我现在正在自己学习如何使用 ZKoss、Maven 和 Spring,我遇到了一些我不理解的问题,如果有人可以帮助我,我将非常感激。 对我来说,Spring 似乎没有在“CalculadoraServlet”中正确实例化我的计算器对象。
这是代码:
Zkoss (inidex.zul):
<?page title="Auto Generated index.zul"?>
<window title="Calculadora" border="normal" width="400px" apply="sdec.CalculadoraServlet">
<grid >
<rows>
<row>
Num1: <textbox id="num1" value="${win$composer.current.num1}" />
</row>
<row>
Num2: <textbox id="num2" value="${win$composer.current.num2}" />
</row>
</rows>
</grid>
<button id="submitButton" label="Submit"/>
<grid >
<rows>
<row>
Resultado <textbox id="result" value="${win$composer.current.result}" />
</row>
</rows>
</grid>
</window>
计算器Servlet:
@Controller
public class CalculadoraServlet extends SelectorComposer<Component>{
/**
*
*/
private static final long serialVersionUID = 1L;
@Autowired
private Calculadora servicioCalculadora;
@Wire
private Textbox num1;
@Wire
private Textbox num2;
@Wire
private Textbox result;
@Listen("onClick = #submitButton")
public void calcula() throws IOException {
int numero1=Integer.parseInt(num1.getValue());
int numero2=Integer.parseInt(num2.getValue());
int resultado=servicioCalculadora.sumar(numero1, numero2);
String resul=Integer.toString(resultado);
result.setValue(resul);
System.out.println(resultado);
}
}
最后是 Calculadora:
package sdec;
public class Calculadora {
public Calculadora(){
//"Traza". Se mostrará cada vez que inicie la app y spring instancie un obj calculadora
System.out.println("Calculadora inicializada por Spring");
}
public int sumar(int num1, int num2){
return num1+num2;
}
}
提前非常感谢!!我是一名初级程序员,这有点难以理解! =(
编辑:(添加applicationContext文件):
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:oxm="http://www.springframework.org/schema/oxm"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/oxm http://www.springframework.org/schema/oxm/spring-oxm-3.0.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">
<context:annotation-config />
<context:component-scan base-package="sdec" />
<bean id="servicioCalculadora" class="sdec.Calculadora"/>
</beans>
当我按下“提交”sk按钮时,我得到的错误是可怕的空指针异常:
abr 01, 2014 9:41:30 AM org.zkoss.zk.ui.impl.UiEngineImpl handleError:1359
Grave: >>java.lang.NullPointerException
>> at sdec.CalculadoraServlet.calcula(CalculadoraServlet.java:37)
>> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>> at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
>> at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>> at java.lang.reflect.Method.invoke(Method.java:606)
...
非常感谢大家!真的吗!这一定是有史以来最有帮助的论坛!
最佳答案
好的,
首先在您的CalculadoraServlet
中释放@Controller
。
其次,您尝试从 spring 容器中初始化 spring bean,并且 zk 有一个 zk 容器,因此 zk 找不到您的 Calculadora
类是正常的。
您必须对 Calculadora
类使用 @WireVariable
。
所以应该是这样的:
public class CalculadoraServlet extends SelectorComposer<Component>{
private static final long serialVersionUID = 1L;
@WireVariable
private Calculadora servicioCalculadora;
....
}
关于java - Spring 未正确实例化对象。为什么?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/22767115/