java 字节码 java 获取字节码文件的几种方法总结

public class Person {
  private int age;
  private String name;

  public Person() {
    System.out.println("person run");
  }

  public Person(String name, int age) {
    this.age = age;
    this.name = name;
    System.out.println("Person param run..." + this.name + ":" + this.age);
  }

  public void showInfo() {
    System.out.println(this.name + "......" + this.age);
  }
}

public class GetClassFile {
  public static void main(String[] args) throws ClassNotFoundException {
    getClassObject_3();
  }

  /**
   * 通过给定的类的字符串名称就可以获取该类的字节码文件，更利于扩展
   * 可以用Class类中的"forName()"方法来完成
   */
  public static void getClassObject_3() throws ClassNotFoundException {
  // 包名一定要写全，否则会报"java.lang.ClassNotFoundException"异常
    String className = "src.Person"; 
    Class clazz = Class.forName(className);
    System.out.println(clazz);
  }

  /**
   * 任何数据类型都具备一个静态属性
   * 通过".class"来获取对应的Class对象
   * 扩展性较差
   */
  public static void getClassObject_2() {
    Class clazz = Person.class;
    Class clazz1 = Person.class;
    System.out.println(clazz == clazz1);
  }

  /**
   * 运用Object类中的getClass方法
   * 用这个方法时，必须明确具体的类，并创建对象
   * 比较麻烦
   */
  public static void getClassObject_1() {
    Person p = new Person();
    Class clazz = p.getClass();
    Person p1 = new Person();
    Class clazz1 = p1.getClass();
    System.out.println(clazz == clazz1);
  }
}