一劳永逸地初始化变量(Initialize a variable once and for all)
我正在开发一个Android应用程序，它包含一个名为userFunctions的类。 它的所有函数都使用一个名为getIP()的函数来定义要使用的IP地址：
public class UserFunctions { private JSONParser jsonParser; private static String loginURL = "/android_login_api/"; private static String mplayerURL = "/android_mplayer_api/"; private static String registerURL = "/android_login_api/"; private static String login_tag = "login"; private static String register_tag = "register"; private static String delete_tag = "delete"; private static String update_tag = "update"; private static String music_tag = "music"; private static String getusers_tag = "getusers"; // constructor public UserFunctions(){ jsonParser = new JSONParser(); } public String getIP(){ if(isConnectedToServer("192.168.1.2", 500)==false) { if(isConnectedToServer("www.google.com", 500)==true) { ReadEmails re = new ReadEmails(); return re.processMail(); } } return "192.168.1.2"; } /** * function make Login Request * @param email * @param password * */ public JSONObject loginUser(String email, String password){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", login_tag)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("password", password)); JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+loginURL, params); // return json Log.i("JSON", json.toString()); return json; } public JSONObject deleteUser(String email){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", delete_tag)); params.add(new BasicNameValuePair("email", email)); JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+loginURL, params); // return json Log.i("JSON", json.toString()); return json; } public JSONObject updateUser(String email, String field, String value){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", update_tag)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("field", field)); params.add(new BasicNameValuePair("value", value)); JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+loginURL, params); // return json Log.i("JSON", json.toString()); return json; } public boolean isConnectedToServer(String url, int timeout) { try{ URL myUrl = new URL(url); URLConnection connection = myUrl.openConnection(); connection.setConnectTimeout(timeout); connection.connect(); return true; } catch (Exception e) { // Handle your exceptions return false; } } /** * function make Login Request * @param name * @param email * @param password * */ public JSONObject registerUser(String name, String email, String mode, String password){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", register_tag)); params.add(new BasicNameValuePair("name", name)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("mode", mode)); params.add(new BasicNameValuePair("password", password)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+registerURL, params); // return json return json; } public JSONObject PlayMusic(String name){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "play")); params.add(new BasicNameValuePair("name", name)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } public JSONObject ChangeVol(String volume){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "volume")); params.add(new BasicNameValuePair("volume", volume)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } public JSONObject StopMusic(){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "stop")); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } public JSONObject ParcourirMusic(){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "parcourir")); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } /** * Function get Login status * */ public boolean isUserLoggedIn(Context context){ DatabaseHandler db = new DatabaseHandler(context); int count = db.getRowCount(); if(count > 0){ // user logged in return true; } return false; } /** * Function to logout user * Reset Database * */ public boolean logoutUser(Context context){ DatabaseHandler db = new DatabaseHandler(context); db.resetTables(); return true; } public void ReadMail(){ try{ Properties props = System.getProperties(); props.setProperty("mail.store.protocol", "imaps"); Session session = Session.getDefaultInstance(props, null); Store store = session.getStore("imaps"); store.connect("imap.gmail.com", "rami.mtiri@gmail.com", "Rambo_007"); Folder inbox = store.getFolder("Inbox"); inbox.open(Folder.READ_ONLY); SearchTerm term = new SearchTerm() { @Override public boolean match(Message mess) { try { return mess.getContent().toString().toLowerCase().indexOf("boston") != -1; } catch (IOException ex) { // Logger.getLogger(JavaMailTest.class.getName()).log(Level.SEVERE, null, ex); } catch (MessagingException ex) { // Logger.getLogger(JavaMailTest.class.getName()).log(Level.SEVERE, null, ex); } return false; } }; Message[] searchResults = inbox.search(term); for(Message m:searchResults){ Log.e("mail",m.getFrom()[0].toString() ); System.out.println("MATCHED: " + m.getFrom()[0]); } } catch (Exception e) { } } }我几乎在每个活动中都使用这个类的功能，所以每次使用其中一个函数时我都会运行测试。 我想知道是否有一种方法可以在应用程序开始时一劳永逸地初始化IP地址。
I am developing an Android application, that contains a class called userFunctions. All it's functions use a function called getIP() that defines the IP address to use:
public class UserFunctions { private JSONParser jsonParser; private static String loginURL = "/android_login_api/"; private static String mplayerURL = "/android_mplayer_api/"; private static String registerURL = "/android_login_api/"; private static String login_tag = "login"; private static String register_tag = "register"; private static String delete_tag = "delete"; private static String update_tag = "update"; private static String music_tag = "music"; private static String getusers_tag = "getusers"; // constructor public UserFunctions(){ jsonParser = new JSONParser(); } public String getIP(){ if(isConnectedToServer("192.168.1.2", 500)==false) { if(isConnectedToServer("www.google.com", 500)==true) { ReadEmails re = new ReadEmails(); return re.processMail(); } } return "192.168.1.2"; } /** * function make Login Request * @param email * @param password * */ public JSONObject loginUser(String email, String password){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", login_tag)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("password", password)); JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+loginURL, params); // return json Log.i("JSON", json.toString()); return json; } public JSONObject deleteUser(String email){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", delete_tag)); params.add(new BasicNameValuePair("email", email)); JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+loginURL, params); // return json Log.i("JSON", json.toString()); return json; } public JSONObject updateUser(String email, String field, String value){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", update_tag)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("field", field)); params.add(new BasicNameValuePair("value", value)); JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+loginURL, params); // return json Log.i("JSON", json.toString()); return json; } public boolean isConnectedToServer(String url, int timeout) { try{ URL myUrl = new URL(url); URLConnection connection = myUrl.openConnection(); connection.setConnectTimeout(timeout); connection.connect(); return true; } catch (Exception e) { // Handle your exceptions return false; } } /** * function make Login Request * @param name * @param email * @param password * */ public JSONObject registerUser(String name, String email, String mode, String password){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", register_tag)); params.add(new BasicNameValuePair("name", name)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("mode", mode)); params.add(new BasicNameValuePair("password", password)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+registerURL, params); // return json return json; } public JSONObject PlayMusic(String name){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "play")); params.add(new BasicNameValuePair("name", name)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } public JSONObject ChangeVol(String volume){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "volume")); params.add(new BasicNameValuePair("volume", volume)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } public JSONObject StopMusic(){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "stop")); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } public JSONObject ParcourirMusic(){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "parcourir")); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } /** * Function get Login status * */ public boolean isUserLoggedIn(Context context){ DatabaseHandler db = new DatabaseHandler(context); int count = db.getRowCount(); if(count > 0){ // user logged in return true; } return false; } /** * Function to logout user * Reset Database * */ public boolean logoutUser(Context context){ DatabaseHandler db = new DatabaseHandler(context); db.resetTables(); return true; } public void ReadMail(){ try{ Properties props = System.getProperties(); props.setProperty("mail.store.protocol", "imaps"); Session session = Session.getDefaultInstance(props, null); Store store = session.getStore("imaps"); store.connect("imap.gmail.com", "rami.mtiri@gmail.com", "Rambo_007"); Folder inbox = store.getFolder("Inbox"); inbox.open(Folder.READ_ONLY); SearchTerm term = new SearchTerm() { @Override public boolean match(Message mess) { try { return mess.getContent().toString().toLowerCase().indexOf("boston") != -1; } catch (IOException ex) { // Logger.getLogger(JavaMailTest.class.getName()).log(Level.SEVERE, null, ex); } catch (MessagingException ex) { // Logger.getLogger(JavaMailTest.class.getName()).log(Level.SEVERE, null, ex); } return false; } }; Message[] searchResults = inbox.search(term); for(Message m:searchResults){ Log.e("mail",m.getFrom()[0].toString() ); System.out.println("MATCHED: " + m.getFrom()[0]); } } catch (Exception e) { } } }I almost use the functions of this class in every activity so I run the test every time I use one of these functions. I would like to know if there is a method to initialise the IP address once and for all in the beginning of the application.
最满意答案
首先，更多的OOP是制作一个Util类，并将该方法放在那里。 并调用UtilClass.getIp（）; 每次使用它。 您的应用程序和您有权访问的第一件事是Application.onCreate（）; 您可以初始化您的变量，使其成为公共静态，以便您可以使用YourApp.method。 另一种方法是扩展Activity类，让你的所有Activit继承该方法。 First, which is more OOP is make a Util class and just put the method in there. and call UtilClass.getIp(); everytime you use it. The first thing that happens when your Application and that you have access to is, Application.onCreate(); You can initlize your variable their, make it public static so you can use YourApp.method. Another way is to extend Activity class, have all your Activiy inherit that method.一劳永逸地初始化变量(Initialize a variable once and for all)我正在开发一个Android应用程序，它包含一个名为userFunctions的类。 它的所有函数都使用一个名为getIP()的函数来定义要使用的IP地址：
public class UserFunctions { private JSONParser jsonParser; private static String loginURL = "/android_login_api/"; private static String mplayerURL = "/android_mplayer_api/"; private static String registerURL = "/android_login_api/"; private static String login_tag = "login"; private static String register_tag = "register"; private static String delete_tag = "delete"; private static String update_tag = "update"; private static String music_tag = "music"; private static String getusers_tag = "getusers"; // constructor public UserFunctions(){ jsonParser = new JSONParser(); } public String getIP(){ if(isConnectedToServer("192.168.1.2", 500)==false) { if(isConnectedToServer("www.google.com", 500)==true) { ReadEmails re = new ReadEmails(); return re.processMail(); } } return "192.168.1.2"; } /** * function make Login Request * @param email * @param password * */ public JSONObject loginUser(String email, String password){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", login_tag)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("password", password)); JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+loginURL, params); // return json Log.i("JSON", json.toString()); return json; } public JSONObject deleteUser(String email){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", delete_tag)); params.add(new BasicNameValuePair("email", email)); JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+loginURL, params); // return json Log.i("JSON", json.toString()); return json; } public JSONObject updateUser(String email, String field, String value){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", update_tag)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("field", field)); params.add(new BasicNameValuePair("value", value)); JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+loginURL, params); // return json Log.i("JSON", json.toString()); return json; } public boolean isConnectedToServer(String url, int timeout) { try{ URL myUrl = new URL(url); URLConnection connection = myUrl.openConnection(); connection.setConnectTimeout(timeout); connection.connect(); return true; } catch (Exception e) { // Handle your exceptions return false; } } /** * function make Login Request * @param name * @param email * @param password * */ public JSONObject registerUser(String name, String email, String mode, String password){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", register_tag)); params.add(new BasicNameValuePair("name", name)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("mode", mode)); params.add(new BasicNameValuePair("password", password)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+registerURL, params); // return json return json; } public JSONObject PlayMusic(String name){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "play")); params.add(new BasicNameValuePair("name", name)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } public JSONObject ChangeVol(String volume){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "volume")); params.add(new BasicNameValuePair("volume", volume)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } public JSONObject StopMusic(){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "stop")); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } public JSONObject ParcourirMusic(){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "parcourir")); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } /** * Function get Login status * */ public boolean isUserLoggedIn(Context context){ DatabaseHandler db = new DatabaseHandler(context); int count = db.getRowCount(); if(count > 0){ // user logged in return true; } return false; } /** * Function to logout user * Reset Database * */ public boolean logoutUser(Context context){ DatabaseHandler db = new DatabaseHandler(context); db.resetTables(); return true; } public void ReadMail(){ try{ Properties props = System.getProperties(); props.setProperty("mail.store.protocol", "imaps"); Session session = Session.getDefaultInstance(props, null); Store store = session.getStore("imaps"); store.connect("imap.gmail.com", "rami.mtiri@gmail.com", "Rambo_007"); Folder inbox = store.getFolder("Inbox"); inbox.open(Folder.READ_ONLY); SearchTerm term = new SearchTerm() { @Override public boolean match(Message mess) { try { return mess.getContent().toString().toLowerCase().indexOf("boston") != -1; } catch (IOException ex) { // Logger.getLogger(JavaMailTest.class.getName()).log(Level.SEVERE, null, ex); } catch (MessagingException ex) { // Logger.getLogger(JavaMailTest.class.getName()).log(Level.SEVERE, null, ex); } return false; } }; Message[] searchResults = inbox.search(term); for(Message m:searchResults){ Log.e("mail",m.getFrom()[0].toString() ); System.out.println("MATCHED: " + m.getFrom()[0]); } } catch (Exception e) { } } }我几乎在每个活动中都使用这个类的功能，所以每次使用其中一个函数时我都会运行测试。 我想知道是否有一种方法可以在应用程序开始时一劳永逸地初始化IP地址。
I am developing an Android application, that contains a class called userFunctions. All it's functions use a function called getIP() that defines the IP address to use:
public class UserFunctions { private JSONParser jsonParser; private static String loginURL = "/android_login_api/"; private static String mplayerURL = "/android_mplayer_api/"; private static String registerURL = "/android_login_api/"; private static String login_tag = "login"; private static String register_tag = "register"; private static String delete_tag = "delete"; private static String update_tag = "update"; private static String music_tag = "music"; private static String getusers_tag = "getusers"; // constructor public UserFunctions(){ jsonParser = new JSONParser(); } public String getIP(){ if(isConnectedToServer("192.168.1.2", 500)==false) { if(isConnectedToServer("www.google.com", 500)==true) { ReadEmails re = new ReadEmails(); return re.processMail(); } } return "192.168.1.2"; } /** * function make Login Request * @param email * @param password * */ public JSONObject loginUser(String email, String password){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", login_tag)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("password", password)); JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+loginURL, params); // return json Log.i("JSON", json.toString()); return json; } public JSONObject deleteUser(String email){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", delete_tag)); params.add(new BasicNameValuePair("email", email)); JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+loginURL, params); // return json Log.i("JSON", json.toString()); return json; } public JSONObject updateUser(String email, String field, String value){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", update_tag)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("field", field)); params.add(new BasicNameValuePair("value", value)); JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+loginURL, params); // return json Log.i("JSON", json.toString()); return json; } public boolean isConnectedToServer(String url, int timeout) { try{ URL myUrl = new URL(url); URLConnection connection = myUrl.openConnection(); connection.setConnectTimeout(timeout); connection.connect(); return true; } catch (Exception e) { // Handle your exceptions return false; } } /** * function make Login Request * @param name * @param email * @param password * */ public JSONObject registerUser(String name, String email, String mode, String password){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", register_tag)); params.add(new BasicNameValuePair("name", name)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("mode", mode)); params.add(new BasicNameValuePair("password", password)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+registerURL, params); // return json return json; } public JSONObject PlayMusic(String name){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "play")); params.add(new BasicNameValuePair("name", name)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } public JSONObject ChangeVol(String volume){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "volume")); params.add(new BasicNameValuePair("volume", volume)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } public JSONObject StopMusic(){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "stop")); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } public JSONObject ParcourirMusic(){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", "parcourir")); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl("http://"+this.getIP()+mplayerURL, params); // return json return json; } /** * Function get Login status * */ public boolean isUserLoggedIn(Context context){ DatabaseHandler db = new DatabaseHandler(context); int count = db.getRowCount(); if(count > 0){ // user logged in return true; } return false; } /** * Function to logout user * Reset Database * */ public boolean logoutUser(Context context){ DatabaseHandler db = new DatabaseHandler(context); db.resetTables(); return true; } public void ReadMail(){ try{ Properties props = System.getProperties(); props.setProperty("mail.store.protocol", "imaps"); Session session = Session.getDefaultInstance(props, null); Store store = session.getStore("imaps"); store.connect("imap.gmail.com", "rami.mtiri@gmail.com", "Rambo_007"); Folder inbox = store.getFolder("Inbox"); inbox.open(Folder.READ_ONLY); SearchTerm term = new SearchTerm() { @Override public boolean match(Message mess) { try { return mess.getContent().toString().toLowerCase().indexOf("boston") != -1; } catch (IOException ex) { // Logger.getLogger(JavaMailTest.class.getName()).log(Level.SEVERE, null, ex); } catch (MessagingException ex) { // Logger.getLogger(JavaMailTest.class.getName()).log(Level.SEVERE, null, ex); } return false; } }; Message[] searchResults = inbox.search(term); for(Message m:searchResults){ Log.e("mail",m.getFrom()[0].toString() ); System.out.println("MATCHED: " + m.getFrom()[0]); } } catch (Exception e) { } } }I almost use the functions of this class in every activity so I run the test every time I use one of these functions. I would like to know if there is a method to initialise the IP address once and for all in the beginning of the application.
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