Java数学表示式解析工具- jeval

标签：java 数学表达式解析器

Jeval下载地址：http://www.oschina.net/p/jeval 目前最新版本是0.9.4 Beta

public class EvalTest {
	
	private static final double X_VALUE = 1.0;
	private static final double Y_VALUE = 270;

//	testJeval/testJeval2需要手動包裝變量，testJeval3增加了變量包裝方法
	public static void main(String[] args) throws Exception {		
		testJeval();
		testJeval2();
		testJeval3();
	}

	private static void testJeval() throws Exception {
		String exp = "2 + (7-5) * 3.14159 * #{x} + sin(#{y})";

		// compile
		Evaluator eva = new Evaluator();
		
		eva.putVariable("x", Double.toString(X_VALUE));
		eva.putVariable("y", Double.toString(Y_VALUE));

		// evaluate
		double result = Double.parseDouble(eva.evaluate(exp));

		System.out.println(result);//-> 2.0
	}
	
	public static void testJeval2(){
		// 我们的游戏公式 ahit-(blv-alv)*(6*beva/100)+32
		String exp = "#{ahit}-(#{blv}-#{alv})*(6*#{beva}/100)+32";
		Evaluator eva = new Evaluator();
		try {
		/** * 添加变量到 Evaluator 类实例.  */
		eva.putVariable("ahit", "33");
		eva.putVariable("blv", "10");
		eva.putVariable("alv", "10");
		eva.putVariable("beva", "5");
		/** * 简单输出变量. */
		/*System.out.println(eva.evaluate("#{ahit}"));
		System.out.println(eva.evaluate("#{blv}"));
		System.out.println(eva.evaluate("#{alv}"));
		System.out.println(eva.evaluate("#{beva}"));*/
		//公式计算
		System.out.println(eva.evaluate(exp));
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	public static void testJeval3(){
		// 我们的游戏公式 ahit-(blv-alv)*(6*beva/100)+32
		String exp = "ahit-(blv-alv)*(6*beva/100)+32";
		Evaluator eva = new Evaluator();
		try {
		/** * 添加变量到 Evaluator 类实例.  */
		eva.putVariable("ahit", "33");
		eva.putVariable("blv", "10");
		eva.putVariable("alv", "10");
		eva.putVariable("beva", "5");
		
		//公式计算
		System.out.println(eva.evaluate(formatExpression(exp)));
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	public static String formatExpression(String exp){
		//英文字母變量用#{ }包裝：如變量x，#{x}
		String re = "([a-zA-Z]+)";
		Pattern pattern = Pattern.compile(re);
		Matcher matcher = pattern.matcher(exp);
		StringBuffer sb = new StringBuffer();
		while(matcher.find()){
			matcher.appendReplacement(sb, "#{" + matcher.group(1) + "}");
		}
		matcher.appendTail(sb);
		return sb.toString();
	}

}

Java数学表示式解析工具- jeval

标签：java 数学表达式解析器

原文地址：http://blog.csdn.net/kuyuyingzi/article/details/42100945