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; 
}   
  
} 
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>