org.hibernate.PropertyNotFoundException: Could not find a setter for property id in class

请高手耐心分析下,小B感激不尽!
以下是异常信息:
org.hibernate.PropertyNotFoundException: Could not find a setter for property id in class com.gdms.domain.Messages
org.hibernate.property.BasicPropertyAccessor.createSetter(BasicPropertyAccessor.java:156)
org.hibernate.property.BasicPropertyAccessor.getSetter(BasicPropertyAccessor.java:150)
org.hibernate.mapping.Property.getSetter(Property.java:245)
org.hibernate.tuple.PojoTuplizer.buildPropertySetter(PojoTuplizer.java:241)
org.hibernate.tuple.AbstractTuplizer.<init>(AbstractTuplizer.java:55)
org.hibernate.tuple.PojoTuplizer.<init>(PojoTuplizer.java:54)
org.hibernate.tuple.TuplizerLookup.create(TuplizerLookup.java:47)
org.hibernate.tuple.EntityMetamodel.<init>(EntityMetamodel.java:218)
org.hibernate.persister.entity.BasicEntityPersister.<init>(BasicEntityPersister.java:400)
org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:104)
org.hibernate.persister.PersisterFactory.createClassPersister(PersisterFactory.java:55)
org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:211)
org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1005)
com.gdms.dao.hibernate.HibernateUtil.<clinit>(HibernateUtil.java:15)
com.gdms.web.struts.action.LoginAction.execute(LoginAction.java:47)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
com.gdms.util.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:66)Messages类:
package com.gdms.domain;import java.util.Random;//import java.util.Random;
public class Messages implements java.io.Serializable {    // Fields
private static final long serialVersionUID = 1L;    private String id;    private String title;    private String name;    private String mail;    private String content;    private String times;
    // 留言时间
    private Random r;    /** default constructor */
    public Messages() {
    }    /** full constructor */
    public Messages(String id, String title, String name, String mail,
                    String times, String content) {
        this.id = id;
        this.title = title;
        this.name = name;
        this.mail = mail;
        this.times = times;
        this.content = content;
    }
        public String getId() {
return id;
} public void setId() {
while (true) {
           r = new Random();
           int x = r.nextInt(9999);
           if (x > 1000) {
               this.id = "4" + x; 
               break;
           }
       }

} public String getContent() {
return content;
} public void setContent(String content) {
this.content = content;
} public String getMail() {
return mail;
} public void setMail(String mail) {
this.mail = mail;
} public String getName() {
return name;
} public void setName(String name) {
this.name = name;
} public String getTimes() {
return times;
} public void setTimes() {
java.util.Calendar cl = java.util.Calendar.getInstance();
        java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat(
                "yyyy-MM-dd HH:mm:ss");
        this.times = sdf.format(cl.getTime());
} public String getTitle() {
return title;
} public void setTitle(String title) {
this.title = title;
}  
  
}
以下是Message.hbm.xml:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
<hibernate-mapping>
    <class name="com.gdms.domain.Messages" table="messages">
        <id name="id" type="string" >
            <column name="id" length="32" />
            <generator class="identity" />
        </id>
        <property name="title" type="string">
            <column name="title" length="50" />
        </property>
        <property name="name" type="string">
            <column name="name" length="20" />
        </property>
        <property name="mail" type="string">
            <column name="mail" length="20" />
        </property>
        <property name="times" type="string">
            <column name="times" length="50" />
        </property>
        <property name="content" type="string">
            <column name="content" length="200" />
        </property>    </class>
</hibernate-mapping>