當在Bean中設置值時出現「PropertyNotWritableException：設置操作的非法語法」錯誤

Question

嘗試從jsf頁面向bean發送一些值時出現此錯誤。

我想將值設置到bean中的字段，然後創建一個Airplane實例並將其添加到我的數據庫中。但是我得到一個錯誤，告訴我我使用非法語法來設置bean的setter部分。

爲什麼我得到那個錯誤？我沒有在這個網站上找到任何幫助我解決問題的東西。

這裏是JSF部分：

<h4>Add A Plane</h4> 

       <c:if test="#{not empty listAirplaneBB.error}"> 
        <div class="alert alert-danger"> 
         <span class="glyphicon glyphicon-remove"></span> <h:outputText value="#{listAirplaneBB.error}" /> 
        </div> 
       </c:if> 
       <h:form> 
       <table class="table"> 
        <thead> 
         <tr> 
          <th>Plane Make</th> 
          <th colspan="1">Plane Model</th> 
          <th colspan="1">Plane Seats</th> 
         </tr> 
        </thead> 
        <tr>  
         <td> 
          <h:inputText value="#{addAirplaneCtrl.setMake(make)}"> 
           <f:validateLength minimum="3" /> 
          </h:inputText> 
         </td> 
         <td> 
          <h:inputText id="lastname" value="#{addAirplaneCtrl.setModel(model)}"> 
           <f:validateLength minimum="3" /> 
          </h:inputText> 
         </td> 
         <td> 
          <h:inputText value="#{addAirplaneCtrl.setSeats(seats)}"> 
           <f:validateLength minimum="1" /> 
          </h:inputText> 
         </td> 
         <td> 
          <h:commandButton value="Add Plane" class="btn btn-primary" action="#{addAirplaneCtrl.addPlane()}" /> 
         </td> 
        </tr> 
       </table> 
       </h:form> 

這裏是bean：

@Named 
@RequestScoped 
public class AddAirplaneCtrl implements Serializable{ 

@Inject 
private FlightModel flightModel; 

private ListAirplaneBB listAirplaneBB; 

private String make; 
private String model; 
private String seats; 

private static final String PLANE_EXIST = "Plane already exists"; 
private static final String EMPTY_FIELDS = "Please fill in all fields"; 

protected AddAirplaneCtrl(){ 
    ; 
} 

/* 
TO DO LIST 
    error handling 
*/ 

public String addPlane(){ 

    //make sure all fields are filled, otherwise set error and return redirect false 
    if(make == null || model == null || seats == null){ 
     listAirplaneBB.setError(EMPTY_FIELDS); 
     return "/private/admin/admincenter?faces-redirect=false"; 
    } 

    //create planeId 
    String pId = make.substring(0, 1); 
    pId += model; 

    //upload photo in new method [Meet requirements, rename photoID planeId, upload to folder] 

    //check if exist 
    List<Airplane> airplaneList = flightModel.getAirplaneList().getByAirplaneId(pId); 
    if(!airplaneList.isEmpty()){ 
     listAirplaneBB.setError(PLANE_EXIST); 
     return "/private/admin/admincenter?faces-redirect=false"; 
    } 

    //add plane 
    Airplane airplane = new Airplane(make, model, pId, seats); 
    flightModel.getAirplaneList().create(airplane); 
    return "/private/admin/admincenter?faces-redirect=true"; 
} 

public String deleteAirplane(String planeId){ 
    return ""; 
} 

/** 
* @param make the make to set 
*/ 
public void setMake(String make) { 
    this.make = make; 
} 

/** 
* @param model the model to set 
*/ 
public void setModel(String model) { 
    this.model = model; 
} 

/** 
* @param seats the seats to set 
*/ 
public void setSeats(String seats) { 
    this.seats = seats; 
} 

}

以下是錯誤：

javax.faces.component.UpdateModelException: javax.el.PropertyNotWritableException: /private/admin/admincenter.xhtml @118,87 value="#{addAirplaneCtrl.setMake(make)}": Illegal Syntax for Set Operation 
at javax.faces.component.UIInput.updateModel(UIInput.java:866) 
at javax.faces.component.UIInput.processUpdates(UIInput.java:749) 
at javax.faces.component.UIForm.processUpdates(UIForm.java:281) 
at javax.faces.component.UIComponentBase.processUpdates(UIComponentBase.java:1286) 
at javax.faces.component.UIComponentBase.processUpdates(UIComponentBase.java:1286) 
at javax.faces.component.UIViewRoot.processUpdates(UIViewRoot.java:1254) 
at com.sun.faces.lifecycle.UpdateModelValuesPhase.execute(UpdateModelValuesPhase.java:78) 
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) 
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198) 
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646) 
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:344) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214) 
at edu.cth.dzenkyair.frontend.auth.AdminFilter.doFilter(AdminFilter.java:40) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214) 
at edu.cth.dzenkyair.frontend.auth.UserFilter.doFilter(UserFilter.java:39) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214) 
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:316) 
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160) 
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734) 
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673) 
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99) 
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174) 
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415) 
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:282) 
at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459) 
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167) 
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201) 
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175) 
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235) 
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119) 
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284) 
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201) 
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133) 
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112) 
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77) 
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561) 
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112) 
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117) 
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56) 
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137) 
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565) 
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545) 
at java.lang.Thread.run(Thread.java:745) 
Caused by: javax.el.PropertyNotWritableException: /private/admin/admincenter.xhtml @118,87 value="#{addAirplaneCtrl.setMake(make)}": Illegal Syntax for Set Operation 
at com.sun.faces.facelets.el.TagValueExpression.setValue(TagValueExpression.java:136) 
at javax.faces.component.UIInput.updateModel(UIInput.java:832) 
... 45 more 
Caused by: javax.el.PropertyNotWritableException: Illegal Syntax for Set Operation 
at com.sun.el.parser.AstValue.setValue(AstValue.java:228) 
at com.sun.el.ValueExpressionImpl.setValue(ValueExpressionImpl.java:294) 
at org.jboss.weld.el.WeldValueExpression.setValue(WeldValueExpression.java:64) 
at com.sun.faces.facelets.el.TagValueExpression.setValue(TagValueExpression.java:131) 
... 46 more 

Answer 1

JSF使用ManagedBeans，託管bean使用bean的標準，即實現串行接口，封裝和一個空的構造

的小面可以通過表達式語言與託管bean通信，並使用與任何EditableValueHolder UIComponent。

在你的情況下，EditableValueHolder的您使用的是<h:inputText />組件，當您使用value=""屬性，調用setter方法的正確途徑將只使用您要設置的屬性的名稱，這裏有一個例子：

豆：

@Named or @ManageBean 
@some_scope 
public class YourBean implements Serializable{ 

private String make; 

public void setMake(String make){ 
    this.make = make; 
} 

public String getMake(){ 
    return this.make; 
} 

} 

的facelet：

// will call the setMake(String make) method 
<h:inputText value="#{yourBean.make}" /> 

// will call the getMake() method 
<h:outputText value="#{yourBean.make}" /> 

Answer 2

你不需要寫下「set」的描述在表達式語言離子，你只需要編寫

<h:inputText value="#{addAirplaneCtrl.make}">

，然後JSF將嘗試找到提交你的bean的方法setMake，因爲你把它放在一個inputText組件。