package com.bdqn.service;
import java.lang.reflect.Method;
import java.util.Arrays;
import javax.tools.JavaCompiler;
import javax.tools.ToolProvider;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtConstructor;
import javassist.CtField;
import javassist.CtMethod;
import javassist.CtNewMethod;
import javassist.Modifier;
public class Demo2 {
/**
* 处理类的基本用法
* @throws Exception
*/
public static void test01() throws Exception{
ClassPool pool = ClassPool.getDefault();
CtClass cc = pool.get("com.bdqn.service.Emp");
byte[] bytes = cc.toBytecode();
System.out.println(Arrays.toString(bytes));
System.out.println(cc.getName()); //获取类名
System.out.println(cc.getSimpleName()); //获取简要类名
System.out.println(cc.getSuperclass()); //获得父类
System.out.println(cc.getInterfaces()); //获得接口
}
/**
* 测试产生新的方法
* @throws Exception
*/
public static void test02() throws Exception{
ClassPool pool = ClassPool.getDefault();
CtClass cc = pool.get("com.bjsxt.test.Emp");
// CtMethod m = CtNewMethod.make("public int add(int a,int b){return a+b;}", cc);
CtMethod m = new CtMethod(CtClass.intType,"add",
new CtClass[]{CtClass.intType,CtClass.intType},cc);
m.setModifiers(Modifier.PUBLIC);
m.setBody("{System.out.println("www.sxt.cn");return $1+$2;}");
cc.addMethod(m);
//通过反射调用新生成的方法
Class clazz = cc.toClass();
Object obj = clazz.newInstance(); //通过调用Emp无参构造器,创建新的Emp对象
Method method = clazz.getDeclaredMethod("add", int.class,int.class);
Object result = method.invoke(obj, 200,300);
System.out.println(result);
}
/**
修改已有的方法的信息,修改方法体的内容
* @throws Exception
*/
public static void test03() throws Exception{
ClassPool pool = ClassPool.getDefault();
CtClass cc = pool.get("com.bjsxt.test.Emp");
CtMethod cm = cc.getDeclaredMethod("sayHello",new CtClass[]{CtClass.intType});
cm.insertBefore("System.out.println($1);System.out.println("start!!!");");
cm.insertAt(9, "int b=3;System.out.println("b="+b);");
cm.insertAfter("System.out.println("end!!!");");
//通过反射调用新生成的方法
Class clazz = cc.toClass();
Object obj = clazz.newInstance(); //通过调用Emp无参构造器,创建新的Emp对象
Method method = clazz.getDeclaredMethod("sayHello", int.class);
method.invoke(obj, 300);
}
/**
* 属性的操作
* @throws Exception
*/
public static void test04() throws Exception{
ClassPool pool = ClassPool.getDefault();
CtClass cc = pool.get("com.bjsxt.test.Emp");
// CtField f1 = CtField.make("private int empno;", cc);
CtField f1 = new CtField(CtClass.intType,"salary",cc);
f1.setModifiers(Modifier.PRIVATE);
cc.addField(f1);
// cc.getDeclaredField("ename"); //获取指定的属性
//增加相应的set和get方法
cc.addMethod(CtNewMethod.getter("getSalary", f1));;
cc.addMethod(CtNewMethod.getter("setSalary", f1));;
}
/**
* 构造方法的操作
* @throws Exception
*/
public static void test05() throws Exception {
ClassPool pool = ClassPool.getDefault();
CtClass cc = pool.get("com.bjsxt.test.Emp");
CtConstructor[] cs = cc.getConstructors();
for (CtConstructor c : cs) {
System.out.println(c.getLongName());
}
}
public static void test06() throws Exception{
CtClass cc = ClassPool.getDefault().get("com.bjsxt.test.Emp");
Object[] all = cc.getAnnotations();
Author a = (Author)all[0];
String name = a.name();
int year = a.year();
System.out.println("name: " + name + ", year: " + year);
}
public static void main(String[] args) throws Exception {
test01();
}
}