core java 例题 利用反射分析类

 

import java.util.*;import java.lang.reflect.*;public class ReflectionTest{public static void main(String args[]){String name;if(args.length > 0) name = args[0];else{Scanner in = new Scanner(System.in);System.out.println("Enter class name(e.g. java.util.Date): ");name = in.next();}try{Class cl = Class.forName(name);//获得输入的类的Class对象Class supercl = cl.getSuperclass();//获得该类的父类 或接口String modifiers = Modifier.toString(cl.getModifiers());//获得该类的修饰符if(modifiers.length()>0)System.out.print(modifiers + " ");//打印出修饰符System.out.print("class "+name);//打印累的额名字if(supercl != null && supercl != Object.class)System.out.print(" extends " + supercl.getName());//如果有父类或接口且不是object类时 输出父类System.out.print("/n{/n");printConstructors(cl);//打印出构造方法System.out.println();printMethods(cl);//打印出成员方法System.out.println();printFields(cl);//打印成员变量System.out.println("}");}catch (Exception e){e.printStackTrace();}System.exit(0);}public static void printConstructors(Class cl){Constructor[] constructors = cl.getDeclaredConstructors();//获取构造方法 并存入数组中for(Constructor c: constructors){String name = c.getName();//获取构造方法的名字System.out.print(" ");String modifiers = Modifier.toString(c.getModifiers());//获取构造方法的修饰符if(modifiers.length()>0)System.out.print(modifiers + " ");//如果有修饰符就打印出来System.out.print(name + "(");//打印构造方法的名字Class[] paramTypes = c.getParameterTypes();//获取构造方法的参数 并存入数组中//打印出参数for(int j = 0;j < paramTypes.length;j++){if(j > 0)System.out.print(", ");System.out.print(paramTypes[j].getName());}System.out.println(")");}}public static void printMethods(Class cl){Method[] methods = cl.getDeclaredMethods();//获取成员方法for(Method m : methods){Class retType = m.getReturnType();//获取方法的返回类型String name = m.getName();//获取方法的名字System.out.print(" ");String modifiers = Modifier.toString(m.getModifiers());//解码并获取方法的修饰符if(modifiers.length()>0)System.out.print(modifiers + " ");//打印修饰符System.out.print(retType.getName() + " "+name + "(");//打印方法的名字Class[] paramTypes = m.getParameterTypes();//获取方法的参数//打印方法的参数for(int j = 0; j<paramTypes.length;j++){if(j > 0 )System.out.print(", ");System.out.print(paramTypes[j].getName());}System.out.println(")");}}public static void printFields(Class cl){Field[] fields = cl .getDeclaredFields();//获取成员变量for(Field f : fields){Class type = f.getType();//获取成员变量的类型String name = f.getName();//获取成员变量的名字System.out.print(" ");String modifiers = Modifier.toString(f.getModifiers());//解码并获取成员变量的修饰符if(modifiers.length()>0)System.out.print(modifiers + " ");//打印成员变量的修饰符System.out.println(type.getName() + " "+name + ";");//打印成员变量名字}}}