Java EE 6 java.lang.NoClassDefFoundError玻璃鱼

Question

我是Java EE 6的新手，并且正在关注Java EE 6教程 。 我创建了一个启用了上下文和DI的Java EE 6项目。

我收到以下错误：

java.lang.NoClassDefFoundError：Lboundaries / UsersFacade;

环境：Netbeans 7.3，JDK 1.6和Glassfish3.1.2。 请为我解决问题。

（一）web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <context-param>
        <param-name>javax.faces.PROJECT_STAGE</param-name>
        <param-value>Development</param-value>
    </context-param>
    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.jsf</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>faces/index.xhtml</welcome-file>
    </welcome-file-list>
</web-app>

（b）beans.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://java.sun.com/xml/ns/javaee"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/beans_1_0.xsd">

</beans>

（c）来自数据库，用户的实体Bean（程序包名称：entities在users-ejb中）

    /*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package entities;

import java.io.Serializable;
import javax.persistence.Basic;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.Table;
import javax.validation.constraints.Size;
import javax.xml.bind.annotation.XmlRootElement;

/**
 *
 * @author abc
 */
@Entity
@Table(catalog = "", schema = "USER")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "Users.findAll", query = "SELECT u FROM Users u"),
    @NamedQuery(name = "Users.findByUserid", query = "SELECT u FROM Users u WHERE u.userid = :userid"),
    @NamedQuery(name = "Users.findByUseridPassword", query = "SELECT u FROM Users u WHERE u.userid = :userid AND u.password=:password"),
    @NamedQuery(name = "Users.findByUsername", query = "SELECT u FROM Users u WHERE u.username = :username"),
    @NamedQuery(name = "Users.findByPassword", query = "SELECT u FROM Users u WHERE u.password = :password"),
    @NamedQuery(name = "Users.findByEnabled", query = "SELECT u FROM Users u WHERE u.enabled = :enabled")})
public class Users implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(nullable = false)
    private Integer userid;
    @Size(max = 30)
    @Column(length = 30)
    private String username;
    @Size(max = 30)
    @Column(length = 30)
    private String password;
    @Size(max = 1)
    @Column(length = 1)
    private String enabled;

    public Users() {
    }

    public Users(Integer userid) {
        this.userid = userid;
    }

    public Integer getUserid() {
        return userid;
    }

    public void setUserid(Integer userid) {
        this.userid = userid;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getEnabled() {
        return enabled;
    }

    public void setEnabled(String enabled) {
        this.enabled = enabled;
    }

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (userid != null ? userid.hashCode() : 0);
        return hash;
    }

    @Override
    public boolean equals(Object object) {
        // TODO: Warning - this method won't work in the case the id fields are not set
        if (!(object instanceof Users)) {
            return false;
        }
        Users other = (Users) object;
        if ((this.userid == null && other.userid != null) || (this.userid != null && !this.userid.equals(other.userid))) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "entities.Users[ userid=" + userid + " ]";
    }

}

（d）实体Bean，UsersFacade（程序包名称：users-ejb中的界限）的会话Bean具有方法：

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package boundaries;

import entities.Users;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

/**
 *
 * @author abc
 */
@Stateless
public class UsersFacade extends AbstractFacade<Users> {

    @PersistenceContext(unitName = "sbg-ejbPU")
    private EntityManager em;

    @Override
    protected EntityManager getEntityManager() {
        return em;
    }

    public UsersFacade() {
        super(Users.class);
    }

    public Users validUser(String username, String password) {
        Query query = getEntityManager().createNamedQuery("Users.findByUseridPassword").setParameter("username", username).setParameter("password", password);
        Users user = (Users) query.getSingleResult();
        return user;
    }
}

（e）创建了JSF Managed Bean，LoginBean（程序包名称：users-war中的com.users）

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package com.xyz;

import boundaries.UsersFacade;
import entities.Users;
import javax.ejb.EJB;
import javax.inject.Named;
import javax.enterprise.context.RequestScoped;

/**
 *
 * @author abc
 */
@Named(value = "loginBean")
@RequestScoped
public class LoginBean {

    @EJB
    private UsersFacade usersFacade;
    private Users currentUser;

    /**
     * Creates a new instance of LoginBean
     */
    public LoginBean() {
    }


    /**
     * @param currentUser the currentUser to set
     */
    public void setCurrentUser(Users currentUser) {
        this.currentUser = currentUser;
    }

    /**
     * @return the currentUser
     */
    public Users getCurrentUser() {
        if(currentUser==null){
            currentUser= new Users();
        }
        return currentUser;
    }

    public String validUser(){
        String outcome="index?faces-redirect=true";
        Users user=usersFacade.validUser(getCurrentUser().getUsername(), getCurrentUser().getPassword());
        if(user!=null){
            outcome="/view/home?faces-redirect=true";
        }else{
            System.out.println("Unable to find User with User Id:"+getCurrentUser().getUsername()+"!");
        }
        return outcome;
    }
}

Answer 1

还要检查类路径

Issue-java.lang.NoClassDefFoundError

根本原因：环境变量部分中设置的Java路径不正确

解决方案：设置正确的JAVA_HOME路径

步骤->环境变量设置（我的右击->属性->环境变量->高级选项卡->变量）

创建新的JAVA_HOME环境变量。

JAVA_HOME。; C：\\ Program Files（x86）\\ Java \\ jdk1.6.0_14

在“ PATH变量”部分中设置JAVA_HOME变量。

路径％JAVA_HOME％\\ bin

在CLASSPATH变量中设置JAVA_HOME变量

CLASSPATH％JAVA_HOME％\\ jre \\ lib

重启系统

验证所有变量

回声％CLASSPATH％

回声％JAVA_HOME％

回声％PATH％

编译并运行程序