1.1 第二部分：遠程接口調用方式HttpClient
問題：現在我們已經開發好了接口了，那該如何調用這個接口呢？
答：使用Httpclient客戶端。
1.1.1 Httpclient簡介
1.1.1.1 什么是httpclient
HttpClient 是 Apache Jakarta Common 下的子項目，用來提供高效的、最新的、功能豐富的支持 HTTP 協議的客戶端編程工具包，並且它支持 HTTP 協議最新的版本和建議。實現了所有 HTTP 的方法（GET,POST,PUT,HEAD 等）
1.1.1.2 httpclient作用
在java代碼中，發送Http請求。通常用來實現遠程接口調用。
1.1.2 HttpClient測試
說明：在ego-base中測試
在ego-base工程中添加httpclient的pom依賴。
| <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> </dependency> |
1.1.2.1 執行GET請求
| public static void doGet(){ // 創建Httpclient對象 CloseableHttpClient httpclient = HttpClients.createDefault();
// 創建http GET請求 HttpGet httpGet = new HttpGet("http://www.oschina.net/");
CloseableHttpResponse response = null; try { // 執行請求 response = httpclient.execute(httpGet); System.out.println(response.getStatusLine()); // 判斷返回狀態是否為200 if (response.getStatusLine().getStatusCode() == 200) { String content = EntityUtils.toString(response.getEntity(), "UTF-8"); System.out.println("內容長度：" + content.length()); } }catch(Exception e){ e.printStackTrace();
} finally { if (response != null) { try { response.close(); } catch (IOException e) { e.printStackTrace(); } } try { httpclient.close(); } catch (IOException e) { e.printStackTrace(); } } |
1.1.2.2 執行GET帶參數
| public static void doGetParam(){ // 創建Httpclient對象 CloseableHttpClient httpclient = HttpClients.createDefault(); CloseableHttpResponse response = null; try {
// 定義請求的參數 URI uri = new URIBuilder("http://www.baidu.com/s").setParameter("wd", "數據庫").build();
System.out.println(uri);
// 創建http GET請求 HttpGet httpGet = new HttpGet(uri);
// 執行請求 response = httpclient.execute(httpGet); // 判斷返回狀態是否為200 if (response.getStatusLine().getStatusCode() == 200) { String content = EntityUtils.toString(response.getEntity(), "UTF-8"); System.out.println(content); } }catch(Exception e){ e.printStackTrace();
}finally { if (response != null) { try { response.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } try { httpclient.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } |
1.1.2.3 執行post請求
| public static void doPost(){ // 創建Httpclient對象 CloseableHttpClient httpclient = HttpClientBuilder.create().setRedirectStrategy(new LaxRedirectStrategy()).build();
// 創建http POST請求 HttpPost httpPost = new HttpPost("http://www.oschina.net/");
CloseableHttpResponse response = null; try { // 執行請求 response = httpclient.execute(httpPost); System.out.println(response.getStatusLine()); // 判斷返回狀態是否為200 if (response.getStatusLine().getStatusCode() == 200) { String content = EntityUtils.toString(response.getEntity(), "UTF-8"); System.out.println(content); } }catch(Exception e){ e.printStackTrace();
}finally { if (response != null) { try { response.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } try { httpclient.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } |
1.1.2.4 執行post帶參數
| public static void doPostParam() throws Exception{ // 創建Httpclient對象 CloseableHttpClient httpclient = HttpClientBuilder.create().setRedirectStrategy(new LaxRedirectStrategy()).build();
// 創建http POST請求 HttpPost httpPost = new HttpPost("http://www.oschina.net/search");
// 設置2個post參數，一個是scope、一個是q List<NameValuePair> parameters = new ArrayList<NameValuePair>(); parameters.add(new BasicNameValuePair("scope", "project")); parameters.add(new BasicNameValuePair("q", "java")); // 構造一個form表單式的實體 UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(parameters); // 將請求實體設置到httpPost對象中 httpPost.setEntity(formEntity);
CloseableHttpResponse response = null; try { // 執行請求 response = httpclient.execute(httpPost); System.out.println(response.getStatusLine()); // 判斷返回狀態是否為200 if (response.getStatusLine().getStatusCode() == 200) { String content = EntityUtils.toString(response.getEntity(), "UTF-8"); System.out.println(content); } } finally { if (response != null) { response.close(); } httpclient.close(); } } |
1.1.3 httpclient常見問題及解決方案
1.1.3.1 請求參數亂碼
設置請求的編碼格式：
| obj.addHeader("Content-Type","application/x-www-form-urlencoded; charset=UTF-8"); |
1.1.3.2 響應HTTP/1.1 403 Forbidden
原因：網站設置了反爬蟲機制，禁止非法訪問。
解決方案：偽裝瀏覽器。
| obj.addHeader("User-Agent"," Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537. 36 (KHTML, like Gecko) Chrome/31.0.1650.63")
|