core/src/main/java/flex/messaging/io/PagedRowSet.java - flex-blazeds - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License.  You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 package flex.messaging.io;

 import flex.messaging.util.UUIDUtils;

 import javax.sql.RowSet;
 import java.sql.Blob;
 import java.sql.Clob;
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;

 /**
  * A wrapper for a RowSet to make it pageable. This technique is recommended
  * if the RowSet is 'too big' to download all at once, AND the developer's
  * client-side code is capable of dealing with non-fully-populated recordsets,
  * that is, ActionScript RecordSets which are missing some of their data.
  *
  * @version 1.0
  */
 public class PagedRowSet implements PageableRowSet {
     private RowSet rowSet;
     private String[] colNames;
     private int pageSize = 50; //Default to 50 records a page
     private int colCount = 0;
     private int rowCount = 0;

     private String id = null;
     private String serviceName = null;

     /**
      * Pageable Rowset Service Name.
      */
     public static final String DEFAULT_PAGING_SERVICE_NAME = "PageableRowSetCache";


     /**
      * Constructor
      * <p>
      * Creates a UUID for this object. Format: `XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX'
      * </p>
      *
      * @param r The RowSet to be paged.
      * @param p The initial page size.
      */
     public PagedRowSet(RowSet r, int p) {
         serviceName = DEFAULT_PAGING_SERVICE_NAME;
         rowSet = r;
         pageSize = p;
         id = UUIDUtils.createUUID();
         init();
     }

     /**
      * Allows the unique id generation of the RowSet to be toggled.
      *
      * @param r        the row set
      * @param p        the page size
      * @param createID should we create an id?
      * @see #PagedRowSet(RowSet, int)
      */
     public PagedRowSet(RowSet r, int p, boolean createID) {
         serviceName = DEFAULT_PAGING_SERVICE_NAME;
         rowSet = r;
         pageSize = p;
         if (createID) {
             id = UUIDUtils.createUUID();
         }
         init();
     }

     private void init() {
         if (rowSet != null) {
             //Initialize columns
             initColumns();

             //Initialize records
             initRecords();
         } else {
             colNames = new String[0];
         }
     }


     private synchronized void initColumns() {
         try {
             ResultSetMetaData rsmd = rowSet.getMetaData();
             if (rsmd != null) {
                 colCount = rsmd.getColumnCount();
             }
         } catch (SQLException ex) {
             colCount = 0;
         }
     }


     private synchronized void initRecords() {
         //Determine rs size
         if (rowSet != null) {
             try {
                 int currentIndex = rowSet.getRow();

                 //Go to the end and get that row number
                 if (rowSet.last()) {
                     rowCount = rowSet.getRow();
                 }

                 //Put the cursor back
                 if (currentIndex > 0) {
                     rowSet.absolute(currentIndex);
                 } else {
                     rowSet.beforeFirst();
                 }
             } catch (SQLException ex) {
                 //TODO: Decide whether if absolute() not be supported, try first() as a last resort??
                 try {
                     rowSet.first();
                 } catch (SQLException se) {
                     //we won't try anymore.
                 }
             }
         }
     }


     /**
      * List the column names of the result set.
      *
      * @return String[] An array of the column names as strings, as ordered
      * by the result set provider's column number assignment.
      */
     public synchronized String[] getColumnNames() {
         //  Cache the column names lookup
         if (colNames == null) {
             try {
                 //Ensure column count is initialized
                 if (colCount == 0) {
                     initColumns();
                 }

                 colNames = new String[colCount];

                 for (int i = 0; i < colCount; i++) {
                     //Note: column numbers start at 1
                     colNames[i] = rowSet.getMetaData().getColumnName(i + 1);
                 }
             } catch (SQLException ex) {
                 colNames = new String[0];
             }
         }

         // Create a copy
         String[] ret = new String[colNames.length];
         System.arraycopy(colNames, 0, ret, 0, colNames.length);
         return ret;
     }


     /**
      * Use this method to get a map of the index used to start the data page,
      * and an array of arrays of the actual data page itself.
      *
      * @param startIndex starting index
      * @param count      how many records to return
      * @return Map A map with two fields, the index of the row to start the page, and an array of
      * arrays for the actual data page.
      * @throws SQLException if unable to get data from the rowset
      */
     public synchronized Map getRecords(int startIndex, int count) throws SQLException {
         List aRecords = new ArrayList(); //Don't initialize with count as it could be Integer.MAX_VALUE

         //Ensure column count is initialized
         if (colCount == 0) {
             initColumns();
         }

         //Starting index cannot be less than 1
         if (startIndex < 1)
             startIndex = 1;

         //Populate the page, moving cursor to index
         if (rowSet.absolute(startIndex)) {
             //Loop over the result set for the count specified
             for (int i = 0; i < count; i++) {
                 boolean hasNext;

                 List row;

                 if (colCount > 0) {
                     row = new ArrayList(rowCount + 1);
                     //Loop over columns to create an array for the row
                     for (int j = 1; j <= colCount; j++) {
                         Object data = rowSet.getObject(j);
                         if (data instanceof Clob) {
                             Clob clob = (Clob) data;
                             row.add(clob.getSubString(0, (int) clob.length()));
                         } else if (data instanceof Blob) {
                             Blob blob = (Blob) data;
                             byte[] bytes = blob.getBytes(1, (int) blob.length());
                             row.add(bytes);
                         } else
                             row.add(data);
                     }
                 } else //HACK: Handle any ColdFusion Query Objects that have no column metadata!
                 {
                     row = new ArrayList();

                     try {
                         //Get as many columns as possible to build the row
                         //Stop on error or the first null column returned.
                         for (int j = 1; j <= 50; j++) {
                             Object o = rowSet.getObject(j);
                             if (o != null) {
                                 row.add(o);
                             } else {
                                 break;
                             }
                         }
                     } catch (SQLException ex) {
                         //Stop looking and just add the row.
                     }
                 }

                 aRecords.add(row.toArray());

                 hasNext = rowSet.next();

                 //Cursor beyond last row, stop!
                 if (!hasNext) {
                     break;
                 }
             }
         }

         Map result = new HashMap(2);
         result.put(PAGE, aRecords.toArray());
         result.put(CURSOR, Integer.valueOf(startIndex));

         return result;
     }

     /**
      * Get the row count.
      *
      * @return int The total number of rows in the result set.
      */
     public int getRowCount() {
         return rowCount;
     }

     /**
      * If this function returns a number &gt;= the total number of rows in the result set,
      * then the result set should be simply returned to the client in full. However,
      * if it is &lt; the total size, then this object itself is saved in Session data,
      * and tagged with a unique ID.
      *
      * @return the page size
      */
     public int getInitialDownloadCount() {
         return pageSize;
     }

     /**
      * Return the id of this row set.
      *
      * @return the id
      */
     public String getID() {
         return id;
     }

     /**
      * Get the service name.
      *
      * @return String The name of the service that will manage this paged result.
      */
     public String getServiceName() {
         return serviceName;
     }

     /**
      * Set the service name.
      *
      * @param serviceName Update the name of the service that manages the pages for this query.
      */
     public void setServicename(String serviceName) {
         this.serviceName = serviceName;
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	package flex.messaging.io;

	import flex.messaging.util.UUIDUtils;

	import javax.sql.RowSet;
	import java.sql.Blob;
	import java.sql.Clob;
	import java.sql.ResultSetMetaData;
	import java.sql.SQLException;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Map;

	/**
	* A wrapper for a RowSet to make it pageable. This technique is recommended
	* if the RowSet is 'too big' to download all at once, AND the developer's
	* client-side code is capable of dealing with non-fully-populated recordsets,
	* that is, ActionScript RecordSets which are missing some of their data.
	*
	* @version 1.0
	*/
	public class PagedRowSet implements PageableRowSet {
	private RowSet rowSet;
	private String[] colNames;
	private int pageSize = 50; //Default to 50 records a page
	private int colCount = 0;
	private int rowCount = 0;

	private String id = null;
	private String serviceName = null;

	/**
	* Pageable Rowset Service Name.
	*/
	public static final String DEFAULT_PAGING_SERVICE_NAME = "PageableRowSetCache";


	/**
	* Constructor
	* <p>
	* Creates a UUID for this object. Format: `XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX'
	* </p>
	*
	* @param r The RowSet to be paged.
	* @param p The initial page size.
	*/
	public PagedRowSet(RowSet r, int p) {
	serviceName = DEFAULT_PAGING_SERVICE_NAME;
	rowSet = r;
	pageSize = p;
	id = UUIDUtils.createUUID();
	init();
	}

	/**
	* Allows the unique id generation of the RowSet to be toggled.
	*
	* @param r the row set
	* @param p the page size
	* @param createID should we create an id?
	* @see #PagedRowSet(RowSet, int)
	*/
	public PagedRowSet(RowSet r, int p, boolean createID) {
	serviceName = DEFAULT_PAGING_SERVICE_NAME;
	rowSet = r;
	pageSize = p;
	if (createID) {
	id = UUIDUtils.createUUID();
	}
	init();
	}

	private void init() {
	if (rowSet != null) {
	//Initialize columns
	initColumns();

	//Initialize records
	initRecords();
	} else {
	colNames = new String[0];
	}
	}


	private synchronized void initColumns() {
	try {
	ResultSetMetaData rsmd = rowSet.getMetaData();
	if (rsmd != null) {
	colCount = rsmd.getColumnCount();
	}
	} catch (SQLException ex) {
	colCount = 0;
	}
	}


	private synchronized void initRecords() {
	//Determine rs size
	if (rowSet != null) {
	try {
	int currentIndex = rowSet.getRow();

	//Go to the end and get that row number
	if (rowSet.last()) {
	rowCount = rowSet.getRow();
	}

	//Put the cursor back
	if (currentIndex > 0) {
	rowSet.absolute(currentIndex);
	} else {
	rowSet.beforeFirst();
	}
	} catch (SQLException ex) {
	//TODO: Decide whether if absolute() not be supported, try first() as a last resort??
	try {
	rowSet.first();
	} catch (SQLException se) {
	//we won't try anymore.
	}
	}
	}
	}


	/**
	* List the column names of the result set.
	*
	* @return String[] An array of the column names as strings, as ordered
	* by the result set provider's column number assignment.
	*/
	public synchronized String[] getColumnNames() {
	// Cache the column names lookup
	if (colNames == null) {
	try {
	//Ensure column count is initialized
	if (colCount == 0) {
	initColumns();
	}

	colNames = new String[colCount];

	for (int i = 0; i < colCount; i++) {
	//Note: column numbers start at 1
	colNames[i] = rowSet.getMetaData().getColumnName(i + 1);
	}
	} catch (SQLException ex) {
	colNames = new String[0];
	}
	}

	// Create a copy
	String[] ret = new String[colNames.length];
	System.arraycopy(colNames, 0, ret, 0, colNames.length);
	return ret;
	}


	/**
	* Use this method to get a map of the index used to start the data page,
	* and an array of arrays of the actual data page itself.
	*
	* @param startIndex starting index
	* @param count how many records to return
	* @return Map A map with two fields, the index of the row to start the page, and an array of
	* arrays for the actual data page.
	* @throws SQLException if unable to get data from the rowset
	*/
	public synchronized Map getRecords(int startIndex, int count) throws SQLException {
	List aRecords = new ArrayList(); //Don't initialize with count as it could be Integer.MAX_VALUE

	//Ensure column count is initialized
	if (colCount == 0) {
	initColumns();
	}

	//Starting index cannot be less than 1
	if (startIndex < 1)
	startIndex = 1;

	//Populate the page, moving cursor to index
	if (rowSet.absolute(startIndex)) {
	//Loop over the result set for the count specified
	for (int i = 0; i < count; i++) {
	boolean hasNext;

	List row;

	if (colCount > 0) {
	row = new ArrayList(rowCount + 1);
	//Loop over columns to create an array for the row
	for (int j = 1; j <= colCount; j++) {
	Object data = rowSet.getObject(j);
	if (data instanceof Clob) {
	Clob clob = (Clob) data;
	row.add(clob.getSubString(0, (int) clob.length()));
	} else if (data instanceof Blob) {
	Blob blob = (Blob) data;
	byte[] bytes = blob.getBytes(1, (int) blob.length());
	row.add(bytes);
	} else
	row.add(data);
	}
	} else //HACK: Handle any ColdFusion Query Objects that have no column metadata!
	{
	row = new ArrayList();

	try {
	//Get as many columns as possible to build the row
	//Stop on error or the first null column returned.
	for (int j = 1; j <= 50; j++) {
	Object o = rowSet.getObject(j);
	if (o != null) {
	row.add(o);
	} else {
	break;
	}
	}
	} catch (SQLException ex) {
	//Stop looking and just add the row.
	}
	}

	aRecords.add(row.toArray());

	hasNext = rowSet.next();

	//Cursor beyond last row, stop!
	if (!hasNext) {
	break;
	}
	}
	}

	Map result = new HashMap(2);
	result.put(PAGE, aRecords.toArray());
	result.put(CURSOR, Integer.valueOf(startIndex));

	return result;
	}

	/**
	* Get the row count.
	*
	* @return int The total number of rows in the result set.
	*/
	public int getRowCount() {
	return rowCount;
	}

	/**
	* If this function returns a number >= the total number of rows in the result set,
	* then the result set should be simply returned to the client in full. However,
	* if it is < the total size, then this object itself is saved in Session data,
	* and tagged with a unique ID.
	*
	* @return the page size
	*/
	public int getInitialDownloadCount() {
	return pageSize;
	}

	/**
	* Return the id of this row set.
	*
	* @return the id
	*/
	public String getID() {
	return id;
	}

	/**
	* Get the service name.
	*
	* @return String The name of the service that will manage this paged result.
	*/
	public String getServiceName() {
	return serviceName;
	}

	/**
	* Set the service name.
	*
	* @param serviceName Update the name of the service that manages the pages for this query.
	*/
	public void setServicename(String serviceName) {
	this.serviceName = serviceName;
	}
	}