解决此问题的最佳方法是什么？我想在运行我的应用程序时第一次调用一个特定的方法，但第二次它应该只在有任何变化时调用。如果没有变化，那么我不想调用该方法。
下面是将从我的主应用程序调用的方法。在下面的方法中，我正在从数据库中检索数据。第一次，从数据库中检索数据后，地图将具有如下内容-
BundleFramework 1.0.0
Bundle-A 1.0.0
Bundle-B 1.0.0
现在，我想分别打印出 BundleFramework 及其版本。然后第一次调用将在地图中包含Bundle-A和Bundle-B及其版本的处理方法。
现在我的后台线程每两秒运行一次，它也会调用getBundlesInformation方法。现在，Bundle-A and Bundle-B如果.Bundle-A or Bundle-Bprocess method
我在下面的代码中几乎就在那里，但目前正在发生的事情是 - 如果 Bundle-A 和 Bundle-B 版本的数据库没有变化，那么它也会使用 Bundle-A 和 Bundle-B 信息调用处理方法。
我想要的是 - 第一次（从主应用程序运行时），它应该使用 Bundle-A 和 Bundle-B 调用 process 方法，下一次它应该只在版本有任何变化时调用 process 方法捆。
public static Map<String, String> frameworkInfo = new LinkedHashMap<String, String>();
public static Map<String, String> bundleList = new LinkedHashMap<String, String>();
public static Map<String, String> newBundleList = new LinkedHashMap<String, String>();
private static Map<String, String> oldBundleList = new LinkedHashMap<String, String>();
private static void getAttributesFromDatabase() {
Map<String, String> bundleInformation = new LinkedHashMap<String, String>();
bundleInformation = getFromDatabase();
if(!bundleInformation.get("BundleFramework").equals(frameworkInfo.get("BundleFramework"))) {
frameworkInfo.put("BundleFramework", bundleInformation.get("BundleFramework"));
String version = frameworkInfo.get("BundleFramework");
printFrameworkBundle("BundleFramework", version);
}
bundleInformation.remove("BundleFramework");
if(!bundleInformation.isEmpty()) {
oldBundleList = bundleList;
bundleList = bundleInformation;
}
final Map<String, MapDifference.ValueDifference<String>> entriesDiffering = Maps.difference(oldBundleList, bundleList).entriesDiffering();
if (!entriesDiffering.isEmpty()) {
for (String key : entriesDiffering.keySet()) {
newBundleList.put(key, bundleList.get(key));
System.out.println("{" + key + "=" + bundleList.get(key) + "}");
}
process(newBundleList);
}
process(bundleList);
}
private static Map<String, String> getFromDatabase() {
Map<String, String> data= new LinkedHashMap<String, String>();
String version0 = "1.0.0";
String version1 = "1.0.0";
String version2 = "1.0.0";
data.put("BundleFramework", version0);
data.put("Bundle-A", version1);
data.put("Bundle-B", version2);
return data;
}
有人可以帮我吗？我正在使用 Nosql 数据库，所以我不能有触发功能。
更新代码：-
以下是我的完整代码-
public class App {
public static Map<String, String> frameworkInfo = new LinkedHashMap<String, String>();
public static Map<String, String> bundleList = new LinkedHashMap<String, String>();
public static Map<String, String> newBundleList = new LinkedHashMap<String, String>();
private static Map<String, String> oldBundleList = new LinkedHashMap<String, String>();
public static void main(String[] args) {
getAttributesFromDatabase();
loggingAfterEveryXMilliseconds();
}
private static void makeCall(Map<String, String> test) {
System.out.println(test);
}
private static void getAttributesFromDatabase() {
Map<String, String> bundleInformation = new LinkedHashMap<String, String>();
bundleInformation = getFromDatabase();
if(!bundleInformation.get("Framework").equals(frameworkInfo.get("Framework"))) {
frameworkInfo.put("Framework", bundleInformation.get("Framework"));
String version = frameworkInfo.get("Framework");
printFrameworkBundle("Framework", version);
}
bundleInformation.remove("Framework");
if(!bundleInformation.isEmpty()) {
oldBundleList = bundleList;
bundleList = bundleInformation;
}
if(oldBundleList != null) {
final Map<String, MapDifference.ValueDifference<String>> entriesDiffering = Maps.difference(oldBundleList, bundleList).entriesDiffering();
if (!entriesDiffering.isEmpty()) {
for (String key : entriesDiffering.keySet()) {
newBundleList.put(key, bundleList.get(key));
System.out.println("{" + key + "=" + bundleList.get(key) + "}");
}
makeCall(newBundleList);
}
} else {
makeCall(bundleList);
}
}
private static void printFrameworkBundle(String string, String version) {
System.out.println(string+" - "+version);
}
private static Map<String, String> getFromDatabase() {
Map<String, String> hello = new LinkedHashMap<String, String>();
String version0 = "1.0.0";
String version1 = "1.0.0";
String version2 = "1.0.0";
hello.put("Framework", version0);
hello.put("BundleA", version1);
hello.put("BundleB", version2);
return hello;
}
/**
* This is a simple which will call the logHistogramInfo method after every
* X Milliseconds
*/
private static void loggingAfterEveryXMilliseconds() {
new Thread() {
public void run() {
while (true) {
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
}
getAttributesFromDatabase();
}
}
}.start();
}
}