java – 当唯一部分在循环/ try-catch中时避免重复代码
内容导读
互联网集市收集整理的这篇技术教程文章主要介绍了java – 当唯一部分在循环/ try-catch中时避免重复代码，小编现在分享给大家，供广大互联网技能从业者学习和参考。文章包含6337字，纯文字阅读大概需要10分钟。
内容图文
我有一个类有两个方法,有很多重复的代码但是唯一的位在整个事件的中间.根据我的研究,我认为我应该做“执行周围方法”模式,但我找不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,我已粘贴在下面.我已经将这些方法的独特部分包装在一起,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
* https://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
* https://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“执行周围方法”模式来保存代码重复吗？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明智的替代方案吗？
解决方法:
可以通过将“唯一”代码提取到特殊工作者中来完成.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,你总是可以切换到创建匿名类：
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
}
});
内容总结
以上是互联网集市为您收集整理的java – 当唯一部分在循环/ try-catch中时避免重复代码全部内容，希望文章能够帮你解决java – 当唯一部分在循环/ try-catch中时避免重复代码所遇到的程序开发问题。 如果觉得互联网集市技术教程内容还不错，欢迎将互联网集市网站推荐给程序员好友。
内容备注
版权声明：本文内容由互联网用户自发贡献，该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请发送邮件至 gblab@vip.qq.com 举报，一经查实，本站将立刻删除。
内容手机端
扫描二维码推送至手机访问。
来源：【匿名】