这个功能对学习Java有些帮助，比如在学习内部类或者泛型的时候查看这些类的结构，可以帮助我们理解这些机制的本质。代码如下，感兴趣的可以看下。
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Scanner;
public class ClassAnalyzer {
private static final String tab = " ";//缩进
public static void analyzer(String className) throws ClassNotFoundException{
Class c = Class.forName(className);
System.out.print(Modifier.toString(c.getModifiers()));
System.out.print(" ");
System.out.print(c.toString());
Class superC = c.getSuperclass();
if(superC != null){
System.out.print(" extends "+superC.getName());
}
System.out.println("{");//类开始括号
//打印域
System.out.println(tab+"//域");
Field[] fields = c.getDeclaredFields();
for(Field field:fields){
printField(field);
}
//打印构造器
System.out.println(tab+"//构造器");
Constructor[] constructors = c.getDeclaredConstructors();
for(Constructor constructor:constructors){
printConstructor(constructor);
}
//打印方法
System.out.println(tab+"//方法");
Method[] methods = c.getDeclaredMethods();
for(Method method:methods){
printMethod(method);
}
System.out.println("}");//类结束括号
}
//打印域
private static void printField(Field field){
System.out.print(tab);
System.out.print(Modifier.toString(field.getModifiers()));
System.out.print(" ");
Class fieldType = field.getType();
if(fieldType.isArray()){
System.out.print(getArrayTypeName(fieldType));
}else{
System.out.print(field.getType().getName());
}
System.out.print(" ");
System.out.print(field.getName());
System.out.println(";");
}
//打印构造器
private static void printConstructor(Constructor constructor){
System.out.print(tab);
System.out.print(Modifier.toString(constructor.getModifiers()));
System.out.print(" ");
System.out.print(constructor.getDeclaringClass().getSimpleName());
Class[] varTypes = constructor.getParameterTypes();
System.out.print("(");
printParameters(varTypes);
System.out.println(");");
}
//打印方法
private static void printMethod(Method method){
System.out.print(tab);
System.out.print(Modifier.toString(method.getModifiers()));
System.out.print(" ");
Class returnType = method.getReturnType();
if(returnType.isArray()){
System.out.print(getArrayTypeName(returnType));
}else{
System.out.print(method.getReturnType().getName());
}
System.out.print(" ");
System.out.print(method.getName());
System.out.print("(");
Class[] varTypes = method.getParameterTypes();
printParameters(varTypes);
System.out.print(")");
//声明抛出的异常
Class[] exceptionType = method.getExceptionTypes();
if(exceptionType.length != 0){
System.out.print(" throws ");
for(int i=0;i<exceptionType.length;i++){
System.out.print(exceptionType[i].getName());
if(i < (exceptionType.length - 1)){
System.out.print(",");
}
}
}
System.out.println(";");
}
//打印构造器和方法的参数列表
private static void printParameters(Class[] varTypes){
if(varTypes.length > 0){
for(int i = 0; i < varTypes.length; i++){
if(varTypes[i].isArray()){
System.out.print(getArrayTypeName(varTypes[i]));
}else{
System.out.print(varTypes[i].getName());
}
if( i < (varTypes.length - 1)){
System.out.print(", ");
}
}
}else{
System.out.print(" ");
}
}
public static String getArrayTypeName(Class type){
StringBuffer buffer = new StringBuffer(getArrayType(type).getName());
int dimension = countArrayDimension(type);
for(int i=1;i<=dimension;i++){
buffer.append("[]");
}
return buffer.toString();
}
public static int countArrayDimension(Class type){
int dimension = 0;
if(type.isArray()){
Class tempType = type;
while((tempType = tempType.getComponentType()) != null){
dimension++;
}
}
return dimension;
}
public static Class getArrayType(Class type){
Class arrayType = null;
if(type.isArray()){
Class tempType = type.getComponentType();
do{
arrayType = tempType;
}while((tempType = tempType.getComponentType()) != null);
}
return arrayType;
}
public static void main(String[] args) {
try {
Scanner in = new Scanner(System.in);
System.out.print("Input class name:");
String className = in.next();
in.close();
analyzer(className);
} catch (ClassNotFoundException ex) {
ex.printStackTrace();
}
}
}