2017-06-13

Spring MVC系列文章（二）：Spring MVC+Hibernate JPA搭建的博客系统项目中所遇到的坑

项目代码地址：https://github.com/zhisheng17/springmvc

最近在学习 Spring MVC ，其中在做一个简单的博客系统demo，是使用 SpringMVC 集成

Spring Data JPA（由 Hibernate JPA 提供），来进行强大的数据库访问。结果其中遇到的坑不

是一点点啊，我差点崩溃了，其中最大的原因就是由于 Hibernate JPA 中的bug了，反正一开始

还不知道是这个问题，导致折腾了快一天的时间。想想都可怕啊。

mvc-dispatch-servlet.xml代码


<?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:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:jpa="http://www.springframework.org/schema/data/jpa"
       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/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
       http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd
       http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!--指明 controller 所在包，并扫描其中的注解-->
    <context:component-scan base-package="cn.zhisheng.controller"/>

    <!-- 静态资源(js、image等)的访问 -->
    <mvc:default-servlet-handler/>

    <!-- 开启注解 -->
    <mvc:annotation-driven/>

    <!--ViewResolver 视图解析器-->
    <!--用于支持Servlet、JSP视图解析-->
    <bean id="jspViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
        <property name="prefix" value="/WEB-INF/pages/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

    <!-- 表示JPA Repository所在的包 -->
    <jpa:repositories base-package="cn.zhisheng.repository"/>

    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="persistenceUnitName" value="defaultPersistenceUnit"/>
        <property name="packagesToScan" value="cn.zhisheng.model" />
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
        </property>
        <property name="jpaProperties">
            <props>
                <prop key="hibernate.connection.driver_class">com.mysql.jdbc.Driver</prop>
                <prop key="hibernate.connection.url">jdbc:mysql://localhost:3306/springdemo?useSSL=false</prop>
                <prop key="hibernate.connection.username">root</prop>
                <prop key="hibernate.connection.password">root</prop>
                <prop key="hibernate.show_sql">false</prop>
                <prop key="hibernate.connection.useUnicode">true</prop>
                <prop key="hibernate.connection.characterEncoding">UTF-8</prop>
                <prop key="hibernate.format_sql">true</prop>
                <prop key="hibernate.use_sql_comments">true</prop>
                <prop key="hibernate.hbm2ddl.auto">update</prop>
                <prop key="hibernate.connection.autoReconnect">true</prop>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
                <prop key="connection.autoReconnectForPools">true</prop>
                <prop key="connection.is-connection-validation-required">true</prop>

                <prop key="hibernate.c3p0.validate">true</prop>
                <prop key="hibernate.connection.provider_class">org.hibernate.service.jdbc.connections.internal.C3P0ConnectionProvider</prop>
                <prop key="hibernate.c3p0.min_size">5</prop>
                <prop key="hibernate.c3p0.max_size">600</prop>
                <prop key="hibernate.c3p0.timeout">1800</prop>
                <prop key="hibernate.c3p0.max_statements">50</prop>
                <prop key="hibernate.c3p0.preferredTestQuery">SELECT 1;</prop>
                <prop key="hibernate.c3p0.testConnectionOnCheckout">true</prop>
                <prop key="hibernate.c3p0.idle_test_period">3000</prop>
                <prop key="javax.persistence.validation.mode">none</prop>
            </props>
        </property>
    </bean>

    <!-- 事务管理 -->
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory"/>
    </bean>

    <!-- 开启事务管理注解 -->
    <tx:annotation-driven transaction-manager="transactionManager"/>
</beans>

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>cn.zhisheng</groupId>
  <artifactId>springmvc</artifactId>
  <packaging>war</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>springmvc Maven Webapp</name>
  <url>http://maven.apache.org</url>

  <properties>
    <spring.version>4.2.6.RELEASE</spring.version>
    <hibernate.version>5.1.0.Final</hibernate.version>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework.data</groupId>
      <artifactId>spring-data-jpa</artifactId>
      <version>1.10.1.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-entitymanager</artifactId>
      <version>${hibernate.version}</version>
    </dependency>

    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-c3p0</artifactId>
      <version>${hibernate.version}</version>
    </dependency>

    <dependency>
      <groupId>com.mchange</groupId>
      <artifactId>c3p0</artifactId>
      <version>0.9.5.2</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.39</version>
    </dependency>


  </dependencies>
  <build>
    <finalName>springmvc</finalName>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

一开始我是用默认的在resources文件里面生成了persistence.xml配置文件进行数据库配置的，后来由于用那种方法，碰到的问题有很多，自己搞了好几个个小时都没弄好，只好换种方法，没想到竟然还是这种效果（泪崩），看来是不治标也不治本。

无奈，只好硬刚了，碰到错误，百度+google，看了大量的的解决方法，都是没用，慢慢的我所加的jar包越来越多，用maven管理的依赖的也变得多起来了，但终究是不能够解决问题的。

其实这时我看了这么多的博客和解决方法，我已经知道了是 Hibernate JPA 的bug问题，途中自己也换了一些版本，还是没能解决办法。

最后在吃完完晚饭后，又折腾了快三小时，终于找到可靠有用的解决方案了。

运行成功后，我当时就激动起来了。马丹，老子终于将你解决了。

所以在这里立马就将自己这次的血崩历史纪录下来。

下面写下遇到的问题：（其中有些可能还不记得写了）

java.lang.ClassNotFoundException: javax.persistence.EntityManager
java.lang.NoSuchMethodError: javax.persistence.JoinColumn.foreignKey()Ljavax/persistence/ForeignKey;

javax.persistence.PersistenceException: No Persistence provider for EntityManager named defaultPersistenceUnit
javax.persistence.PersistenceException: No Persistence provider for EntityManager named defaultPersi
java.lang.NoClassDefFoundError: org/hibernate/ejb/HibernatePersistence
java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory
java.lang.ClassNotFoundException: org.hibernate.MappingException
NoSuchMethodError: javax.persistence.xxx

等，还有几个，忘记了。。

首先通过报错信息可以知道有些是因为jar包的问题，但是并不是光是缺少jar包的问题，很大的原

因就是因为jar包的版本不同，刚好那个jar包又是有问题的（自身有bug）。

就比如错误：

java.lang.NoSuchMethodError: javax.persistence.JoinColumn.foreignKey()Ljavax/persistence/ForeignKey;

就是因为JAVAEE6.0中的 javax.persistence.jar与 hibernate4.3.8中的hibernate-jpa-2.1-api-1.0.0.Final.jar冲突

JoinColumn.foreignKey() was introduced with JPA 2.1, which was not implemented by Hibernate 4 until version 4.3. If you’re using an older version of Hibernate 4 then try upgrading to 4.3.x.

If you’re already using Hibernate 4.3 then make sure you’re also using JPA 2.1 to make sure the API and implementation match up.

这里写图片描述

图片来自 : http://stackoverflow.com/questions/24588860/error-javax-persistence-joincolumn-foreignkeyljavax-persistence-foreignkey-wi

I finally solved this similar problem, there was an old version(hibernate-jpa-2.0-api-1.0.0-Final.jar) in my lib folder which I guess has been preventing maven dependency from loading.

So after I manually deleted it and added (hibernate-jpa-2.1-api-1.0.0-Final.jar) everything started to work.

意思大概就是：

因为JAVAEE6.0中的 javax.persistence.jar与 hibernate4.3.8中的hibernate-jpa-2.1-api-1.0.0.Final.jar冲突，我们在pom文件下添加依赖后，竟然没发现在 springmvc（项目名称）\target\springmvc（项目名称）\WEB-INF\lib 下看到 javax.persistence.jar 文件，结果竟然在 springmvc\lib下找到他了。

解决办法就是在 pom文件和 mvc-dispatcher-servlet.xml 都配置好的情况下，将 springmvc\lib下的 javax.persistence.jar 删除。

最后再说一句：Though the error drove almost crazy, hold on, you wil get smile ！ Fighting