设计一个复数类Complex，并在该类中实现将对象自身保存到文件的功能，实例方法void save（String fileName）；从文件恢复数据的静态方法static Complex load（String fileName）

好的，我可以帮你设计一个Java的复数类Complex，并在该类中实现将对象自身保存到文件的功能，并实现从文件恢复数据的静态方法。下面是代码实现：

import java.io.*;

public class Complex implements Serializable {
    private double real;
    private double imag;

    public Complex(double real, double imag) {
        this.real = real;
        this.imag = imag;
    }

    public void save(String fileName) {
        try {
            ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(fileName));
            out.writeObject(this);
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static Complex load(String fileName) {
        Complex c = null;
        try {
            ObjectInputStream in = new ObjectInputStream(new FileInputStream(fileName));
            c = (Complex)in.readObject();
            in.close();
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }
        return c;
    }

    public double getReal() {
        return real;
    }

    public double getImag() {
        return imag;
    }

    public void setReal(double real) {
        this.real = real;
    }

    public void setImag(double imag) {
        this.imag = imag;
    }

    public Complex add(Complex other) {
        double r = this.real + other.real;
        double i = this.imag + other.imag;
        return new Complex(r, i);
    }

    public Complex subtract(Complex other) {
        double r = this.real - other.real;
        double i = this.imag - other.imag;
        return new Complex(r, i);
    }

    public Complex multiply(Complex other) {
        double r = this.real * other.real - this.imag * other.imag;
        double i = this.real * other.imag + this.imag * other.real;
        return new Complex(r, i);
    }

    public Complex divide(Complex other) {
        double r = (this.real * other.real + this.imag * other.imag) / (other.real * other.real + other.imag * other.imag);
        double i = (this.imag * other.real - this.real * other.imag) / (other.real * other.real + other.imag * other.imag);
        return new Complex(r, i);
    }

    public String toString() {
        return "(" + real + ", " + imag + "i)";
    }
}

在该类中，我们使用ObjectOutputStream和ObjectInputStream来实现将对象自身保存到文件的功能，以及从文件恢复数据的静态方法。注意，在实现这两个方法时，我们需要让Complex类实现Serializable接口。

使用示例：

public static void main(String[] args) {
    Complex c1 = new Complex(1, 2);
    c1.save("complex.dat");

    Complex c2 = Complex.load("complex.dat");
    System.out.println(c2);
}

执行该程序，输出结果为：

(1.0, 2.0i)