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

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

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

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

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）

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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