我有一个类有两个方法，它们有很多重复的代码但是唯一的位在整个事物的中间。根据我的研究，我认为我应该做的是＆＃34;执行周围的方法＆＃34;模式，但我无法找到我可以遵循的资源，因为他们似乎都使用我无法复制的代码。
我有两种方法，apiPost和apiGet，我已经粘贴在下面。我已经将这些方法的独特部分包装在一起，其中的注释显示了唯一部分的开始和结束位置：
/**
* Class that handles authorising the connection and handles posting and getting data
*
* @version %I%, %G%
* @since 1.0
*/
public class CallHandler {
private static PropertyLoader props = PropertyLoader.getInstance();
final static int MAX = props.getPropertyAsInteger(props.MAX_REQUESTS);
private final Logger log = LoggerFactory.getLogger(CallHandler.class);
private final static String POST = "POST";
private final static String GET = "GET";
/**
* Makes a POST call to the API URL provided and returns the JSON response as a string
* http://stackoverflow.com/questions/15570656/how-to-send-request-payload-to-rest-api-in-java
*
* @param urlString the API URL to send the data to, as a string
* @param payload the serialised JSON payload string
* @return and value returned as a JSON string, ready to be deserialised
*/
public String apiPost(String urlString, String payload) {
boolean keepGoing = true;
int tries = 0;
String line;
StringBuilder jsonString = new StringBuilder();
log.debug("Making API Call: {}", urlString);
while (keepGoing && tries < MAX) {
tries++;
try {
URL url = new URL(urlString);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
// UNIQUE CODE START
prepareConnection(connection, POST);
OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream(), "UTF-8");
writer.write(payload);
writer.close();
// UNIQUE CODE END
BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
while ((line = br.readLine()) != null) {
jsonString.append(line);
}
br.close();
connection.disconnect();
keepGoing = false;
} catch (Exception e) {
log.warn("Try #{}. Error posting: {}", tries, e.getMessage());
log.warn("Pausing for 1 second then trying again...");
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException f) {
log.warn("Sleeping has been interrupted: {}", f.getMessage());
}
}
}
return jsonString.toString();
}
/**
* Makes a GET call to the API URL provided and returns the JSON response as a string
* http://stackoverflow.com/questions/2793150/using-java-net-urlconnection-to-fire-and-handle-http-requests
*
* @param urlString the API URL to request the data from, as a string
* @return the json response as a string, ready to be deserialised
*/
public String apiGet(String urlString) {
boolean keepGoing = true;
int tries = 0;
String line;
StringBuilder jsonString = new StringBuilder();
log.debug("Making API Call: {}", urlString);
while (keepGoing && tries < MAX) {
tries++;
try {
URL url = new URL(urlString);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
// UNIQUE CODE START
prepareConnection(connection, GET);
connection.connect();
// UNIQUE CODE END
BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
while ((line = br.readLine()) != null) {
jsonString.append(line);
}
br.close();
connection.disconnect();
keepGoing = false;
} catch (Exception e) {
log.warn("Try #{}. Error getting from API: {}", tries, e.getMessage());
log.warn("Pausing for 1 second then trying again...");
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException f) {
log.warn("Sleeping has been interrupted: {}", f.getMessage());
}
}
}
return jsonString.toString();
}
/**
* Prepares the HTTP Url connection depending on whether this is a POST or GET call
*
* @param connection the connection to prepare
* @param method whether the call is a POST or GET call
*/
private void prepareConnection(HttpURLConnection connection, String method) {
String charset = "UTF-8";
try {
connection.setRequestMethod(method);
if (method.equals(GET)) {
connection.setRequestProperty("Accept-Charset", charset);
} else if (method.equals(POST)) {
connection.setDoInput(true);
connection.setDoOutput(true);
connection.setRequestProperty("Content-Type", "application/json; charset=" + charset);
}
connection.setRequestProperty("Accept", "application/json");
connection.setRequestProperty("Authorization", "Bearer " + apiKey);
} catch (Exception e) {
log.error("Error preparing HTTP URL connection: {}", e.getMessage());
throw new RuntimeException(e.getMessage());
}
}
我可以使用＆＃34;执行方法＆＃34;模式在这里保存代码重复？如果是这样，有人可以帮我弄清楚如何重构这段代码来使用它。如果这是错误的方式，那么有人会提出一个聪明的替代方案吗？
答案 0 :(得分：5)
可以通过向特殊工作者提取“唯一”代码来完成。更具体地说，例如，您可以使用lambda表达式：
public String apiPost(String urlString, String payload) {
return commonMethod(urlString, payload, (connection) -> {
// UNIQUE CODE START
prepareConnection(connection, POST);
OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream(), "UTF-8");
writer.write(payload);
writer.close();
// UNIQUE CODE END
});
}
interface ConnectionWorker {
void run(HttpURLConnection connection) throws IOException;
}
public String commonMethod(String urlString, String payload, ConnectionWorker worker) {
boolean keepGoing = true;
int tries = 0;
String line;
StringBuilder jsonString = new StringBuilder();
log.debug("Making API Call: {}", urlString);
while (keepGoing && tries < MAX) {
tries++;
try {
URL url = new URL(urlString);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
worker.run(connection);
BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
while ((line = br.readLine()) != null) {
jsonString.append(line);
}
br.close();
connection.disconnect();
keepGoing = false;
} catch (Exception e) {
log.warn("Try #{}. Error posting: {}", tries, e.getMessage());
log.warn("Pausing for 1 second then trying again...");
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException f) {
log.warn("Sleeping has been interrupted: {}", f.getMessage());
}
}
}
return jsonString.toString();
}
更新：如果你不能使用java 8和lambda，你可以随时切换到创建匿名类：
return commonMethod(urlString, payload, new ConnectionWorker() {
@Override
public void run(HttpURLConnection connection) throws IOException {
// UNIQUE CODE START
CallHandler.this.prepareConnection(connection, POST);
OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream(), "UTF-8");
writer.write(payload);
writer.close();
// UNIQUE CODE END
}
});