java 反射机制

package day19;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.Method;import java.lang.reflect.Type;class AException extends Exception{ }class BException extends AException{ }class CException extends BException{ }class
DException extends Exception{ }class Fu{ void div(){ }}class Zi extends Fu{ void div(){ //System.out.println("zi...div"); //throw new BException(); try{ throw new DException(); }catch(DException e){ System.out.println("sss"); } }}public class Demo1 { public
static void main(String[] args) throws Exception{ Demo1 d = new Demo1(); d.getConstructor(); } public void getConstructor() throws Exception { Class c = null; c = Class.forName("java.lang.Long"); Class cs[] = {java.lang.String.class}; System.out.println("\n-------------------------------\n");
Constructor cst1 = c.getConstructor(cs); System.out.println("1、通过参数获取指定Class对象的构造方法："); System.out.println(cst1.toString()); Constructor cst2 = c.getDeclaredConstructor(cs); System.out.println("2、通过参数获取指定Class对象所表示的类或接口的构造方法："); System.out.println(cst2.toString());
Constructor cst3 = c.getEnclosingConstructor(); System.out.println("3、获取本地或匿名类Constructor 对象，它表示基础类的立即封闭构造方法。"); if (cst3 != null) System.out.println(cst3.toString()); else System.out.println("-- 没有获取到任何构造方法！"); Constructor[] csts = c.getConstructors(); System.out.println("4、获取指定Class对象的所有构造方法：");
for (int i = 0; i < csts.length; i++) { System.out.println(csts[i].toString()); } System.out.println("\n-------------------------------\n"); Type types1[] = c.getGenericInterfaces(); System.out.println("1、返回直接实现的接口："); for (int i = 0; i < types1.length; i++)
{ System.out.println(types1[i].toString()); } Type type1 = c.getGenericSuperclass(); System.out.println("2、返回直接超类："); System.out.println(type1.toString()); Class[] cis = c.getClasses(); System.out.println("3、返回超类和所有实现的接口："); for (int i = 0; i < cis.length;
i++) { System.out.println(cis[i].toString()); } Class cs1[] = c.getInterfaces(); System.out.println("4、实现的接口"); for (int i = 0; i < cs1.length; i++) { System.out.println(cs1[i].toString()); } System.out.println("\n-------------------------------\n"); Field
fs1[] = c.getFields(); System.out.println("1、类或接口的所有可访问公共字段："); for (int i = 0; i < fs1.length; i++) { System.out.println(fs1[i].toString()); } Field f1 = c.getField("MIN_VALUE"); System.out.println("2、类或接口的指定已声明指定公共成员字段："); System.out.println(f1.toString());
Field fs2[] = c.getDeclaredFields(); System.out.println("3、类或接口所声明的所有字段："); for (int i = 0; i < fs2.length; i++) { System.out.println(fs2[i].toString()); } Field f2 = c.getDeclaredField("serialVersionUID"); System.out.println("4、类或接口的指定已声明指定字段："); System.out.println(f2.toString());
System.out.println("\n-------------------------------\n"); Method m1[] = c.getMethods(); System.out.println("1、返回类所有的公共成员方法："); for (int i = 0; i < m1.length; i++) { System.out.println(m1[i].toString()); } Method m2 = c.getMethod("longValue", new Class[]{});
System.out.println("2、返回指定公共成员方法："); System.out.println(m2.toString()); }}