How to Read Files from Your Computer Using PL/SQL in Oracle APEX

Oracle APEX is a powerful platform for building robust web applications, and integrating file reading capabilities can elevate your projects to the next level. In this comprehensive tutorial, you'll learn how to seamlessly read files from your computer and display them within an Oracle APEX application using PL/SQL.

 

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Why Integrate File Reading in Oracle APEX?

Incorporating file reading functionality into your Oracle APEX application allows you to:

• Gain direct access to local file systems for data enrichment.
• Automate file-related processes, such as logs or configuration file handling.
• Expand the scope and versatility of your application by working with external data sources.

 

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Step-by-Step Guide to File Reading in Oracle APEX

Follow these steps to implement file reading functionality into your Oracle APEX application.

 

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Step 1: Secure Login and Execute Code in SQL*Plus

Start by securely logging into SQL*Plus using the sys account. This establishes the foundation for file reading integration.

 

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CONN sys/Password@//localhost:1521/orclpdb AS SYSDBA

 

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Step 2: Execute Statements and Grant Privileges

After logging in, execute the necessary SQL statements to grant the required permissions:

 

SQL

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EXEC DBMS_JAVA.grant_permission('TEST', 'java.io.FilePermission', '<>', 'read');

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EXEC DBMS_JAVA.grant_permission('TEST', 'SYS:java.lang.RuntimePermission', 'readFileDescriptor', '');

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GRANT JAVAUSERPRIV TO TEST;

 

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Step 3: Assign Roles and Log In as User TEST

Grant all necessary roles to the TEST user and log in with their account to ensure privileges are correctly applied.

 

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CONN test/Password@//localhost:1521/orclpdb

 

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Step 4: Implement the Java and PL/SQL Code

Copy and paste the following code to enable file reading functionality within Oracle APEX.

Java Code

This Java class lists all files in the specified directory:

 

Java

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CREATE OR REPLACE AND COMPILE JAVA SOURCE NAMED "FileListHandler" AS

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import java.lang.*;

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import java.util.*;

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import java.io.*;

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public class FileListHandler {

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    public static String list(String path) {

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        String list = "";

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        File myFile = new File(path);

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        String[] arrayList = myFile.list();

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        Arrays.sort(arrayList, String.CASE_INSENSITIVE_ORDER);

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        for (int i = 0; i < arrayList.length; i++) {

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            if ((list.length() + arrayList[i].length() + 1) > 32767) break;

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            if (!list.equals("")) list += "," + arrayList[i];

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            else list += arrayList[i];

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        }

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        return list;

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    }

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};

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/

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SHOW ERRORS JAVA SOURCE "FileListHandler";

PL/SQL Code

Link the Java functionality to Oracle using PL/SQL:

 

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CREATE OR REPLACE PACKAGE file_list_api AS

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    FUNCTION list(p_path IN VARCHAR2) RETURN VARCHAR2

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    AS LANGUAGE JAVA

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    NAME 'FileListHandler.list (java.lang.String) return java.lang.String';

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END file_list_api;

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/

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SHOW ERRORS;

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CREATE OR REPLACE TYPE t_varchar2_arr AS TABLE OF VARCHAR2(500);

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/

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CREATE OR REPLACE FUNCTION get_files(p_dir IN VARCHAR2)

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RETURN t_varchar2_arr PIPELINED AS

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    l_array APEX_APPLICATION_GLOBAL.vc_arr2;

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BEGIN

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    l_array := APEX_STRING.string_to_table(FILE_LIST_API.list(p_dir), ',');

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    FOR i IN 1 .. l_array.count LOOP

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        PIPE ROW(l_array(i));

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    END LOOP;

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    RETURN;

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END;

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/

 

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Step 5: Test the Implementation

Run the following commands in PL/SQL or SQL to validate the file reading functionality:

PL/SQL Example

 

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DECLARE

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    l_array APEX_APPLICATION_GLOBAL.vc_arr2;

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BEGIN

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    l_array := APEX_STRING.string_to_table(FILE_LIST_API.list('/path/to/directory'), ',');

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    FOR i IN 1 .. l_array.count LOOP

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        DBMS_OUTPUT.put_line('Array(' || i || '): ' || l_array(i));

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    END LOOP;

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END;

SQL Example

 

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SELECT column_value AS file_name

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FROM TABLE(get_files('/path/to/directory'));

 

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Step 6: Optional - Create a View for Fixed Paths

If needed, define a view to access files from a fixed directory:

 

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CREATE OR REPLACE VIEW trace_files_v AS

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SELECT column_value AS file_name

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FROM TABLE(get_files('/u01/app/oracle/diag/rdbms/cdb1/cdb1/trace'));

 

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Step 7: Wrapping Up

Congratulations! You have successfully implemented file reading capabilities in Oracle APEX. You can now display and interact with files from your computer within your application, adding a valuable layer of functionality.

 

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Key Takeaways

• Versatility: File reading expands the capabilities of Oracle APEX applications.
• Simplicity: The provided code requires minimal modifications to fit your environment.
• Scalability: Use this setup as a foundation for advanced file handling processes.

Start experimenting with this feature and explore how it can enhance your Oracle APEX projects!

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