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javax.el.PropertyNotFoundException: Property 'username' not found on type pers.wsf.multiBlog.pojo.Ar

發(fā)布時(shí)間：2024/1/1 编程问答 62 豆豆

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my：${a.username}獲取不到值的問(wèn)題

簡(jiǎn)略錯(cuò)誤信息：

message?javax.el.PropertyNotFoundException: Property 'username' not found on type pers.wsf.multiBlog.pojo.Article

root cause

javax.el.PropertyNotFoundException: Property 'username' not found on type pers.wsf.multiBlog.pojo.Article

文章最后面放全部錯(cuò)誤提示！！！

前端視圖中的 EL表達(dá)式獲取不到相應(yīng)的值：username！！！

錯(cuò)誤寫(xiě)法：
${a.username}
正確寫(xiě)法：
<span>${a.getUser().getUsername() }</span>

總結(jié)：
使用<c:forEach var="a" items="${articles}">來(lái)調(diào)用List<Article> articles中的數(shù)據(jù)
而articles中的數(shù)據(jù)聯(lián)合了 user pojo中的數(shù)據(jù)，故使用${a.username}是無(wú)法獲取articles中的username 的

原因：因?yàn)閡sername是屬于user類(lèi)的，雖然article聯(lián)合了user，但無(wú)法直接獲取，要從user中獲取。
用getter方法獲取user，再用getter方法獲取username。

-----------------------------------------------------！！！--------------------------------------------------------------------------------
其他相關(guān)信息：
1.Article類(lèi)：

public class Article implements Comparable,Serializable{

?? ?private int article_id;
?? ?private int user_id;
?? ?private String title;?? ??? ??? ?
?? ?private String time;
?? ?private int star;
?? ?private int comment;
?? ?private int visit;
?? ?private String content;
?? ?Tag tag;?? ?
?? ?User user;
?? ?Sort sort;
?? ?
?? ?public Article() {}
?? ?public Tag getTag() {
?? ??? ?return tag;
?? ?}

?? ?public User getUser() {
?? ??? ?return user;
?? ?}

?? ?public Sort getSort() {
?? ??? ?return sort;
?? ?}

?? ?public int getArticle_id() {
?? ??? ?return article_id;
?? ?}

?? ?public void setArticle_id(int article_id) {
?? ??? ?this.article_id = article_id;
?? ?}

?? ?public int getUser_id() {
?? ??? ?return user_id;
?? ?}

?? ?public void setUser_id(int user_id) {
?? ??? ?this.user_id = user_id;
?? ?}

?? ?public String getTitle() {
?? ??? ?return title;
?? ?}
?? ?public void setTitle(String title) {
?? ??? ?this.title = title;
?? ?}
?? ?
?? ?public int getStar() {
?? ??? ?return star;
?? ?}
?? ?public void setStar(int star) {
?? ??? ?this.star = star;
?? ?}
?? ?public int getComment() {
?? ??? ?return comment;
?? ?}
?? ?public void setComment(int comment) {
?? ??? ?this.comment = comment;
?? ?}
?? ?public int getVisit() {
?? ??? ?return visit;
?? ?}
?? ?public void setVisit(int visit) {
?? ??? ?this.visit = visit;
?? ?}
?? ?public String getContent() {
?? ??? ?return content;
?? ?}
?? ?public void setContent(String content) {
?? ??? ?this.content = content;
?? ?}

?? ?public String getTime() {
?? ??? ?return time;
?? ?}

?? ?public void setTime(String time) {
?? ??? ?this.time = time;
?? ?}

?? ?@Override
?? ?public int compareTo(Object o) {
?? ??? ?if (o instanceof Article) {
?? ??? ??? ?Article article = (Article) o;

?? ??? ??? ?Date this_date = null;
?? ??? ??? ?Date other_date = null;
?? ??? ??? ?try {
?? ??? ??? ??? ?this_date = DateUtils.getDate(this.time);
?? ??? ??? ??? ?other_date = DateUtils.getDate(article.getTime());
?? ??? ??? ?} catch (ParseException e) {
?? ??? ??? ??? ?// TODO Auto-generated catch block
?? ??? ??? ??? ?e.printStackTrace();
?? ??? ??? ?}

?? ??? ??? ?return -this_date.compareTo(other_date);
?? ??? ?}
?? ??? ?return 0;
?? ?}

?? ?@Override
?? ?public String toString() {
?? ??? ?return "Article [article_id=" + article_id + ", user_id=" + user_id + ", title=" + title + ", time=" + time
?? ??? ??? ??? ?+ ", star=" + star + ", comment=" + comment + ", visit=" + visit + ", content=" + content + ", tag="
?? ??? ??? ??? ?+ tag + ", user=" + user + ", sort=" + sort + "]";
?? ?}?? ?

}

2.mapper層中Article.xml
<select id="getUserArticle" parameterType="Integer" resultMap="getUserArticleResultMap">
?? ??? ?select a.article_id,a.title,a.time,u.username from t_article as a
?? ??? ?join t_user as u on u.user_id = a.user_id
?? ??? ?where u.user_id=#{user_id}
</select>

------------------------------------------------------！！！-----------------------------------------------------------------------------

錯(cuò)誤提示！！！

HTTP Status 500 - javax.el.PropertyNotFoundException: Property 'username' not found on type pers.wsf.multiBlog.pojo.Article

type?Exception report

message?javax.el.PropertyNotFoundException: Property 'username' not found on type pers.wsf.multiBlog.pojo.Article

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

exception

org.apache.jasper.JasperException: javax.el.PropertyNotFoundException: Property 'username' not found on type pers.wsf.multiBlog.pojo.Articleorg.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:549)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:405)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:349)javax.servlet.http.HttpServlet.service(HttpServlet.java:725)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.doGet(FrameworkServlet.java:857)javax.servlet.http.HttpServlet.service(HttpServlet.java:618)org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)javax.servlet.http.HttpServlet.service(HttpServlet.java:725)org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

root cause

javax.el.PropertyNotFoundException: Property 'username' not found on type pers.wsf.multiBlog.pojo.Articlejavax.el.BeanELResolver$BeanProperties.get(BeanELResolver.java:245)javax.el.BeanELResolver$BeanProperties.access$300(BeanELResolver.java:222)javax.el.BeanELResolver.property(BeanELResolver.java:332)javax.el.BeanELResolver.getValue(BeanELResolver.java:95)org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:110)org.apache.el.parser.AstValue.getValue(AstValue.java:167)org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:187)org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:956)org.apache.jsp.page.userManageArticle_jsp._jspx_meth_c_005fforEach_005f0(userManageArticle_jsp.java:205)org.apache.jsp.page.userManageArticle_jsp._jspService(userManageArticle_jsp.java:134)org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)javax.servlet.http.HttpServlet.service(HttpServlet.java:725)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:405)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:349)javax.servlet.http.HttpServlet.service(HttpServlet.java:725)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.doGet(FrameworkServlet.java:857)javax.servlet.http.HttpServlet.service(HttpServlet.java:618)org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)javax.servlet.http.HttpServlet.service(HttpServlet.java:725)org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

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