如何在Java客户端调用RESTful服务

在这个例子中，我们将看到如何使用java.net包实用工具，创建一个访问REST服务RESTful的客户端。当然这不是创建一个RESTful客户端最简单的方法，因为你必须自己读取服务器端的响应，以及Json和Java对象的转换。

请求Get

public class JavaNetURLRESTFulClient {

private static final String targetURL = "http://localhost:8080/JerseyJSONExample/rest/jsonServices/print/Jamie";

public static void main(String[] args) {

try {

URL restServiceURL = new URL(targetURL);

HttpURLConnection httpConnection = (HttpURLConnection) restServiceURL.openConnection();
                     httpConnection.setRequestMethod("GET");
                     httpConnection.setRequestProperty("Accept", "application/json");

if (httpConnection.getResponseCode() != 200) {
                            throw new RuntimeException("HTTP GET Request Failed with Error code : "
                                          + httpConnection.getResponseCode());
                     }

BufferedReader responseBuffer = new BufferedReader(new InputStreamReader(
                            (httpConnection.getInputStream())));

String output;
                     System.out.println("Output from Server:  \n");

while ((output = responseBuffer.readLine()) != null) {
                            System.out.println(output);
                     }

httpConnection.disconnect();

} catch (MalformedURLException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}

}
}

运行后输出结果是：

Output from Server:      {"id":1,"firstName":"Jamie","age":22,"lastName":"Diaz"}

POST提交：

public class JavaNetURLRESTFulClient {

private static final String targetURL = "http://localhost:8080/JerseyJSONExample/rest/jsonServices/send";

public static void main(String[] args) {

try {

URL targetUrl = new URL(targetURL);

HttpURLConnection httpConnection = (HttpURLConnection) targetUrl.openConnection();
                     httpConnection.setDoOutput(true);
                     httpConnection.setRequestMethod("POST");
                     httpConnection.setRequestProperty("Content-Type", "application/json");

String input = "{\"id\":1,\"firstName\":\"Liam\",\"age\":22,\"lastName\":\"Marco\"}";

OutputStream outputStream = httpConnection.getOutputStream();
                     outputStream.write(input.getBytes());
                     outputStream.flush();

if (httpConnection.getResponseCode() != 200) {
                            throw new RuntimeException("Failed : HTTP error code : "
                                   + httpConnection.getResponseCode());
                     }

BufferedReader responseBuffer = new BufferedReader(new InputStreamReader(
                                   (httpConnection.getInputStream())));

String output;
                     System.out.println("Output from Server:\n");
                     while ((output = responseBuffer.readLine()) != null) {
                            System.out.println(output);
                     }

httpConnection.disconnect();

} catch (MalformedURLException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}

}     
}