汽车销售租赁管理平台Java代码

汽车销售租赁管理平台涉及到多个模块，包含前端和后端。以下是一个简单的Java代码示例，实现了一个汽车租赁模块的后端代码：

package com.example.carrental.demo.controller;

import com.example.carrental.demo.entity.Car;
import com.example.carrental.demo.entity.RentalRecord;
import com.example.carrental.demo.service.CarService;
import com.example.carrental.demo.service.RentalRecordService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.Date;
import java.util.List;

@RestController
@RequestMapping("/rental")
public class RentalRecordController {

    @Autowired
    private RentalRecordService rentalRecordService;

    @Autowired
    private CarService carService;

    @GetMapping("/getAllRentalRecords")
    public List<RentalRecord> getAllRentalRecords() {
        return rentalRecordService.getAllRentalRecords();
    }

    @PostMapping("/addRentalRecord")
    public void addRentalRecord(@RequestBody RentalRecord rentalRecord) {
        rentalRecordService.addRentalRecord(rentalRecord);
        Car car = carService.getCarById(rentalRecord.getCarId());
        car.setIsRented(true);
        carService.updateCar(car);
    }

    @PostMapping("/returnCar")
    public void returnCar(@RequestParam int rentalRecordId) {
        RentalRecord rentalRecord = rentalRecordService.getRentalRecordById(rentalRecordId);
        rentalRecord.setReturnDate(new Date());
        int days = (int) ((rentalRecord.getReturnDate().getTime() - rentalRecord.getRentalDate().getTime()) / (1000 * 3600 * 24));
        Car car = carService.getCarById(rentalRecord.getCarId());
        car.setIsRented(false);
        car.setMileage(car.getMileage() + rentalRecord.getDistance());
        carService.updateCar(car);
        rentalRecord.setRentalFee(days * car.getDailyRentalFee());
        rentalRecordService.updateRentalRecord(rentalRecord);
    }

}

该代码中，使用了Spring Boot框架，实现了一个租赁记录的控制器类。包含了获取所有租赁记录、添加租赁记录、归还车辆等方法。具体实现过程中，调用了租赁记录服务类和汽车服务类，实现对租赁记录和汽车信息的增删改查操作。