爲什麼我得到org.apache.jasper.JasperException：PWC6049：嘗試空對象

Question

我得到org.apache.jasper.JasperException: PWC6049: Attempted a bean operation on a null object對Bean操作，當我點擊提交按鈕，請求轉到下面的JSP：

<jsp:useBean id="namebean" class="BeanTesters.Bean"> 
     <jsp:setProperty name="namebean" property="name" param="Name" /> 
    </jsp:useBean> 

    <%--Now check if the text-field data has been stored--%> 
    <jsp:getProperty name="beanname" property="name" /> 

HTML代碼：

<form method="get" action="straighttojsp.jsp"> 
     <input type="text" name="Name" /> <br /> 
     <input type="submit" value="Submit data"/> 
    </form> 

Bean類：

package BeanTesters; 

public class Bean { 

private String name = null; 

public void setName(String n) { 
    name = n; 
} 

public String getName() { 
    return name;   
} 
} 

爲什麼我得到這個例外？

Answer 1

你在豆namebean設置屬性，並試圖找回它從豆beanname，這顯然是null

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