public class JavassistTest {


    public static void main(String[] args) throws CannotCompileException, IOException {
//        ClassPool cp = ClassPool.getDefault();
//        CtClass ctClass = cp.makeClass("org.example.javassist.Hello");
//        ctClass.writeFile("./");

        URL resource = JavassistTest.class.getClassLoader().getResource("");
        String file = resource.getFile();
        System.out.println("文件存储路径:"+file);

        ClassPool cp = ClassPool.getDefault();
        CtClass ctClass = cp.makeClass("com.ssdmbbl.javassist.Hello");
        CtMethod ctMethod = new CtMethod(CtClass.voidType, "hello", new CtClass[] {
            CtClass.intType,CtClass.doubleType
        }, ctClass);

        ctMethod.setModifiers(Modifier.PUBLIC);

        ctClass.addMethod(ctMethod);

// 新增一个变量
        CtField ctField = new CtField(CtClass.intType, "value", ctClass);
        ctField.setModifiers(Modifier.PRIVATE);
        ctClass.addField(ctField);

         //为value变量添加set方法
        CtMethod setValue = new CtMethod(CtClass.voidType, "setValue", new CtClass[]{CtClass.intType}, ctClass);
        setValue.setModifiers(Modifier.PUBLIC);


        //设置方法体
//        setValue.setBody("this.value = var1;");
//        setValue.setBody("this.value = $1;");
        ctMethod.setBody("this.value = $1 + $2;");

        ctClass.addMethod(setValue);

        //为value变量添加get方法
        CtMethod getValue = new CtMethod(CtClass.intType, "getValue", new CtClass[]{}, ctClass);
        getValue.setModifiers(Modifier.PUBLIC);

     //设置方法体
        getValue.setBody("return this.value;");

        ctClass.addMethod(getValue);


              //添加一个hello1的方法
        CtMethod ctMethod1 = new CtMethod(CtClass.voidType, "hello1", new CtClass[]{CtClass.intType, CtClass.doubleType}, ctClass);
        ctMethod1.setModifiers(Modifier.PUBLIC);
        ctMethod1.setBody("this.value = $1 + $2;");
        ctMethod1.insertBefore("System.out.println(\"我在前面插入了：\"+$1);");
        ctMethod1.insertAfter("System.out.println(\"我在最后插入了：\"+$1);");
        ctClass.addMethod(ctMethod1);

        ctClass.writeFile(file);
    }
}

public static CtClass booleanType;
public static CtClass charType;
public static CtClass byteType;
public static CtClass shortType;
public static CtClass intType;
public static CtClass longType;
public static CtClass floatType;
public static CtClass doubleType;
public static CtClass voidType;

// 新增一个变量
        CtField ctField = new CtField(CtClass.intType, "value", ctClass);
        ctField.setModifiers(Modifier.PRIVATE);
        ctClass.addField(ctField);

 //为value变量添加set方法
        CtMethod setValue = new CtMethod(CtClass.voidType, "setValue", new CtClass[]{CtClass.intType}, ctClass);
        setValue.setModifiers(Modifier.PUBLIC);
        ctClass.addMethod(setValue);

        //为value变量添加get方法
        CtMethod getValue = new CtMethod(CtClass.intType, "getValue", new CtClass[]{}, ctClass);
        getValue.setModifiers(Modifier.PUBLIC);
        ctClass.addMethod(getValue);

        //设置方法体
//        setValue.setBody("this.value = var1;");
//        setValue.setBody("this.value = $1;");
        ctMethod.setBody("this.value = $1 + $2;");

     //设置方法体
        getValue.setBody("return this.value;");

      //添加一个hello1的方法
        CtMethod ctMethod1 = new CtMethod(CtClass.voidType, "hello1", new CtClass[]{CtClass.intType, CtClass.doubleType}, ctClass);
        ctMethod1.setModifiers(Modifier.PUBLIC);
        ctMethod1.setBody("this.value = $1 + $2;");
        ctMethod1.insertBefore("System.out.println(\"我在前面插入了：\"+$1);");
        ctMethod1.insertAfter("System.out.println(\"我在最后插入了：\"+$1);");
        ctClass.addMethod(ctMethod1);