Java BigDecimal验证

Question

这是属性定义

public class Item {
@Digits(integer=6, fraction=2)
@DecimalMin("0.00") 
private BigDecimal goods_cost;

和getter / setter

public String getGoods_cost() {
    return goods_cost.toString();
}
public void setGoods_cost(String goods_cost) {
    this.goods_cost = new BigDecimal(goods_cost);
}

数据来自网页

<td><form:input path="goods_cost" type="text" size="10" maxlength="20"/></td> 

如果输入有效，如0.01或10.15或42，一切正常，但如果输入无效，则生成-10.00或12.333异常。有例外

org.apache.jasper.JasperException: java.lang.IllegalArgumentException: source to convert from must be an instance of @javax.validation.constraints.Digits @javax.validation.constraints.DecimalMin java.lang.String; instead it was a java.math.BigDecimal
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:548)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:469)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:168)
org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303)
org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1244)
org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1027)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:971)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:868)
javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:85)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

root cause
java.lang.IllegalArgumentException: source to convert from must be an instance of @javax.validation.constraints.Digits @javax.validation.constraints.DecimalMin java.lang.String; instead it was a java.math.BigDecimal
org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:188)
org.springframework.validation.AbstractPropertyBindingResult.formatFieldValue(AbstractPropertyBindingResult.java:125)
org.springframework.validation.AbstractBindingResult.getFieldValue(AbstractBindingResult.java:232)
org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:120)
org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getBindStatus(AbstractDataBoundFormElementTag.java:168)
org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getPropertyPath(AbstractDataBoundFormElementTag.java:188)
org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getName(AbstractDataBoundFormElementTag.java:154)
org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.autogenerateId(AbstractDataBoundFormElementTag.java:141)
org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.resolveId(AbstractDataBoundFormElementTag.java:132)
org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.writeDefaultAttributes(AbstractDataBoundFormElementTag.java:116)
org.springframework.web.servlet.tags.form.AbstractHtmlElementTag.writeDefaultAttributes(AbstractHtmlElementTag.java:422)
org.springframework.web.servlet.tags.form.InputTag.writeTagContent(InputTag.java:142)
org.springframework.web.servlet.tags.form.AbstractFormTag.doStartTagInternal(AbstractFormTag.java:84)
org.springframework.web.servlet.tags.RequestContextAwareTag.doStartTag(RequestContextAwareTag.java:80)
org.apache.jsp.WEB_002dINF.jsp.goods_jsp._jspx_meth_form_005finput_005f1(goods_jsp.java:325)
org.apache.jsp.WEB_002dINF.jsp.goods_jsp._jspService(goods_jsp.java:193)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:431)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:168)
org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303)
org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1244)
org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1027)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:971)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:868)
javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:85)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

请帮忙！这有什么问题？