In this post let’s take a requirement that we read a pdf file from java code and store it into database and then from another java class we read that blob data from database and store it as a pdf file.
A little introduction about how java handles io streams: In Java it has two variety of streams to handle io, one for binary data(image, pdf, video, audio) and another for text data. When we are handling with binary data then we should use binary stream classes to handle them (the class names which ends with Stream are used to handle binary data).
Classes to use when working with binary data: InputStream, OutputStream, BufferedInputStream, BufferedOutputStream, FileInputStream, FileOutputStream.
Classes to use when working with text data & inputs from keyboard: InputStreamReader, OutputStreamWriter, BufferedReader, BufferedWriter, FileReader, FileWriter.
1. Create table with blob column:
create table emps(empId int primary key,empFile blob);
2. Insert data into table (blob column) [Here inserting is done using java code by reading data from a file]
package upload;
import java.io.File;
import java.io.FileInputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
public class Pdf_insert{
static String url = "jdbc:oracle:thin:@localhost:1521:XE";
static String username = "HR";
static String password = "hr";
public static void main(String[] args) throws Exception{
Class.forName("oracle.jdbc.driver.OracleDriver");
Connection conn = DriverManager.getConnection(url, username, password);
String sql = "insert into emps (empid,empfile) values (?,?)";
//String sql = "update emps set empfile = ? where empid = 100";
File blob = new File("D:\\small.pdf");
FileInputStream in = new FileInputStream(blob);
//InputStream in = new ByteArrayInputStream(blob.getBytes()); // if blob is a string not a file (eg: blob = "hexdata");
PreparedStatement stmt = conn.prepareStatement(sql);
stmt.setInt(1, 100);
stmt.setBinaryStream(2, in, (int)blob.length());
stmt.executeUpdate();
in.close();
conn.close();
}}
3. Read data from table (blob column) and generate pdf file from that data.
package upload;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class Pdf_read
{
static String url = "jdbc:oracle:thin:@punitp406381d:1521:XE";
static String username = "HR";
static String password = "hr";
static int BUFFER_SIZE = 4096;
public static void main(String[] args) throws Exception
{
Class.forName("oracle.jdbc.driver.OracleDriver");
Connection conn = DriverManager.getConnection(url, username, password);
String sql = "SELECT empfile FROM emps where empId = '100'";
PreparedStatement stmt = conn.prepareStatement(sql);
ResultSet resultSet = stmt.executeQuery();
if (resultSet.next()) {
System.out.println("if");
Blob blob = resultSet.getBlob("empfile");
InputStream inputStream = blob.getBinaryStream();
OutputStream outputStream = new FileOutputStream("D:\\ourFile.pdf");
int bytesRead = -1;
byte[] buffer = new byte[BUFFER_SIZE];
while ((bytesRead = inputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}
inputStream.close();
outputStream.close();
System.out.println("File is saved");
}
conn.close();
}
}
Let’s have a look at few more examples.
Below code used when you have a hex string and you need to generate a file from it.
package upload;
import java.io.FileOutputStream;
public class pdf_insert
{
static String hex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
public static void main(String[] args) throws Exception
{
String str = "";
for(int i=0;i<hex.length();i+=2)
{
String s = hex.substring(i, (i + 2));
int decimal = Integer.parseInt(s, 16);
str = str + (char) decimal;
}
System.out.println("str:"+str);
FileOutputStream fos = new FileOutputStream("D:\\sampleFile.pdf");
int i = 0;
while (i < str.length()) {
fos.write(str.charAt(i));
i++;
}
fos.close();
}
}
For this example reference:
https://stackoverflow.com/questions/13990941/how-to-convert-hex-string-to-java-string
Other References:
http://www.codejava.net/java-se/file-io/how-to-read-and-write-binary-files-in-java
Note: For online conversion of hex to binary, vice versa you can check below site
http://tomeko.net/online_tools/hex_to_file.php?lang=en
Hope you enjoyed the post!
Ravi Teja's TechCollect Blog 