Java访问远程服务

摘要: Java访问远程服务

随着webService的崛起，我们开始中会越来越多的使用到访问远程webService服务。当然对于不同的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，那么必然需要在自己的代码中引入它的包，如果同时调运了多个不同框架的webService，那么就需要同时引入多个不同的client包，这样做是很烦的。Java本生提供访问远程服务的包，在java.net.*下。接下来我们就用Java原生的package访问webService。

1、发送GET请求

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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");//此处访问有道的webService服务，参数都在url中 URLConnection connection = url.openConnection();//得到一个连接对象 InputStream is = connection.getInputStream(); InputStreamReader isr = new InputStreamReader(is, "UTF-8"); BufferedReader br = new BufferedReader(isr);//用于读取返回的数据流 StringBuffer sb = new StringBuffer();//用于接收返回的数据 String line = null; while ((line = br.readLine()) != null) { sb.append(line); } System.out.println(sb.toString()); br.close();//关闭各种连接 isr.close(); is.close(); } catch (IOException e) { e.printStackTrace(); } } }

2、发送POST请求

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class ReadByPost implements Runnable { public void run() { try { URL url = new URL("http://fanyi.youdao.com/openapi.do");//此处通过post访问有道webService // URLConnection connection = url.openConnection(); HttpURLConnection connection = (HttpURLConnection) url .openConnection();//得到一个http的连接对象 connection.addRequestProperty("encoding", "UTF-8"); connection.setRequestMethod("POST");//设置请求方式 connection.setDoInput(true);//设置可写入 connection.setDoOutput(true);//设置可读取 OutputStream os = connection.getOutputStream(); OutputStreamWriter osw = new OutputStreamWriter(os, "UTF-8"); BufferedWriter bw = new BufferedWriter(osw);//定义写入流对象 bw.write("keyfrom=gusi123123&key=1075925116&type=data&doctype=xml&version=1.1&q=hello"); bw.flush();//通过写入流对象写入请求参数 InputStream is = connection.getInputStream(); InputStreamReader isr = new InputStreamReader(is, "UTF-8"); BufferedReader br = new BufferedReader(isr);//定义读取流对象 StringBuffer sb = new StringBuffer(); String line = null; while ((line = br.readLine()) != null) { sb.append(line); }//通过读取流读取返回数据 //关闭各种连接对象 br.close(); isr.close(); is.close(); bw.close(); osw.close(); os.close(); System.out.println(sb.toString()); } catch (IOException e) { e.printStackTrace(); } } }

通过上面也发现使用java原生的package访问webService比较麻烦，然后我们伟大的apache也给我们提供通用的访问webService的jar包，需要的jar包依赖是：（使用到的类在org.apache.http.*）
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.3.6</version>
</dependency>

3、通过httpclient发送GET请求

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public class ReadByClientGet implements Runnable { HttpClient client = HttpClients.createDefault(); public void run() { String uri = "http://www.baidu.com";//访问百度 HttpGet get = new HttpGet(uri);//得到请求对象 try { HttpResponse response = client.execute(get);//执行访问请求 HttpEntity entity = response.getEntity();//得到返回数据 String result = EntityUtils.toString(entity, "UTF-8");//将返回数据输出 System.out.println(result); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }

4、通过httpclient发送POST请求

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public class ReadByClientPost implements Runnable { HttpClient client = HttpClients.createDefault();//创建一个client对象 public void run() { try { String uri = "http://fanyi.youdao.com/openapi.do";//post访问有道webService HttpPost post = new HttpPost(uri);//得到post请求对象 //构造请求参数，通过NameValuePair对象（类似于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);//执行post请求，并且接收返回数据 HttpEntity entity = response.getEntity(); String result = EntityUtils.toString(entity, "UTF-8"); System.out.println(result);//输出返回数据 } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }

通过上面httpclient只是最简单的基本的访问webService服务。当然还有很多其他细节以及功能可以设计和处理。接下来通过测试方法测试上面的四种访问请求的结果：（输出结果不再粘贴）

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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(); } }