JAVA反射了解
被反射类文件：
package ref.lect; import java.util.Date; public class Exe1 { public void publicMethod(String str){ System.out.println("调用了::共有的方法，参数为:: " + str); } protected void protectedMethod(String str){ System.out.println("调用了::受保护的方法，参数为:: " + str); } void xMethod(String str){ System.out.println("调用了::受保护的方法，参数为:: " + str); } private int privateMethod(int num){ System.out.println("调用了::受保护的方法，参数为:: " + num); return num; } private int id; public String name; protected Date birthday; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } public static void main(String[] args) { System.out.println("执行main方法了..."); } }
使用反射类文件：
package ref.lect.invok; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.Date; import ref.lect.Exe1; public class Envok1 { public static void main(String[] args) { try { System.out.println("=================获取类对象==============="); Class<?> exe1 = Class.forName("ref.lect.Exe1"); System.out.println("类名 :: "+exe1.getName()); System.out.println("=================获取方法名==============="); Method[] ms = exe1.getMethods(); for (int i = 0; i < ms.length; i++) { System.out.println("方法名"+i+":: "+ms[i]); } System.out.println("=================获取成员名==============="); Field[] fs = exe1.getDeclaredFields(); for (int i = 0; i < fs.length; i++) { System.out.println("成员名"+i+":: "+fs[i]); } System.out.println("================= 设置列 private protected public ==============="); Object obj = Class.forName("ref.lect.Exe1").getConstructor().newInstance(); Field fn = Class.forName("ref.lect.Exe1").getField("name"); // public fn.set(obj, "刘德华"); Exe1 e1 = (Exe1)obj; System.out.println("1:: 被set后的name值:: "+ e1.getName()); System.out.println("1:: 被set后的birthday值:: "+ e1.getBirthday()); System.out.println("1:: 被set后的id值:: "+ e1.getId()); Field fb = Class.forName("ref.lect.Exe1").getDeclaredField("birthday"); // protected fb.setAccessible(true); // 暴力反射 fb.set(obj, new Date()); Exe1 e2 = (Exe1)obj; System.out.println("2:: 被set后的name值:: "+ e2.getName()); System.out.println("2:: 被set后的birthday值:: "+ e2.getBirthday()); System.out.println("2:: 被set后的id值:: "+ e2.getId()); Field fi = Class.forName("ref.lect.Exe1").getDeclaredField("id"); // private fi.setAccessible(true); // 暴力反射 fi.set(obj, 10086); Exe1 e3 = (Exe1)obj; System.out.println("3:: 被set后的name值:: "+ e3.getName()); System.out.println("3:: 被set后的birthday值:: "+ e3.getBirthday()); System.out.println("3:: 被set后的id值:: "+ e3.getId()); System.out.println("=======================调用method======================"); Object mPublic = Class.forName("ref.lect.Exe1").getConstructor().newInstance(); Method m1 = Class.forName("ref.lect.Exe1").getMethod("publicMethod",String.class); System.out.println(m1); Exe1 exe4 = (Exe1)mPublic; m1.invoke(exe4, "张三"); Object mPrivate = Class.forName("ref.lect.Exe1").getConstructor().newInstance(); Method m2 = Class.forName("ref.lect.Exe1").getDeclaredMethod("privateMethod",int.class); System.out.println(m2); m2.setAccessible(true); Exe1 exe5 = (Exe1)mPrivate; int num = (Integer) m2.invoke(exe5, 666); System.out.println("返回结果 ==> num ==> :: " + num ); System.out.println("========================执行main方法================================"); Object mMain = Class.forName("ref.lect.Exe1").getConstructor().newInstance(); Method m3 = Class.forName("ref.lect.Exe1").getMethod("main",String[].class); m3.invoke(mMain, (Object)new String[]{"a","b","c"}); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SecurityException e) { e.printStackTrace(); } catch (NoSuchMethodException e) { e.printStackTrace(); } catch (IllegalArgumentException e) { e.printStackTrace(); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (InvocationTargetException e) { e.printStackTrace(); }catch (NoSuchFieldException e) { e.printStackTrace(); } } }
执行结果：
=================获取类对象=============== 类名 :: ref.lect.Exe1 =================获取方法名=============== 方法名0:: public static void ref.lect.Exe1.main(java.lang.String[]) 方法名1:: public java.lang.String ref.lect.Exe1.getName() 方法名2:: public int ref.lect.Exe1.getId() 方法名3:: public void ref.lect.Exe1.setName(java.lang.String) 方法名4:: public java.util.Date ref.lect.Exe1.getBirthday() 方法名5:: public void ref.lect.Exe1.publicMethod(java.lang.String) 方法名6:: public void ref.lect.Exe1.setId(int) 方法名7:: public void ref.lect.Exe1.setBirthday(java.util.Date) 方法名8:: public final native void java.lang.Object.wait(long) throws java.lang.InterruptedException 方法名9:: public final void java.lang.Object.wait() throws java.lang.InterruptedException 方法名10:: public final void java.lang.Object.wait(long,int) throws java.lang.InterruptedException 方法名11:: public boolean java.lang.Object.equals(java.lang.Object) 方法名12:: public java.lang.String java.lang.Object.toString() 方法名13:: public native int java.lang.Object.hashCode() 方法名14:: public final native java.lang.Class java.lang.Object.getClass() 方法名15:: public final native void java.lang.Object.notify() 方法名16:: public final native void java.lang.Object.notifyAll() =================获取成员名=============== 成员名0:: private int ref.lect.Exe1.id 成员名1:: public java.lang.String ref.lect.Exe1.name 成员名2:: protected java.util.Date ref.lect.Exe1.birthday ================= 设置列 private protected public =============== 1:: 被set后的name值:: 刘德华 1:: 被set后的birthday值:: null 1:: 被set后的id值:: 0 2:: 被set后的name值:: 刘德华 2:: 被set后的birthday值:: Tue May 08 16:55:27 CST 2018 2:: 被set后的id值:: 0 3:: 被set后的name值:: 刘德华 3:: 被set后的birthday值:: Tue May 08 16:55:27 CST 2018 3:: 被set后的id值:: 10086 =======================调用method====================== public void ref.lect.Exe1.publicMethod(java.lang.String) 调用了::共有的方法，参数为:: 张三 private int ref.lect.Exe1.privateMethod(int) 调用了::受保护的方法，参数为:: 666 返回结果 ==> num ==> :: 666 ========================执行main方法================================ 执行main方法了...
