@PersistenceContext無法解析爲

Question

我正在運行代碼，其中存在依賴關係@PersistenceContext和字段private EntityManager em;這兩個都不能解析爲一個類型，這個錯誤的含義是什麼，我該如何解決它？
的代碼是在這裏：

package org.jboss.tools.examples.util;  

import java.util.logging.Logger;  
import javax.enterprise.context.RequestScoped;  
import javax.enterprise.inject.Produces;  
import javax.enterprise.inject.spi.InjectionPoint;  
import javax.faces.context.FacesContext;  

/**  
* This class uses CDI to alias Java EE resources, such as the persistence context, to  
CDI beans  
*  
* <p>  
* Example injection on a managed bean field:  
* </p>  
*  
* <pre>  
* &#064;Inject  
* private EntityManager em;  
* </pre>  
*/  
public class Resources {  
    // use @SuppressWarnings to tell IDE to ignore warnings about field not being   referenced directly  
    @SuppressWarnings("unused")  
    @Produces  
    @PersistenceContext  
    private EntityManager em;  

    @Produces  
    public Logger produceLog(InjectionPoint injectionPoint) {  
     return Logger.getLogger(injectionPoint.getMember().getDeclaringClass().getName());  
    }  

    @Produces  
    @RequestScoped  
    public FacesContext produceFacesContext() {  
     return FacesContext.getCurrentInstance();  
    }  
}  

Answer 1

你缺少import語句PersistenceContext註解和EntityManager的

import javax.persistence.PersistenceContext; 
import javax.persistence.EntityManager;