calculatorjava.java

计算简单字符串的java类 例如：IF:(1>0)TRUE(1)

package DBListen.inServer;

import java.util.Hashtable;
import java.util.Vector;

public class CalculatorJava {
	private int nextElement;

	private char[] elements = null;
 
	private Hashtable key_value = null;

	private Vector stack = null;

	private boolean isOver = false;

	private String errMsg = null;

	private Double cussVariable = null;

	private String Exp = "";
	
	private String excMsg = null;
	
	private String[] keyWords="<,>,=,<=,>=,<>,&,|,IIF,TRUE,FALSE".split(",");
	
	private String keyWords2 = "<>=:?&|";
	
	private String keyWord3 = "+-*/<>&|=";
	
	private String keyWord4 = "+-*/<>=&|IIF:1.0IIF:0.0TRUEFALSE";
	/**构造 CalculatorJava 实例 
 * */
	public CalculatorJava() {

	}
/**
 * 构造  CalculatorJava 实例 并设置公式
 * */
	public CalculatorJava(String src) {
		this.Exp = src.trim();
	}
	/**
	 * 设置公式,计算公式的结果
	 * 如果没有设置公式,将报告"公式没有设置"的错误
	 * @since;
	 * */
	public void setExpressions(String Exp) {
		this.Exp = Exp.trim();
	}
    //初始化
	private void initializes() {
		this.elements = this.Exp.toCharArray();
		nextElement = 0;
		this.stack = new Vector();
		this.errMsg = "";
		excMsg = "";
		this.nextElement = 0;
		this.isOver = false;
	}
   // 析构方法
	private void to() {

		this.elements = null;

		this.key_value = null;

		this.stack = null;

		this.Exp = "";

		this.cussVariable = null;
	}

	/**
	 * 计算公式并把结果返回,如果产生错误会返回:Float.MAX_VALUE.错误信息通过 showmsg()方法返回
	 *  
	 */ 
	public double calculatorRun() {
		double rv = 0;
		if (this.Exp.length() < 1) {
			this.isOver = true;
			this.errMsg = "错误:公式未经初始化 "+errMsg;
		} else{
			this.initializes();
		}
		try {
			while (!isover()) {
				this.calculatorEngine();
			}
		} catch (Exception e) {
			e.printStackTrace();
			this.errMsg = "发生意想不到的错误,请检查公式 "+errMsg;
		}
		if(this.cussVariable!=null&&this.cussVariable.isNaN()){
			this.errMsg +=this.excMsg; 
		}
		if (!(this.errMsg.length()>0))
			rv = this.endValue();
		else
			rv = Double.MAX_VALUE;
		this.to();
		return rv;
	}

	// 返回最终结果
	private double endValue() {
		double rv = 0;
		rv = this.cussVariable.doubleValue();
		return rv;
	}

	// 定义变量
	/**
	 * 定义变量并赋值,如果calculatorRun()发现了没有定义的变量将产生"变量未定义"的错误.
	 * */
	public void addVariable(String key, double v) {
		if (this.key_value == null) {
			this.key_value = new Hashtable();
		}
		this.key_value.put(key, new Double(v));
	}
/**返回错误信息
 * */
	public String showmsg() {
		return this.errMsg;
	}

	private boolean isover() throws Exception {
		if(this.isOver||this.nextElement >= this.elements.length){
				if(this.cussVariable!=null){
					boolean isnone = false;
					if (this.stack.size() > 0) {
						while (!isnone && this.stack.size() > 0) {
							String[] stackEle = this.outStack();
							stackEle[2] = this.cussVariable.toString();
							this.cussVariable = this.clrStack(stackEle);
						}
					}
				}
				this.isOver = true;
			}
		return this.isOver;
	}

	private void calculatorEngine() {
		char tempCh = this.elements[this.nextElement];
		/* 
		 * 1.处理字符 包括：变量，IIF ? :
		 *  */
		if (Character.isLetterOrDigit(tempCh)) {
			if (Character.isDigit(tempCh)) {
				this.addDigit();
				return;
			} else if (Character.isLetter(tempCh)) {
				this.transferVariable();
				return;
			}
		} else if (tempCh == '(') {
			if (this.cussVariable != null) {
				this.isOver = true;
				this.errMsg = "\""+ this.elements[this.nextElement<this.elements.length?this.nextElement:this.nextElement-1]+"\" 位置" + this.nextElement + " 语法错误 "+errMsg;
				return;
			}
			this.addDelimit();

			return;
		} else if (tempCh == ')') {
			if (this.cussVariable == null) {
				this.isOver = true;
				this.errMsg = "\""+ this.elements[this.nextElement<this.elements.length?this.nextElement:this.nextElement-1]+"\"  位置" + this.nextElement + " 语法错误 "+errMsg;
				return;
			}
			try {
				this.reDelimit();
			} catch (Exception e) {
				this.isOver = true;
				this.errMsg = "错误:请检查公式 "+errMsg;
			}
			return;
		} else if (tempCh == '+') {
			this.addition();
			return;
		} else if (tempCh == '-') {
			this.subtration();
			return;
		} else if (tempCh == '*') {
			this.multiplication();
			return;
		} else if (tempCh == '/') {
			this.division();
			return;
		} else if (tempCh == ':') {
			this.IIFStat();
			return;
		} else {
			isOver = true;
			this.errMsg ="\""+ this.elements[this.nextElement<this.elements.length?this.nextElement:this.nextElement-1]+"\"  非法字符  " + this.nextElement + "  "+errMsg;
		}
	}

	// '(' 定界符
	private void addDelimit() {
		String[] stackEle = new String[3];
		stackEle[0] = null;
		stackEle[1] = "(";
		stackEle[2] = null;
		this.inStack(stackEle);
		this.nextElement++;
	}

	// ')' 定界符结束
	private void reDelimit() throws Exception {
		if (this.stack.size() > 0) {
			while (true) {
				String[] stackEle = this.outStack();
				if (stackEle[1] == "(")
					break;
				else {
					stackEle[2] = this.cussVariable.toString();
					this.cussVariable = this.clrStack(stackEle);
				}
			}
		} else{
			this.outStack();
		}
		this.nextElement++;
	}

	// '+' 加法
	private void addition() {
		String[] stackElement = new String[3];

		if (this.cussVariable == null) {
			this.isOver = true;
			this.errMsg = "\""+ this.elements[this.nextElement<this.elements.length?this.nextElement:this.nextElement-1]+"\" 位置" + this.nextElement + " 语法错误  "+errMsg;
			return;
		}
		try {
			this.adjustLevel("+");
		} catch (Exception e) {
			this.isOver = true;
			return;
		}
		stackElement[0] = this.cussVariable.toString();
		stackElement[1] = "+";
		stackElement[2] = null;
		this.inStack(stackElement);
		this.cussVariable = null;
		this.nextElement++;
	}

	// '-' 减法
	private void subtration() {
		String[] stackElement = new String[3];

		if (this.cussVariable == null) {
			this.isOver = true;
			this.errMsg = "\""+ this.elements[this.nextElement<this.elements.length?this.nextElement:this.nextElement-1]+"\" 位置" + this.nextElement + " 语法错误  "+errMsg;
			return;
		}
		try {
			this.adjustLevel("-");
		} catch (Exception e) {
			this.isOver = true;
			return;
		}
		stackElement[0] = this.cussVariable.toString();
		stackElement[1] = "-";
		stackElement[2] = null;
		this.inStack(stackElement);
		this.cussVariable = null;
		this.nextElement++;
	}

	// '*' 乘法
	private void multiplication() {
		String[] stackElement = new String[3];

		if (this.cussVariable == null) {
			this.isOver = true;
			this.errMsg = "\""+ this.elements[this.nextElement<this.elements.length?this.nextElement:this.nextElement-1]+"\" 位置" + this.nextElement + " 语法错误  "+errMsg;
			return;
		}
		try {
			this.adjustLevel("*");
		} catch (Exception e) {
			this.isOver = true;
			return;
		}

		stackElement[0] = this.cussVariable.toString();
		stackElement[1] = "*";
		stackElement[2] = null;

		this.inStack(stackElement);
		this.cussVariable = null;
		this.nextElement++;
	}

	// '/' 除法
	private void division() {
		String[] stackElement = new String[3];

		if (this.cussVariable == null) {
			this.isOver = true;
			this.errMsg = "\""+ this.elements[this.nextElement<this.elements.length?this.nextElement:this.nextElement-1]+"\" 位置" + this.nextElement + " 语法错误  "+errMsg;
			return;
		}
		try {
			this.adjustLevel("/");
		} catch (Exception e) {
			this.isOver = true;
			return;
		}
		stackElement[0] = this.cussVariable.toString();
		stackElement[1] = "/";
		stackElement[2] = null;

		this.inStack(stackElement);
		this.cussVariable = null;
		this.nextElement++;
	}
    // 关系运算
	public void connOperation(String ch){
		String[] stackElement = new String[3];
		
		if("IIF".equals(ch)){
			stackElement[0] = null;