<!--google 算法包-->
        <dependency>
            <groupId>com.google.ortools</groupId>
            <artifactId>ortools-java</artifactId>
            <version>9.9.3963</version>
        </dependency>
        <!--google 算法包-->

    @Override
    public List<FsBill> solverBill(CheckingBill_Req req) {
        List<FsBill> fsBills = findCheckingBill(req);
        //背包算法只支持Long，所以amount*1000转换
        //由于不需要考虑价值因素，所以设置values=amount.这样可以匹配正好的金额。
        long[] values = fsBills.stream().mapToLong(x -> x.getTotalRateAmount().multiply(new BigDecimal(1000)).longValue()).toArray();
        //金额:小数*1000，作整数处理。
        long[][] amount = {values};
        //总金额*1000，作整数处理。
        long[] capacities = {req.getTotalAmount().multiply(new BigDecimal(1000)).longValue()};
        List<Integer> fsBillIndexs = knapsackSolver_invoice(values, amount, capacities);
        List<FsBill> solverBill = new ArrayList<>();
        if (!CollectionUtils.isEmpty(fsBillIndexs)) {
            for (Integer i : fsBillIndexs) {
                solverBill.add(fsBills.get(i));
            }
        }
        return solverBill;
    }

@Override
    public List<Integer> knapsackSolver_invoice(long[] values, long[][] weights, long[] capacities) {
        //加载OR-TOOL本地库
        Loader.loadNativeLibraries();
        //开始业务
        System.out.println("=========Begin : 匹配发票");
        KnapsackSolver solver = new KnapsackSolver(
                KnapsackSolver.SolverType.KNAPSACK_MULTIDIMENSION_BRANCH_AND_BOUND_SOLVER, "test");
 
        solver.init(values, weights, capacities);
        final long computedValue = solver.solve();
 
        ArrayList<Integer> packedItems = new ArrayList<>();
        ArrayList<Long> packedWeights = new ArrayList<>();
        int totalWeight = 0;
        for (int i = 0; i < values.length; i++) {
            if (solver.bestSolutionContains(i)) {
                packedItems.add(i);
                packedWeights.add(weights[0][i]);
                totalWeight = (int) (totalWeight + weights[0][i]);
            }
        }
        //匹配金额
        System.out.println("Target amounts: " + capacities[0]);
        //总价值
        System.out.println("Total values: " + computedValue);
        //总重量
        System.out.println("Total amounts: " + totalWeight);
        //装载项的下标，可对应List<发票>的下标
        System.out.println("Packed items: " + packedItems);
        //装载项的重量
        System.out.println("Packed amounts: " + packedWeights);
        System.out.println("=========End : 匹配发票");
        //如果没有完全匹配金额，则清空packedItems
        if (capacities[0] != totalWeight) {
            packedItems.clear();
        }
        return packedItems;
    }