient去實現。

本文用httpclient去實現，需要導入httpclient和httpcore兩個jar包，測試時用的httpclient-4.5.1和httpcore-4.4.3。

HttpMethod.java

package demo;public enum HttpMethod { GET, POST;}

HttpHeader.java

package demo;import java.util.HashMap;import java.util.Map;/** * 請求頭 */public class HttpHeader { private Map<String, String> params = new HashMap<String, String>(); public HttpHeader addParam(String name, String value) { this.params.put(name, value); return this; } public Map<String, String> getParams() { return this.params; }}

HttpParamers.java

package demo;import java.io.IOException;import java.net.URLEncoder;import java.util.HashMap;import java.util.Map;import java.util.Set;import com.alibaba.fastjson.JSON;/** * 請求參數 */public class HttpParamers { private Map<String, String> params = new HashMap<String, String>(); private HttpMethod httpMethod; private String jsonParamer = ''; public HttpParamers(HttpMethod httpMethod) { this.httpMethod = httpMethod; } public static HttpParamers httpPostParamers() { return new HttpParamers(HttpMethod.POST); } public static HttpParamers httpGetParamers() { return new HttpParamers(HttpMethod.GET); } public HttpParamers addParam(String name, String value) { this.params.put(name, value); return this; } public HttpMethod getHttpMethod() { return this.httpMethod; } public String getQueryString(String charset) throws IOException { if ((this.params == null) || (this.params.isEmpty())) { return null; } StringBuilder query = new StringBuilder(); Set<Map.Entry<String, String>> entries = this.params.entrySet(); for (Map.Entry<String, String> entry : entries) { String name = entry.getKey(); String value = entry.getValue(); query.append('&').append(name).append('=').append(URLEncoder.encode(value, charset)); } return query.substring(1); } public boolean isJson() { return !isEmpty(this.jsonParamer); } public Map<String, String> getParams() { return this.params; } public String toString() { return 'HttpParamers ' + JSON.toJSONString(this); } public String getJsonParamer() { return this.jsonParamer; } public void setJsonParamer() { this.jsonParamer = JSON.toJSONString(this.params); } private static boolean isEmpty(CharSequence cs) { return (cs == null) || (cs.length() == 0); }}

HttpClient.java

package demo;import java.io.IOException;import java.util.Map;import java.util.Set;import org.apache.http.HttpEntity;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.methods.HttpRequestBase;import org.apache.http.entity.StringEntity;import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.protocol.HTTP;import org.apache.http.util.EntityUtils;public class HttpClient { public static final String DEFAULT_CHARSET = 'UTF-8'; public static final String JSON_CONTENT_FORM = 'application/json;charset=UTF-8'; public static final String CONTENT_FORM = 'application/x-www-form-urlencoded;charset=UTF-8'; public static String doService(String url, HttpParamers paramers, HttpHeader header, int connectTimeout, int readTimeout) throws Exception { HttpMethod httpMethod = paramers.getHttpMethod(); switch (httpMethod) { case GET:return doGet(url, paramers, header, connectTimeout, readTimeout); case POST:return doPost(url, paramers, header, connectTimeout, readTimeout); } return null; } /** * post方法 * @param url * @param paramers * @param header * @param connectTimeout * @param readTimeout * @return * @throws IOException */ public static String doPost(String url, HttpParamers paramers, HttpHeader header, int connectTimeout, int readTimeout) throws IOException { String responseData = ''; CloseableHttpClient httpClient = null; CloseableHttpResponse httpResponse = null;try{ String query = null;HttpPost httpPost = new HttpPost(url); setHeader(httpPost, header); if (paramers.isJson()) {//json數據httpPost.setHeader(HTTP.CONTENT_TYPE, JSON_CONTENT_FORM);query = paramers.getJsonParamer(); } else {//表單數據httpPost.setHeader(HTTP.CONTENT_TYPE, CONTENT_FORM);query = paramers.getQueryString(DEFAULT_CHARSET); } if(query != null){HttpEntity reqEntity = new StringEntity(query);httpPost.setEntity(reqEntity); } httpClient = HttpClients.createDefault(); httpResponse = httpClient.execute(httpPost); HttpEntity resEntity = httpResponse.getEntity(); responseData = EntityUtils.toString(resEntity); } catch (Exception e){ e.printStackTrace(); } finally{ httpResponse.close(); httpClient.close(); } return responseData; } /** * get方法 * @param url * @param params * @param header * @param connectTimeout * @param readTimeout * @return * @throws IOException */ public static String doGet(String url, HttpParamers params, HttpHeader header, int connectTimeout, int readTimeout) throws IOException { String responseData = ''; CloseableHttpClient httpClient = null; CloseableHttpResponse httpResponse = null;try{String query = params.getQueryString(DEFAULT_CHARSET);url = buildGetUrl(url, query); HttpGet httpGet = new HttpGet(url); setHeader(httpGet, header);httpClient = HttpClients.createDefault(); httpResponse = httpClient.execute(httpGet); HttpEntity resEntity = httpResponse.getEntity(); responseData = EntityUtils.toString(resEntity); } catch (Exception e){ e.printStackTrace(); } finally{ httpResponse.close(); httpClient.close(); } return responseData; } private static void setHeader(HttpRequestBase httpRequestBase, HttpHeader header){ if(header != null){ Map<String,String> headerMap = header.getParams(); if (headerMap != null && !headerMap.isEmpty()) { Set<Map.Entry<String, String>> entries = headerMap.entrySet(); for (Map.Entry<String, String> entry : entries) { String name = entry.getKey(); String value = entry.getValue(); httpRequestBase.setHeader(name, value);} } } } private static String buildGetUrl(String url, String query) throws IOException { if (query == null || query.equals('')) { return url; } StringBuilder newUrl = new StringBuilder(url); boolean hasQuery = url.contains('?'); boolean hasPrepend = (url.endsWith('?')) || (url.endsWith('&')); if (!hasPrepend) { if (hasQuery) {newUrl.append('&'); } else {newUrl.append('?');hasQuery = true; } } newUrl.append(query); hasPrepend = false; return newUrl.toString(); }}

HttpService.java

package demo;import java.util.Map;import com.alibaba.fastjson.JSONObject;import com.alibaba.fastjson.TypeReference;public class HttpService { private String serverUrl; private int connectTimeout = 15000; private int readTimeout = 30000; public HttpService(String serverUrl) { this.serverUrl = serverUrl.trim(); } public Map<String, Object> commonService(String serviceUrl, HttpParamers paramers) throws Exception{ return commonService(serviceUrl, paramers, null); } public Map<String, Object> commonService(String serviceUrl, HttpParamers paramers, HttpHeader header) throws Exception{ String response = service(serviceUrl, paramers, header); try { Map<String, Object> result = JSONObject.parseObject(response, new TypeReference<Map<String, Object>>() {}); if ((result == null) || (result.isEmpty())) {throw new Exception('遠程服務返回的數據無法解析'); } Integer code = (Integer) result.get('code'); if ((code == null) || (code.intValue() != 0)) {throw new Exception((String) result.get('message')); } return result; } catch (Exception e) { throw new Exception('返回結果異常,response:' + response, e); } } public String service(String serviceUrl, HttpParamers paramers) throws Exception { return service(serviceUrl, paramers, null); } public String service(String serviceUrl, HttpParamers paramers, HttpHeader header) throws Exception { String url = this.serverUrl + serviceUrl; String responseData = ''; try { responseData = HttpClient.doService(url, paramers, header, this.connectTimeout, this.readTimeout); } catch (Exception e) { throw new Exception(e.getMessage(), e); } return responseData; } public String getServerUrl() { return this.serverUrl; } public int getConnectTimeout() { return this.connectTimeout; } public int getReadTimeout() { return this.readTimeout; } public void setConnectTimeout(int connectTimeout) { this.connectTimeout = connectTimeout; } public void setReadTimeout(int readTimeout) { this.readTimeout = readTimeout; }}

測試例子Test1.java

package demo;import org.junit.Ignore;import org.junit.Test;public class Test1 { //免費的在線REST服務, 提供測試用的HTTP請求假數據 //接口信息說明可見：http://www.hangge.com/blog/cache/detail_2020.html String uri = 'http://jsonplaceholder.typicode.com'; //get方式請求數據 //請求地址：http://jsonplaceholder.typicode.com/posts @Ignore('暫時忽略') @Test public void test1() { System.out.print('n' + 'test1---------------------------'+ 'n'); HttpParamers paramers = HttpParamers.httpGetParamers(); String response = ''; try { HttpService httpService = new HttpService(uri); response = httpService.service('/posts', paramers); } catch (Exception e) { e.printStackTrace(); } System.out.print(response); } //get方式請求數據 //請求地址：http://jsonplaceholder.typicode.com/posts?userId=5 @Ignore('暫時忽略') @Test public void test2() { System.out.print('n' + 'test2---------------------------'+ 'n'); HttpParamers paramers = HttpParamers.httpGetParamers(); paramers.addParam('userId', '5'); String response = ''; try { HttpService httpService = new HttpService(uri); response = httpService.service('/posts', paramers); } catch (Exception e) { e.printStackTrace(); } System.out.print(response); } //post方式請求數據 //請求地址：http://jsonplaceholder.typicode.com/posts @Test public void test3() { System.out.print('n' + 'test3---------------------------'+ 'n'); HttpParamers paramers = HttpParamers.httpPostParamers(); paramers.addParam('time', String.valueOf(System.currentTimeMillis())); String response = ''; try { HttpService httpService = new HttpService(uri); response = httpService.service('/posts', paramers); } catch (Exception e) { e.printStackTrace(); } System.out.print(response); }}

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持好吧啦網。