[英]org.hibernate.AnnotationException: No identifier specified for entity: login.Users
I am getting an error while reuest goes to servlet ,I try alot for resolved this but not get proper solution. 请求servlet时出现错误,我尝试了很多解决方法,但没有找到适当的解决方案。
Registration.java (Servlet class file) Registration.java(Servlet类文件)
package login;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.SessionFactory;
@WebServlet("/Registration")
public class Registration extends HttpServlet {
private static final long serialVersionUID = 1L;
public Registration() {
super();
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username = request.getParameter("username");
String password = request.getParameter("password");
String name = request.getParameter("name");
Users u = new Users();
u.setUsername(username);
u.setPassword(password);
u.setName(name);
String uname = u.getUsername();
System.out.println(uname);
SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
Session session = sessionFactory.openSession();
session.beginTransaction();
session.save(u);
session.getTransaction().commit();
session.close();
sessionFactory.close();
}
} }
Users.java this class is used to stored the user information in "Users" table Users.java此类用于将用户信息存储在“用户”表中
package login;
import javax.persistence.Entity;
import javax.persistence.Table;
@Entity
@Table(name="Users")
public class Users {
private String username;
private String password;
private String name;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
hibernate.cfg.xml hibernate.cfg.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration SYSTEM "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/login</property>
<property name="connection.username">root</property>
<property name="connection.password"></property>
<property name="connection.pool_size">1</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<property name="show_sql">true</property>
<property name="hbm2ddl.auto">create</property>
<mapping class ="login.Users" />
</session-factory>
Console Logs 控制台日志
EVERE: Servlet.service() for servlet [Registration] in context with path [/loginapp] threw exception
org.hibernate.AnnotationException: No identifier specified for entity: login.Users
at org.hibernate.cfg.InheritanceState.determineDefaultAccessType(InheritanceState.java:265)
at org.hibernate.cfg.InheritanceState.getElementsToProcess(InheritanceState.java:211)
at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:710)
at org.hibernate.boot.model.source.internal.annotations.AnnotationMetadataSourceProcessorImpl.processEntityHierarchies(AnnotationMetadataSourceProcessorImpl.java:245)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess$1.processEntityHierarchies(MetadataBuildingProcess.java:222)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:265)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:83)
at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:418)
at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:87)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:692)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:724)
at login.Registration.doPost(Registration.java:47)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
You are missing a field that serves as identifier for an entity. 您缺少一个用作实体标识符的字段。 Something like this: 像这样:
@Id
@GeneratedValue
private long id;
Also do not forget a getter for this field. 也不要忘记此领域的吸气剂。
Hope this helps. 希望这可以帮助。
You also have to use the right import. 您还必须使用正确的导入。
org.springframework.data.annotation.Id => Did not work org.springframework.data.annotation.Id =>无效
javax.persistence.Id => Worked javax.persistence.Id =>正常工作
You didn't specify a primary key: 您没有指定主键:
@Id
@GeneratedValue
@Column(name = "id")
private int id;
You need to find out which column is unique in your table and assign it as an ID 您需要找出表中哪一列是唯一的,并将其分配为ID
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