Question

“实体类”可不可以动态添加“字段”和“属性”

Answer 1

可以的，你用 javassist, cglib 或者更为底层的工具 ASM 都是可以。

ASM 的话相对复杂一些，参考代码：

下面这个是用 ASM 工具为 Student 类添加一个 public String 类型的 address 属性：

1，需要添加属性的原始类：Student.java

Java code?

public class Student {
private int age;
private String name;
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}

2，添加属性的适配器：AddFieldAdapter.java

Java code?

import org.objectweb.asm.ClassAdapter;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.FieldVisitor;

public class AddFieldAdapter extends ClassAdapter {
private int accessModifier;
private String name;
private String desc;
private boolean isFieldPresent;

public AddFieldAdapter(ClassVisitor cv, int accessModifier, String name, String desc) {
super(cv);
this.accessModifier = accessModifier;
this.name = name;
this.desc = desc;
}