1. 測試實體類

public class TestClass {

    public String classInfo;

    public String getClassInfo() {
        return classInfo;
    }

    public TestClass(String classInfo) {
        this.classInfo = classInfo;
        System.out.println("invoke this param classInfo constructor.");
    }

    public TestClass()
    {
        System.out.println("invoke this default constructor.");
    }
    public void setClassInfo(String classInfo) {
        this.classInfo = classInfo;
    }

    static {
        System.out.println("init first class.");
    }

    public void showinfo()
    {
        System.out.println("this is default show info method.");
    }

    public void showinfo(String info)
    {
        System.out.println("this is have param method.");
        System.out.println("param context:"+info);
    }



}

1. 　　測試實現類

import org.junit.Test;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;

public class getClassInfoTest {
    @Test
    public void testDemo() throws Exception
    {
        /**
         * 1.實現反射的第一步：獲取對象的類型信息，java中指存放類型信息的.class文件
         * 2.在這裏是獲取對象的所有構造方法.
         * 3.找到需要的構造方法.
         * 4.調用指定構造方法,創建對象.
         */
        Class clazz=Class.forName("TestClass");
        /**
         * 獲取構造方法
         * 調用newInstance(...) 相當於 new TestClass(...)
         */
        Constructor[] constructors=clazz.getConstructors();
        System.out.println("constructor item:"+‘\n‘);
        arrayToStringItem(constructors);
        Object test=constructors[0].newInstance();
        Object test2=constructors[1].newInstance("hello");

        /**
         * 獲取屬性
         */
        Field[] fields=clazz.getFields();
        System.out.println("field item:"+‘\n‘);
        arrayToStringItem(fields);
        Field field=fields[0];
        System.out.println("field name:"+field.getName());
        System.out.println("get dafault constructor field value:"+field.get(test));
        System.out.println("get have param constructor field value:"+field.get(test2));

        /**
         * 獲取方法
         */
        Method[] methods=clazz.getMethods();
        System.out.println("method item:"+‘\n‘);
        arrayToStringItem(methods);
        System.out.println("invoke "+methods[0].getName()+" get return value:"+methods[0].invoke(test2));
    }

    public void arrayToStringItem(Object[] args)
    {
        for (Object c:args)
        {
            System.out.println(c);
        }
    }
}

java反射常用類