JDBC Learning Note: Working with JDBC for large pieces of data

1. Database--Create a data table

1 Create Table   clob_test2(3integernotnullPrimary  key,4textnotnull5 );

2. Working with JDBC for large pieces of text data

(1) Writing text data to the database

1 @Test2      Public voidCreate ()throwsSQLException, IOException {3Connection conn =NULL;4PreparedStatement PS =NULL;5ResultSet rs =NULL;6         Try {7             //Establish a connection8conn =jdbcutils.getconnection ();9String sql = "INSERT into Clob_test (Big_text) VALUES (?)";TenPS =conn.preparestatement (SQL); OneFile File =NewFile ("Src/cn/itcast/jdbc/jdbcutils.java"); AReader reader =NewBufferedReader (Newfilereader (file)); -Ps.setcharacterstream (1, Reader, (int) file.length ()); -              the             inti =ps.executeupdate (); - reader.close (); -System.out.println ("i =" +i); -}finally { + Jdbcutils.free (RS, PS, conn); -         } +}

(2) Read the text data from the database

1 @Test2      Public voidRead ()throwsSQLException, IOException {3Connection conn =NULL;4Statement st =NULL;5ResultSet rs =NULL; 6         Try {7conn =jdbcutils.getconnection ();8St =conn.createstatement ();9rs = St.executequery ("Select Big_text from Clob_test");Ten              One              while(Rs.next ()) { AClob Clob = Rs.getclob (1); -Reader reader =Clob.getcharacterstream (); -                 //reader = Rs.getcharacterstream (1) the                  -                 //writes large pieces of text data read from the database to the Jdbcutils_bak.java file -File File =NewFile ("Jdbcutils_bak.java"); -Writer writer =NewBufferedWriter (NewFileWriter (file)); +                 Char[] Buff =New Char[1024]; -                  +                  for(inti = 0; (I=reader.read (buff)) > 0;) { AWriter.write (Buff, 0, i); at                 } - writer.close (); - reader.close (); -             } -}finally { - Jdbcutils.free (RS, St, conn); in         } -}

(3) Writing binary type data to the database

1 @Test2      Public voidCreate ()throwsSQLException, IOException {3Connection conn =NULL;4PreparedStatement PS =NULL;5ResultSet rs =NULL;6         Try {7conn =jdbcutils.getconnection ();8String sql = "INSERT into Blob_test (big_bit) VALUES (?)";9PS =conn.preparestatement (SQL);TenFile File =NewFile ("14.jpg");//file in root directory, size cannot exceed 64k OneInputStream in =NewBufferedinputstream (Newfileinputstream (file)); A              -Ps.setbinarystream (1, IN, (int) file.length ()); -              the             inti =ps.executeupdate (); - in.close (); -System.out.println ("i =" +i); -}finally { + Jdbcutils.free (RS, PS, conn); -         } +}

(4) Reading binary type data from a database

1 @Test2      Public voidRead ()throwsSQLException, IOException {3Connection conn =NULL;4Statement st =NULL;5ResultSet rs =NULL;6         Try {7conn =jdbcutils.getconnection ();8St =conn.createstatement ();9rs = St.executequery ("Select Big_bit from Blob_test");Ten              One              while(Rs.next ()) { AInputStream in = Rs.getbinarystream (1); -                  -File File =NewFile ("14_bak.jpg"); theOutputStream out =NewBufferedoutputstream (Newfileoutputstream (file)); -                 byte[] Buff =New byte[1024]; -                  for(inti = 0; (i = in.read (buff)) > 0;) { -Out.write (Buff, 0, i); +                 } - out.close (); + in.close (); A             } at}finally { - Jdbcutils.free (RS, St, conn); -         } -}

@Test
public void Read () throws SQLException, IOException {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
try {
conn = Jdbcutils.getconnection ();
st = Conn.createstatement ();
rs = St.executequery ("Select Big_bit from Blob_test");

while (Rs.next ()) {
InputStream in = Rs.getbinarystream (1);

File File = new file ("14_bak.jpg");
OutputStream out = new Bufferedoutputstream (new FileOutputStream (file));
byte[] buff = new byte[1024];
for (int i = 0; (i = in.read (buff)) > 0;) {
Out.write (buff, 0, i);
}
Out.close ();
In.close ();
}
} finally {
Jdbcutils.free (RS, St, conn);
}
}

JDBC Learning Note: Working with JDBC for large pieces of data