再回首，Java温故知新(十一)：Java反射

package com.demo.reflect;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Scanner;

/**
 * Java反射获取类内容
 * @author liweitao
 *
 */
public class PrintClass {

    public static void main(String[] args) {
        
        Scanner scanner = new Scanner(System.in);
        System.out.println("enter a class name");
        String name = scanner.nextLine();
        
        try {
            Class cls = Class.forName(name);
            String modifier = Modifier.toString(cls.getModifiers());
            Class superCls = cls.getSuperclass();
            Class[] interCls = cls.getInterfaces();
            
            System.out.print(modifier +" class " + name);
            
            if(superCls != null && superCls != Object.class){
                System.out.print(" extends " + superCls.getName());
            }
            
            for(int i = 0; i < interCls.length; i++){
                if(i == 0){
                    System.out.print(" implements ");
                }else if(i > 0){
                    System.out.print(",");
                }
                System.out.print(interCls[i].getName());
            }
            System.out.println("{");
            printFields(cls);
            printConstructors(cls);
            printMethods(cls);
            System.out.print("}");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        
        
    }
    
    /**
     * 打印字段
     * @param cls
     */
    public static void printFields(Class cls){
        Field[] fields = cls.getDeclaredFields();
        for(Field field : fields){
            StringBuffer result = new StringBuffer();
            Class type = field.getType();
            String name = field.getName();
            String modifiers = Modifier.toString(field.getModifiers());
            if(modifiers.length() > 0){
                result.append("\t").append(modifiers).append(" ")
                    .append(type.getName()).append(" ").append(name);
            }
            System.out.println(result.toString());
        }
    }

    /**
     * 打印构造器
     * @param cls
     */
    public static void printConstructors(Class cls){
        Constructor[] constructors = cls.getDeclaredConstructors();
        for(Constructor constructor : constructors){
            StringBuffer result = new StringBuffer();
            String name = constructor.getName();
            String modifiers = Modifier.toString(constructor.getModifiers());
            if(modifiers.length() > 0){
                result.append("\t").append(modifiers).append(" ").append(name).append("(");
            }
            
            Class[] params = constructor.getParameterTypes();
            for(int j = 0; j < params.length; j++){
                if(j > 0){
                    result.append(",");
                }
                result.append(params[j].getName());
            }
            result.append(")");
            System.out.println(result.toString());
        }
    }
    
    public static void printMethods(Class cls){
        Method[] methods = cls.getDeclaredMethods();
        for(Method method : methods){
            StringBuffer result = new StringBuffer();
            String name = method.getName();
            Class returnType = method.getReturnType();
            String modifier = Modifier.toString(method.getModifiers());
            Class[] params = method.getParameterTypes();
            
            if(modifier.length() > 0){
                result.append("\t").append(modifier).append(" ")
                    .append(returnType.getName()).append(" ").append(name).append("(");
            }
            
            for(int j = 0; j < params.length; j++){
                if(j > 0){
                    result.append(",");
                }
                result.append(params[j].getName());
            }
            result.append(")");
            System.out.println(result.toString());
        }
    }
    
}