我的动态 Web 项目（JPA、JSP）中的 MySQL 驱动程序问题

Question

切入正题。

Persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
    version="2.0">

        <persistence-unit name="fishsticks" transaction-type="RESOURCE_LOCAL">
            <class>model.Customer</class>
            <etc etc>

            <properties>
                <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
                <property name="javax.persistence.jdbc.url" value="jdbc:mysql://127.0.0.1:3306/fishsticks" />
                <property name="javax.persistence.jdbc.user" value="user" />
                <property name="javax.persistence.jdbc.password" value="pass" />

                <!-- EclipseLink should create the database schema automatically -->
                <property name="eclipselink.ddl-generation" value="drop-and-create-tables" />
                <property name="eclipselink.ddl-generation.output-mode"
                    value="database" />
                <property name="eclipselink.logging.level" value="OFF" />
            </properties>
        </persistence-unit>
</persistence>

Eclipse 构建路径：

项目设置：

我的页面出错： enter link description here

页面是用jsp制作的

我不知道如何解决这个问题......

这是我的 DAO 文件：

import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.PersistenceContext;
import model.Customer;
import model.Milestone;
import model.Project;
import model.Task;
import model.User;

public class JpaDAO implements DAO {
    private static JpaDAO dao;

    public static JpaDAO getInstance() {
        if (dao == null)
            dao = new JpaDAO();
        return dao;
    }

    private EntityManagerFactory emf = Persistence.createEntityManagerFactory("fishsticks");

    @PersistenceContext(name="fishsticksEM")
    private EntityManager em = emf.createEntityManager();
    private EntityTransaction tx = em.getTransaction();

    private JpaDAO() {
        // singleton
    }
}

Answer 1

您是否听从了tomcat documentation 的建议？

在继续之前，不要忘记 将 JDBC 驱动程序的 jar 复制到 $CATALINA_HOME/lib

这适用于 Tomcat 6.0 和 7.0。

对于 Tomcat 5.5：$CATALINA_HOME/common/lib