初次接触oracle的xmltype

 

最近一个项目中用到了oracle的xmltype数据类型，发现这个网站比较详细，记录一下，比较简单，例子就不上传了：

http://stanford.edu/dept/itss/docs/oracle/10g/appdev.101/b10790/xdb11jav.htm#i1030427

12 Java API for XMLType

This chapter describes how to use XMLType in Java, including fetching XMLType data through JDBC.

This chapter contains these topics:

• Introducing Java DOM API for XMLType

• Java DOM API for XMLType

• Loading a Large XML Document into the Database With JDBC

• Java DOM API for XMLType Features

• Java DOM API for XMLType Classes

Introducing Java DOM API for XMLType

Oracle XML DB supports the Java Document Object Model (DOM) Application Program Interface (API) for XMLType. This is a generic API for client and server, for both XML schema-based and non- schema-based documents. It is implemented using the Java package oracle.xdb.dom . DOM is an in-memory tree-based object representation of XML documents that enables programmatic access to their elements and attributes. The DOM object and interface are part of a W3C recommendation. DOM views the parsed document as a tree of objects.

To access XMLType data using JDBC use the class oracle.xdb.XMLType .

For XML documents that do not conform to any XML schema, you can use the Java DOM API for XMLType because it can handle any valid XML document.

See Also: Oracle XML API Reference Appendix E, " Java APIs: Quick Reference "

Java DOM API for XMLType

Java DOM API for XMLType handles all kinds of valid XML documents irrespective of how they are stored in Oracle XML DB. It presents to the application a uniform view of the XML document irrespective of whether it is XML schema-based or non- schema-based, whatever the underlying storage. Java DOM API works on client and server.

As discussed in Chapter 10, " PL/SQL API for XMLType " , the Oracle XML DB DOM APIs are compliant with W3C DOM Level 1.0 and Level 2.0 Core Recommendation.

Java DOM API for XMLType can be used to construct an XMLType instance from data encoded in different character sets. It also provides a new getBlobVal() method to retrieve the XML contents in the requested character set.

See Also: Appendix E, " Java APIs: Quick Reference "

Accessing XML Documents in Repository

Oracle XML DB resource API for Java API allows Java applications to access XML documents stored in the Oracle XML DB repository. Naming conforms to the Java binding for DOM as specified by the W3C DOM Recommendation. Oracle XML DB repository hierarchy can store both XML schema-based and non- schema-based documents.

See Also: Chapter 22, " Java Access to Repository Data Using Resource API for Java"

Accessing XML Documents Stored in Oracle Database (Java)

Oracle XML DB provides the following way (part of the Java Resource APIs) for Java applications to access XML data stored in a database:

Using JDBC to Access XMLType Data

This is a SQL-based approach for Java applications for accessing any data in Oracle Database, including XML documents in Oracle XML DB. Use the oracle.xdb.XMLType class, createXML() method.

How Java Applications Use JDBC to Access XML Documents in Oracle XML DB

JDBC users can query an XMLType table to obtain a JDBC XMLType interface that supports all methods supported by the SQL XMLType data type. The Java (JDBC) API for XMLType interface can implement the DOM document interface.

Example 12-1 XMLType Java: Using JDBC to Query an XMLType Table

The following is an example that illustrates using JDBC to query an XMLType table:

import oracle.xdb.XMLType; 
            ... 
   OraclePreparedStatement stmt = (OraclePreparedStatement)
 conn.prepareStatement("select e.poDoc from po_xml_tab e"); 
       ResultSet rset = stmt.executeQuery(); 
       OracleResultSet orset = (OracleResultSet) rset; 

while(orset.next())
        { 
       // get the XMLType 
       XMLType poxml = XMLType.createXML(orset.getOPAQUE(1)); 
       // get the XMLDocument as a string... 
Document podoc = (Document)poxml.getDOM(); 
        }

Example 12-2 XMLType Java: Selecting XMLType Data

You can select the XMLType data in JDBC in one of two ways:

• Use the getClobVal() , getStringVal() or getBlobVal(csid) in SQL and get the result as an oracle.sql.CLOB, java.lang.String or oracle.sql.BLOB in Java. The following Java code snippet shows how to do this:

  DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
  
   Connection conn = 
      DriverManager.getConnection("jdbc:oracle:oci8:@", "scott", "tiger");
  
   OraclePreparedStatement stmt = 
      (OraclePreparedStatement) conn.prepareStatement(
            "select e.poDoc.getClobVal() poDoc, "+
                    "e.poDoc.getStringVal() poString "+
            " from po_xml_tab e");
  
  ResultSet rset = stmt.executeQuery();
  OracleResultSet orset = (OracleResultSet) rset;
  
  while(orset.next())
          {
  // the first argument is a CLOB
  oracle.sql.CLOB clb = orset.getCLOB(1);
  
  
  
  // the second argument is a string..
  String poString = orset.getString(2);
  
  // now use the CLOB inside the program
          }

• Use getOPAQUE() call in the PreparedStatement to get the whole XMLType instance, and use the XMLType constructor to construct an oracle.xdb.XMLType class out of it. Then you can use the Java functions on the XMLType class to access the data.

  import oracle.xdb.XMLType;
  ...
  
   OraclePreparedStatement stmt = 
      (OraclePreparedStatement) conn.prepareStatement(
            "select e.poDoc from po_xml_tab e");
  
  ResultSet rset = stmt.executeQuery();
  OracleResultSet orset = (OracleResultSet) rset;
  
  // get the XMLType
  XMLType poxml = XMLType(orset.getOPAQUE(1));
  
  
  
  // get the XML as a string...
  String poString = poxml.getStringVal();

Example 12-3 XMLType Java: Directly Returning XMLType Data

This example shows the use of getObject to directly get the XMLType from the ResultSet . This code snippet is the easiest way to get the XMLType from the ResultSet .

import oracle.xdb.XMLType;
...
PreparedStatement stmt =  conn.prepareStatement( 
          "select e.poDoc from po_xml_tab e"); 
ResultSet rset = stmt.executeQuery(); 
while(rset.next())
{ 
// get the XMLType 
XMLType poxml = (XMLType)rset.getObject(1); 

// get the XML as a string...
String poString = poxml.getStringVal();
 }

Example 12-4 XMLType Java: Returning XMLType Data and Registering the Output Parameter as XMLType

This example illustrates how to bind an OUT variable of XMLType to a SQL statement.

public void doCall (String[] args) 
  throws Exception 
  { 
 
//  create or replace function getPurchaseOrder(reference varchar2) 
//  return XMLType 
//  as 
//    xml XMLType; 
//  begin 
//    select value(p) 
//    into xml 
//    from PURCHASEORDER p 
//    where extractValue(value(p),'/PurchaseOrder/Reference') = reference; 
//    return xml; 
//  end; 
 
    String SQLTEXT = "{? = call 
getPurchaseOrder('BLAKE-2002100912333601PDT')}"; 
    CallableStatement sqlStatement = null; 
    XMLType xml = null; 
    
    super.doSomething(args); 
    createConnection(); 
    try 
    { 
      System.out.println("SQL := " + SQLTEXT); 
      sqlStatement = getConnection().prepareCall(SQLTEXT); 
      sqlStatement.registerOutParameter (1, OracleTypes.OPAQUE,"SYS.XMLTYPE"); 
      sqlStatement.execute(); 
      xml = (XMLType) sqlStatement.getObject(1); 
      System.out.println(xml.getStringVal()); 
    } 
    catch (SQLException SQLe) 
    { 
      if (sqlStatement != null) 
      { 
        sqlStatement.close(); 
        throw SQLe; 
      } 
    }

Using JDBC to Manipulate XML Documents Stored in a Database

You can also update, insert, and delete XMLType data using JDBC.

Note: extract() , transform() , and existsNode() methods only work with the Thick JDBC driver. Not all oracle.xdb.XMLType functions are supported by the Thin JDBC driver. However, if you do not use oracle.xdb.XMLType classes and OCI driver, you could loose performance benefits associated with the intelligent handling of XML.

Example 12-5 XMLType Java: Updating, Inserting, or Deleting XMLType Data

You can insert an XMLType in Java in one of two ways:

• Bind a CLOB or a string to an INSERT or UPDATE or DELETE statement, and use the XMLType constructor inside SQL to construct the XML instance:

  OraclePreparedStatement stmt = 
      (OraclePreparedStatement) conn.prepareStatement(
          "update po_xml_tab set poDoc = XMLType(?) ");
  
  // the second argument is a string..
  String poString = "<PO><PONO>200</PONO><PNAME>PO_2</PNAME></PO>";
  
  // now bind the string..
  stmt.setString(1,poString);
  stmt.execute();

• Use the setObject() or setOPAQUE() call in the PreparedStatement to set the whole XMLType instance:

  import oracle.xdb.XMLType;
  ...
  OraclePreparedStatement stmt = 
      (OraclePreparedStatement) conn.prepareStatement(
          "update po_xml_tab set poDoc = ? ");
  
  // the second argument is a string
  String poString = "<PO><PONO>200</PONO><PNAME>PO_2</PNAME></PO>";
  XMLType poXML = XMLType.createXML(conn, poString);
  
  // now bind the string..
  stmt.setObject(1,poXML);
  stmt.execute();

Example 12-6 XMLType Java: Getting Metadata on XMLType

When selecting out XMLType values, JDBC describes the column as an OPAQUE type. You can select the column type name out and compare it with "XMLTYPE " to check if you are dealing with an XMLType :

import oracle.sql.*;
import oracle.jdbc.*;
...
OraclePreparedStatement stmt = 
    (OraclePreparedStatement) conn.prepareStatement(
        "select poDoc from po_xml_tab");

OracleResultSet rset = (OracleResultSet)stmt.exuecuteQuery();

// Now, we can get the resultset metadata
OracleResultSetMetaData mdata = 
        (OracleResultSetMetaData)rset.getMetaData();

// Describe the column = the column type comes out as OPAQUE
// and column type name comes out as XMLTYPE
if (mdata.getColumnType(1) == OracleTypes.OPAQUE && 
    mdata.getColumnTypeName(1).compareTo("SYS.XMLTYPE") == 0)
{
   // we know it is an XMLtype
}

Example 12-7 XMLType Java: Updating an Element in an XMLType Column

This example updates the discount element inside PurchaseOrder stored in an XMLType column. It uses Java (JDBC) and the oracle.xdb.XMLType class. This example also shows you how to insert, update, or delete XMLType s using Java (JDBC). It uses the parser to update an in-memory DOM tree and write the updated XML value to the column.

-- create po_xml_hist table to store old PurchaseOrders
create table po_xml_hist (
 xpo XMLType
);

/*
   DESCRIPTION
    Example for oracle.xdb.XMLType

   NOTES
   Have classes12.zip, xmlparserv2.jar, and xdb.jar in CLASSPATH

*/

import java.sql.*;
import java.io.*;

import oracle.xml.parser.v2.*;
import org.xml.sax.*;
import org.w3c.dom.*;

import oracle.jdbc.driver.*;
import oracle.sql.*;

import oracle.xdb.XMLType;

public class tkxmtpje
{

  static String conStr = "jdbc:oracle:oci8:@";
  static String user = "scott";
  static String pass = "tiger";
  static String qryStr = 
        "SELECT x.poDoc from po_xml_tab x "+
        "WHERE  x.poDoc.extract('/PO/PONO/text()').getNumberVal()=200";

 static String updateXML(String xmlTypeStr)
  {
     System.out.println("\n===============================");
     System.out.println("xmlType.getStringVal():");
     System.out.println(xmlTypeStr);
     System.out.println("===============================");
     String outXML = null;
     try{
        DOMParser parser  = new DOMParser();
        parser.setValidationMode(false);
        parser.setPreserveWhitespace (true);    

        parser.parse(new StringReader(xmlTypeStr));
        System.out.println("xmlType.getStringVal(): xml String is well-formed");

        XMLDocument doc = parser.getDocument();

        NodeList nl = doc.getElementsByTagName("DISCOUNT");

        for(int i=0;i<nl.getLength();i++){
           XMLElement discount = (XMLElement)nl.item(i);
           XMLNode textNode = (XMLNode)discount.getFirstChild();
           textNode.setNodeValue("10");
        }

       StringWriter sw = new StringWriter();
       doc.print(new PrintWriter(sw));

       outXML = sw.toString();

      //print modified xml
       System.out.println("\n===============================");
       System.out.println("Updated PurchaseOrder:");
       System.out.println(outXML);
       System.out.println("===============================");
      }
    catch ( Exception e )
    {
      e.printStackTrace(System.out);
    }
    return outXML;
  }

 public static void main(String args[]) throws Exception
  {
    try{

        System.out.println("qryStr="+ qryStr);

        DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());

        Connection conn = 
          DriverManager.getConnection("jdbc:oracle:oci8:@", user, pass);

        Statement s = conn.createStatement();
        OraclePreparedStatement stmt;

        ResultSet rset = s.executeQuery(qryStr);
        OracleResultSet orset = (OracleResultSet) rset;

        while(orset.next()){

        //retrieve PurchaseOrder xml document from database
         XMLType xt = XMLType.createXML(orset.getOPAQUE(1));
         
         //store this PurchaseOrder in po_xml_hist table
         stmt = (OraclePreparedStatement)conn.prepareStatement(
                   "insert into po_xml_hist values(?)");

         stmt.setObject(1,xt);  // bind the XMLType instance
         stmt.execute();

         //update "DISCOUNT" element
         String newXML = updateXML(xt.getStringVal());

         // create a new instance of an XMLtype from the updated value
         xt = XMLType.createXML(conn,newXML);

        // update PurchaseOrder xml document in database
         stmt = (OraclePreparedStatement)conn.prepareStatement(
           "update po_xml_tab x set x.poDoc =? where "+
             "x.poDoc.extract('/PO/PONO/text()').getNumberVal()=200");

         stmt.setObject(1,xt);  // bind the XMLType instance
         stmt.execute();

         conn.commit();
         System.out.println("PurchaseOrder 200 Updated!");

        }

       //delete PurchaseOrder 1001
        s.execute("delete from po_xml x"+
           "where x.xpo.extract"+
              "('/PurchaseOrder/PONO/text()').getNumberVal()=1001");
        System.out.println("PurchaseOrder 1001 deleted!");
    }
    catch( Exception e )
    {
      e.printStackTrace(System.out);
    }
  }
}

---------------------- 
-- list PurchaseOrders
----------------------

set long 20000
set pages 100
select x.xpo.getClobVal()
from po_xml x;

Here is the resulting updated purchase order in XML:

<?xml version = "1.0"?>
<PurchaseOrder>
  <PONO>200</PONO>
  <CUSTOMER>
   <CUSTNO>2</CUSTNO>
   <CUSTNAME>John Nike</CUSTNAME>
   <ADDRESS>
    <STREET>323 College Drive</STREET>
    <CITY>Edison</CITY>
    <STATE>NJ</STATE>
    <ZIP>08820</ZIP>
   </ADDRESS>
   <PHONELIST>
    <VARCHAR2>609-555-1212</VARCHAR2>
    <VARCHAR2>201-555-1212</VARCHAR2>
   </PHONELIST>
  </CUSTOMER>
  <ORDERDATE>20-APR-97</ORDERDATE>
  <SHIPDATE>20-MAY-97 12.00.00.000000 AM</SHIPDATE>
  <LINEITEMS>
   <LINEITEM_TYP LineItemNo="1">
    <ITEM StockNo="1004">
     <PRICE>6750</PRICE>
     <TAXRATE>2</TAXRATE>
    </ITEM>
    <QUANTITY>1</QUANTITY>
    <DISCOUNT>10</DISCOUNT>
   </LINEITEM_TYP>
   <LINEITEM_TYP LineItemNo="2">
    <ITEM StockNo="1011">
     <PRICE>4500.23</PRICE>
     <TAXRATE>2</TAXRATE>
    </ITEM>
    <QUANTITY>2</QUANTITY>
    <DISCOUNT>10</DISCOUNT>
   </LINEITEM_TYP>
  </LINEITEMS>
  <SHIPTOADDR>
   <STREET>55 Madison Ave</STREET>
   <CITY>Madison</CITY>
   <STATE>WI</STATE>
   <ZIP>53715</ZIP>
  </SHIPTOADDR>
</PurchaseOrder>

Example 12-8 Manipulating an XMLType Column

This example performs the following:

• Selects an XMLType from an XMLType table

• Extracts portions of the XMLType based on an XPath expression

• Checks for the existence of elements

• Transforms the XMLType to another XML format based on XSL

• Checks the validity of the XMLType document against an XML schema

import java.sql.*;
import java.io.*;
import java.net.*;
import java.util.*;

import oracle.xml.parser.v2.*;
import oracle.xml.parser.schema.*;
import org.xml.sax.*;
import org.w3c.dom.*;

import oracle.xml.sql.dataset.*;
import oracle.xml.sql.query.*;
import oracle.xml.sql.docgen.*;
import oracle.xml.sql.*;

import oracle.jdbc.driver.*;
import oracle.sql.*;

import oracle.xdb.XMLType;

public class tkxmtpk1
{

  static String conStr = "jdbc:oracle:oci8:@";
  static String user = "tpjc";
  static String pass = "tpjc";
  static String qryStr = "select x.resume from t1 x where id<3";
  static String xslStr =
                "<?xml version='1.0'?> " +
                "<xsl:stylesheet version='1.0' xmlns:xsl='http://www.w3.org/1
999/XSL/Transform'> " +
                "<xsl:template match='ROOT'> " +
                "<xsl:apply-templates/> " +
                "</xsl:template> " +
                "<xsl:template match='NAME'> " +
                "<html> " +
                "  <body> " +
                "      This is Test " +
                "  </body> " +
                "</html> " +
                "</xsl:template> " +
                "</xsl:stylesheet>";

  static void parseArg(String args[])
  {
    conStr = (args.length >= 1 ? args[0]:conStr);
    user = (args.length >= 2 ? args[1].substring(0, args[1].indexOf("/")):user);
    pass = (args.length >= 2 ? args[1].substring(args[1].indexOf("/")+1):pass);
    qryStr = (args.length >= 3 ? args[2]:qryStr);
  }
  /**
   * Print the byte array contents
   */
  static void showValue(byte[] bytes) throws SQLException
  {
    if (bytes == null)
      System.out.println("null");
    else if (bytes.length == 0)
      System.out.println("empty");
    else
    {
      for(int i=0; i<bytes.length; i++)
        System.out.print((bytes[i]&0xff)+" ");
      System.out.println();
    }
  }

public static void main(String args[]) throws Exception
{
 tkxmjnd1 util = new tkxmjnd1();

 try{

     if( args != null )
         parseArg(args);

     //      System.out.println("conStr=" + conStr);
     System.out.println("user/pass=" + user + "/" +pass );
     System.out.println("qryStr="+ qryStr);

     DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());

     Connection conn = DriverManager.getConnection(conStr, user, pass);
     Statement s = conn.createStatement();

     ResultSet rset = s.executeQuery(qryStr);
     OracleResultSet orset = (OracleResultSet) rset;
     OPAQUE xml;

     while(orset.next()){
      xml = orset.getOPAQUE(1);
      oracle.xdb.XMLType xt = oracle.xdb.XMLType.createXML(xml);

      System.out.println("Testing getDOM() ...");
      Document doc = xt.getDOM();
      util.printDocument(doc);

      System.out.println("Testing getBytesValue() ...");
      showValue(xt.getBytesValue());

      System.out.println("Testing existsNode() ...");
      try {
        System.out.println("existsNode(/)" + xt.existsNode("/", null));
      }
      catch (SQLException e) {
        System.out.println("Thin driver Expected exception: " + e);
      }

      System.out.println("Testing extract() ...");
      try {
        XMLType xt1 = xt.extract("/RESUME", null);
        System.out.println("extract RESUME: " + xt1.getStringVal());
        System.out.println("should be Fragment: " + xt1.isFragment());
      }
      catch (SQLException e) {
        System.out.println("Thin driver Expected exception: " + e);
      }

      System.out.println("Testing isFragment() ...");
      try {
        System.out.println("isFragment = " + xt.isFragment());       }
          catch (SQLException e) 
     {
        System.out.println("Thin driver Expected exception: " + e);
      }

     System.out.println("Testing isSchemaValid() ...");
      try {
     System.out.println("isSchemaValid(): " + xt.isSchemaValid(null,"RES UME"));
      }
      catch (SQLException e) {
        System.out.println("Thin driver Expected exception: " + e);
      }

      System.out.println("Testing transform() ...");
      System.out.println("XSLDOC: \n" + xslStr + "\n");
      try {
      /*  XMLType xslDoc = XMLType.createXML(conn, xslStr);
      System.out.println("XSLDOC Generated");
      System.out.println("After transformation:\n" + (xt.transform(xslDoc,
            null)).getStringVal()); */
      System.out.println("After transformation:\n" + (xt.transform(null, 
            null)).getStringVal());
          }
      catch (SQLException e) {
        System.out.println("Thin driver Expected exception: " + e);
      }

      System.out.println("Testing createXML(conn, doc) ...");
      try {
        XMLType xt1 = XMLType.createXML(conn, doc);
        System.out.println(xt1.getStringVal());
      }
     catch (SQLException e) {
        System.out.println("Got exception: " + e);
      }

    }
}
catch( Exception e )
{
  e.printStackTrace(System.out);
}
}
}

Loading a Large XML Document into the Database With JDBC

If a large XML document (greater than 4000 characters, typically) is inserted into an XMLType table or column using a String object in JDBC, this run-time error occurs:

"java.sql.SQLException: Data size bigger than max size for this type"

This error can be avoided by using a Java CLOB object to hold the large XML document. Example 12-9 demonstrates this technique, loading a large document into an XMLType column; the same approach can be used for XMLType tables. The CLOB object is created using class oracle.sql.CLOB on the client side. This class is the Oracle JDBC driver implementation of the standard JDBC interface java.sql.Clob .

Example 12-9 Loading a Large XML Document

In this example, method insertXML() inserts a large XML document into the purchaseOrder XMLType column of table poTable . It uses a CLOB object containing the XML document to do this. The CLOB object is bound to a JDBC prepared statement, which inserts the data into the XMLType column.

Prerequisites for running this example are as follows:

• Oracle Database, version 9.2.0.1 or later.

• Classes12.zip or Classes12.jar , available in ORACLE_HOME\jdbc\lib , should be included in the CLASSPATH environment variable.

• The target database table. Execute the following SQL before running the example:

  CREATE TABLE poTable (purchaseOrder XMLType);

Method insertXML()

The formal parameters of method insertXML() are as follows:

• xmlData – XML data to be inserted into the XMLType column

• conn – database connection object (Oracle Connection Object)

...
import oracle.sql.CLOB; 
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.PreparedStatement;
... 
 
private void insertXML

(String xmlData, Connection conn) {
  CLOB clob = null;
  String query;
    // Initialize statement Object
  PreparedStatement pstmt = null;
  try{
    query = "INSERT INTO potable (purchaseOrder) VALUES (XMLType(?)) ";
    // Get the statement Object
    pstmt = conn.prepareStatement(query);
 
    // xmlData is the string that contains the XML Data.
    // Get the CLOB object using the getCLOB method.
    clob = getCLOB(xmlData, conn);
    // Bind this CLOB with the prepared Statement
    pstmt.setObject(1, clob);
    // Execute the Prepared Statement
    if (pstmt.executeUpdate () == 1) {
    System.out.println ("Successfully inserted a Purchase Order");
    }
  } catch(SQLException sqlexp){
    sqlexp.printStackTrace();
  } catch(Exception exp){
    exp.printStackTrace();
  }
}

Method getCLOB()

Method insertXML() calls method getCLOB() to create and return the CLOB object that holds the XML data. The formal parameters of getCLOB() are as follows:

• xmlData – XML data to be inserted into the XMLType column

• conn – database connection object (Oracle Connection Object)

...
import oracle.sql.CLOB; 
import java.sql.Connection;
import java.sql.SQLException;
import java.io.Writer;
... 
 
private CLOB getCLOB

(String xmlData, Connection conn) throws SQLException{
  CLOB tempClob = null;
  try{
    // If the temporary CLOB has not yet been created, create one
    tempClob = CLOB.createTemporary(conn, true, CLOB.DURATION_SESSION); 
 
    // Open the temporary CLOB in readwrite mode, to enable writing
    tempClob.open(CLOB.MODE_READWRITE); 
    // Get the output stream to write
    Writer tempClobWriter = tempClob.getCharacterOutputStream(); 
    // Write the data into the temporary CLOB
    tempClobWriter.write(xmlData); 
 
    // Flush and close the stream
    tempClobWriter.flush();
    tempClobWriter.close(); 
 
    // Close the temporary CLOB 
    tempClob.close();    
  } catch(SQLException sqlexp){
    tempClob.freeTemporary(); 
    sqlexp.printStackTrace();
  } catch(Exception exp){
    tempClob.freeTemporary(); 
    exp.printStackTrace();
  }
  return tempClob; 
}

See Also: Oracle Database Application Developer's Guide - Large Objects

Java DOM API for XMLType Features

When using Java DOM API to retrieve XML data from Oracle XML DB, you get the following results:

• If the connection is thin, then you get an XMLDocument instance

• If the Connection is thick or kprb, then you get an XDBDocument instance

Both of these are instances of the W3C Document Object Model (DOM) interface. From this document interface you can access the document elements and perform all the operations specified in the W3C DOM Recommendation. The DOM works on:

• Any type of XML document:

  • XML schema-based

  • Non-XML schema-based

• Any type of underlying storage used by the document:

  • Character Large Object (CLOB)

  • Binary Large Object (BLOB)

  • Object-relational.

The Java DOM API for XMLType supports deep or shallow searching in the document to retrieve children and properties of XML objects such as name, namespace, and so on. Conforming to the DOM 2.0 recommendation, Java DOM API for XMLType is namespace aware.

Creating XML Documents Programmatically

Java API for XMLType also allows applications to create XML documents programmatically. This way applications can create XML documents on the fly (or dynamically) that either conform to a preregistered XML schema or are non-XML schema-based documents.

Creating XML Schema-Based Documents

To create XML schema-based documents, Java DOM API for XMLType uses an extension to specify which XML schema URL to use. For XML schema-based documents, it also verifies that the DOM being created conforms to the specified XML schema, that is, that the appropriate children are being inserted under the appropriate documents.

Note: In this release, Java DOM API for XMLType does not perform type and constraint checks.

Once the DOM object has been created, it can be saved to Oracle XML DB repository using the Oracle XML DB resource API for Java. The XML document is stored in the appropriate format:

• As a BLOB for non-XML schema-based documents.

• In the format specified by the XML schema for XML schema-based documents.

Example 12-10 Java DOM API for XMLType: Creating a DOM Object and Storing It in the Format Specified by the XML Schema

The following example shows how you can use Java DOM API for XMLType to create a DOM object and store it in the format specified by the XML schema. Note that the validation against the XML schema is not shown here.

import oracle.xdb.XMLType;
...
OraclePreparedStatement stmt = 
    (OraclePreparedStatement) conn.prepareStatement(
        "update po_xml_XMLTypetab set poDoc = ? ");

// the second argument is a string
String poString = "<PO><PONO>200</PONO><PNAME>PO_2</PNAME></PO>";
XMLType poXML = XMLType.createXML(conn, poString);
Document poDOM = (Document)poXML.getDOM();

Element rootElem = poDOM.createElement("PO");
poDOM.insertBefore(poDOM, rootElem, null);

// now bind the string..
stmt.setObject(1,poXML);
stmt.execute();

JDBC or SQLJ

An XMLType instance is represented in Java by oracle.xdb.XMLType . When an instance of XMLType is fetched using JDBC, it is automatically manifested as an object of the provided XMLType class. Similarly, objects of this class can be bound as values to Data Manipulation Language (DML) statements where an XMLType is expected. The same action is supported in SQLJ clients.

Note: The SQLJ precompiler has been desupported from Oracle Database 10g release 1 (10.1) and Oracle Application Server 10g release 1 (10.1). Oracle9i release 2 (9.2) and Oracle9i AS release 9.0.4 are the last Oracle products to offer SQLJ support. From this release, only the SQLJ precompiler that generates .java files from .sqlj files is desupported through both command-line and JDeveloper. However, both the client-side and server-side SQLJ runtimes are maintained to support JPublisher and existing precompiled SQLJ applications. No new SQLJ application development is possible using Oracle products. Customer priority one (P1) bugs will continue to be fixed. Although the term SQLJ runtime has been renamed to JPublisher runtime, the term SQLJ Object Types is still used.

Java DOM API for XMLType Classes

Oracle XML DB supports the W3C DOM Level 2 Recommendation. In addition to the W3C Recommendation, Oracle XML DB DOM API also provides Oracle-specific extensions, to facilitate your application interfacing with Oracle XDK for Java. A list of the Oracle extensions is found at:

http://otn.oracle.com/tech/xml/index.html

XDBDocument is a class that represents the DOM for the instantiated XML document. You can retrieve the XMLType from the XML document using the function getXMLType() on XDBDocument class.

Table 12-1 lists the Java DOM API for XMLType classes and the W3C DOM interfaces they implement.

Table 12-1 Java DOM API for XMLType: Classes

Java DOM API for XMLType Class W3C DOM Interface Recommendation Class

oracle.xdb.dom.XDBDocument	org.w3c.dom.Document
oracle.xdb.dom.XDBCData	org.w3c.dom.CDataSection
oracle.xdb.dom.XDBComment	org.w3c.dom.Comment
oracle.xdb.dom.XDBProcInst	org.w3c.dom.ProcessingInstruction
oracle.xdb.dom.XDBText	org.w3c.dom.Text
oracle.xdb.dom.XDBEntity	org.w3c.dom.Entity
oracle.xdb.dom.DTD	org.w3c.dom.DocumentType
oracle.xdb.dom.XDBNotation	org.w3c.dom.Notation
oracle.xdb.dom.XDBNodeList	org.w3c.dom.NodeList
oracle.xdb.dom.XDBAttribute	org.w3c.dom.Attribute
oracle.xdb.dom.XDBDOMImplementation	org.w3c.dom.DOMImplementation
oracle.xdb.dom.XDBElement	org.w3c.dom.Element
oracle.xdb.dom.XDBNamedNodeMap	org.w3c.dom.NamedNodeMap
oracle.xdb.dom.XDBNode	org.w3c.dom.Node

Java Methods Not Supported

The following are methods documented in release 2 (9.2.0.1) but not currently supported:

• XDBDocument.getElementByID

• XDBDocument.importNode

• XDBNode.normalize

• XDBNode.isSupported

• XDBDomImplementation.hasFeature

Java DOM API for XMLType: Calling Sequence

The following Java DOM API for XMLType calling sequence description assumes that your XML data is pre-registered with an XML schema and that it is stored in an XMLType datatype column. To use the Java DOM API for XMLType , follow these steps:

1. Retrieve the XML data from the XMLType table or XMLType column in the table. When you fetch XML data, Oracle creates an instance of an XMLType . You can then use the getDom() method to retrieve a Document instance. You can then manipulate elements in the DOM tree using Java DOM API for XMLType .

2. Use the Java DOM API for XMLType to perform operations and manipulations on elements of the DOM tree.

3. The XMLType holds the modified data, but the data is sent back using a JDBC update.

The XMLType and XDBDocument objects should be closed using the close() method in the respective classes. This releases any underlying memory that is held.

Figure 12-1 illustrates the Java DOM API for XMLType calling sequence.

Figure 12-1 Java DOM API for XMLType: Calling Sequence

Description of the illustration adxdb024.gif

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