Lighting@刘迎光

Could not open JPA EntityManager for transaction; nested exception is javax.pers

java jpa exception 2017-07-19 22:15:22 1330

错误栈：

org.zkoss.zk.ui.UiException: Could not open JPA EntityManager for transaction; nested exception is javax.persistence.PersistenceException: org.hibernate.TransactionException: JDBC begin transaction failed: at [file:/C:/Users/lyg21_000/git/Saas/target/classes/main.zul, line:26]

at org.zkoss.bind.impl.MiscUtil.mergeExceptionInfo(MiscUtil.java:175) ~[zkbind-7.0.4.jar:7.0.4]

at org.zkoss.bind.BindComposer.doBeforeComposeChildren(BindComposer.java:161) ~[zkbind-7.0.4.jar:7.0.4]

at org.zkoss.zk.ui.impl.UiEngineImpl.doBeforeComposeChildren(UiEngineImpl.java:930) ~[zk-7.0.4.jar:7.0.4]

at org.zkoss.zk.ui.impl.UiEngineImpl.execCreateChild0(UiEngineImpl.java:869) ~[zk-7.0.4.jar:7.0.4]

at org.zkoss.zk.ui.impl.UiEngineImpl.execCreateChild(UiEngineImpl.java:826) ~[zk-7.0.4.jar:7.0.4]

at org.zkoss.zk.ui.impl.UiEngineImpl.execCreate0(UiEngineImpl.java:735) ~[zk-7.0.4.jar:7.0.4]

at org.zkoss.zk.ui.impl.UiEngineImpl.execCreateChild(UiEngineImpl.java:797) ~[zk-7.0.4.jar:7.0.4]

at org.zkoss.zk.ui.imp

More

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.12.4:test (default-test)

java exception 2017-07-19 22:14:16 1355

分析bug原因：

是因为某次下载jar包的时候出错，导致下文红色部分标注的jar包没有下载下来，在repository目录下，删除此jar包的文件夹，重新下载即可

我这里是junit3的jar包，但是也可能是其他jar包，这个是不确定的

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.12.4:test (default-test) on project hello: Unable to generate classpath: org.apache.maven.artifact.resolver.MultipleArtifactsNotFoundException: Missing:
[ERROR] ----------
[ERROR] 1) org.apache.maven.surefire:surefire-junit3:jar:2.12.4
[ERROR]
[ERROR] Try downloading the file manually from the project website.
[ERROR]
[ERROR] Then, install it using the command:
[ERROR] mvn install:install-file -DgroupId=org.apache.maven.surefire -DartifactId=surefire-junit3 -Dversion=2.12.4 -Dpackaging=jar -Dfile=/path/to/file
[ERROR]
[ERROR] Alternatively, if you host your own repository you can deploy the file there:
[ERROR] mvn deploy:deploy-file -DgroupId=org.apache.maven.surefire -DartifactId=surefire-junit3 -Dversion=2.12.4 -Dpackaging=jar -Dfile=/path/to/file -Durl=[url] -DrepositoryId=[id]
[ERROR]
[ERR

More

Caused by: org.hibernate.PersistentObjectException: detached entity passed to persist

hibernate java exception 2017-07-19 22:13:27 1118

Caused by: org.hibernate.PersistentObjectException: detached entity passed to persist

今天用JPA保存数据的时候出现此错误。

原因: ID生成策略我设置的自动。但是代码里面还是手动给对象ID设置了值

解决方案：去掉手动给ID设置值的代码即可。

如：

@Id

@GeneratedValue(strategy = GenerationType.IDENTITY)

@Column(name = "id", unique = true, nullable = false)

这种情况下，会报错，因为对id仅仅是设置了主键，并没有设置自增长，将