Question

有这个课程：

$ ./test.sh
service = 'default'
node    = 'default'

$ ./test.sh -s hello -n world
service = 'hello'
node    = 'world'

$ ./test.sh -n world -s hello
service = 'hello'
node    = 'world'

$ ./test.sh -e eh
./test.sh: illegal option -- e

将方法public class DataPeriod { private final String key; private final LocalDate from; private final LocalDate to; private final Map<LocalDate, DataPoint> dataPoints = new HashMap<LocalDate, DataPoint>(); public DataPeriod(String key, LocalDate from, LocalDate to) { this.key = key; this.from = from; this.to = to; } public LocalDate getFrom() { return from; } public LocalDate getTo() { return to; } public void hit(int id) { DataPoint dataPoint = getOrCreate(); dataPoint.hit(id); } private DataPoint getOrCreate() { LocalDate now = LocalDate.now(); String dataPointKey = key + now.toString(); if ( !dataPoints.containsKey(now) ) { DataPoint dataPoint = new DataPoint(dataPointKey); dataPoints.put(now, dataPoint); } return dataPoints.get(dataPointKey); } public long count() { long count = 0l; for (DataPoint dataPoint : dataPoints.values()) { count += dataPoint.count(); } return count; }和hit(int id)作为服务或帮助程序提取到其他类可能是一个好主意。但是应该修改它们以便接收getOrCreate()的参数。

我认为将它们包含在DataPoint类中是有道理的，因为它们代表了DataPoint必须知道的行为。

这种情况有一些模式吗？在并发提取或不提取方面这些方法有何不同？

Answer 1

这似乎是使用 动态属性 的经典案例。
如果您有一个可以从其他属性计算出的属性，则将其声明为 dynamic 属性，并为其编写自定义的属性处理程序。

例如-如果您有持久性属性（您存储在数据库中的属性），例如生日，则可以声明 dynamic 属性 age 并在运行时对其进行计算，而无需将其存储在数据库中。您将需要像AgeAttributeHandler.java这样的自定义动态属性处理程序。

具有动态属性的另一个动机是所有模型豆必须仅具有 getters 和 setters 。 业务逻辑应保留在模型bean之外。

您的情况是，首先创建一个DynamicAttributeHandler.java-

public interface DynamicAttributeHandler<VALUE, MODEL extends Object> {
    VALUE get(MODEL var1);

    void set(MODEL var1, VALUE var2);
}

然后，为count和dataPoints创建动态属性处理程序。

public class CountAttributeHandler implements DynamicAttributeHandler<Long, DatePeriod> {

    @Override
    public Long get(DatePeriod model) {
        long count = 0l;
        Map<LocalDate, DataPoint> dataPoints = model.getDataPoints();
        for (DataPoint dataPoint : dataPoints.values()) {
            count += dataPoint.count();
        }
        return count;
    }

    @Override
    public void set(DatePeriod model, Long aLong) {

    }
}

public class DataPointsAttributeHandler implements DynamicAttributeHandler<Map<LocalDate, DataPoint>, DatePeriod> {

    @Override
    public Map<LocalDate, DataPoint> get(DatePeriod model) {
        LocalDate now = LocalDate.now();
        String dataPointKey = model.getKey() + now.toString();
        Map<LocalDate, DataPoint> dataPoints = model.getDataPoints();
        if (!dataPoints.containsKey(now)) {
            DataPoint dataPoint = new DataPoint(dataPointKey);
            dataPoints.put(now, dataPoint);
        }
        return dataPoints;
    }

    @Override
    public void set(DatePeriod model, Map<LocalDate, DataPoint> localDateDataPointMap) {

    }
}

现在，仅使用 getters 和 setters 即可创建模型。

public class DatePeriod {

    private final String key;
    private final LocalDate from;
    private final LocalDate to;
    private final Map<LocalDate, DataPoint> dataPoints;
    private final long count;

    public DatePeriod(String key, LocalDate from, LocalDate to, Map<LocalDate, DataPoint> dataPoints, long count) {
        this.key = key;
        this.from = from;
        this.to = to;
        this.dataPoints = dataPoints;
        this.count = count;
    }

    public LocalDate getFrom() {
        return from;
    }

    public LocalDate getTo() {
        return to;
    }

    public String getKey() {
        return key;
    }

    public Map<LocalDate, DataPoint> getDataPoints() {
        DynamicAttributeHandler<Map<LocalDate, DataPoint>, DatePeriod> dataPointsAttributeHandler = new DataPointsAttributeHandler();
        return dataPointsAttributeHandler.get(this);
    }

    public long getCount() {
        DynamicAttributeHandler<Long, DatePeriod> countAttributeHandler = new CountAttributeHandler();
        return countAttributeHandler.get(this);
    }
}

域对象中的业务逻辑

1 个答案: