bigdecimalconsole.java

这个是一个计算表达式的java包

/*
Created 18 Dec 2006 - Richard Morris
*/
package com.singularsys.jepexamples.consoles;

import java.math.MathContext;

import com.singularsys.jep.Jep;
import com.singularsys.jep.bigdecimal.BigDecComponents;

public class BigDecimalConsole extends Console {
	private static final long serialVersionUID = 1L;

	BigDecComponents bdc;
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		BigDecimalConsole bdc = new BigDecimalConsole();
		bdc.run(args);
	}

	@Override
	public void initialise() {
		bdc = new BigDecComponents(MathContext.UNLIMITED);
		jep = new Jep(bdc);
	}

	@Override
	public String getPrompt() {
		return "BigDecConsole > ";
	}

	@Override
	public SPEC_ACTION testSpecialCommands(String command) {
		if(command.startsWith("setPrec")) {
			String[] args = split(command);
			String prec = args[1];
			String rm;
			if(args.length>=3)
				rm = args[2];
			else
				rm = "HALF_UP";
			bdc.setMathContext(new MathContext("precision="+prec+" roundingMode="+rm));
			return SPEC_ACTION.BREAK;
		}
		return super.testSpecialCommands(command);
	}

	@Override
	public void printHelp() {
		super.printHelp();
		println("'setPrec precision rounding_mode' sets the precision and rounding mode");
		println("\tprecision is the number of decimal digit accuracy, 0 is infinite precision");
		println("\trounding_mode is HALF_UP by default, see java.math.RoundingMode.");
	}

}