Oracle char type issue in Hibernate HQL query

问题

I have Oracle table, which contains char type columns. In my Entity class i mapped oracle char type to java string type.

Here is the code for my Entity class.

@Entity
@Table(name="ORG")
public class Organization  {

private String serviceName;
private String orgAcct;

     //Some other properties goes here...

@Column(name="ORG_ACCT", nullable=false, length=16)
public String getOrgAcct() {
    return this.orgAcct;
}

public void setOrgAcct(String orgAcct) {
    this.orgAcct = orgAcct;
}


@Column(name="SERVICE_NAME",nullable=true, length=16)
public String getServiceName() {
    return this.serviceName;
}

public void setServiceName(String serviceName) {
    this.serviceName = serviceName;
}

}

Here both serviceName and orgAcct are char type variables in Oracle

In my DAO class I wrote a HQL query to fetch Oranization entity object using serviceName and orgAcct properties.

@Repository
@Scope("singleton") //By default scope is singleton
public class OrganizationDAOImpl implementsOrganizationDAO {

public OrganizationDAOImpl(){
}

public Organization findOrganizationByOrgAcctAndServiceName(String orgAcct,String serviceName){
    String hqlQuery = "SELECT org FROM  Organization org WHERE org.serviceName = :serName AND org.orgAcct = :orgAct";
    Query query = getCurrentSession().createQuery(hqlQuery)
        .setString("serName", serviceName)
        .setString("orgAct", orgAcct);

    Organization org =  findObject(query);
    return org;
}
 }

But when I call findOrganizationByOrgAcctAndServiceName() method , I am getting Organization object as null(i.e. HQL query is not retrieving Char type data ).

Please help me to fix this issue. Here I can't change Oracle type char to Varchar2. I need to work with oracle char type variables.

@EngineerDollery After going throw above post, I modified my Entity class with columnDefinition , @Column annotation attribute.

@Column(name="SERVICE_NAME",nullable=true,length=16,columnDefinition="CHAR")
    public String getServiceName() {
        return this.serviceName;
    }

But still I am not able to retrieve the data for corresponding columns.

and I added column size as well in columnDefinition attribute.

@Column(name="SERVICE_NAME",nullable=true,length=16,columnDefinition="CHAR(16)

But still same issue I am facing. Any thing Am I doing wrong. Please help me.

回答1:

I resolved this problem using OraclePreparedStatement and Hibernate UserType interface.

Crated a new UserType class by extending org.hibernate.usertype.UserType interface and provided implementation for nullSafeSet(), nullSafeGet() methods .

nullSafeSet() method, we have first parameter as PreparedStatement, inside the method I casted PreparedStatement into OraclePreparedStatement object and pass String value using setFixedCHAR() method.

Here is the complete code of UserType impl class.

package nc3.jws.persistence.userType;

import java.io.Serializable;
import java.sql.PreparedStatement; 
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;

import org.apache.commons.lang.StringUtils;
import org.hibernate.type.StringType;
import org.hibernate.usertype.UserType;

/**
* 
* based on www.hibernate.org/388.html
*/

 public class OracleFixedLengthCharType implements UserType {

public OracleFixedLengthCharType() {
    System.out.println("OracleFixedLengthCharType constructor");
}

public int[] sqlTypes() {
    return new int[] { Types.CHAR };
}



public Class<String> returnedClass() {
    return String.class;
}

public boolean equals(Object x, Object y) {
    return (x == y) || (x != null && y != null && (x.equals(y)));
}

@SuppressWarnings("deprecation")
public Object nullSafeGet(ResultSet inResultSet, String[] names, Object o) throws SQLException {
    //String val = (String) Hibernate.STRING.nullSafeGet(inResultSet, names[0]);
    String val = StringType.INSTANCE.nullSafeGet(inResultSet, names[0]);
    //System.out.println("From nullSafeGet method valu is "+val);
    return val == null ? null : StringUtils.trim(val);
}


public void nullSafeSet(PreparedStatement inPreparedStatement, Object o,
        int i)
                throws SQLException {

    String val = (String) o;
    //Get the delegatingStmt object from DBCP connection pool PreparedStatement object.
    org.apache.commons.dbcp.DelegatingStatement delgatingStmt = (org.apache.commons.dbcp.DelegatingStatement)inPreparedStatement;
    //Get OraclePreparedStatement object using deletatingStatement object.

    oracle.jdbc.driver.OraclePreparedStatement oraclePreparedStmpt = (oracle.jdbc.driver.OraclePreparedStatement)delgatingStmt.getInnermostDelegate();
    //Call setFixedCHAR method, by passing string type value .
    oraclePreparedStmpt.setFixedCHAR(i, val);
}


public Object deepCopy(Object o) {
    if (o == null) {
        return null;
    }
    return new String(((String) o));
}


public boolean isMutable() {
    return false;
}

public Object assemble(Serializable cached, Object owner) {
    return cached;
}


public Serializable disassemble(Object value) {
    return (Serializable) value;
}

public Object replace(Object original, Object target, Object owner) {
    return original;
}

public int hashCode(Object obj) {
    return obj.hashCode();
}

  }

Configured this class with @TypeDefs annotation in Entity class.

@TypeDefs({
@TypeDef(name = "fixedLengthChar", typeClass = nc3.jws.persistence.userType.OracleFixedLengthCharType.class)

})

Added this type to CHAR type columns

@Type(type="fixedLengthChar")
@Column(name="SERVICE_NAME",nullable=true,length=16)
public String getServiceName() {
    return this.serviceName;
}

回答2:

char types are padded with spaces in the table. This means that if you have

foo

in one of these columns, what you actually have is

foo<space><space><space>...

until the actual length of the string is 16.

Consequently, if you're looking for an organization having "foo" as its service name, you won't find any, because the actual value in the table if foo padded with 13 spaces.

You'll thus have to make sure all your query parameters are also padded with spaces.

来源：https://stackoverflow.com/questions/23699867/oracle-char-type-issue-in-hibernate-hql-query