合同开始日期：2023-01-01，结束日期：2026-01-01，免租起始期：2023-01-01，免租终止日期：023-01-31，计费面积：100平方米，月租单价20/平方米，计算方式：按1个月计算一次，收款方式为按3个月收一次，提前收款期为1个月，基本租期1年，超过基本租期后按1年一个递增周期，一个递增周期内月租单价按递增率计算,下一个递增周期内月租单价按上一个递增周期内月租单价复合递增，年递增率为6%，按java7的语法：按计算方式产生合同期内含收款日期、租期起始日期、租期终止日期、租期单价、租期（月数）租金的计划列表，生成一个完整示例并配上代码说明

好的，根据您的要求，我为您生成了以下示例代码：

import java.math.BigDecimal;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.List;

public class RentContract {

    private static final int BASIC_PERIOD_MONTHS = 12;
    private static final int INCREASE_PERIOD_MONTHS = 12;
    private static final BigDecimal INITIAL_PRICE = new BigDecimal("20");
    private static final BigDecimal INCREASE_RATE = new BigDecimal("0.06");

    private Date startDate;
    private Date endDate;
    private Date freeStartDate;
    private Date freeEndDate;
    private BigDecimal area;
    private BigDecimal pricePerSquareMeter;
    private int billingCycleMonths;
    private int advanceBillingMonths;
    private int basicPeriodMonths;
    private int increasePeriodMonths;
    private BigDecimal initialPrice;
    private BigDecimal increaseRate;

    public RentContract(Date startDate, Date endDate, Date freeStartDate, Date freeEndDate,
                        BigDecimal area, BigDecimal pricePerSquareMeter, int billingCycleMonths,
                        int advanceBillingMonths, int basicPeriodMonths, int increasePeriodMonths,
                        BigDecimal initialPrice, BigDecimal increaseRate) {
        this.startDate = startDate;
        this.endDate = endDate;
        this.freeStartDate = freeStartDate;
        this.freeEndDate = freeEndDate;
        this.area = area;
        this.pricePerSquareMeter = pricePerSquareMeter;
        this.billingCycleMonths = billingCycleMonths;
        this.advanceBillingMonths = advanceBillingMonths;
        this.basicPeriodMonths = basicPeriodMonths;
        this.increasePeriodMonths = increasePeriodMonths;
        this.initialPrice = initialPrice;
        this.increaseRate = increaseRate;
    }

    public List<RentPlan> generateRentPlan() {
        List<RentPlan> rentPlanList = new ArrayList<>();
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(startDate);
        BigDecimal currentPrice = initialPrice;
        int currentMonthCount = 0;
        while (calendar.getTime().before(endDate)) {
            if (calendar.getTime().before(freeEndDate)) {
                // 免租期内不产生租金
                rentPlanList.add(new RentPlan(calendar.getTime(), null, null, null, null));
            } else {
                BigDecimal currentRent = area.multiply(currentPrice);
                Date rentStartDate = calendar.getTime();
                calendar.add(Calendar.MONTH, billingCycleMonths);
                Date rentEndDate = calendar.getTime();
                if (rentEndDate.after(endDate)) {
                    rentEndDate = endDate;
                    currentRent = calculateFinalRent(rentStartDate, rentEndDate, currentPrice, currentMonthCount);
                }
                RentPlan rentPlan = new RentPlan(rentStartDate, rentEndDate, currentPrice, billingCycleMonths, currentRent);
                rentPlanList.add(rentPlan);
                currentMonthCount += billingCycleMonths;
                if (currentMonthCount % (basicPeriodMonths + increasePeriodMonths) == 0) {
                    currentPrice = currentPrice.multiply(BigDecimal.ONE.add(increaseRate)).setScale(2, BigDecimal.ROUND_HALF_UP);
                }
            }
            calendar.add(Calendar.MONTH, advanceBillingMonths);
        }
        return rentPlanList;
    }

    private BigDecimal calculateFinalRent(Date rentStartDate, Date rentEndDate, BigDecimal currentPrice, int currentMonthCount) {
        int months = (int) ((rentEndDate.getTime() - rentStartDate.getTime()) / (1000 * 60 * 60 * 24 * 30L));
        int basicPeriods = currentMonthCount / basicPeriodMonths;
        int remainingMonths = currentMonthCount % basicPeriodMonths;
        BigDecimal finalPrice = currentPrice;
        for (int i = 0; i < basicPeriods; i++) {
            finalPrice = finalPrice.multiply(BigDecimal.ONE.add(increaseRate)).setScale(2, BigDecimal.ROUND_HALF_UP);
        }
        for (int i = 0; i < remainingMonths; i++) {
            finalPrice = finalPrice.multiply(BigDecimal.ONE.add(increaseRate)).setScale(2, BigDecimal.ROUND_HALF_UP);
        }
        for (int i = 0; i < months - currentMonthCount; i++) {
            finalPrice = finalPrice.multiply(BigDecimal.ONE.add(increaseRate)).setScale(2, BigDecimal.ROUND_HALF_UP);
        }
        return area.multiply(finalPrice);
    }

    public static void main(String[] args) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        Date startDate = null;
        Date endDate = null;
        Date freeStartDate = null;
        Date freeEndDate = null;
        try {
            startDate = sdf.parse("2023-01-01");
            endDate = sdf.parse("2026-01-01");
            freeStartDate = sdf.parse("2023-01-01");
            freeEndDate = sdf.parse("2023-01-31");
        } catch (Exception e) {
            e.printStackTrace();
        }
        BigDecimal area = new BigDecimal("100");
        BigDecimal pricePerSquareMeter = new BigDecimal("20");
        int billingCycleMonths = 1;
        int advanceBillingMonths = 3;
        int basicPeriodMonths = BASIC_PERIOD_MONTHS;
        int increasePeriodMonths = INCREASE_PERIOD_MONTHS;
        BigDecimal initialPrice = INITIAL_PRICE;
        BigDecimal increaseRate = INCREASE_RATE;
        RentContract rentContract = new RentContract(startDate, endDate, freeStartDate, freeEndDate,
                area, pricePerSquareMeter, billingCycleMonths, advanceBillingMonths, basicPeriodMonths,
                increasePeriodMonths, initialPrice, increaseRate);
        List<RentPlan> rentPlanList = rentContract.generateRentPlan();
        for (RentPlan rentPlan : rentPlanList) {
            System.out.println(rentPlan.toString());
        }
    }

}

class RentPlan {

    private Date startDate;
    private Date endDate;
    private BigDecimal price;
    private int months;
    private BigDecimal rent;

    public RentPlan(Date startDate, Date endDate, BigDecimal price, int months, BigDecimal rent) {
        this.startDate = startDate;
        this.endDate = endDate;
        this.price = price;
        this.months = months;
        this.rent = rent;
    }

    public Date getStartDate() {
        return startDate;
    }

    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }

    public Date getEndDate() {
        return endDate;
    }

    public void setEndDate(Date endDate) {
        this.endDate = endDate;
    }

    public BigDecimal getPrice() {
        return price;
    }

    public void setPrice(BigDecimal price) {
        this.price = price;
    }

    public int getMonths() {
        return months;
    }

    public void setMonths(int months) {
        this.months = months;
    }

    public BigDecimal getRent() {
        return rent;
    }

    public void setRent(BigDecimal rent) {
        this.rent = rent;
    }

    @Override
    public String toString() {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        String startDateStr = startDate != null ? sdf.format(startDate) : "";
        String endDateStr = endDate != null ? sdf.format(endDate) : "";
        String priceStr = price != null ? price.toString() : "";
        String rentStr = rent != null ? rent.toString() : "";
        return String.format("起始日期：%s，终止日期：%s，租金单价：%s，租期：%d个月，租金：%s", startDateStr, endDateStr, priceStr, months, rentStr);
    }

}

上述代码实现了一个租赁合同的计划生成器，其主要逻辑如下：

1. 初始化合同参数，包括起始日期、结束日期、免租期、计费面积、月租单价、计算方式等；
2. 根据起始日期和结束日期，按计算方式逐个月生成租金计划；
3. 对于免租期内的月份，不产生租金计划；
4. 对于非免租期内的月份，根据计费面积和月租单价计算租金，生成租金计划；
5. 对于超过基本租期的租期，按照递增周期计算租金单价；
6. 对于递增周期内的月份，租金单价按照递增率逐月复合递增；
7. 最后一个周期内的租金单价按照剩余月份计算。

示例代码中，我们通过一个 `RentContract` 类来封装合同参数和租金计划生成逻辑，以及一个 `RentPlan` 类来封装租金计划数据。在 `main` 方法中，我们初始化合同参数并调用 `generateRentPlan` 方法生成租金计划，最后打印出所有租金计划的信息。

需要注意的是，在计算租金单价和租金总额时，我们使用了 `BigDecimal` 类型来避免浮点数精度误差带来的问题。同时，在格式化输出租金计划信息时，我们使用了 `String.format` 方法来格式化输出，增强了代码的可读性。