public class Test{ public static void main(String[] args) throws Exception {   String str = "(a or b) and c";   str = str.replaceAll("or", "||");   str = str.replaceAll("and", "&&");   System.out.println(str);   ScriptEngineManager manager = new ScriptEngineManager();   ScriptEngine engine = manager.getEngineByName("js");   engine.put("a",true);   engine.put("b",false);   engine.put("c",true);     Object result = engine.eval_r(str);   System.out.println("結果類型:" + result.getClass().getName() + ",計算結果:" + result);  }}

/** * @Project:  BizRule   * @File:   org.coffeesweet.util.MathExpress.java * @Author:  coffeesweet * @Date:   2011-3-28 * @Description: 2011 coffeesweet Inc. All rights reserved. */package org.coffeesweet.util;import java.math.BigDecimal;import java.math.MathContext;import java.math.RoundingMode;import java.util.ArrayList;import java.util.LinkedList;import java.util.List;import java.util.StringTokenizer;import java.util.regex.Matcher;import java.util.regex.Pattern;/** * @author coffeesweet * +,-,*,/四則運算的表達式逆波蘭解析計算類,精確計算,應用BigDecimal類處理 * 支持負數,但規范除整個表達式第一個數為負數時可以不出現在'('后，其它表達式中間任何位置的 * 負數必須出現在'('后,即：用括號括起來。比如：-3+(-2+1)*10或-3+((-2)+1)*10或(-3)+(-2+1)*10或(-3)+((-2)+1)*10 */public class MathExpress { /**  * +  */ private final static String OP1 = "+"; /**  * -  */ private final static String OP2 = "-"; /**  * *  */ private final static String OP3 = "*"; /**  * /  */ private final static String OP4 = "/"; /**  * ^  */// private final static String OP5 = "^"; /**  * %  */// private final static String OP6 = "%"; /**  * (  */ private final static String OPSTART = "("; /**  * )  */ private final static String OPEND = ")"; /**  * !用來替代負數前面的'-'  */// private final static String NEGATIVESING = "!"; /**  * !用來替代負數前面的'+'  */// private final static String PLUSSING = "@"; /**  * '#'用來代表運算級別最低的特殊字符  */// private final static String LOWESTSING = "#"; //最原始的四則運算式 private String expBase; //經過初始化處理后的四則運算式 private String expInited; //精度 private int precision=10; //取舍模式 private RoundingMode roundingMode=RoundingMode.HALF_UP; //精度上下文 private MathContext mc; //四則運算解析 private List<String> expList = new ArrayList<String>(); //存放逆波蘭表達式 private List<String> rpnList = new ArrayList<String>(); public MathExpress(){ } public MathExpress(String expBase) {  init(expBase,this.precision,this.roundingMode); } public MathExpress(String expBase,int precision,RoundingMode roundingMode){  init(expBase,precision,roundingMode); } public void init(String expBase,int precision,RoundingMode roundingMode){  this.expBase = expBase;  this.precision = precision;  this.roundingMode = roundingMode;  this.mc = new MathContext(precision,roundingMode);  this.expInited = initExpress(expBase);  StringTokenizer st = new StringTokenizer(this.expInited,"+-*/^%()",true);  while(st.hasMoreElements()){   this.expList.add(st.nextElement().toString().trim());  }  this.rpnList = initRPN(this.expList); } /**  * @return the expBase  */ public String getExpBase() {  return expBase; } /**  * @param expBase the expBase to set  */ public void setExpBase(String expBase) {  this.expBase = expBase; } /**  * @return the expInited  */ public String getExpInited() {  return expInited; } /**  * @param expInited the expInited to set  */ public void setExpInited(String expInited) {  this.expInited = expInited; } /**  * @return the precision  */ public int getPrecision() {  return precision; } /**  * @param precision the precision to set  */ public void setPrecision(int precision) {  this.precision = precision; } /**  * @return the roundingMode  */ public RoundingMode getRoundingMode() {  return roundingMode; } /**  * @param roundingMode the roundingMode to set  */ public void setRoundingMode(RoundingMode roundingMode) {  this.roundingMode = roundingMode; } /**  * @return the expList  */ public List<String> getExpList() {  return expList; } /**  * @param expList the expList to set  */ public void setExpList(List<String> expList) {  this.expList = expList; } /**  * @return the rpnList  */ public List<String> getRpnList() {  return rpnList; } /**  * @param rpnList the rpnList to set  */ public void setRpnList(List<String> rpnList) {  this.rpnList = rpnList; } /**  * @return the mc  */ public MathContext getMc() {  return mc; } /**  * @param mc the mc to set  */ public void setMc(MathContext mc) {  this.mc = mc; } /**  * 去除空白字符和在負號'-'前加'0',便于后面的StringTokenizer  * @param exp  * @return  */ private static String initExpress(String exp){  String reStr = null;  reStr = exp.replaceAll("//s", "");  if(reStr.startsWith("-")){   reStr = "0"+reStr;  }  reStr = reStr.replaceAll("//(//-", "(0-");  return reStr; } /**  * 是否是整數或是浮點數,但默認-05.15這種也認為是正確的格式  * @param str  * @return  */ private boolean isNumber(String str){  Pattern p = Pattern.compile("^(-?//d+)(//.//d+)?$");  Matcher m = p.matcher(str);  boolean isNumber = m.matches();  return isNumber; } /**  * 設置優先級順序()設置與否無所謂  * @param sign  * @return  */ private int precedence(String str){  char sign = str.charAt(0);  switch(sign){   case '+':   case '-':    return 1;   case '*':   case '/':    return 2;   case '^':   case '%':    return 3;   case '(':   case ')'://   case '#':   default:    return 0;  } } /**  * 轉變為逆波蘭表達式  * @param strList  * @return  */ public List<String> initRPN(List<String> strList){  List<String> returnList = new ArrayList<String>();  //用來存放操作符的棧  Stack stack = new Stack();//  stack.push(LOWESTSING);  int length = strList.size();  for(int i=0;i<length;i++ ){   String str = strList.get(i);   if(isNumber(str)){    returnList.add(str);   }else{    if(str.equals(OPSTART)){     //'('直接入棧     stack.push(str);    }else if(str.equals(OPEND)){     //')'     //進行出棧操作，直到棧為空或者遇到第一個左括號      while (!stack.isEmpty()) {       //將棧頂字符串做出棧操作       String tempC = stack.pop();       if (!tempC.equals(OPSTART)) {        //如果不是左括號，則將字符串直接放到逆波蘭鏈表的最后        returnList.add(tempC);       }else{        //如果是左括號，退出循環操作        break;       }      }     }else{     if (stack.isEmpty()) {      //如果棧內為空       //將當前字符串直接壓棧       stack.push(str);      }else{      //棧不空,比較運算符優先級順序      if(precedence(stack.top())>=precedence(str)){       //如果棧頂元素優先級大于當前元素優先級則       while(!stack.isEmpty() && precedence(stack.top())>=precedence(str)){        returnList.add(stack.pop());       }      }      stack.push(str);     }    }   }  }  //如果棧不為空，則將棧中所有元素出棧放到逆波蘭鏈表的最后   while (!stack.isEmpty()) {   returnList.add(stack.pop());  }  return returnList; } /**  * 計算逆波蘭表達式  * @param rpnList  * @return  */ public String caculate(List<String> rpnList){  Stack numberStack = new Stack();   int length=rpnList.size();   for(int i=0;i<length;i++){    String temp=rpnList.get(i);    if(isNumber(temp)){     numberStack.push(temp);    }else{     BigDecimal tempNumber1 = new BigDecimal(numberStack.pop(),this.mc);    BigDecimal tempNumber2 = new BigDecimal(numberStack.pop(),this.mc);    BigDecimal tempNumber = new BigDecimal("0",this.mc);    if(temp.equals(OP1)){      tempNumber=tempNumber2.add(tempNumber1);     }else if(temp.equals(OP2)){      tempNumber=tempNumber2.subtract(tempNumber1);     }else if(temp.equals(OP3)){      tempNumber=tempNumber2.multiply(tempNumber1);     }else if(temp.equals(OP4)){      tempNumber=tempNumber2.divide(tempNumber1,        precision,        roundingMode);     }     numberStack.push(tempNumber.toString());    }   }   return numberStack.pop(); } /**  * 按照類的缺省參數進行計算  * @return  */ public String caculate(){  return caculate(this.rpnList); } /**  * 數字條件表達式精確比較  * eg: "3.0>2" "1<5" "1==5" "1!=5" "(1.0+2)>3" "((-0.9+3)>=2. 1)"  * 不支持&&,||等連接符  * @param str  * @return  */ public static boolean compareTo(String strParm){  boolean reBoolean = false;  boolean isParentheses = false;//標記是否有()括上整個字符串  String str = initExpress(strParm);  Pattern p = Pattern.compile("^//([//s//S]*//)$");  Matcher m = p.matcher(str);  isParentheses = m.matches();  if(-1==str.indexOf(">=")&&-1==str.indexOf("<=")&&-1==str.indexOf("==")&&-1==str.indexOf("!=")){   if(-1==str.indexOf(">")&&-1==str.indexOf("<"))   throw new IllegalArgumentException("異常:條件表達式不正確!");  }  if(-1 != str.indexOf(">=")){   String[] strTemps = str.split(">=");   if(isParentheses){    strTemps[0] = strTemps[0] + ")";    strTemps[1] = "(" + strTemps[1];   }   int r = new BigDecimal((new MathExpress(strTemps[0]).caculate())).compareTo(new BigDecimal((new MathExpress(strTemps[1]).caculate())));   if( -1 == r ){    reBoolean = false;   }else{    reBoolean = true;   }  }else if(-1 != str.indexOf("<=")){   String[] strTemps = str.split("<=");   if(isParentheses){    strTemps[0] = strTemps[0] + ")";    strTemps[1] = "(" + strTemps[1];   }   int r = new BigDecimal((new MathExpress(strTemps[0]).caculate())).compareTo(new BigDecimal((new MathExpress(strTemps[1]).caculate())));   if( 1 == r ){    reBoolean = false;   }else{    reBoolean = true;   }  }else if(-1 != str.indexOf("==")){   String[] strTemps = str.split("==");   if(isParentheses){    strTemps[0] = strTemps[0] + ")";    strTemps[1] = "(" + strTemps[1];   }   int r = new BigDecimal((new MathExpress(strTemps[0]).caculate())).compareTo(new BigDecimal((new MathExpress(strTemps[1]).caculate())));   if( 0 == r ){    reBoolean = true;   }else{    reBoolean = false;   }  }else if(-1 != str.indexOf("!=")){   String[] strTemps = str.split("!=");   if(isParentheses){    strTemps[0] = strTemps[0] + ")";    strTemps[1] = "(" + strTemps[1];   }   int r = new BigDecimal((new MathExpress(strTemps[0]).caculate())).compareTo(new BigDecimal((new MathExpress(strTemps[1]).caculate())));   if( 0 != r ){    reBoolean = true;   }else{    reBoolean = false;   }  }else if((-1 != str.indexOf(">")) && (-1 == str.indexOf("="))){   String[] strTemps = str.split(">");   if(isParentheses){    strTemps[0] = strTemps[0] + ")";    strTemps[1] = "(" + strTemps[1];   }   int r = new BigDecimal((new MathExpress(strTemps[0]).caculate())).compareTo(new BigDecimal((new MathExpress(strTemps[1]).caculate())));   if( 1 == r ){    reBoolean = true;   }else{    reBoolean = false;   }  }else if((-1 != str.indexOf("<")) && (-1 == str.indexOf("="))){   String[] strTemps = str.split("<");   if(isParentheses){    strTemps[0] = strTemps[0] + ")";    strTemps[1] = "(" + strTemps[1];   }   int r = new BigDecimal((new MathExpress(strTemps[0]).caculate())).compareTo(new BigDecimal((new MathExpress(strTemps[1]).caculate())));   if( -1 == r ){    reBoolean = true;   }else{    reBoolean = false;   }  }  return reBoolean; } public static void main(String...args){//  MathExpress me = new MathExpress("-(-0.5+0.1)*10+2",10,RoundingMode.HALF_UP);//  System.out.println(me.getExpList());//  List<String> tempList = me.initRPN(me.getExpList());//  System.out.println(tempList);//  String resultStr = me.caculate(tempList);//  System.out.println(resultStr);  MathExpress me = new MathExpress("-(-1.5000000003+0.1)*10+2");  String resultStr = me.caculate();  BigDecimal bd = new BigDecimal(resultStr);  BigDecimal bd2 = bd.setScale(2, RoundingMode.HALF_UP);  System.out.println(me.caculate());  System.out.println(bd.toString());  System.out.println(bd.scale());  System.out.println(bd2.toString());  System.out.println(bd2.scale());//  System.out.println("------------------------------------");//  Pattern p = Pattern.compile("^//([//s//S]*//)$");//匹配類似以'('開頭')'結尾的字符串//  Matcher m = p.matcher("(2. 0>2.22)");//  System.out.println(m.matches());  boolean reBoolean = MathExpress.compareTo("((-8.0+3)>=2. 1)");  System.out.println(reBoolean); } /**  * 棧  */ private class Stack {  LinkedList<String> stackList = new LinkedList<String>();  public Stack() {  }  /**   * 入棧   * @param expression   */  public void push(String expression) {   stackList.addLast(expression);  }  /**   * 出棧   * @return   */  public String pop() {   return stackList.removeLast();  }  /**   * 棧頂元素   * @return   */  public String top() {   return stackList.getLast();  }  /**   * 棧是否為空   * @return   */  public boolean isEmpty() {   return stackList.isEmpty();  } }}