ReflectionTest--java反射的简单测试

package test;
import java.util.*;
import java.lang.reflect.*;

public class ReflectionTest {

/**
this program uses reflection to print all features of a class.
@version 1.1 2004-02-01
@author Cay Horstmann
@deprecated 关于反射：利用反射分析类的能力：（反射机制最重要的内容——检查类结构）
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
//read class name from command line args or user input
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();
System.out.println("------------------------declare this class is begin......!------------------------\n");
}
try{
//print class name and superclass name (if!=object)
Class cl=Class.forName(name);
Class supercl=cl.getClass();

String modifiers=Modifier.toString(cl.getModifiers());
if(modifiers.length()>0)System.out.print(modifiers+" ");
System.out.print("class "+name);
if(supercl!=null&&supercl!=Object.class){
System.out.println(" extends " +supercl.getName());
System.out.print("{");

//System.out.println("------------------------printConstructors()is begin!------------------------");
    printConstructors(cl);
    //System.out.println("------------------------printConstructors()is end!------------------------");
    System.out.println();
   
    //System.out.println("------------------------printMethods()is begin!------------------------");
    printMethods(cl);
    //System.out.println("------------------------printMethods()is end!------------------------");
    System.out.println();
   
    //System.out.println("------------------------printFields()is begin!------------------------");
    printFields(cl);
    //System.out.println("------------------------printFields()is end!------------------------");
   
    System.out.println("}");
}

}catch(ClassNotFoundException e){
e.printStackTrace();
}
System.exit(0);

}
/**
* prints all constructors of a class
* @param cl a class
*/
public static void printConstructors(Class cl)
{
Constructor[] constructors=cl.getDeclaredConstructors();

for(Constructor c:constructors){
String name=c.getName();
System.out.println("  ");
String modifiers=Modifier.toString(c.getModifiers());
if(modifiers.length()>0)System.out.print(modifiers+" ");
System.out.print(name+"(");

//print parameter types
Class[] paramTypes=c.getParameterTypes();
for(int j=0;j<paramTypes.length;j++){
if(j>0)System.out.print(" ,");
System.out.print(paramTypes[j].getName());
}
System.out.print(");");
}
}

/**
* print all methods of a class
* param cl is a class
*/
public static void printMethods(Class cl){
Method[] methods=cl.getDeclaredMethods();

for(Method m:methods){
Class retType=m.getReturnType();
String name=m.getName();

System.out.println("  ");
//print modifiers ,return type,and method name
String modifiers=Modifier.toString(m.getModifiers());
if(modifiers.length()>0){
System.out.print(modifiers+" "+retType.getName()+" "+name+"(");
//print parameter types
Class[] paramTypes=m.getParameterTypes();
for(int j=0;j<paramTypes.length;j++){
if (j>0) {
System.out.print(",");
}
System.out.print(paramTypes[j].getName());
}
System.out.println(");");
}
}
}
/**
* print all fields of a class
* @param cl
*/
public static void printFields(Class cl){
Field[] fields=cl.getDeclaredFields();

for(Field f:fields){
Class type=f.getType();
String name=f.getName();
System.out.print(" ");
String modifiers=Modifier.toString(f.getModifiers());
if(modifiers.length()>0)System.out.print(modifiers+" ");
System.out.println(type.getName()+" "+name+" ;");
}
// System.out.println(" printFields()is ends!");
}

}

/***
* java.lang.Double测试得结果：
*
*
public final class java.lang.Double extends java.lang.Class
{ 
public java.lang.Double(java.lang.String); 
public java.lang.Double(double);
 
public int hashCode();
 
public static native long doubleToRawLongBits(double);
 
public static long doubleToLongBits(double);
 
public static native double longBitsToDouble(long);
 
public volatile int compareTo(java.lang.Object);
 
public int compareTo(java.lang.Double);
 
public boolean equals(java.lang.Object);
 
public static java.lang.String toString(double);
 
public java.lang.String toString();
 
public static java.lang.String toHexString(double);
 
public static int compare(double,double);
 
public static java.lang.Double valueOf(double);
 
public static java.lang.Double valueOf(java.lang.String);
 
public static boolean isNaN(double);
 
public boolean isNaN();
 
public byte byteValue();
 
public double doubleValue();
 
public float floatValue();
 
public int intValue();
 
public boolean isInfinite();
 
public static boolean isInfinite(double);
 
public long longValue();
 
public short shortValue();
 
public static double parseDouble(java.lang.String);

public static final double POSITIVE_INFINITY ;
public static final double NEGATIVE_INFINITY ;
public static final double NaN ;
public static final double MAX_VALUE ;
public static final double MIN_NORMAL ;
public static final double MIN_VALUE ;
public static final int MAX_EXPONENT ;
public static final int MIN_EXPONENT ;
public static final int SIZE ;
public static final java.lang.Class TYPE ;
private final double value ;
private static final long serialVersionUID ;
}
*/


注意:如果数据类型输入错误或不规范均会发生异常.