Mybatis学习--10.利用javassist动态生成类

利用javassist动态生成类

package com.deng.javaSsist;

import javassist.CtClass;
import javassist.CtMethod;
import org.junit.Test;
import javassist.ClassPool;

import java.lang.reflect.Method;

public class javassistTest {
    @Test
    public void testGenerateFirstClass() throws Exception{
        //get the class pool
        ClassPool pool = ClassPool.getDefault();
        //make a class;
        CtClass ctClass = pool.makeClass("com.deng.bank.dao.impl.AccountDaoIml");
        //make a function
        String methodCode = "public void insert(){System.out.println(123);}";
        CtMethod method = CtMethod.make(methodCode, ctClass);
        ctClass.addMethod(method);
        //在内存中生成该类
        ctClass.toClass();
        //use reflect to instance the object
        Class<?> aClass = Class.forName("com.deng.bank.dao.impl.AccountDaoIml");
        Object o = aClass.newInstance();
        Method insert = aClass.getDeclaredMethod("insert");
        //call the function
        insert.invoke(o);
    }
}

利用javassist动态生成类并实现接口中方法

public void testGenerateInterface() throws Exception{
    ClassPool pool = ClassPool.getDefault();
    CtClass ctClass = pool.makeClass("com.deng.bank.dao.impl.AccountDaoIml");
    //generate the interface
    CtClass anInterface = pool.makeInterface("com.deng.bank.dao.AccountDao");
    //let the class implements the interface
    ctClass.addInterface(anInterface);
    String methCode = "public void delete(){System.out.println(\"hello world\");}";
    CtMethod method = CtMethod.make(methCode, ctClass);
    ctClass.addMethod(method);

    Class<?> aClass = ctClass.toClass();
    AccountDao accountDao = (AccountDao) aClass.newInstance();
    accountDao.delete();
}