struts2+hibernate3+spring2出现java.lang.NullPointerException

Question

action代码package action.loginandregister;
import java.util.*;
import com.opensymphony.xwork2.ActionContext;
import action.base.BaseAction;
import exception.CommonException;
public class Login extends BaseAction{
private String username;
private String password;
private String usertype;
private String vercode;

@Override
public String execute() throws Exception{
Map session = ActionContext.getContext().getSession();
String ver2 = (String )session.get("rand");
//清空用户Session的随机验证码字符串。
session.put("rand" , null);
if(vercode.equals(ver2)){
if(usertype.equals("student")){
Integer userId=studentUser.validLogin(username,password);
if(userId<0){
 addActionError("用户名/密码不匹配");
             return "failure";
}else{
 session.put("userId" , userId);
 session.put("username", username);
 session.put("usertype", usertype);
             return "student";
}
}else if(usertype.equals("social")){
Integer userId=socialUser.validLogin(username,password);
if(userId<0){
addActionError("用户名/密码不匹配");
            return "failure";
}else{
 session.put("userId" , userId);
 session.put("username", username);
 session.put("usertype", usertype);
             return "social";
}
}else if(usertype.equals("enterprise")){
Integer userId=enterpriseUser.validLogin(username,password);
if(userId<0){
addActionError("用户名/密码不匹配");
            return "failure";
}else{
 session.put("userId" , userId);
 session.put("username", username);
 session.put("usertype", usertype);
             return "enterprise";
}
}
}else{
addActionError("验证码不匹配,请重新输入");
return "failure";
}
return "failure";
}

public void setUsername(String username){
this.username=username;
}
public String getUsername(){
return this.username;
}
public void setPassword(String password){
this.password=password;
}
public String getPassword(String password){
return this.password;
}
public void setUsertype(String usertype){
this.usertype=usertype;
}
public String getUsertype(){
return this.usertype;
}
public void setVercode(String vercode){
this.vercode=vercode;
}
public String getVercode(){
return this.vercode;
}
}

Answer 1

service代码/**
 * 根据用户名，密码验证用户登陆
 * @param username用户名
 * @param pass密码
 * @return 返回用户id号
 */
public Integer validLogin(String username,String pass)throws CommonException{
try{
Fstudentuser user=fuserDao.findUserByNameAndPass(username, pass);
if(user==null){
return null;
}
return user.getId();
}catch(Exception e){
log.debug(e.getMessage());
throw new CommonException("对不起，获取用户出错,请重试!");
}
}
dao代码
[code=Java]
/**
 * 根据用户名和密码查找用户
 * @param username使用户的用户名
 * @param pass是用户的密码
 * @return 对应用户
 */
public Fstudentuser findUserByNameAndPass(String username,String pass){
String agrs[]={username,pass};
List ul=getHibernateTemplate().find("from Fstudentuser fs where fs.username=? and fs.password=?",agrs);
if(ul.size()==1){
return (Fstudentuser)ul.get(0);
}
return null;
}
/code]

Answer 2

model代码/**
 * 根据用户名和密码查找用户
 * @param username使用户的用户名
 * @param pass是用户的密码
 * @return 对应用户
 */
public Fstudentuser findUserByNameAndPass(String username,String pass){
String agrs[]={username,pass};
List ul=getHibernateTemplate().find("from Fstudentuser fs where fs.username=? and fs.password=?",agrs);
if(ul.size()==1){
return (Fstudentuser)ul.get(0);
}
return null;
}

Answer 3

model代码  package model;
import java.io.Serializable;
import java.util.Date;
import java.util.Set;
import java.util.HashSet;
public class Fstudentuser implements Serializable{
private Integer id;
private Integer freeze;//冻结标志0为部冻结1为冻结
private Date freezedate;//冻结日期
private String image;
private String username;
private String password;
private String email;
private Fortes fortes;
private FortesType sfortes;
private StudentType studenttype;
private Provance provance;
private City city;
private Town town;
private School school;
private BigQualify bigqualify;//专业粗略分类
private Qualify qualify;
private Date enrolldate;
private String realname;
private Date dateofbirth;
private String sex;
private Nation nation;
private String marrige;
private String chance;
private String netname;
private String personnet;
private NetType nettype;
private Integer groom;
private Date overdue;//推荐过期
private Set<Tstudentuser> threefile=new HashSet<Tstudentuser>();
//private Set<Confidant> confidant=new HashSet<Confidant>();
private Date regdate;
private Integer count;
public void setId(Integer id){
this.id=id;
}
public Integer getId(){
return this.id;
}
public void setFreeze(int freeze){
this.freeze=freeze;
}
public int getFreeze(){
return this.freeze;
}
public void setFreezedate(Date freezedate){
this.freezedate=freezedate;
}
public Date getFreezedate(){
return this.freezedate;
}
public void setImage(String image){
this.image=image;
}
public String getImage(){
return this.image;
}
public void setUsername(String username){
this.username=username;
}
public String getUsername(){
return this.username;
}
public void setPassword(String password){
this.password=password;
}
public String getPassword(){
return this.password;
}
public void setEmail(String email){
this.email=email;
}
public String getEmail(){
return this.email;
}
public void setFortes(Fortes fortes){
this.fortes=fortes;
}
public Fortes getFortes(){
return this.fortes;
} 
public void setSfortes(FortesType sfortes){
this.sfortes=sfortes;
}
public FortesType getSfortes(){
return this.sfortes;
}
public void setStudenttype(StudentType studenttype){
this.studenttype=studenttype;
}
public StudentType getStudenttype(){
return this.studenttype;
}
public void setProvance(Provance provance){
this.provance=provance;
}
public Provance getProvance(){
return this.provance;
}
public void setCity(City city){
this.city=city;
}
public City getCity(){
return this.city;
}
public void setTown(Town town){
this.town=town;
}
public Town getTown(){
return this.town;
}
public void setSchool(School school){
this.school=school;
}
public School getSchool(){
return this.school;
}
public void setBigqualify(BigQualify bigqualify){
this.bigqualify=bigqualify;
}
public BigQualify getBigqualify(){
return this.bigqualify;
}
public void setQualify(Qualify qualify){
this.qualify=qualify;
}
public Qualify getQualify(){
return this.qualify;
}
public void setEnrolldate(Date enrolldate){
this.enrolldate=enrolldate;
}
public Date getEnrolldate(){
return this.enrolldate;
}
public void setRealname(String realname){
this.realname=realname;
}
public String getRealname(){
return this.realname;
}
public void setDateofbirth(Date dateofbirth){
this.dateofbirth=dateofbirth;
}
public Date getDateofbirth(){
return this.dateofbirth;
}
public void setSex(String sex){
this.sex=sex;
}
public String getSex(){
return this.sex;
}
public void setNation(Nation nation){
this.nation=nation;
}
public Nation getNation(){
return this.nation;
}
public void setMarrige(String marrige){
this.marrige=marrige;
}
public String getMarrige(){
return this.marrige;
}
public void setChance(String chance){
this.chance=chance;
}
public String getChance(){
return this.chance;
}
public void setNetname(String netname){
this.netname=netname;
}
public String getNetname(){
return this.netname;
}
public void setPersonnet(String personnet){
this.personnet=personnet;
}
public String getPersonnet(){
return this.personnet;
}
public void setNettype(NetType nettype){
this.nettype=nettype;
}
public NetType getNettype(){
return this.nettype;
}
public void setGroom(int groom){
this.groom=groom;
}
public int getGroom(){
return this.groom;
}
public void setOverdue(Date overdue){
this.overdue=overdue;
}
public Date getOverdue(){
return this.overdue;
}
public void setthreefile(Set<Tstudentuser> threefile){
this.threefile=threefile;
}
public Set<Tstudentuser> getThreefile(){
return this.threefile;
}
/*
public void setConfidant(Set<Confidant> confidant){
this.confidant=confidant;
}
public Set<Confidant> getConfidant(){
return this.confidant;
}
*/
public void setRegdate(Date regdate){
this.regdate=regdate;
}
public Date getRegdate(){
return this.regdate;
}
public void setCount(int count){
this.count=count;
}
public int getCount(){
return this.count;
}
public int hashCode(){
return username.hashCode()+email.hashCode(); 
}
public boolean equals(Object obj){
if(obj instanceof Fsocialuser){
Fstudentuser user=new Fstudentuser();
if(user.getUsername()==username||user.getEmail()==email){
return true;
}
}
return false;
}
}

Answer 4

你把你的Login类里下面的变量。初始化数值！！！！
由
    private String username;
    private String password;
    private String usertype;
    private String vercode;改成：
    private String username=“”;
    private String password=“”;
    private String usertype=“”;
    private String vercode=“”;感觉。这里要改。
如果有其他问题，请留言。。我们再讨论。

Answer 5

if(vercode.equals(ver2)){
这句话肯定会报空指针异常的,(java.lang.NullPointerException)
因为你这样private String vercode;就相当于private String vercode = null;
null.eauals(ver2)不就异常了吗?
还有你下面的usertype.equals("student")){也是会出现空指针异常的.
给你一点建议,判断字符串是否相等的时候,把常量写在前面
"student".equals(usertype)){这样就会避免无谓的空指针异常了.        

Answer 6

原因是,在你没输入用户名和密码时,用了equals方法,报空指针异常
解决方法:if(null!=vercode&&vercode.equals(ver2)){null!=vercode很重要,是不出空指针的最好方法