import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.util.ArrayList;import java.util.List;import java.util.regex.Pattern;import javax.script.ScriptEngine;import javax.script.ScriptEngineManager;import javax.script.ScriptException;import com.tf.arithmetic.bean.Exterior;/** * 自定义计算表达式解析器和计算器 * 表达式的写法：@{占位变量} * @author yzl * */public class ExpressionResolver {    private ExpressionResolver(){}    private static ExpressionResolver resolver = null;    public static ExpressionResolver getInstance(){        if(null==resolver){            resolver = new ExpressionResolver();        }        return resolver;    }        /**     * 计算表达式的结果     * @param expression  解析包含@{}的表达式     * @param bean     * @param precision     * @return     * @throws ScriptException     * @throws NoSuchMethodException     * @throws SecurityException     * @throws IllegalAccessException     * @throws IllegalArgumentException     * @throws InvocationTargetException     */    public double getExecuteResult(String expression, Object bean, int precision) throws ScriptException, NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {        expression = this.parse(expression, bean);        ScriptEngine se = new ScriptEngineManager().getEngineByName("JavaScript");        double result = (Double) se.eval(expression);        return MathUtils.multiply(result, 1d, precision);    }        /**     * 解析自定义的@{}表达式     * (@{ys}*0.3+@{csd}*0.25+@{jg}*0.15+@{sf}*0.12+@{yf}*0.1+@{sd}*0.08)*10     * @param expression     * @param bean     * @return     * @throws SecurityException      * @throws NoSuchMethodException      * @throws InvocationTargetException      * @throws IllegalArgumentException      * @throws IllegalAccessException      */    private String parse(String expression, Object bean) throws NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException{        //保存表达式中的所有变量        List<String> variableList = new ArrayList<String>();                String reg = "@\\{";        String reg2 = "\\}";        Pattern pattern = Pattern.compile(reg);        Pattern pattern2 = Pattern.compile(reg2);        String[] arr = pattern.split(expression);        for(int i=0; i<arr.length; i++){            if(!"(".equals(arr[i]) && !")".equals(arr[i])){                variableList.add(pattern2.split(arr[i])[0]);            }        }                String fieldName = null;        String methodName = null;        Object result = null;                //用值替换表达式中的变量        if(variableList.size()>0){            Field[] field = bean.getClass().getDeclaredFields();            for(int i=0; i<field.length; i++){                fieldName = field[i].getName();                methodName = "get"+fieldName.substring(0,1).toUpperCase()+fieldName.substring(1);                result = bean.getClass().getMethod(methodName, null).invoke(bean);                expression = expression.replace("@{"+fieldName+"}", result.toString());            }        }                return expression;    }        public static void main(String[] args) throws Exception {        String input = "(@{ys}*0.3+@{csd}*0.25+@{jg}*0.15+@{sf}*0.12+@{yf}*0.1+@{sd}*0.08)*10";        String reg = "@\\{";        String reg2 = "\\}";        Pattern pattern = Pattern.compile(reg);        Pattern pattern2 = Pattern.compile(reg2);        String[] arr = pattern.split(input);        for(int i=0; i<arr.length; i++){            if(!"(".equals(arr[i]) && !")".equals(arr[i])){                System.out.println("得到变量:"+pattern2.split(arr[i])[0]);            }        }                Exterior bean = new Exterior(8,8,8,8,8,8);        double val = ExpressionResolver.getInstance().getExecuteResult(input, bean, 2);        System.out.println(val);    }}

/** * 某模型的pojo对象 * @author yzl * */public class Exterior {    private int ys;    private int csd;    private int jg;    private int sf;    private int yf;    private int sd;        public int getYs() {        return ys;    }    public void setYs(int ys) {        this.ys = ys;    }    public int getCsd() {        return csd;    }    public void setCsd(int csd) {        this.csd = csd;    }    public int getJg() {        return jg;    }    public void setJg(int jg) {        this.jg = jg;    }    public int getSf() {        return sf;    }    public void setSf(int sf) {        this.sf = sf;    }    public int getYf() {        return yf;    }    public void setYf(int yf) {        this.yf = yf;    }    public int getSd() {        return sd;    }    public void setSd(int sd) {        this.sd = sd;    }        public Exterior(int ys, int csd, int jg, int sf, int yf, int sd) {        super();        this.ys = ys;        this.csd = csd;        this.jg = jg;        this.sf = sf;        this.yf = yf;        this.sd = sd;    }        public Exterior() {        super();    }}