用spring数据jpa启动。我使用@OneToMany注释作为双向。当我第一次运行这个应用程序时，它正在按预期给出结果。但是在第二次运行中，它试图再次创建已经存在于数据库中的表。将hbm2ddl.auto属性的属性更改为更新，仍然面临同样的问题。
Here is the exception that I am facing
2017-06-02 10:51:59.145 INFO 1148 --- [ main] org.hibernate.Version : HHH000412: Hibernate Core {5.0.12.Final}
2017-06-02 10:51:59.147 INFO 1148 --- [ main] org.hibernate.cfg.Environment : HHH000206: hibernate.properties not found
2017-06-02 10:51:59.148 INFO 1148 --- [ main] org.hibernate.cfg.Environment : HHH000021: Bytecode provider name : javassist
2017-06-02 10:51:59.180 INFO 1148 --- [ main] o.hibernate.annotations.common.Version : HCANN000001: Hibernate Commons Annotations {5.0.1.Final}
2017-06-02 10:51:59.261 INFO 1148 --- [ main] org.hibernate.dialect.Dialect : HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect
2017-06-02 10:51:59.649 INFO 1148 --- [ main] org.hibernate.tool.hbm2ddl.SchemaUpdate : HHH000228: Running hbm2ddl schema update
2017-06-02 10:51:59.662 INFO 1148 --- [ main] rmationExtractorJdbcDatabaseMetaDataImpl : HHH000262: Table not found: dept
2017-06-02 10:51:59.664 INFO 1148 --- [ main] rmationExtractorJdbcDatabaseMetaDataImpl : HHH000262: Table not found: dept
2017-06-02 10:51:59.673 WARN 1148 --- [ main] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory
2017-06-02 10:51:59.677 INFO 1148 --- [ main] o.apache.catalina.core.StandardService : Stopping service Tomcat
2017-06-02 10:51:59.686 INFO 1148 --- [ main] utoConfigurationReportLoggingInitializer :
Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2017-06-02 10:51:59.692 ERROR 1148 --- [ main] o.s.boot.SpringApplication : Application startup failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1628) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1081) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:856) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:314) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
at com.jilani.springdatajpa.SpringDataJpaApplication.main(SpringDataJpaApplication.java:33) [classes/:na]
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.persistenceException(EntityManagerFactoryBuilderImpl.java:954) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:882) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:60) ~[spring-orm-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:353) ~[spring-orm-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:370) ~[spring-orm-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:359) ~[spring-orm-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1687) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1624) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
... 16 common frames omitted
Caused by: org.hibernate.tool.schema.spi.SchemaManagementException: Unable to execute schema management to JDBC target [create table dept (dept_no integer not null auto_increment, dept_loc varchar(255), dept_name varchar(255), primary key (dept_no))]
at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:59) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlString(SchemaMigratorImpl.java:431) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlStrings(SchemaMigratorImpl.java:420) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.createTable(SchemaMigratorImpl.java:236) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigrationToTargets(SchemaMigratorImpl.java:167) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigration(SchemaMigratorImpl.java:60) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
at org.hibernate.tool.hbm2ddl.SchemaUpdate.execute(SchemaUpdate.java:134) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
at org.hibernate.tool.hbm2ddl.SchemaUpdate.execute(SchemaUpdate.java:101) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:472) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:444) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:879) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
... 22 common frames omitted
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'dept' already exists
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_121]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_121]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_121]
at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_121]
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) ~[mysql-connector-java-5.1.41.jar:5.1.41]
at com.mysql.jdbc.Util.getInstance(Util.java:408) ~[mysql-connector-java-5.1.41.jar:5.1.41]
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:943) ~[mysql-connector-java-5.1.41.jar:5.1.41]
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973) ~[mysql-connector-java-5.1.41.jar:5.1.41]
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909) ~[mysql-connector-java-5.1.41.jar:5.1.41]
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2527) ~[mysql-connector-java-5.1.41.jar:5.1.41]
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2680) ~[mysql-connector-java-5.1.41.jar:5.1.41]
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2497) ~[mysql-connector-java-5.1.41.jar:5.1.41]
at com.mysql.jdbc.StatementImpl.executeUpdateInternal(StatementImpl.java:1540) ~[mysql-connector-java-5.1.41.jar:5.1.41]
at com.mysql.jdbc.StatementImpl.executeLargeUpdate(StatementImpl.java:2595) ~[mysql-connector-java-5.1.41.jar:5.1.41]
at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1468) ~[mysql-connector-java-5.1.41.jar:5.1.41]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_121]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_121]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_121]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_121]
at org.apache.tomcat.jdbc.pool.StatementFacade$StatementProxy.invoke(StatementFacade.java:114) ~[tomcat-jdbc-8.5.14.jar:na]
at com.sun.proxy.$Proxy69.executeUpdate(Unknown Source) ~[na:na]
at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:56) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
... 32 common frames omitted
==================
这是我的Spring Boot类
import java.util.List;
import javax.transaction.Transactional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import com.jilani.springboot.model.Department;
import com.jilani.springboot.model.Employee;
import com.jilani.springboot.repository.DepartmentRepository;
import com.jilani.springboot.repository.EmployeeRepository;
@SpringBootApplication
@ComponentScan({"com."})
@EntityScan("com.jilani.springboot.model")
@EnableJpaRepositories("com.jilani.springboot.repository")
public class SpringDataJpaApplication implements CommandLineRunner {
@Autowired
DepartmentRepository deptRepository;
@Autowired
EmployeeRepository empRepository;
public static void main(String[] args) {
SpringApplication.run(SpringDataJpaApplication.class, args);
}
@Override
public void run(String... arg0) throws Exception {
clearData();
saveData();
showData();
}
@Transactional
private void clearData() {
deptRepository.deleteAll();
empRepository.deleteAll();
}
@Transactional
private void saveData() {
Employee hrEmp = new Employee("Jilani1", 10001, "SE1");
Employee hrEmp1 = new Employee("Rahul1", 20001, "SSE1");
Employee itEmp = new Employee("Manju1", 30001, "AGM1");
Employee itEmp1 = new Employee("Rahul1", 40001, "GM1");
Department hrDept = new Department("HR1", "HYD1");
Department itDept = new Department("IT1", "BNG1");
hrEmp.setDept(hrDept);
hrEmp1.setDept(hrDept);
itEmp.setDept(itDept);
itEmp1.setDept(itDept);
hrDept.getEmployees().add(hrEmp);
hrDept.getEmployees().add(hrEmp1);
itDept.getEmployees().add(itEmp);
itDept.getEmployees().add(itEmp1);
deptRepository.save(hrDept);
deptRepository.save(itDept);
empRepository.save(hrEmp);
empRepository.save(hrEmp1);
empRepository.save(itEmp);
empRepository.save(itEmp1);
}
@Transactional
private void showData() {
List<Employee> empList = empRepository.findAll();
List<Department> deptList = deptRepository.findAll();
System.out.println("===================Employee List:==================");
empList.forEach(System.out::println);
System.out.println("===================Department List:==================");
deptList.forEach(System.out::println);
}
}
这是我的实体（员工）
import java.io.Serializable;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import org.json.JSONObject;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
@Entity
@Table(name="employee")
public class Employee implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int empId;
private String empName;
private double empSal;
private String job;
@ManyToOne(fetch = FetchType.EAGER)
//@JoinColumn(name = "dept_no")
private Department dept;
public Employee() {
}
public Employee(String empName, double empSal, String job) {
this.empName = empName;
this.empSal = empSal;
this.job = job;
}
public Employee(String empName, double empSal, String job, Department dept){
this.empName = empName;
this.empSal = empSal;
this.job = job;
this.dept = dept;
}
public int getEmpId() {
return empId;
}
public void setEmpId(int empId) {
this.empId = empId;
}
public String getEmpName() {
return empName;
}
public void setEmpName(String empName) {
this.empName = empName;
}
public double getEmpSal() {
return empSal;
}
public void setEmpSal(double empSal) {
this.empSal = empSal;
}
public String getJob() {
return job;
}
public void setJob(String job) {
this.job = job;
}
public Department getDept() {
return dept;
}
public void setDept(Department dept) {
this.dept = dept;
}
public String toString(){
String info = "";
JSONObject jsonInfo = new JSONObject();
jsonInfo.put("name",this.empName);
JSONObject deptObj = new JSONObject();
deptObj.put("name", this.dept.getDeptName());
jsonInfo.put("company", deptObj);
info = jsonInfo.toString();
return info;
}
}
这是另一个实体（部门）
import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import org.json.JSONArray;
import org.json.JSONObject;
@Entity
@Table(name="dept")
public class Department implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int deptNo;
private String deptName;
private String deptLoc;
@OneToMany(cascade = CascadeType.ALL, mappedBy = "dept", fetch = FetchType.EAGER)
private Set<Employee> employees = new HashSet<Employee>();
public Department() {
}
public Department(String deptName, String deptLoc) {
this.deptName = deptName;
this.deptLoc = deptLoc;
}
public Department(String deptName, String deptLoc, Set<Employee> employees){
this.deptName = deptName;
this.deptLoc = deptLoc;
this.employees = employees;
}
public int getDeptId() {
return deptNo;
}
public void setDeptId(int deptId) {
this.deptNo = deptId;
}
public String getDeptName() {
return deptName;
}
public void setDeptName(String deptName) {
this.deptName = deptName;
}
public String getDeptLoc() {
return deptLoc;
}
public void setDeptLoc(String deptLoc) {
this.deptLoc = deptLoc;
}
public Set<Employee> getEmployees() {
return employees;
}
public void setEmployees(Set<Employee> employees) {
this.employees = employees;
}
public String toString(){
String info = "";
JSONObject jsonInfo = new JSONObject();
jsonInfo.put("name",this.deptName);
JSONArray empArray = new JSONArray();
if(this.employees != null){
this.employees.forEach(emp->{
JSONObject subJson = new JSONObject();
subJson.put("name", emp.getEmpName());
empArray.put(subJson);
});
}
jsonInfo.put("products", empArray);
info = jsonInfo.toString();
return info;
}
}
最后，这是我在配置文件中设置的属性
spring.datasource.url=jdbc:mysql://localhost:3306/mysql?useSSL=false
spring.datasource.username=root
spring.datasource.password=root
spring.jpa.generate-ddl=true
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
spring.jpa.hibernate.ddl-auto=update
server.port=9999