反射调用小例子

1，用是的TestBean

package cn.itcast.day1;
/**
 *
 * @version 创建时间：2012-2-22 下午12:20:49
 *
 */

public class TestBean
{
    private int x;
    private String str;
    public int y;


    public TestBean() {
        super();
    }


    public TestBean(int x,int y) {
        super();
        this.x = x;
        this.y = y;
    }
    public TestBean(int x, String str, int y) {
        super();
        this.x = x;
        this.str = str;
        this.y = y;
    }
    public int getX() {
        return x;
    }
    public void setX(int x) {
        this.x = x;
    }
    public String getStr() {
        return str;
    }
    public void setStr(String str) {
        this.str = str;
    }
    public int getY() {
        return y;
    }
    public void setY(int y) {
        this.y = y;
    }

    public int toSum() {
        return (x+y);
    }
    @Override
    public String toString() {
        return "TestBean [x=" + x + ", str=" + str + ", y=" + y + "]";
    }

}

2,构造方法的反射

package cn.itcast.day1;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;


public class ConstrutctorReflect {

    public static void main(String[] args) throws Exception{
        // TODO Auto-generated method stub
        Constructor constructor1 = Class.forName("cn.itcast.day1.TestBean").getConstructor(int.class,int.class);//想要哪个构造方法就传哪个类型
        TestBean tb1=(TestBean) constructor1.newInstance(1,2);

        Constructor constructor2 = Class.forName("cn.itcast.day1.TestBean").getConstructor(int.class,String.class,int.class);//想要哪个构造方法就传哪个类型
        TestBean tb2=(TestBean) constructor2.newInstance(1,"abc",2);

        System.out.println(tb1+"----"+tb2);
    }

}

3，作用域反射
  把TestBean 的set get方法全部屏蔽掉也可以用的，是无影响的；
  对私有域的访问，要注意啦
  

package cn.itcast.day1;

import java.lang.reflect.Field;

public class FieldsReflect
{


    public static void main(String[] args) throws Exception
    {
        TestBean tb=new TestBean();
        Field y=Class.forName("cn.itcast.day1.TestBean").getField("y");
        y.set(tb,3);
        System.out.println(y.get(tb));
        Field x=Class.forName("cn.itcast.day1.TestBean").getField("x");
        x.set(tb,1);
        System.out.println(x.get(tb));

    }

}

//输出
3
Exception in thread "main" java.lang.NoSuchFieldException: x
    at java.lang.Class.getField(Unknown Source)
    at cn.itcast.day1.FieldsReflect.main(FieldsReflect.java:15)/*再来个一个,综合一点*/
package cn.itcast.day1;

import java.lang.reflect.Field;

public class FieldsReflect
{


public static void main(String[] args) throws Exception
{
TestBean tb=new TestBean();
Field y=Class.forName("cn.itcast.day1.TestBean").getField("y");
y.set(tb,3);
System.out.println(y.get(tb));
Field x=Class.forName("cn.itcast.day1.TestBean").getDeclaredField("x");//取得声明过的变量，不管可见性
x.setAccessible(true);//设为可见的
x.set(tb,1);
Field str=Class.forName("cn.itcast.day1.TestBean").getDeclaredField("str");
str.setAccessible(true);
str.set(tb, "abc");
tb=(TestBean) func(tb);
System.out.println(str.get(tb));
}

public static Object func(Object obj) throws Exception
{
Field [] fields=obj.getClass().getDeclaredFields();//获取所有声明属性
for(Field field:fields)
{
if(field.getType()==java.lang.String.class)
{
field.setAccessible(true);
String orgstr=(String)field.get(obj);
//orgstr.replaceAll("a", "b");
field.set(obj, orgstr.replaceAll("a", "b"));
System.out.println(field.get(obj));
break;
}
}

return obj;
}

}//输出
3
bbc
bbc

  
4，普通方法反射

package cn.itcast.day1;

import java.lang.reflect.Method;


public class MethodsReflect {

    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        TestBean tb=new TestBean();
        Method printMethod=Class.forName("cn.itcast.day1.TestBean").getMethod("print", int.class,String.class,int.class);
        printMethod.invoke(tb,1,"vs",2);// 如果tb是null，则调用静态先可以为null，否则出错
    }

}

5，一个综合的例子