javaBean和jsp实现复数的4则运算（不使用脚本let）

首先，我们需要定义一个JavaBean来表示复数，包含实部和虚部两个属性：

public class Complex {
    private double real; // 实部
    private double imag; // 虚部

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

    public double getReal() {
        return real;
    }

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

    public double getImag() {
        return imag;
    }

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

    // 复数加法
    public Complex add(Complex other) {
        return new Complex(this.real + other.real, this.imag + other.imag);
    }

    // 复数减法
    public Complex subtract(Complex other) {
        return new Complex(this.real - other.real, this.imag - other.imag);
    }

    // 复数乘法
    public Complex multiply(Complex other) {
        double real = this.real * other.real - this.imag * other.imag;
        double imag = this.real * other.imag + this.imag * other.real;
        return new Complex(real, imag);
    }

    // 复数除法
    public Complex divide(Complex other) {
        double denominator = other.real * other.real + other.imag * other.imag;
        double real = (this.real * other.real + this.imag * other.imag) / denominator;
        double imag = (this.imag * other.real - this.real * other.imag) / denominator;
        return new Complex(real, imag);
    }
}

然后，在JSP页面中使用JavaBean进行复数运算：

<jsp:useBean id="complex1" class="com.example.Complex" scope="page">
    <jsp:setProperty name="complex1" property="real" value="${param.real1}" />
    <jsp:setProperty name="complex1" property="imag" value="${param.imag1}" />
</jsp:useBean>

<jsp:useBean id="complex2" class="com.example.Complex" scope="page">
    <jsp:setProperty name="complex2" property="real" value="${param.real2}" />
    <jsp:setProperty name="complex2" property="imag" value="${param.imag2}" />
</jsp:useBean>

<p>复数加法：${complex1.add(complex2)}</p>
<p>复数减法：${complex1.subtract(complex2)}</p>
<p>复数乘法：${complex1.multiply(complex2)}</p>
<p>复数除法：${complex1.divide(complex2)}</p>

在浏览器中访问这个JSP页面，输入两个复数的实部和虚部，就可以得到四则运算的结果。注意，这里不能使用脚本let，而是使用JSP的EL表达式来调用JavaBean的方法进行运算。