记一次比较好的设计（单例（双重校验+volatitle）、反射（反射过后会缓存减少反射次数）、缓存（防止缓存穿透、缓存击穿））
package spzc.module.fileImport.fileExport.exportor;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public class FileExportorManager {
public static final String EXPORTOR_PACKAGE = "spzc.module.fileImport.fileExport.exportor.impl.";
public static final String EXPORTOR_SUFFIX = "Exportor";
private Map<String, IFileExportor> importors = new ConcurrentHashMap<>();
private volatile static FileExportorManager instance;
private FileExportorManager() {
}
public static FileExportorManager getInstance() {
if (instance == null) {
synchronized (FileExportorManager.class) {
if (instance == null) {
instance = new FileExportorManager();
}
}
}
return instance;
}
@SuppressWarnings({ "unchecked", "deprecation" })
public IFileExportor get(String key) {
if (importors == null) {
return null;
}
if (importors.containsKey(key)) {
return importors.get(key);
}
IFileExportor exportor = null;
synchronized (Object.class) {
if (importors.containsKey(key)) {
return importors.get(key);
}
try {
Class<? extends IFileExportor> clazz = (Class<? extends IFileExportor>) Class
.forName(EXPORTOR_PACKAGE + key + EXPORTOR_SUFFIX);
exportor = clazz.newInstance();
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) {
e.printStackTrace();
}
importors.put(key, exportor);
}
return exportor;
}
}
