Hibernate exception handling

I've got a little 'complex' question.

I'm using Hibernate/JPA to make transactions with a DB.

I'm not the DBA, and a client consumes my application, a RESTful web service. My problem is that the DB is altered (not very often, but it still changes). Also, the client does not always respect input for my application (length, type, etc.). When this happens Hibernate throws an exception. The exception is difficult to translate and read from the log, because it has nested exceptions and consists of a lot of text: like I said, very difficult to understand.

I want to know if it's possible to handle exceptions on entity level, throwing maybe a customized exception.

I thank your patience and help in advance.

EDIT:

Fianlly I managed to do what I wanted, not sure if it's done the right way.

App.java

package com.mc;  

import org.hibernate.Session;  
import com.mc.stock.Stock;  
import com.mc.util.HibernateUtil;  
import javax.persistence.EntityManager;  

public class App {  

    public static void main(String[] args) {  
        Set<ConstraintViolation<Stock>> violations;
        validator = Validation.buildDefaultValidatorFactory().getValidator();
        Scanner scan = new Scanner(System.in);

        EntityManager em = null;

        System.out.println("Hibernate one to many (Annotation)");
        Session session = HibernateUtil.getSessionFactory().openSession();

        session.beginTransaction();


        Stock stock = new Stock();
        String nextLine = scan.nextLine();
        stock.setStockCode(nextLine.toString());
        nextLine = scan.nextLine();
        stock.setStockName(nextLine.toString());


        violations = validator.validate(stock);
        if (violations.size() > 0) {
            StringBuilder excepcion = new StringBuilder();
            for (ConstraintViolation<Stock> violation : violations) {
                excepcion.append(violation.getMessageTemplate());
                excepcion.append("\n");
            }
            System.out.println(excepcion.toString());
        }
        session.save(stock);
        session.getTransaction().commit();
    }  
}  

FieldMatch.java

package com.mc.constraints;  

import com.mc.constraints.impl.FieldMatchValidator;  

import javax.validation.Constraint;  
import javax.validation.Payload;  
import java.lang.annotation.Documented;  
import static java.lang.annotation.ElementType.ANNOTATION_TYPE;  
import static java.lang.annotation.ElementType.TYPE;  
import java.lang.annotation.Retention;  
import static java.lang.annotation.RetentionPolicy.RUNTIME;  
import java.lang.annotation.Target;  

@Target({TYPE, ANNOTATION_TYPE})  
@Retention(RUNTIME)  
@Constraint(validatedBy = FieldMatchValidator.class)  
@Documented  
public @interface FieldMatch {  

    String message() default "{constraints.fieldmatch}";  

    Class<?>[] groups() default {};  

    Class<? extends Payload>[] payload() default {};  

    String first();  

    String second();  

    @Target({TYPE, ANNOTATION_TYPE})  
    @Retention(RUNTIME)  
    @Documented  
    @interface List {  

        FieldMatch[] value();  
    }  
}  

FieldMatchValidator.java

package com.mc.constraints.impl;  

import javax.validation.ConstraintValidator;  
import javax.validation.ConstraintValidatorContext;  
import com.mc.constraints.FieldMatch;  
import org.apache.commons.beanutils.BeanUtils;  

public class FieldMatchValidator implements ConstraintValidator<FieldMatch, Object> {  

    private String firstFieldName;  
    private String secondFieldName;  

    @Override  
    public void initialize(final FieldMatch constraintAnnotation) {  
        firstFieldName = constraintAnnotation.first();  
        secondFieldName = constraintAnnotation.second();  
    }  

    @Override  
    public boolean isValid(final Object value, final ConstraintValidatorContext context) {  
        try {  
            final Object firstObj = BeanUtils.getProperty(value, firstFieldName);  
            final Object secondObj = BeanUtils.getProperty(value, secondFieldName);  

            return firstObj == null && secondObj == null || firstObj != null && firstObj.equals(secondObj);  
        } catch (final Exception ignore) {  
            // ignore  
        }  
        return true;  
    }  
}  

Stock.java

package com.mc.stock;  

import com.mc.constraints.FieldMatch;  
import java.io.Serializable;  
import java.util.HashSet;  
import java.util.Set;  
import javax.persistence.Basic;  
import javax.persistence.Column;  
import javax.persistence.Entity;  
import javax.persistence.GeneratedValue;  
import javax.persistence.GenerationType;  
开发者_StackOverflowimport javax.persistence.Id;  
import javax.persistence.NamedQueries;  
import javax.persistence.NamedQuery;  
import javax.persistence.OneToMany;  
import javax.persistence.SequenceGenerator;  
import javax.persistence.Table;  
import javax.xml.bind.annotation.XmlRootElement;  
import javax.xml.bind.annotation.XmlTransient;  
import org.hibernate.annotations.Cascade;  
import org.hibernate.annotations.CascadeType;  
import org.hibernate.validator.constraints.Length;  

@Entity  
@Table(name = "STOCK")  
@XmlRootElement  
@NamedQueries({  
    @NamedQuery(name = "Stock.findAll", query = "SELECT s FROM Stock s"),  
    @NamedQuery(name = "Stock.findByStockId", query = "SELECT s FROM Stock s WHERE s.stockId = :stockId"),  
    @NamedQuery(name = "Stock.findByStockCode", query = "SELECT s FROM Stock s WHERE s.stockCode = :stockCode"),  
    @NamedQuery(name = "Stock.findByStockName", query = "SELECT s FROM Stock s WHERE s.stockName = :stockName")})  
@FieldMatch.List({  
    @FieldMatch(first = "stockCode", second = "stockName", message = "Code and Stock must have same value")  
})  
public class Stock implements Serializable {  

    private static final long serialVersionUID = 1L;  
    @Id  
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq_stock_id")  
    @SequenceGenerator(name = "seq_stock_id", sequenceName = "seq_stock_id", initialValue = 1, allocationSize = 1)  
    @Basic(optional = false)  
    @Column(name = "STOCK_ID", unique = true, nullable = false)  
    private Integer stockId;  
    @Column(name = "STOCK_CODE")  
    private String stockCode;  
    @Length(min = 1, max = 20, message = "{wrong stock name length}")  
    @Column(name = "STOCK_NAME")  
    private String stockName;  

    public Stock() {  
    }  

    public Stock(Integer stockId) {  
        this.stockId = stockId;  
    }  

    public Integer getStockId() {  
        return stockId;  
    }  

    public void setStockId(Integer stockId) {  
        this.stockId = stockId;  
    }  

    public String getStockCode() {  
        return stockCode;  
    }  

    public void setStockCode(String stockCode) {  
        this.stockCode = stockCode;  
    }  

    public String getStockName() {  
        return stockName;  
    }  

    public void setStockName(String stockName) {  
        this.stockName = stockName;  
    }  

    @Override  
    public int hashCode() {  
        int hash = 0;  
        hash += (stockId != null ? stockId.hashCode() : 0);  
        return hash;  
    }  

    @Override  
    public boolean equals(Object object) {  
        // TODO: Warning - this method won't work in the case the id fields are not set  
        if (!(object instanceof Stock)) {  
            return false;  
        }  
        Stock other = (Stock) object;  
        if ((this.stockId == null && other.stockId != null) || (this.stockId != null && !this.stockId.equals(other.stockId))) {  
            return false;  
        }  
        return true;  
    }  

    @Override  
    public String toString() {  
        return "com.mc.stock.Stock[ stockId=" + stockId + " ]";  
    }  
}  

HibernateUtil.java

package com.mc.util;  

import org.hibernate.SessionFactory;  
import org.hibernate.cfg.Configuration;  

public class HibernateUtil {  

    private static final SessionFactory sessionFactory = buildSessionFactory();  

    private static SessionFactory buildSessionFactory() {  
        try {  
            // Create the SessionFactory from hibernate.cfg.xml  
            return new Configuration().configure().buildSessionFactory();  
        } catch (Throwable ex) {  
            // Make sure you log the exception, as it might be swallowed  
            System.err.println("Initial SessionFactory creation failed." + ex);  
            throw new ExceptionInInitializerError(ex);  
        }  
    }  

    public static SessionFactory getSessionFactory() {  
        return sessionFactory;  
    }  

    public static void shutdown() {  
        // Close caches and connection pools  
        getSessionFactory().close();  
    }  
}  

Oracle DB Structure

CREATE TABLE stock  
(  
    STOCK_ID  NUMBER(5)  NOT NULL ,  
    STOCK_CODE  VARCHAR2(10)  NULL ,  
    STOCK_NAME  VARCHAR2(20)  NULL   
);  

ALTER TABLE stock  
    add CONSTRAINT PK_STOCK_ID  PRIMARY KEY (STOCK_ID);  

create sequence seq_stock_id   
   start with 1   
   increment by 1   
   nomaxvalue;  

I'm inclined to do as much validation before you get the the DB level. Have a look at Hibernate Validator, http://www.hibernate.org/subprojects/validator.html which is the reference implementation of JSR-303.

Using standard annotations you can enforce constraints and get good error messages before you attempt to put the entities into your database.

I believe this will allow you to validate at the entity level as requested.

I am not sure what you mean about "entity level", but sure. Put a try/catch around the code that is invoking Hibernate. Catch Throwable and rethrow whatever you want. The trick is putting some reason that makes sense in the exception you are throwing.

Of course, one major point is that you should validate all input.

You can implement your own SQLExceptionConverter and handle it the way you want.

Use the property 'hibernate.jdbc.sql_exception_converter' to set your custom converter.

I am unable to find more documentation this, you need to dig into implementations by Hibernate to find more.

By the way, why can't you have a global filter, which catches every exception and decide which exception to re throw as it is or throw a new exception? You will be doing more or less same even if you implement your own SQLExceptionConverter.

according to my experience, you should catch the SQLException, and then u can get easily the SQL error code for specific database. Eg: your database is mysql and u got error code 1062 . So you can know that error is Duplicated entry error. You can check the mysql error code http://www.briandunning.com/error-codes/?source=MySQL