关于clob字段的一些讨论

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Oracle Hibernate Weblogic SQL JBoss

在网上闲逛找到了解决方案：
 现在3.x中对blob和clob增加了org.hibernate.lob.SerializableBlob和org.hibernate.lob.SerializableClob类的封装。

其次如果你将前面的测试程序放到weblogic的容器中通过weblogic的数据源得到连接的话，你会发现oracle.sql.BLOB blob = (oracle.sql.BLOB)person.getImage();和 oracle.sql.CLOB clob = (oracle.sql.CLOB)person.getArticle();这俩行会出错，原因就是weblogic进行了包装。

现在将以上两个问题的综合解决方案用以下代码说明：

 for (int i = 0; i < 10; i++) {
 LargeObject large = new LargeObject();
 large.setId(i + "");
 large.setName("林意炜");

 // 插入一个小数据数据
 large.setImage(Hibernate.createBlob(new byte[1]));
 large.setArticle(Hibernate.createClob(" "));

 session.save(large);
 session.flush();

 // 锁定该记录
 session.refresh(large, LockMode.UPGRADE);

 // 插入图片数据
 String fileName = "E:/AAA/" + i + ".jpg";
 SerializableBlob sb = (SerializableBlob)large.getImage();
 java.sql.Blob wrapBlob = sb.getWrappedBlob();
 // 通过非weblogic容器中数据源获得连接的情况
 if(wrapBlob instanceof oracle.sql.BLOB){
 oracle.sql.BLOB blob = (oracle.sql.BLOB) wrapBlob;
 OutputStream out = blob.getBinaryOutputStream();
 out.write(getData(fileName));
 out.close();
 }
 // 使用weblogic的Oracle Thin driver类型连接池，驱动类名：oracle.jdbc.OracleDriver
 else if(wrapBlob instanceof weblogic.jdbc.vendor.oracle.OracleThinBlob){
 OracleThinBlob blob = (OracleThinBlob)wrapBlob;
 OutputStream out = blob.getBinaryOutputStream();
 out.write(getData(fileName));
 out.close();
 }

 // 插入文章数据
 fileName = "E:/AAA/" + i + ".java";
 SerializableClob cb = (SerializableClob)large.getArticle();
 java.sql.Clob wrapClob = cb.getWrappedClob();
 // 通过非weblogic容器中数据源获得连接的情况
 if(wrapClob instanceof oracle.sql.CLOB){
 oracle.sql.CLOB clob = (oracle.sql.CLOB) wrapClob;
 Writer writer = clob.getCharacterOutputStream();
 String article = new String(getData(fileName));
 writer.write(article);
 writer.close();
 }
 // 使用weblogic的Oracle Thin driver类型连接池，驱动类名：oracle.jdbc.OracleDriver
 else if(wrapClob instanceof weblogic.jdbc.vendor.oracle.OracleThinClob){
 OracleThinClob clob = (OracleThinClob)wrapClob;
 Writer writer = clob.getCharacterOutputStream();
 String article = new String(getData(fileName));
 writer.write(article);
 writer.close();
 }
 }

***************************************************
采用得是ORACLE9i数据库，Jboss或Weblogic。
JDBC采用ORACLE9i自带的Class12.jar
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数据库结构：

java代码:

CREATE TABLE SNCPARAMETERS
(
ID NUMBER(19) NOT NULL,
SNCID NUMBER(19),
NAME VARCHAR2(255),
VALUE CLOB
)

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BO采用xdoclet建立的：

java代码:

publicclass SNCParameters extends BaseObject
{

/**
* Returns the id.
*
* @return long
* @hibernate.id
* column = "id"
* type = "long"
* generator-class = "native"
* unsaved-value = "null"
*/
publicLong getId()
{
return id;
}

/**
* Sets the Id attribute of the SNCParameters object
*
* @param id The new Id value
*/
publicvoid setId(Long id)
{
this.id = id;
}

/**
* Returns the name.
*
* @return String
*
* @hibernate.property
* column = "name"
* type = "string"
* not-null = "true"
* unique = "false"
*/

publicString getName()
{
return name;
}

/**
* Sets the Name attribute of the SNCParameters object
*
* @param name The new Name value
*/
publicvoid setName(String name)
{
this.name = name;
}

/**
* Returns the sncId.
*
* @return Long
*
* @hibernate.property
* column = "sncId"
* type = "long"
* not-null = "true"
* unique = "false"
*/

publicLong getSncId()
{
return sncId;
}

/**
* Sets the SncId attribute of the SNCParameters object
*
* @param sncId The new SncId value
*/
publicvoid setSncId(Long sncId)
{
this.sncId = sncId;
}

/**
* Returns the values.
*
* @return Clob
*
* @hibernate.property
* column = "value"
* type = "clob"
* not-null = "true"
* unique = "false"
*/

publicClob getValue()
{
return value;
}

/**
* Sets the Values attribute of the SNCParameters object
*
* @param values The new Values value
*/
publicvoid setValue(Clob value)
{
this.value = value;
}
privateLong id;
privateLong sncId;
privateString name;
privateClob value;
privateString valueString;
publicString getValueString()
{
return valueString;
}
publicvoid setValueString(String valueString)
{
this.valueString = valueString;
}
}

注：valueString并不映射到数据库的CLOB字段，只是方便需要使用这个BO的人用GET、SET 处理这个巨长的CLOB字段
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xdocLet生成的XML文件：

java代码:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
<class
name="com.idncn.mc.bo.SNCParameters"
table="SNCParameters"
dynamic-update="false"
dynamic-insert="false"
>

<id
name="id"
column="id"
type="long"
unsaved-value="null"
>
<generator class="native">
</generator>
</id>

<property
name="name"
type="string"
update="true"
insert="true"
column="name"
not-null="true"
unique="false"
/>

<property
name="sncId"
type="long"
update="true"
insert="true"
column="sncId"
not-null="true"
unique="false"
/>

<property
name="value"
type="clob"
update="true"
insert="true"
column="value"
not-null="true"
unique="false"
/>
</class>

</hibernate-mapping>

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insert的代码：

java代码:

publicList batchAddSncParameters(List sncParametersList, Long sncId)throws DbAccessException
{
logger.enterMethod();
List ret = newArrayList();
try
{
sess = getSession();
if(sncParametersList != null && sncParametersList.size() > 0)
{
for(int i = 0; i < sncParametersList.size(); i++)
{
SNCParameters cp = (SNCParameters) sncParametersList.get(i);
long newId = -1;
if(cp != null)
{
SNCParameters cpNew = new SNCParameters();
cpNew.setSncId(sncId);
cpNew.setName(cp.getName());
cpNew.setValue(Hibernate.createClob(" "));
newId = ((Long) sess.save(cpNew)).longValue();
sess.flush();

sess.refresh(cpNew, LockMode.UPGRADE);
String content = cp.getValueString();

String appserver = System.getProperty("appserver", "jboss");
if(!appserver.equalsIgnoreCase("jboss"))
{
//weblogic
OracleThinClob clob = (OracleThinClob) cpNew.getValue();
java.io.Writer pw = clob.getCharacterOutputStream();
pw.write(content);
pw.flush();
pw.close();
}
else
{
//jboss
oracle.sql.CLOB clob = (oracle.sql.CLOB) cpNew.getValue();
java.io.Writer pw = clob.getCharacterOutputStream();
pw.write(content);
pw.flush();
pw.close();
}
ret.add(newLong(newId));
}
}
}
}
catch(Exception e)
{
logger.error(e);
ErrorReason errorReason = new ErrorReason(ErrorReason.INSERT_OBJECT_FAILED_REASON);
throw new DbAccessException(DbAccessException.DBA_OPERATE_EXCEPTION, errorReason);
}
finally
{
closeSession(sess);
logger.exitMethod();
}
return ret;
}

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注：Weblogic必须使用weblogic.jdbc.vendor.oracle.OracleThinClob
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读取CLOB字段：

java代码:

publicList selectSncParametersBySncId(long sncId)throws DbAccessException
{
logger.enterMethod();
List ret = newArrayList();
try
{
sess = getSession();
String query = "select cp from cp in class com.idncn.mc.bo.SNCParameters where cp.sncId = ?";
logger.debug("SQL=" + query);
List iter = sess.find(query, newLong(sncId), Hibernate.LONG);
for(int i = 0; i < iter.size(); i++)
{
SNCParameters newCp = new SNCParameters();
SNCParameters cp = (SNCParameters)(iter.get(i));
logger.debug("after fetch:" + cp);
newCp.setId(cp.getId());
newCp.setSncId(cp.getSncId());
newCp.setName(cp.getName());
java.sql.Clob clob = cp.getValue();
if(clob != null)
{
logger.debug("b===" + clob.length());
String b = clob.getSubString(1, (int) clob.length());
//logger.debug("b==="+b);
newCp.setValueString(b);
}
ret.add(newCp);
}
}
catch(Exception e)
{
logger.error(e);
ErrorReason errorReason = new ErrorReason(ErrorReason.SELECT_FAILED_REASON);
throw new DbAccessException(DbAccessException.DBA_OPERATE_EXCEPTION, errorReason);
}
finally
{
closeSession(sess);
logger.exitMethod();
}
return ret;
}

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更新这个字段的代码：

java代码:

publicvoid updateSncParameters(SNCParameters newParam)throws DbAccessException
{
logger.enterMethod();
try
{
sess = getSession();

Long id = newParam.getId();
SNCParameters pp = (SNCParameters) sess.load(SNCParameters.class, id, net.sf.hibernate.LockMode.UPGRADE);

pp.setSncId(newParam.getSncId());
pp.setName(newParam.getName());
pp.setId(newParam.getId());

String newValue = newParam.getValueString();
logger.debug("Update Length =" + newValue.length());

String appserver = System.getProperty("appserver", "jboss");
logger.debug("appserver: " + appserver);
if(!appserver.equalsIgnoreCase("jboss"))
{
//weblogic
OracleThinClob clob = (OracleThinClob) pp.getValue();
if(pp != null)
{
java.io.Writer pw = clob.getCharacterOutputStream();
pw.write(newValue);
pw.flush();
pw.close();
}
}
else
{
//jboss
oracle.sql.CLOB clob = (oracle.sql.CLOB) pp.getValue();
if(pp != null)
{
java.io.Writer pw = clob.getCharacterOutputStream();
pw.write(newValue);
pw.flush();
pw.close();
}
}
}
catch(Exception e)
{
logger.error(e);
ErrorReason errorReason = new ErrorReason(ErrorReason.UPDATE_OBJECT_FAILED_REASON);
throw new DbAccessException(DbAccessException.DBA_OPERATE_EXCEPTION, errorReason);
}
finally
{
closeSession(sess);
logger.exitMethod();
}
}

船长 2006-07-11 11:07 发表评论

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