readLargeData.java

/*
 * Microsoft JDBC Driver for SQL Server
 * 
 * Copyright(c) Microsoft Corporation All rights reserved.
 * 
 * This program is made available under the terms of the MIT License. See the LICENSE file in the project root for more information.
 */

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import com.microsoft.sqlserver.jdbc.SQLServerStatement;

public class readLargeData {

    public static void main(String[] args) {

        // Declare the JDBC objects.
        Connection con = null;
        Statement stmt = null;
        ResultSet rs = null;

        String serverName = null;
        String portNumber = null;
        String databaseName = null;
        String username = null;
        String password = null;

        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {

            System.out.print("Enter server name: ");
            serverName = br.readLine();
            System.out.print("Enter port number: ");
            portNumber = br.readLine();
            System.out.print("Enter database name: ");
            databaseName = br.readLine();
            System.out.print("Enter username: ");
            username = br.readLine();
            System.out.print("Enter password: ");
            password = br.readLine();

            // Create a variable for the connection string.
            String connectionUrl = "jdbc:sqlserver://" + serverName + ":" + portNumber + ";" + "databaseName=" + databaseName + ";username="
                    + username + ";password=" + password + ";";

            // Establish the connection.
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
            con = DriverManager.getConnection(connectionUrl);

            createTable(con);

            // Create test data as an example.
            StringBuffer buffer = new StringBuffer(4000);
            for (int i = 0; i < 4000; i++)
                buffer.append((char) ('A'));

            PreparedStatement pstmt = con.prepareStatement("UPDATE Document_JDBC_Sample " + "SET DocumentSummary = ? WHERE (DocumentID = 1)");

            pstmt.setString(1, buffer.toString());
            pstmt.executeUpdate();
            pstmt.close();

            // In adaptive mode, the application does not have to use a server cursor
            // to avoid OutOfMemoryError when the SELECT statement produces very large
            // results.

            // Create and execute an SQL statement that returns some data.
            String SQL = "SELECT Title, DocumentSummary " + "FROM Document_JDBC_Sample";
            stmt = con.createStatement();

            // Display the response buffering mode.
            SQLServerStatement SQLstmt = (SQLServerStatement) stmt;
            System.out.println("Response buffering mode is: " + SQLstmt.getResponseBuffering());

            // Get the updated data from the database and display it.
            rs = stmt.executeQuery(SQL);

            while (rs.next()) {
                Reader reader = rs.getCharacterStream(2);
                if (reader != null) {
                    char output[] = new char[40];
                    while (reader.read(output) != -1) {
                        // Print the chunk of the data that was read.
                        String stringOutput = new String(output);
                        System.out.println("Document_Summary Data Chunk: " + stringOutput);
                    }

                    System.out.println(rs.getString(1) + " has been accessed for the summary column.");
                    // Close the stream.
                    reader.close();
                }
            }
        }
        // Handle any errors that may have occurred.
        catch (Exception e) {
            e.printStackTrace();
        }
        finally {
            if (rs != null)
                try {
                    rs.close();
                }
                catch (Exception e) {
                }
            if (stmt != null)
                try {
                    stmt.close();
                }
                catch (Exception e) {
                }
            if (con != null)
                try {
                    con.close();
                }
                catch (Exception e) {
                }
        }
    }

    private static void createTable(Connection con) throws SQLException {
        Statement stmt = con.createStatement();

        stmt.execute("if exists (select * from sys.objects where name = 'Document_JDBC_Sample')" + "drop table Document_JDBC_Sample");

        String sql = "CREATE TABLE Document_JDBC_Sample (" + "[DocumentID] [int] NOT NULL identity," + "[Title] [char](50) NOT NULL,"
                + "[DocumentSummary] [varchar](max) NULL)";

        stmt.execute(sql);

        sql = "INSERT Document_JDBC_Sample VALUES ('title1','summary1') ";
        stmt.execute(sql);

        sql = "INSERT Document_JDBC_Sample VALUES ('title2','summary2') ";
        stmt.execute(sql);

        sql = "INSERT Document_JDBC_Sample VALUES ('title3','summary3') ";
        stmt.execute(sql);
    }
}