JAVA - 反射

package dawang.model;

public class User {
    
    private int id;
    private String name;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    
    public String show(String str) {
        return str+" [id=" + id + ", name=" + name + "]";
    }
    
    public static void say(String hello,String world) {
        System.out.println(hello+",Java,"+world);
    }
    
    
}

package dawang.model;

public interface IUserDao {
    public void add();
}

package dawang.model;

public class UserADao implements IUserDao {

    @Override
    public void add() {
        System.out.println("a");
    }

}

package dawang.model;

public class UserCDao implements IUserDao {

    @Override
    public void add() {
        System.out.println("c");
    }

}

package dawang.test;


import dawang.model.IUserDao;
import dawang.model.User;
import dawang.model.UserADao;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import org.junit.Test;

public class Test01 {

       //使用类实例化User对象
    @Test
    public void test01() {
        User u = new User();
        u.setId(1);
        u.setName("dawang");
        System.out.println(u.show("User"));
    }
    
       //使用字符串实例化对象
    @Test
    public void test02() {
        try {
            String objStr = "dawang.model.User";
            Class clz = Class.forName(objStr);
            User u = (User)clz.newInstance();
            u.setId(1);
            u.setName("dawang");
            System.out.println(u.show("ref"));
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
    }
    
    @Test
    public void test03() {
        try {
            String objStr = "dawang.model.User";
            Class clz = Class.forName(objStr);
            User u = (User)clz.newInstance();
            u.setId(1);
            u.setName("dawang");
            String mm = "show";
            /**
             * 第一个参数是函数的名称，第二个参数是...（表示有无限个参数）表示函数的参数
             */
            Method method = clz.getMethod(mm, String.class);
            /**
             * 第一个参数是调用函数的对象，第二个参数是函数执行时的参数
             * u.show("dawang");
             */
            String str = (String)method.invoke(u, "dawang");
            System.out.println(str);
            /**
             * 同样可以调用static的方法
             */
            Method m2 = clz.getMethod("say", String.class,String.class);
            /**
             * 调用Static的方法是使用class来调用
             */
            m2.invoke(clz, "ok","world");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (SecurityException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }
    
    @Test
    public void testDao01() {
        IUserDao u1 = new UserADao();
        u1.add();
    }
    
    @Test
    public void testDao02() {
        try {
            //只需要修改配置文件就可以改变类的调用
            String dao = "dawang.model.UserCDao";
            IUserDao ud = (IUserDao)Class.forName(dao).newInstance();
            ud.add();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

}