请教hibernate中报空指针的问题
本人在看孙的hibernate 其中第2章的例子 在运行时报错
java.lang.NullPointerException
at mypack.BusinessService.saveCustomer(BusinessService.java:54)
at mypack.BusinessService.test(BusinessService.java:187)
at mypack.BusinessService.main(BusinessService.java:197)
Exception in thread "main "
其中BusinessService.java如下
public class BusinessService {
public static SessionFactory sessionFactory;
static{
try{
// Create a configuration based on the properties file we 've put
// in the standard place.
Configuration config = new Configuration().configure();
SessionFactory sessionFactory = config.buildSessionFactory();
// Get the session factory we can use for persistence
sessionFactory = config.buildSessionFactory();
}catch(Exception e){e.printStackTrace();}
}
public void findAllCustomers(ServletContext context,OutputStream out) throws Exception{
// Ask for a session using the JDBC information we 've configured
Session session = sessionFactory.openSession();
Transaction tx = null;
try {
tx = session.beginTransaction();
List customers=session.find( "from Customer as c order by c.name asc ");
for (Iterator it = customers.iterator(); it.hasNext();) {
printCustomer(context,out,(Customers) it.next());
}
// We 're done; make our changes permanent
tx.commit();
}catch (Exception e) {
if (tx != null) {
// Something went wrong; discard all partial changes
tx.rollback();
}
throw e;
} finally {
// No matter what, close the session
session.close();
}
}
public void saveCustomer(Customers customer) throws Exception{
// Ask for a session using the JDBC information we 've configured
Session session = sessionFactory.openSession();
Transaction tx = null;
try {
tx = session.beginTransaction();
session.save(customer);
// We 're done; make our changes permanent
tx.commit();
}catch (Exception e) {
if (tx != null) {
// Something went wrong; discard all partial changes
tx.rollback();
}
throw e;
} finally {
// No matter what, close the session
session.close();
}
}
public void loadAndUpdateCustomer(Long customer_id,String address) throws Exception{
// Ask for a session using the JDBC information we 've configured
Session session = sessionFactory.openSession();
Transaction tx = null;
try {
tx = session.beginTransaction();
Customers c=(Customers)session.load(Customers.class,customer_id);
c.setAddress(address);
// We 're done; make our changes permanent
tx.commit();
}catch (Exception e) {
if (tx != null) {
// Something went wrong; discard all partial changes
tx.rollback();
}
throw e;
} finally {
// No matter what, close the session
session.close();
}
}
public void deleteAllCustomers() throws Exception{
// Ask for a session using the JDBC information we 've configured
Session session = sessionFactory.openSession();
Transaction tx = null;
try {
tx = session.beginTransaction();
session.delete( "from Customer as c ");
// We 're done; make our changes permanent
tx.commit();
}catch (Exception e) {
if (tx != null) {
// Something went wrong; discard all partial changes
tx.rollback();
}
throw e;
} finally {
// No matter what, close the session
session.close();
}
}
private void printCustomer(ServletContext context,OutputStream out,Customers customer)throws Exception{
if(out instanceof ServletOutputStream)
printCustomer(context,(ServletOutputStream) out,customer);
else
printCustomer((PrintStream) out,customer);
}
private void printCustomer(PrintStream out,Customers customer)throws Exception{
//save photo
byte[] buffer=customer.getImage();
FileOutputStream fout=new FileOutputStream( "photo_copy.gif ");
fout.write(buffer);
fout.close();
out.println( "------以下是 "+customer.getName()+ "的个人信息------ ");
out.println( "ID: "+customer.getId());
out.println( "口令: "+customer.getPassword());
out.println( "E-Mail: "+customer.getEmail());
out.println( "电话: "+customer.getPhone());
out.println( "地址: "+customer.getAddress());
String sex=customer.getSex()== 'M '? "男 ": "女 ";
out.println( "性别: "+sex);
String marriedStatus=customer.isMarried()? "已婚 ": "未婚 ";
out.println( "婚姻状况: "+marriedStatus);
out.println( "生日: "+customer.getBirthday());
out.println( "注册时间: "+customer.getRegisteredTime());
out.println( "自我介绍: "+customer.getDescription());
}
private void printCustomer(ServletContext context,ServletOutputStream out,Customers customer)throws Exception{
//save photo
byte[] buffer=customer.getImage();
String path=context.getRealPath( "/ ");
FileOutputStream fout=new FileOutputStream(path+ "photo_copy.gif ");
fout.write(buffer);
fout.close();
out.println( "------以下是 "+customer.getName()+ "的个人信息------ "+ " <br> ");
out.println( "ID: "+customer.getId()+ " <br> ");
out.println( "口令: "+customer.getPassword()+ " <br> ");
out.println( "E-Mail: "+customer.getEmail()+ " <br> ");
out.println( "电话: "+customer.getPhone()+ " <br> ");
out.println( "地址: "+customer.getAddress()+ " <br> ");
String sex=customer.getSex()== 'M '? "男 ": "女 ";
out.println( "性别: "+sex+ " <br> ");
String marriedStatus=customer.isMarried()? "已婚 ": "未婚 ";
out.println( "婚姻状况: "+marriedStatus+ " <br> ");
out.println( "生日: "+customer.getBirthday()+ " <br> ");
out.println( "注册时间: "+customer.getRegisteredTime()+ " <br> ");
out.println( "自我介绍: "+customer.getDescription()+ " <br> ");
out.println( " <img src= 'photo_copy.gif ' border=0> <p> ");
}
public void test(ServletContext context,OutputStream out) throws Exception{
Customers customer=new Customers();
customer.setName( "Tom ");
customer.setEmail( "tom@yahoo.com ");
customer.setPassword( "1234 ");
customer.setPhone(55556666);
customer.setAddress( "Shanghai ");
customer.setSex( 'M ');
customer.setDescription( "I am very honest. ");
InputStream in=this.getClass().getResourceAsStream( "photo_copy.gif ");
byte[] buffer = new byte[in.available()];
in.read(buffer);
customer.setImage(buffer);
customer.setBirthday(Date.valueOf( "1980-05-06 "));
saveCustomer(customer);
findAllCustomers(context,out);
loadAndUpdateCustomer(customer.getId(), "Beijing ");
findAllCustomers(context,out);
deleteAllCustomers();
}
public static void main(String args[]) throws Exception {
new BusinessService().test(null,System.out);
sessionFactory.close();
}
}
工具包是 hibernate3.0的 数据库ORACLE
[解决办法]
可能是那个对象是空的
[解决办法]
saveCustomer()中应有个对象是null；
可以简单的加入些打印语句看哪个对象是空的，如：
public void saveCustomer(Customers customer) throws Exception{
// Ask for a session using the JDBC information we 've configured
System.out.println( "sessionFactory: "+sessionFactory);
Session session = sessionFactory.openSession();
Transaction tx = null;
try {
tx = session.beginTransaction();
session.save(customer);
// We 're done; make our changes permanent
tx.commit();
}catch (Exception e) {
if (tx != null) {
// Something went wrong; discard all partial changes
tx.rollback();
}
throw e;
} finally {
// No matter what, close the session
session.close();
}
}
