無法在jsp中讀取bean屬性

我想從jsp中的bean訪問屬性，並遇到奇怪的行爲。我以前做過這樣的事情，我不知道我在這裏做錯了什麼。無法在jsp中讀取bean屬性

控制器方法

@RequestMapping(value = "https://stackoverflow.com/users/{userId}") 
public String get(@PathVariable final String userId, final ModelMap model) { 
    logger.debug("Entering get with userId as {}", userId); 
    final UserDetails userDetails = new UserDetails(); 
    userDetails.setUser(userService.get(userId)); 
    userDetails.setRoles(roleService.fetchRoles()); 
    userDetails.setStatuses(Status.values()); 
    model.addAttribute("userDetails", userDetails); 
    return VIEW_PREFIX + "editUser"; 
}

的UserDetails豆：

public class UserDetails { 

private User user; 
private List<Role> roles; 
private Status[] statuses; 

public List<Role> getRoles() { 
    return roles; 
} 

public Status[] getStatuses() { 
    return statuses; 
} 

public User getUser() { 
    return user; 
} 

public void setRoles(final List<Role> roles) { 
    this.roles = roles; 
} 

public void setStatuses(final Status[] statuses) { 
    this.statuses = statuses; 
} 

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

}

JSP：

     </tr> 
         <tr> 
          <td valign="top"><fmt:message key="page.viewusers.username" /></td> 
          <td valign="top"><form:input path="user.username" cssClass="required" disabled="true" id="username"/></td> 

         </tr> 
         <tr> 
          <td valign="top"><fmt:message key="page.viewusers.emailid" /></td> 
          <td valign="top"><form:input path="user.email" cssClass="required email"/></td> 

         </tr> 
         <tr> 
          <td valign="top"><fmt:message key="page.adduser.role" /></td> 
          <td valign="top"> 
           <form:select path="user.role.id" cssClass="required select" cssStyle="width:220px !important;"> 
            <form:option value="-1">--Select--</form:option> 
            <c:forEach items="${userDetails.roles}" var="role"> 
             <c:out value="${role.id}"></c:out> 
            </c:forEach> 
           </form:select> 
          </td> 
         </tr> 
         <tr> 
          <td valign="top"><fmt:message key="page.viewusers.status" /></td> 
          <td valign="top"> 
           <form:radiobuttons path="user.status" items="${userDetails.statuses}" itemLabel="label" cssClass="required" /> 
         </tr>

我來到這裏的錯誤是：

SEVERE: Servlet.service() for servlet [myapp] in context with path [/myapp] threw exception [An exception occurred processing JSP page /WEB-INF/views/user/editUser.jsp at line 178 

175:         <form:select path="user.role.id" cssClass="required select" cssStyle="width:220px !important;"> 
176:          <form:option value="-1">--Select--</form:option> 
177:          <c:forEach items="${userDetails.roles}" var="role"> 
178:           <c:out value="${role.id}"></c:out> 
179:          </c:forEach> 
180:         </form:select> 
181:        </td> 


Stacktrace:] with root cause 
java.lang.NumberFormatException: For input string: "id" 
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) 
at java.lang.Integer.parseInt(Integer.java:492) 
at java.lang.Integer.parseInt(Integer.java:527) 
at javax.el.ArrayELResolver.coerce(ArrayELResolver.java:166) 
at javax.el.ArrayELResolver.getValue(ArrayELResolver.java:46) 
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:67) 
at org.apache.el.parser.AstValue.getValue(AstValue.java:169) 
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189) 
at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:985) 
at org.apache.jsp.WEB_002dINF.views.user.editUser_jsp._jspx_meth_c_005fout_005f0(editUser_jsp.java:920) 
at org.apache.jsp.WEB_002dINF.views.user.editUser_jsp._jspx_meth_c_005fforEach_005f0(editUser_jsp.java:890) 
at org.apache.jsp.WEB_002dINF.views.user.editUser_jsp._jspService(editUser_jsp.java:394)

如果代碼更改爲

<td valign="top"> 
           <form:select path="user.role.id" cssClass="required select" cssStyle="width:220px !important;"> 
            <form:option value="-1">--Select--</form:option> 
            <form:options items="${userDetails.roles}" itemLabel="name" itemValue="id"/> 

           </form:select> 
          </td>

我得到了以下電子RROR

May 16, 2014 10:58:25 AM org.apache.catalina.core.StandardWrapperValve invoke 
SEVERE: Servlet.service() for servlet [myapp] in context with path [/myapp] threw  exception [An exception occurred processing JSP page /WEB-INF/views/user/editUser.jsp at line 177 

174:        <td valign="top"> 
    175:         <form:select    path="user.role.id" cssClass="required select" cssStyle="width:220px !important;"> 
    176:          <form:option value="-1">--Select--</form:option> 
177:          <form:options items="${userDetails.roles}" itemLabel="name" itemValue="id"/> 
178:            
179:         </form:select> 
180:        </td> 


    Stacktrace:] with root cause 
org.springframework.beans.NotReadablePropertyException: Invalid property 'id' of bean class [[Ljava.lang.Object;]: Bean property 'id' is not readable or has an invalid getter method: Does the return type of the getter match the parameter type of the setter? 
at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:707) 
at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:699) 
at org.springframework.web.servlet.tags.form.OptionWriter.doRenderFromCollection(OptionWriter.java:202) 
at org.springframework.web.servlet.tags.form.OptionWriter.renderFromCollection(OptionWriter.java:180) 
at org.springframework.web.servlet.tags.form.OptionWriter.writeOptions(OptionWriter.java:133) 
at org.springframework.web.servlet.tags.form.OptionsTag.writeTagContent(OptionsTag.java:168) 
at org.springframework.web.servlet.tags.form.AbstractFormTag.doStartTagInternal(AbstractFormTag.java:103) 
at org.springframework.web.servlet.tags.RequestContextAwareTag.doStartTag(RequestContextAwareTag.java:80) 
at org.apache.jsp.WEB_002dINF.views.user.editUser_jsp._jspx_meth_form_005foptions_005f0(editUser_jsp.java:886) 
at org.apache.jsp.WEB_002dINF.views.user.editUser_jsp._jspService(editUser_jsp.java:391) 
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419) 
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391) 
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)

ROLE.java

@Entity 
@Table(name = "ods.Role") 
public class Role implements Serializable { 

private static final long serialVersionUID = -1045869404415273225L; 
@Id 
@Column 
private int id; 

@NotBlank 
@Column 
private String name; 

@Column 
private String description; 



public String getDescription() { 
    return description; 
} 

public int getId() { 
    return id; 
} 

public String getName() { 
    return name; 
} 



public void setDescription(final String description) { 
    this.description = description; 
} 

public void setId(final int id) { 
    this.id = id; 
} 

public void setName(final String name) { 
    this.name = name; 
}

來源

2014-05-16 Rachit Agrawal

發佈'角色'類。 –

@ M.Deinum添加了角色類 –

爲什麼setter方法參數是「final」？你可以嘗試刪除該關鍵字嗎？ –

我已經解決了。

以下是回購代碼（我用的彈簧JPA回購）

@Repository("roleRepo") 
public interface RoleRepo extends JpaRepository<Role, Integer> { 

@Query(value = "Select r.id, r.name, r.description from Role r") 
List<Role> getAllRoles();

}

在這種情況下，即使簽名說：List<Role>返回類型爲List<Object[]>。

因此沒有找到id和name屬性。

但不明白爲什麼這種行爲？如果任何人都可以提供幫助，那就太好了。

來源

2014-05-20 13:29:19

試圖改變

private int id;

到

private Integer id;

在Role類和getter和setter方法爲好。

來源

2014-05-16 12:44:36 Alex

無法在jsp中讀取bean屬性

回答

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