一个不错的java的表达式计算的工具

在我们的项目中，如果是做流程或者是一些涉及到计算的模块时，是不是有动态进行计算的需求呀。

比如，我们从配置里读取到一个公式，比如最简单的 sin(A) + cos(B) 你会怎样实现呢，

这个实现上没有多大的困难，从最简单的hard code的解析，到正则表达解析，或者是AST语法树解析，或者用bsh，jython,jruby/groovy等脚本引擎，或者更有甚者直接用sql执行，等等方法多种多样。不过每种方法或多或少都有自己一定的局限。如何找到一个比较好的解决方案呢。

这里给大家推荐一个比较不错灵活的公式模块的java实现equals

equals是exceoon的david.liu在google codes里贡献的一个项目。是实现公式计算模板的一个解决方案。该项目在多个商业的股票行情软件的自编规则和自编指标的模块中得以广泛应用，有使用过股票软件的朋友，应该对选股器和自定义指标这两个功能比较熟悉吧。

也就是客户自己在编辑器一定义出一个或者是一套计算公式，然后程序会根据你指定的公式进行计算，当然作为商业上的应用，这里的计算不仅仅局限于加减乘除，还包含标准偏差，平均线，移动平均线等指标的计算。

比如下面的这段测试代码

String txt = "DIF:EMA(CLOSE,SHORT)-EMA(OPEN,LONG);"
+ "DEA:EMA(DIF,MID);"

+ "MACD:(DIF-DEA)*2::COLORSTICK;";

先定义一个公式 这个公式是计算股票的指标MACD的。

String[] defs = new String[]
{ "SHORT", "LONG", "MID" };

定义公式中的输入参数

Formula f = null;
f = FormulaBuilder.constructFormula(txt, defs);

声明一个Formula的变量，这里就是整个公式计算的entry

FormulaParameters fp = new FormulaParameters();
fp.addParameter("short", 12);
fp.addParameter("long", 26);
fp.addParameter("mid", 9);

声明公式需要的输入变量。

FormulaResult fr = f.eval(fp);
Map<String, Object> results = fr.getResult();

进行计算得到结果

运行最后的结果

{dea=[0.9358484784928137, 5.223248740604646, 9.484484720782131, 12.812405231923686, 17.625797032274512, 21.48934699188941, 24.338687429831023, 24.967767843873517, 23.713504323762475, 23.419514164728735, 22.735086398910138, 22.495512066265064, 22.42045061047972, 21.686444772033873, 20.699838512275377, 19.800386512274844, 20.637560544699593, 22.159859719130218, 24.403776610862046, 24.227408662528966, 22.137340048573154, 21.27741048836811, 20.240579387890197, 19.05695339586254, 16.70384447055847, 16.076128111445378, 14.878188371277464, 13.761807666795649, 13.446553319790361, 14.507684011227127, 13.374907832743064, 10.633227879860222, 8.01815943098602, 5.102424718335767, 2.3071096698386544, -0.3636299728305956, -1.0764588575814014, -2.007847505375248, -3.3771308924710546, -2.992205267376599, -3.409601523132302, -3.152630485981012, -1.652301728989015, 0.06031436069506646, 2.1743828361502264, 3.225697255197028, 5.4291566819545904, 5.2381674589246146, 6.318190562739442, 6.539097031605232, 8.047663761906332, 6.987127060299267, 6.393116866583883, 5.5090016976278795, 5.697663742732732, 4.697814328207814, 2.9086831988864628, 2.2716142389282123, 1.5414277242134833, 0.511061516567303, 0.5807628095128398, 2.356397569537216, 4.278134723604381, 4.052172273526611, 5.2945745230142816, 4.856523216525936, 4.856215977440695, 4.448840846212395, 4.620369162264453, 4.711465166220274, 5.204702439818421, 6.139324792095153, 6.07435288804274, 5.050472337328575, 2.760808950677174, 1.0762871740060749, -0.3525313760925096, -0.4576312199107083, -0.3576855874336494, -0.047701505433911356, -0.45477110003830445, -1.5058191379602623, -3.437010627869526, -4.072244650056223, -2.541007163949839, -2.0103388844296686, -2.50312479232222, -2.2894491447695273, -0.5914388323214326, -0.4169389134949677, -0.012264436855367211, 0.687085671118843, 2.5344611936514294, 4.747483969091154, 5.063547335745879, 6.866522716801898, 6.918328460171757, 7.541830872993569, 8.271715110463383, 10.144861208894433], macd=[7.48678782794251, 34.29920209689466, 34.08988784141987, 26.623364089132433, 38.5071344028066, 30.90839967691918, 22.794723503532886, 5.032643312339985, -10.03410816088833, -2.3519212722699123, -5.4754221265487715, -1.9165946611605875, -0.6004916462827623, -5.872046707566781, -7.892850078067966, -7.1956160000042715, 6.6973922593979935, 12.178393395444985, 17.951335133854613, -1.4109435866646578, -16.720548911646496, -6.879436481640376, -8.2946488038233, -9.469007936221267, -18.82487140243257, -5.021730872904712, -9.583517921343322, -8.931045635854506, -2.522034776042304, 8.489045531494128, -9.062209427872492, -21.93343962306274, -20.92054759099361, -23.325877701202014, -22.362520387976904, -21.365917141354, -5.702631078006446, -7.4511091823507725, -10.95426709676645, 3.079405000755645, -3.3391700460456244, 2.0557682972103173, 12.002630055935978, 13.70092871747265, 16.91254780364128, 8.410515352374414, 17.627675414060498, -1.5279137842398, 8.640184830518628, 1.7672517509263166, 12.06853384240879, -8.484293612856522, -4.752081549723076, -7.0729213516480325, 1.5092963608388121, -7.998795316199338, -14.313049034570806, -5.096551679666001, -5.8414921177178325, -8.242929661169443, 0.5576103435642941, 14.205078080195007, 15.373897232537331, -1.807699600622163, 9.939217995901362, -3.5044104519067645, -0.002457912681927965, -3.259001049826402, 1.372226528416462, 0.7287680316465632, 3.9458981887851756, 7.476978818213864, -0.5197752324193079, -8.19104440571332, -18.317307093211213, -13.476174213368791, -11.430548400788675, -0.8407987505455898, 0.7995650598164714, 2.4798726559979047, -3.2565567568351446, -8.408384303375662, -15.449531919274108, -5.081872177493574, 12.249899888851068, 4.245346236161361, -3.942287263140411, 1.709405180421541, 13.584082499584758, 1.395999350611719, 3.237395813116804, 5.594800863793681, 14.779004180260689, 17.704182203517796, 2.5285069332377965, 14.423803048448146, 0.41444594695887815, 4.988019302574491, 5.839073899758503, 14.985168787448416], dif=[4.679242392464069, 22.372849789051976, 26.529428641492068, 26.124087276489902, 36.87936423367781, 36.943546830349, 35.736049181597465, 27.48408950004351, 18.69645024331831, 22.24355352859378, 19.997375335635752, 21.53721473568477, 22.120204787338338, 18.750421418250482, 16.753413473241395, 16.20257851227271, 23.98625667439859, 28.24905641685271, 33.37944417778935, 23.521936869196637, 13.777065592749906, 17.83769224754792, 16.093254985978547, 14.322449427751906, 7.291408769342183, 13.565262674993022, 10.086429410605803, 9.296284848868396, 12.18553593176921, 18.75220677697419, 8.843803118806818, -0.33349193167114777, -2.442114364510786, -6.56051413226524, -8.874150524149798, -11.046588543507596, -3.927774396584624, -5.733402096550634, -8.85426444085428, -1.4525027669987765, -5.079186546155114, -2.1247463373758535, 4.349013298978974, 6.910778719431391, 10.630656737970867, 7.430954931384235, 14.24299438898484, 4.4742105668047145, 10.638282977998756, 7.42272290706839, 14.081930683110727, 2.744980253871006, 4.017076091722345, 1.9725410218038633, 6.452311923152138, 0.6984166701081449, -4.24784131839894, -0.276661600904788, -1.3793183346454327, -3.610403314017418, 0.8595679812949868, 9.45893660963472, 11.965083339873047, 3.1483224732155293, 10.264183520964963, 3.1043179905725538, 4.854987021099731, 2.819340321299194, 5.306482426472684, 5.075849182043555, 7.177651534211009, 9.877814201202085, 5.814465271833086, 0.9549501344719147, -6.397844595928433, -5.661799932678321, -6.0678055764868475, -0.8780305951835032, 0.042096942474586285, 1.192234822565041, -2.0830494784558766, -5.710011289648094, -11.16177658750658, -6.61318073880301, 3.583942780475695, 0.11233423365101203, -4.4742684238924255, -1.4347465545587568, 6.200602417470947, 0.2810607618108918, 1.6064334697030347, 3.4844861030156835, 9.923963283781774, 13.599575070850051, 6.327800802364777, 14.07842424102597, 7.1255514336511965, 10.035840524280815, 11.191252060342634, 17.63744560261864]}

这个例子是专门针对股票中的一个指标做的公式。最后的计算结果是测试数据的结果，

项目介绍： http://www.inthirties.com/thread-2708-1-1.html

项目地址： http://code.google.com/p/exceoon/source/browse/trunk#trunk/components/equals