Constants类
说明： Constants类对类的公共静态变量做一些转化
Constants.png
Constants.java构造方法
public Constants(Class<?> clazz) {
Assert.notNull(clazz);
this.className = clazz.getName();
Field[] fields = clazz.getFields();
for (Field field : fields) {
if (ReflectionUtils.isPublicStaticFinal(field)) {
String name = field.getName();
try {
Object value = field.get(null);
this.fieldCache.put(name, value);
}
catch (IllegalAccessException ex) {
// just leave this field and continue
}
}
}
}
Object value = field.get(null);
在java的反射中,通过字段获取对象,是通过public Object get(Object obj)
- 字段不是静态字段的话,要传入反射类的对象.如果传null是会报
java.lang.NullPointerException - 字段是静态字段的话,传入任何对象都是可以的,包括null
ConstantsTest测试用例：
@SuppressWarnings("unused")
private static final class A {
public static final int DOG = 0;
public static final int CAT = 66;
public static final String S1 = "";
public static final int PREFIX_NO = 1;
public static final int PREFIX_YES = 2;
public static final int MY_PROPERTY_NO = 1;
public static final int MY_PROPERTY_YES = 2;
public static final int NO_PROPERTY = 3;
public static final int YES_PROPERTY = 4;
/** ignore these */
protected static final int P = -1;
protected boolean f;
static final Object o = new Object();
}
public class ConstantsTests extends TestCase {
public void testConstants() {
Constants c = new Constants(A.class);
assertEquals(A.class.getName(), c.getClassName());
assertEquals(9, c.getSize());
assertEquals(c.asNumber("DOG").intValue(), A.DOG);
assertEquals(c.asNumber("dog").intValue(), A.DOG);
assertEquals(c.asNumber("cat").intValue(), A.CAT);
try {
c.asNumber("bogus");
fail("Can't get bogus field");
}
catch (ConstantException expected) {
}
assertTrue(c.asString("S1").equals(A.S1));
try {
c.asNumber("S1");
fail("Wrong type");
}
catch (ConstantException expected) {
}
}
public void testGetNames() {
Constants c = new Constants(A.class);
Set<?> names = c.getNames("");
assertEquals(c.getSize(), names.size());
assertTrue(names.contains("DOG"));
assertTrue(names.contains("CAT"));
assertTrue(names.contains("S1"));
names = c.getNames("D");
assertEquals(1, names.size());
assertTrue(names.contains("DOG"));
names = c.getNames("d");
assertEquals(1, names.size());
assertTrue(names.contains("DOG"));
}
public void testGetValues() {
Constants c = new Constants(A.class);
Set<?> values = c.getValues("");
assertEquals(7, values.size());
assertTrue(values.contains(new Integer(0)));
assertTrue(values.contains(new Integer(66)));
assertTrue(values.contains(""));
values = c.getValues("D");
assertEquals(1, values.size());
assertTrue(values.contains(new Integer(0)));
values = c.getValues("prefix");
assertEquals(2, values.size());
assertTrue(values.contains(new Integer(1)));
assertTrue(values.contains(new Integer(2)));
values = c.getValuesForProperty("myProperty");
assertEquals(2, values.size());
assertTrue(values.contains(new Integer(1)));
assertTrue(values.contains(new Integer(2)));
}
public void testGetValuesInTurkey() {
Locale oldLocale = Locale.getDefault();
Locale.setDefault(new Locale("tr", ""));
try {
Constants c = new Constants(A.class);
Set<?> values = c.getValues("");
assertEquals(7, values.size());
assertTrue(values.contains(new Integer(0)));
assertTrue(values.contains(new Integer(66)));
assertTrue(values.contains(""));
values = c.getValues("D");
assertEquals(1, values.size());
assertTrue(values.contains(new Integer(0)));
values = c.getValues("prefix");
assertEquals(2, values.size());
assertTrue(values.contains(new Integer(1)));
assertTrue(values.contains(new Integer(2)));
values = c.getValuesForProperty("myProperty");
assertEquals(2, values.size());
assertTrue(values.contains(new Integer(1)));
assertTrue(values.contains(new Integer(2)));
}
finally {
Locale.setDefault(oldLocale);
}
}
public void testSuffixAccess() {
Constants c = new Constants(A.class);
Set<?> names = c.getNamesForSuffix("_PROPERTY");
assertEquals(2, names.size());
assertTrue(names.contains("NO_PROPERTY"));
assertTrue(names.contains("YES_PROPERTY"));
Set<?> values = c.getValuesForSuffix("_PROPERTY");
assertEquals(2, values.size());
assertTrue(values.contains(new Integer(3)));
assertTrue(values.contains(new Integer(4)));
}
public void testToCode() {
Constants c = new Constants(A.class);
assertEquals(c.toCode(new Integer(0), ""), "DOG");
assertEquals(c.toCode(new Integer(0), "D"), "DOG");
assertEquals(c.toCode(new Integer(0), "DO"), "DOG");
assertEquals(c.toCode(new Integer(0), "DoG"), "DOG");
assertEquals(c.toCode(new Integer(0), null), "DOG");
assertEquals(c.toCode(new Integer(66), ""), "CAT");
assertEquals(c.toCode(new Integer(66), "C"), "CAT");
assertEquals(c.toCode(new Integer(66), "ca"), "CAT");
assertEquals(c.toCode(new Integer(66), "cAt"), "CAT");
assertEquals(c.toCode(new Integer(66), null), "CAT");
assertEquals(c.toCode("", ""), "S1");
assertEquals(c.toCode("", "s"), "S1");
assertEquals(c.toCode("", "s1"), "S1");
assertEquals(c.toCode("", null), "S1");
try {
c.toCode("bogus", "bogus");
fail("Should have thrown ConstantException");
}
catch (ConstantException expected) {
}
try {
c.toCode("bogus", null);
fail("Should have thrown ConstantException");
}
catch (ConstantException expected) {
}
assertEquals(c.toCodeForProperty(new Integer(1), "myProperty"), "MY_PROPERTY_NO");
assertEquals(c.toCodeForProperty(new Integer(2), "myProperty"), "MY_PROPERTY_YES");
try {
c.toCodeForProperty("bogus", "bogus");
fail("Should have thrown ConstantException");
}
catch (ConstantException expected) {
}
assertEquals(c.toCodeForSuffix(new Integer(0), ""), "DOG");
assertEquals(c.toCodeForSuffix(new Integer(0), "G"), "DOG");
assertEquals(c.toCodeForSuffix(new Integer(0), "OG"), "DOG");
assertEquals(c.toCodeForSuffix(new Integer(0), "DoG"), "DOG");
assertEquals(c.toCodeForSuffix(new Integer(0), null), "DOG");
assertEquals(c.toCodeForSuffix(new Integer(66), ""), "CAT");
assertEquals(c.toCodeForSuffix(new Integer(66), "T"), "CAT");
assertEquals(c.toCodeForSuffix(new Integer(66), "at"), "CAT");
assertEquals(c.toCodeForSuffix(new Integer(66), "cAt"), "CAT");
assertEquals(c.toCodeForSuffix(new Integer(66), null), "CAT");
assertEquals(c.toCodeForSuffix("", ""), "S1");
assertEquals(c.toCodeForSuffix("", "1"), "S1");
assertEquals(c.toCodeForSuffix("", "s1"), "S1");
assertEquals(c.toCodeForSuffix("", null), "S1");
try {
c.toCodeForSuffix("bogus", "bogus");
fail("Should have thrown ConstantException");
}
catch (ConstantException expected) {
}
try {
c.toCodeForSuffix("bogus", null);
fail("Should have thrown ConstantException");
}
catch (ConstantException expected) {
}
}
public void testGetValuesWithNullPrefix() throws Exception {
Constants c = new Constants(A.class);
Set<?> values = c.getValues(null);
assertEquals("Must have returned *all* public static final values", 7, values.size());
}
public void testGetValuesWithEmptyStringPrefix() throws Exception {
Constants c = new Constants(A.class);
Set<Object> values = c.getValues("");
assertEquals("Must have returned *all* public static final values", 7, values.size());
}
public void testGetValuesWithWhitespacedStringPrefix() throws Exception {
Constants c = new Constants(A.class);
Set<?> values = c.getValues(" ");
assertEquals("Must have returned *all* public static final values", 7, values.size());
}
public void testWithClassThatExposesNoConstants() throws Exception {
Constants c = new Constants(NoConstants.class);
assertEquals(0, c.getSize());
final Set<?> values = c.getValues("");
assertNotNull(values);
assertEquals(0, values.size());
}
public void testCtorWithNullClass() throws Exception {
try {
new Constants(null);
fail("Must have thrown IllegalArgumentException");
}
catch (IllegalArgumentException expected) {}
}
private static final class NoConstants {
}
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