一種簡單的方法將是從資源加載大小別名。一些示例代碼(將所有文件都在同一個包):
的接口來封裝大小屬性
public interface Sized {
public String getSize();
}
的產品類
public class Product implements Sized {
private final String size;
public Product(String size) {
this.size = size;
}
public String getSize() {
return size;
}
@Override
public String toString() {
return size;
}
}
,做魔術比較器:
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.ResourceBundle;
public class SizedComparator implements Comparator<Sized> {
// maps size aliases to canonical sizes
private static final Map<String, String> sizes = new HashMap<String, String>();
static {
// create the lookup map from a resourcebundle
ResourceBundle sizesBundle = ResourceBundle
.getBundle(SizedComparator.class.getName());
for (String canonicalSize : sizesBundle.keySet()) {
String[] aliases = sizesBundle.getString(canonicalSize).split(",");
for (String alias : aliases) {
sizes.put(alias, canonicalSize);
}
}
}
@Override
public int compare(Sized s1, Sized s2) {
int result;
String c1 = getCanonicalSize(s1);
String c2 = getCanonicalSize(s2);
if (c1 == null && c2 == null) {
result = 0;
} else if (c1 == null) {
result = -1;
} else if (c2 == null) {
result = 1;
} else {
result = c1.compareTo(c2);
}
return result;
}
private String getCanonicalSize(Sized s1) {
String result = null;
if (s1 != null && s1.getSize() != null) {
result = sizes.get(s1.getSize());
}
return result;
}
}
SizedComparator.properties:
1 = Small,tiny
2 = medium,Average
3 = Large,big,HUGE
單元測試(只爲快樂流量):
import org.junit.Before;
import org.junit.Test;
public class FieldSortTest {
private static final String SMALL = "tiny";
private static final String LARGE = "Large";
private static final String MEDIUM = "medium";
private Comparator<Sized> instance;
@Before
public void setup() {
instance = new SizedComparator();
}
@Test
public void testHappy() {
List<Product> products = new ArrayList<Product>();
products.add(new Product(MEDIUM));
products.add(new Product(LARGE));
products.add(new Product(SMALL));
Collections.sort(products, instance);
Assert.assertSame(SMALL, products.get(0).getSize());
Assert.assertSame(MEDIUM, products.get(1).getSize());
Assert.assertSame(LARGE, products.get(2).getSize());
}
}
注意把ResourceBundle被自動緩存。您可以通過編程方式重新加載資源包:
ResourceBundle.clearCache();
(自從Java 1.6)。或者,您可以使用一些Spring magic來創建自動重新加載消息資源。
如果從搖搖晃晃的屬性文件閱讀是不夠的,你冷靜可以很容易讓你的尺寸的別名在數據庫了。
@downvote:請讓我知道這個問題的問題是什麼,我會重新考慮 – thedan
我認爲這可能有助於給出更具體的例子你的數據是什麼樣子。 –