Java訪問遠程服務

    隨着webService的崛起，我們開始中會越來越多的使用到訪問遠程webService服務。當然對於不同的webService框架一般都有自己的client包供使用，但是如果使用webService框架自己的client包，那麼必然需要在自己的代碼中引入它的包，如果同時調運了多個不同框架的webService，那麼就需要同時引入多個不同的client包，這樣做是很煩的。Java本生提供訪問遠程服務的包，在java.net.*下。接下來我們就用Java原生的package訪問webService。

 

1、發送GET請求

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class ReadByGet implements Runnable {     public void run() {         try {             URL url = new URL(                     "http://fanyi.youdao.com/openapi.do?keyfrom=gusi123123&key=1075925116&type=data&doctype=json&version=1.1&q=hello");//此處訪問有道的webService服務，參數都在url中             URLConnection connection = url.openConnection();//得到一個連接對象             InputStream is = connection.getInputStream();             InputStreamReader isr = new InputStreamReader(is, "UTF-8");             BufferedReader br = new BufferedReader(isr);//用於讀取返回的數據流               StringBuffer sb = new StringBuffer();//用於接收返回的數據             String line = null;             while ((line = br.readLine()) != null) {                 sb.append(line);             }             System.out.println(sb.toString());             br.close();//關閉各種連接             isr.close();             is.close();         } catch (IOException e) {             e.printStackTrace();         }     } }

 

2、發送POST請求

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class ReadByPost implements Runnable {     public void run() {         try {             URL url = new URL("http://fanyi.youdao.com/openapi.do");//此處通過post訪問有道webService             // URLConnection connection = url.openConnection();             HttpURLConnection connection = (HttpURLConnection) url                     .openConnection();//得到一個http的連接對象             connection.addRequestProperty("encoding", "UTF-8");             connection.setRequestMethod("POST");//設置請求方式             connection.setDoInput(true);//設置可寫入             connection.setDoOutput(true);//設置可讀取               OutputStream os = connection.getOutputStream();             OutputStreamWriter osw = new OutputStreamWriter(os, "UTF-8");             BufferedWriter bw = new BufferedWriter(osw);//定義寫入流對象               bw.write("keyfrom=gusi123123&key=1075925116&type=data&doctype=xml&version=1.1&q=hello");             bw.flush();//通過寫入流對象寫入請求參數               InputStream is = connection.getInputStream();             InputStreamReader isr = new InputStreamReader(is, "UTF-8");             BufferedReader br = new BufferedReader(isr);//定義讀取流對象               StringBuffer sb = new StringBuffer();             String line = null;             while ((line = br.readLine()) != null) {                 sb.append(line);             }//通過讀取流讀取返回數據               //關閉各種連接對象             br.close();             isr.close();             is.close();             bw.close();             osw.close();             os.close();               System.out.println(sb.toString());         } catch (IOException e) {             e.printStackTrace();         }     } }

 

    通過上面也發現使用java原生的package訪問webService比較麻煩，然後我們偉大的apache也給我們提供通用的訪問webService的jar包，需要的jar包依賴是：（使用到的類在org.apache.http.*）

<dependency>

    <groupId>org.apache.httpcomponents</groupId>

    <artifactId>httpclient</artifactId>

    <version>4.3.6</version>

</dependency>

 

3、通過httpclient發送GET請求

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public class ReadByClientGet implements Runnable {     HttpClient client = HttpClients.createDefault();       public void run() {         String uri = "http://www.baidu.com";//訪問百度         HttpGet get = new HttpGet(uri);//得到請求對象         try {             HttpResponse response = client.execute(get);//執行訪問請求             HttpEntity entity = response.getEntity();//得到返回數據             String result = EntityUtils.toString(entity, "UTF-8");//將返回數據輸出             System.out.println(result);         } catch (ClientProtocolException e) {             e.printStackTrace();         } catch (IOException e) {             e.printStackTrace();         }     } }

 

4、通過httpclient發送POST請求

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public class ReadByClientPost implements Runnable {     HttpClient client = HttpClients.createDefault();//創建一個client對象     public void run() {         try {             String uri = "http://fanyi.youdao.com/openapi.do";//post訪問有道webService             HttpPost post = new HttpPost(uri);//得到post請求對象             //構造請求參數，通過NameValuePair對象（類似於Map集合）             List<NameValuePair> parameters = new ArrayList<NameValuePair>();             parameters.add(new BasicNameValuePair("keyfrom", "gusi123123"));             parameters.add(new BasicNameValuePair("key", "1075925116"));             parameters.add(new BasicNameValuePair("type", "data"));             parameters.add(new BasicNameValuePair("doctype", "json"));             parameters.add(new BasicNameValuePair("version", "1.1"));             parameters.add(new BasicNameValuePair("q", "java"));             post.setEntity(new UrlEncodedFormEntity(parameters,"UTF-8"));               HttpResponse response = client.execute(post);//執行post請求，並且接收返回數據             HttpEntity entity = response.getEntity();             String result = EntityUtils.toString(entity, "UTF-8");             System.out.println(result);//輸出返回數據         } catch (ClientProtocolException e) {             e.printStackTrace();         } catch (IOException e) {             e.printStackTrace();         }     } }

    通過上面httpclient只是最簡單的基本的訪問webService服務。當然還有很多其他細節以及功能可以設計和處理。接下來通過測試方法測試上面的四種訪問請求的結果：（輸出結果不再粘貼）

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public class Main {     public static void main(String[] args) {         // new Thread(new ReadByGet()).start();         // new Thread(new ReadByPost()).start();         // new Thread(new ReadByClientGet()).start();         //new Thread(new ReadByClientPost()).start();     } }

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