您可以使用
ObjectOutputStream和将对象转换为字节数组
ByteArrayOutputStream：
public static int sizeof(Object obj) throws IOException { ByteArrayOutputStream byteOutputStream = new ByteArrayOutputStream(); ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteOutputStream); objectOutputStream.writeObject(obj); objectOutputStream.flush(); objectOutputStream.close(); return byteOutputStream.toByteArray().length;}我只是测试了一下。您要计算
Serializable其大小的对象需要实现（这意味着您可能仅为了获得其大小就必须标记每个对象。这可能是不希望的）。我写了一个快速而肮脏的程序来测试一下：
import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.ObjectOutputStream;import java.io.Serializable;public class Sizeof { public static class Person implements Serializable { private String name; private String age; public Person(String name, String age) { this.name = name; this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAge() { return age; } public void setAge(String age) { this.age = age; } } public static void main(String[] args) { Person p1 = new Person("Alby", "20"); Person p2 = new Person("VeryLongName", "100"); String s1 = "This is it"; String s2 = "This"; try { System.out.println("p1 " + sizeof(p1)); System.out.println("p2 " + sizeof(p2)); System.out.println("s1 " + sizeof(s1)); System.out.println("s2 " + sizeof(s2)); } catch(Exception e) { e.printStackTrace(); } } public static int sizeof(Object obj) throws IOException { ByteArrayOutputStream byteOutputStream = new ByteArrayOutputStream(); ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteOutputStream); objectOutputStream.writeObject(obj); objectOutputStream.flush(); objectOutputStream.close(); return byteOutputStream.toByteArray().length; }}这给了我：
p1 85p2 94s1 17s2 11
编辑
Stephen C的答案突出了此方法的一些注意事项。
