The technical principle application of the Java class library moderate unit API framework

The technical principle application of the Java class library moderate unit API framework Abstract: The API framework of the measurement unit is a widely used tool in the Java class library to process the conversion and calculation of the measurement unit.This article will introduce the technical principles of the framework and provide related Java code examples. introduction: The measurement unit is a way of expression widely used in science, engineering and daily life.In computer programming, the conversion and calculation of the processing unit is a common task, which usually needs to write a large number of code to complete.To simplify this process, the Java class library has developed the API framework of the measurement unit. Technical principle: The API framework of the measurement unit uses a technical principle of Domain Driven Design (DDD) and abstract syntax trees.Its core idea is to abstract the conversion and calculation of the unit into a domain model, and use AST to analyze and perform related operations. Specifically, the API framework of the measurement unit includes the following core components: 1. Unit definition: The framework provides a set of predefined measures, such as length (meter, kilometer, feet, etc.), quality (gram, kg, etc.), temperature (degree Celsius, Hua Shi, etc.).At the same time, users also support their own measurement units. 2. Number representation: The use of a numerical object of the frame represents the number of different measured units.These numerical objects include the two attributes of the unit and the numerical value. Through the operation of the numerical object, the unit can be converted and calculated. 3. Unit conversion: The framework provides a set of conversion rules for mutual conversion of different measurement units.These conversion rules can be expanded and customized according to the needs of user. 4. Unit computing: The framework supports basic mathematical operations such as addition, subtraction, multiplication and removal of the values of different units.It will automatically transform the unit according to the unit of the numerical object. Java code example: Here are some Java code examples of the API framework of the measurement unit. // Import measurement unit API framework import javax.measure.*; import javax.measure.quantity.*; public class MeasurementExample { public static void main(String[] args) { // Define a length object Quantity<Length> length = Quantities.getQuantity(10, SI.METER); // Convert length to feet double feet = length.to(USCustomary.FOOT).getValue(); System.out.println ("length is:" + Feet + "feet"); // Define a quality object Quantity<Mass> mass = Quantities.getQuantity(100, SI.GRAM); // Convert quality to kg double kilograms = mass.to(SI.KILOGRAM).getValue(); System.out.println ("quality is: + kilograms +" kg "); // Perform unit calculation Quantity<Area> area = Quantities.getQuantity(10, SI.SQUARE_METRE); Quantity<Length> side = Quantities.getQuantity(2, SI.METER); Quantity<Volume> volume = side.multiply(area).asType(Volume.class); System.out.println ("volume is: + volume.getvalue () +" cubic meter "); } } Summarize: The API framework of the measurement unit provides a tool for Java developers to facilitate and efficiently process the unit.Its technical principles are based on field -driven design and abstract syntax trees, which simplify the process of measured unit conversion and calculation through abstract and packaging.By using the framework reasonably, developers can reduce the amount of code and improve development efficiency, so as to better apply the function of measurement of unit -related functions.