请你用java语言编写一个一元多项式计算器，一元多项式要从键盘录入或从文件中读取系数、指数数据，要求程序能够能够正确浏览各多项式，计算任意两个一元多项式的加法、减法以及乘法，保留原多项式结果

好的，我可以为您提供一份Java代码，实现一元多项式计算器的功能。请注意，代码中包含读取文件的功能，您可以根据需要自行修改。

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

public class PolynomialCalculator {

    public static void main(String[] args) throws IOException {
        ArrayList<Term> p1 = readPolynomialFromFile("polynomial1.txt");
        ArrayList<Term> p2 = readPolynomialFromFile("polynomial2.txt");

        System.out.println("Polynomial 1: " + polynomialToString(p1));
        System.out.println("Polynomial 2: " + polynomialToString(p2));

        ArrayList<Term> pAdd = addPolynomials(p1, p2);
        ArrayList<Term> pSub = subtractPolynomials(p1, p2);
        ArrayList<Term> pMul = multiplyPolynomials(p1, p2);

        System.out.println("Addition: " + polynomialToString(pAdd));
        System.out.println("Subtraction: " + polynomialToString(pSub));
        System.out.println("Multiplication: " + polynomialToString(pMul));
    }

    public static ArrayList<Term> readPolynomialFromFile(String fileName) throws IOException {
        ArrayList<Term> polynomial = new ArrayList<>();
        File file = new File(fileName);

        BufferedReader br = new BufferedReader(new FileReader(file));
        String line;
        while ((line = br.readLine()) != null) {
            String[] parts = line.split(" ");
            polynomial.add(new Term(Integer.parseInt(parts[0]), Integer.parseInt(parts[1])));
        }
        br.close();

        // sort the terms in descending order of exponents
        Collections.sort(polynomial, new Comparator<Term>() {
            @Override
            public int compare(Term t1, Term t2) {
                return t2.exponent - t1.exponent;
            }
        });

        return polynomial;
    }

    public static ArrayList<Term> addPolynomials(ArrayList<Term> p1, ArrayList<Term> p2) {
        ArrayList<Term> result = new ArrayList<>();

        int i = 0, j = 0;
        while (i < p1.size() && j < p2.size()) {
            Term t1 = p1.get(i), t2 = p2.get(j);
            if (t1.exponent > t2.exponent) {
                result.add(new Term(t1.coefficient, t1.exponent));
                i++;
            } else if (t1.exponent < t2.exponent) {
                result.add(new Term(t2.coefficient, t2.exponent));
                j++;
            } else {
                result.add(new Term(t1.coefficient + t2.coefficient, t1.exponent));
                i++;
                j++;
            }
        }

        while (i < p1.size()) {
            result.add(new Term(p1.get(i).coefficient, p1.get(i).exponent));
            i++;
        }

        while (j < p2.size()) {
            result.add(new Term(p2.get(j).coefficient, p2.get(j).exponent));
            j++;
        }

        return result;
    }

    public static ArrayList<Term> subtractPolynomials(ArrayList<Term> p1, ArrayList<Term> p2) {
        ArrayList<Term> result = new ArrayList<>();

        int i = 0, j = 0;
        while (i < p1.size() && j < p2.size()) {
            Term t1 = p1.get(i), t2 = p2.get(j);
            if (t1.exponent > t2.exponent) {
                result.add(new Term(t1.coefficient, t1.exponent));
                i++;
            } else if (t1.exponent < t2.exponent) {
                result.add(new Term(-t2.coefficient, t2.exponent));
                j++;
            } else {
                result.add(new Term(t1.coefficient - t2.coefficient, t1.exponent));
                i++;
                j++;
            }
        }

        while (i < p1.size()) {
            result.add(new Term(p1.get(i).coefficient, p1.get(i).exponent));
            i++;
        }

        while (j < p2.size()) {
            result.add(new Term(-p2.get(j).coefficient, p2.get(j).exponent));
            j++;
        }

        return result;
    }

    public static ArrayList<Term> multiplyPolynomials(ArrayList<Term> p1, ArrayList<Term> p2) {
        ArrayList<Term> result = new ArrayList<>();

        for (Term t1 : p1) {
            for (Term t2 : p2) {
                int c = t1.coefficient * t2.coefficient;
                int e = t1.exponent + t2.exponent;
                insertTerm(result, new Term(c, e));
            }
        }

        return result;
    }

    public static void insertTerm(ArrayList<Term> polynomial, Term term) {
        int i;
        for (i = 0; i < polynomial.size(); i++) {
            if (polynomial.get(i).exponent < term.exponent) {
                break;
            }
        }
        polynomial.add(i, term);
    }

    public static String polynomialToString(ArrayList<Term> polynomial) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < polynomial.size(); i++) {
            Term t = polynomial.get(i);
            if (t.coefficient > 0 && i > 0) {
                sb.append("+");
            }
            sb.append(t.coefficient);
            sb.append("x^");
            sb.append(t.exponent);
        }
        return sb.toString();
    }

    static class Term {
        int coefficient;
        int exponent;

        public Term(int coefficient, int exponent) {
            this.coefficient = coefficient;
            this.exponent = exponent;
        }
    }
}

代码中的 `Term` 类表示一项，包含系数和指数两个属性。`readPolynomialFromFile` 方法用于从文件中读取多项式数据，并按指数从高到低排序。`addPolynomials`、`subtractPolynomials`、`multiplyPolynomials` 分别实现多项式的加、减、乘运算。`insertTerm` 方法用于将一项插入到多项式中的正确位置。`polynomialToString` 方法将多项式转换为字符串表示，便于输出。

您可以根据需要修改文件名以及多项式的具体数据。