Java的表达式计算引擎 Expr4J

     <p>Expr4J 是一个Java的表达式计算引擎，可以用来计算例如在 Excel 单元格中的表达式等。</p>    <p>示例代码：</p>    <pre class="brush:java; toolbar: true; auto-links: false;">package org.boris.expr.util;  import java.io.*; import org.boris.expr.*; import org.boris.expr.parser.ExprParser;  public class ExprEvaluator {     public static void main(String[] args) throws Exception {         SimpleEvaluationContext context = new SimpleEvaluationContext();         System.out.println("Expr Evaluator v1.0");         BufferedReader br = new BufferedReader(new InputStreamReader(System.in));         while (true) {             try {                 System.out.print(">");                 String line = br.readLine();                 if (line == null)                     break;                 Expr e = ExprParser.parse(line);                 Exprs.toUpperCase(e);                 if (e instanceof ExprEvaluatable) {                     e = ((ExprEvaluatable) e).evaluate(context);                 }                 System.out.println(e);             } catch (Exception e) {                 e.printStackTrace();             }         }     } }  package org.boris.expr.util;  import org.boris.expr.BasicEngineProvider; import org.boris.expr.engine.DependencyEngine; import org.boris.expr.engine.Range;  public class DependencyExample {     public static void main(String[] args) throws Exception {         DependencyEngine e = new DependencyEngine(new BasicEngineProvider());         e.set("B1", "=A1*2");         e.set("A1", "=12*2");         e.set("C1", "=B1*A1");         System.out.println(e.getValue(Range.valueOf("B1")));         System.out.println(e.getValue(Range.valueOf("C1")));         e.set("A1", "2");         System.out.println(e.getValue(Range.valueOf("B1")));         System.out.println(e.getValue(Range.valueOf("C1")));     } }</pre>    <p></p>    <p><strong>项目主页：</strong><a href="http://www.open-open.com/lib/view/home/1326806268546" target="_blank">http://www.open-open.com/lib/view/home/1326806268546</a></p>