java將字串轉成算術運算式

轉自http://bbs.csdn.net/topics/360244167

import javax.script.ScriptEngine;import javax.script.ScriptEngineManager;import javax.script.ScriptException;public class ExpressTest {public static void test1() throws ScriptException {String str = "(a >= 0 && a <= 5)";ScriptEngineManager manager = new ScriptEngineManager();ScriptEngine engine = manager.getEngineByName("js");engine.put("a", 4);Object result = engine.eval(str);System.out.println("結果類型:" + result.getClass().getName() + ",計算結果:" + result);}public static void test2() throws ScriptException {String str = "43*(2 + 1.4)+2*32/(3-2.1)";ScriptEngineManager manager = new ScriptEngineManager();ScriptEngine engine = manager.getEngineByName("js");Object result = engine.eval(str);System.out.println("結果類型:" + result.getClass().getName() + ",計算結果:" + result);}public static void main(String[] args) throws ScriptException {test1();test2();}}

jdk1.6中可以直接這樣用
jdk1.5中需要以下jar：commons-logging-1.1.1.jar, js.jar, bsf-all-3.0.jar