最近在跟着做慕課網上的SSM校園商鋪項目，剛把配置文件弄完，測試dao層就遇到了這樣的錯誤。
這是控制檯DEBUG信息:
DEBUG org.mybatis.spring.SqlSessionUtils - SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@78fa769e] was not registered for synchronization because synchronization is not active
二月 18, 2019 10:31:09 下午 com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource getPoolManager
信息: Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 3, acquireRetryAttempts -> 2, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 10000, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, dataSourceName -> 1hge0ysa1a5z6r1pwvwb4|6d763516, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> com.mysql.jdbc.Driver, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> 1hge0ysa1a5z6r1pwvwb4|6d763516, idleConnectionTestPeriod -> 0, initialPoolSize -> 3, jdbcUrl -> jdbc:mysql://localhost:3306/o2o?useUnicode=true&characterEncoding=utf8, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 0, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 30, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 10, numHelperThreads -> 3, numThreadsAwaitingCheckoutDefaultUser -> 0, preferredTestQuery -> null, properties -> {user=******, password=******}, propertyCycle -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, usesTraditionalReflectiveProxies -> false ]
22:31:10.339 [main] DEBUG org.mybatis.spring.transaction.SpringManagedTransaction - JDBC Connection [com.mchange.v2.c3p0.impl.NewProxyConnection@14f232c4] will not be managed by Spring
這是Junit單元測試變紅的錯誤信息:
java.lang.AbstractMethodError: Method com/mchange/v2/c3p0/impl/NewProxyPreparedStatement.isClosed()Z is abstract
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.isClosed(NewProxyPreparedStatement.java) ......
網上給的解決方案是將c3p0依賴的版本調高:
c3p0-0.9.2.1換成c3p0-0.9.5.2
直接在pom裏面改版本好發現出現錯誤，因爲根本“沒有”這個版本的c3p0！
然後到maven中央倉庫一搜索c3p0，發現有兩種c3p0：
教程裏引用的是下面c3p0中的921版本，它更新到2007年就沒更新了:
<dependency>
<groupId>c3p0</groupId>
<artifactId>c3p0</artifactId>
<version>0.9.1.2</version>
</dependency>
而95+版本其實是上面c3p0的，最新的已經是953了，它們的groupid不同。
所以修改起來也很容易，把之前的c3p0註釋(去)掉，並添加新的c3p0:
<dependency>
<groupId>com.mchange</groupId>
<artifactId>c3p0</artifactId>
<version>0.9.5.3</version>
</dependency>
最後再maven update一下就好了。