在一個(gè)程序中，相對(duì)User這個(gè)領(lǐng)域?qū)ο蟮闹T屬性進(jìn)行修改，用來容納存儲(chǔ)數(shù)據(jù)的ActionForm是這樣寫的：

public final class ModifyUserForm extends ActionForm {
    private static final long serialVersionUID = -3447738664240089399L;

    private User user;
    
    public ModifyUserForm(){

    }

    public void reset(ActionMapping mapping, HttpServletRequest request) {
    }

    public ActionErrors validate(ActionMapping mapping,
                                 HttpServletRequest request) {

        ActionErrors errors = new ActionErrors();

        return (errors);

    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }
}

結(jié)果，進(jìn)行頁面數(shù)據(jù)驗(yàn)證的JS能準(zhǔn)確無誤的進(jìn)行前段驗(yàn)證，但Action中沒有收到請(qǐng)求，驗(yàn)證完畢提交表單后出現(xiàn)下面的異常，

HTTP Status 500 -

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: javax.servlet.ServletException: BeanUtils.populate
org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:286)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
com.heyang.filter.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:35)

root cause

javax.servlet.ServletException: BeanUtils.populate
org.apache.struts.util.RequestUtils.populate(RequestUtils.java:469)
org.apache.struts.chain.commands.servlet.PopulateActionForm.populate(PopulateActionForm.java:50)
org.apache.struts.chain.commands.AbstractPopulateActionForm.execute(AbstractPopulateActionForm.java:60)
org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
com.heyang.filter.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:35)

root cause

java.lang.IllegalArgumentException: No bean specified
org.apache.commons.beanutils.PropertyUtilsBean.getPropertyDescriptor(PropertyUtilsBean.java:751)
org.apache.commons.beanutils.BeanUtilsBean.setProperty(BeanUtilsBean.java:937)
org.apache.commons.beanutils.BeanUtilsBean.populate(BeanUtilsBean.java:811)
org.apache.commons.beanutils.BeanUtils.populate(BeanUtils.java:298)
org.apache.struts.util.RequestUtils.populate(RequestUtils.java:467)
org.apache.struts.chain.commands.servlet.PopulateActionForm.populate(PopulateActionForm.java:50)
org.apache.struts.chain.commands.AbstractPopulateActionForm.execute(AbstractPopulateActionForm.java:60)
org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
com.heyang.filter.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:35)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.10 logs.

Apache Tomcat/6.0.10

發(fā)生這個(gè)錯(cuò)誤的原因應(yīng)該是使用工具類commons beanutil向ActionForm中的屬性u(píng)ser輸入數(shù)據(jù)時(shí)發(fā)生了錯(cuò)誤，解決這個(gè)問題也很簡單，在ActionForm內(nèi)部將屬性u(píng)ser實(shí)例化即可，代碼如下：

public final class ModifyUserForm extends ActionForm {
    private static final long serialVersionUID = -3447738664240089399L;

    private User user=new User();
    
    public ModifyUserForm(){

    }

    public void reset(ActionMapping mapping, HttpServletRequest request) {
    }

    public ActionErrors validate(ActionMapping mapping,
                                 HttpServletRequest request) {

        ActionErrors errors = new ActionErrors();

        return (errors);

    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }
}