1 public class MyTest {
2 public static void main(String args[]) {
3 Class
4 Field[] fieldPublic = cls.getFields();
5 System.out.println("Here are public fields.");
6 for (Field f : fieldPublic) {
7 System.out.println(f.getType());
8 }
9 Field[] fieldDeclared = cls.getDeclaredFields();
10 System.out.println("Here are all declared fields including private "
11 + "and static and protect.");
12 for (Field f : fieldDeclared) {
13 System.out.println(f.getType());
14 }
15 }
16 }
17 /* 输出结果如下：
18 Here are public fields.
19 int
20 int
21 Here are all declared fields including private and static and protect.
22 int
23 int
24 long
25 */
2) 基于域字段的字符串名称获取该域字段的值：
1 public class MyTest {
2 public static void main(String args[]) throws Exception {
3 Object o = new TestClass();
4 //根据域字段的字符串名字反射出与该字段对应Field类对象。
5 Field field = o.getClass().getField("firstValue");
6 //获取该域字段类型的Class对象。
7 Class< > type = field.getType();
8 //根据域字段的类型，调用Field.getXxx()方法获取该对象域字段的值。
9 if (type.toString().equals("double"))
10 System.out.println(field.getDouble(o));
11 else if (type.toString().equals("int"))
12 System.out.println(field.getInt(o));
13 }
14 }
15
16 class TestClass {
17 public double firstValue = 3.14;
18 }
19 /* 输出结果如下：
20 3.14
21 */
3) 获取和设置指定域字段的值：
1 public class MyTest {
2 public static void main(String args[]) throws Exception {
3 Bean demo = new Bean();
4 Class< extends Bean> cl = demo.getClass();
5
6 Field field = cl.getField("id");
7 field.set(demo, new Long(10));
8 Object value = field.get(demo);
9 System.out.println("Value = " + value);
10
11 field = cl.getField("now");
12 field.set(null, new Date());
13 value = field.get(null);
14 System.out.println("Value = " + value);
15 }
16 }
17 class Bean {
18 public static Date now;
19 public Long id;
20 public String name;
21 }
22 /* 输出结果如下：
23 Value = 10
24 Value = Sun Sep 04 11:38:15 CST 2011
25 */
4. 泛型信息的反射：
1) 获取类的泛型接口信息
1 public static void main(String args[]) throws Exception {
2 Class< > c = Class.forName("java.util.ArrayList");
3 System.out.format("Class:%n %s%n", c.getCanonicalName());
4 System.out.format("Modifiers:%n %s%n",
5 Modifier.toString(c.getModifiers()));
6
7 System.out.format("Type Parameters:%n");
8 //获取该泛型类的类型参数数组
9 TypeVariable[] tv = c.getTypeParameters();
10 if (tv.length != 0) {
11 System.out.format(" ");
12 for (TypeVariable t : tv)
13 System.out.format("%s ", t.getName());
14 S