动态类加载及反射演示类
package org.mytest;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
/*
* 动态类加载及反射演示类
*/
publicclass DynamicClassLoader {
private String attribute = "我是DynamicClassLoader类的属性！";
public String str2 = "hi";
public String getAttribute() {
returnattribute;
}
public DynamicClassLoader() {}
publicvoid setAttribute(String attribute) {
this.attribute = attribute;
}
publicint getAttribute2() {
return 110;
}
protectedvoid protectedMethod() {}
privatevoid privateMethod() {}
publicstaticvoid main(String s[]) throws ClassNotFoundException,
InstantiationException, IllegalAccessException,
IllegalArgumentException, InvocationTargetException {
// \\\\\\\\\\\\\\\\\\\\\\动态加载//////////////////
DynamicClassLoader dcl0 = new DynamicClassLoader();// 这是我们通常创建一个类实例的做法--new
System.out.println("new类实例,并打印实例dcl0的属性 = " + dcl0.getAttribute());
Class class1 = Class.forName("org.mytest.DynamicClassLoader");
DynamicClassLoader dcl1 = (DynamicClassLoader) class1.newInstance();
System.out.println("Class.forName动态加载获得的类实例,并打印实例dcl1的属性 = " + dcl1.getAttribute());
Class class2 = ClassLoader.getSystemClassLoader().loadClass("org.mytest.DynamicClassLoader");
DynamicClassLoader dcl2 = (DynamicClassLoader) class2.newInstance();
System.out.println("ClassLoader.loadClass动态加载获得的类实例,并打印实例dcl2的属性 = " + dcl2.getAttribute());
System.out.println("dcl1==dcl2：" + (dcl1==dcl2));
System.out.println("dcl1==dcl0：" + (dcl1==dcl0));
System.out.println("dcl2==dcl0：" + (dcl1==dcl0));
System.out.println("dcl0.getClass().getClassLoader()：" + (dcl0.getClass().getClassLoader()));
System.out.println("dcl1.getClass().getClassLoader()：" + (dcl1.getClass().getClassLoader()));
System.out.println("dcl2.getClass().getClassLoader()：" + (dcl2.getClass().getClassLoader()));
//讲解如果要求按照业务逻辑定义自己的对象比对策略（如hibernate的po可以仅仅比对
//主键、主键等则两个po等），则重写（覆盖）equals方法和hashcode方法
// ///////////////方法反射//////////////////
DynamicClassLoader d = new DynamicClassLoader();
Object o = (Object) d;
System.out.println("o.getClass() = " + o.getClass());
Method[] methods = o.getClass().getMethods();
System.out.println("methods.length = " + methods.length);
for (int i = 0; i < methods.length; i++) {
System.out.print("method" + (i + 1) + ":\t");
System.out.println(methods[i]);
}
System.out.println("---------------------");
Method[] methods2 = o.getClass().getDeclaredMethods();
System.out.println("methods2.length = " + methods2.length);
for (int i = 0; i < methods2.length; i++) {
System.out.print("method" + (i + 1) + ":\t");
System.out.println(methods2[i]);
}
/////////////////穿插属性反射//////////////////
System.out.println("--------穿插属性反射--------");
Field[] fields = o.getClass().getDeclaredFields();
System.out.println(fields.length);
for(int i = 0; i<fields.length; i++){
System.out.print("field" + (i + 1) + ":\t");
System.out.println(fields[i]);
}
System.out.println("---------继续方法反射---------");
/////////////////继续方法反射//////////////////
for(int i = 0; i<methods.length; i++){
System.out.print("method" + (i + 1) + ":\t");
System.out.println(methods[i]);
Method method = methods[i];
String methodName = method.getName();
String returnType = method.getReturnType().getName();
if(methodName.startsWith("get")&&!methodName.startsWith("getClass")){
if(returnType.equals("java.lang.String")){
String returnval = (String)method.invoke(d,null);
System.out.println("java.lang.String reval = "+returnval);
}elseif(returnType.equals("String")){
String returnval = (String)method.invoke(d,null);
System.out.println("String reval = "+returnval);
}elseif(returnType.equals("java.lang.Integer")){
Integer returnval = (Integer)method.invoke(d,null);
System.out.println("Integer reval = "+returnval);
}elseif(returnType.equals("int")){
Integer returnval = (Integer)method.invoke(d,null);
System.out.println("int reval = "+returnval);
}
}
}
}
}
/*
* 几点结论:
* 对于private的方法getMethods()不反射、getDeclaredMethods()反射;
* 对于protected的方法getMethods()不反射、getDeclaredMethods()反射;
* getMethods()反射继承的和自身的public方法、getDeclaredMethods()反射自身声明的所有方法。
*/
Tags: J2SE
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