FindReplace

• Download FindReplace.zip - 7.8 KB

Introduction

In our day to day development there are times where we need some custom utlities which does some repetative task, nothing but an automation. In this article we will see a simple utility developed using Java to find and replace strings in multiple files in a single run.

The Program

Lets classify this utility development into three blocks.

• Backup creation for the files
  
  In this utility first we will create a backup of all the files under the subfolder, backup.
• Find and Replace Map Creation
  
  We need to create a map from .CSV file which contain find and replace strings
• Using the map created in before step we will find string in file replace that string in file.

Now let us get into details of each block of code

Creating a Backup

Let us assume that our files to process are in D:\FindReplace. Now this will be our source folder path.

String sourceFolderPath = "D:\\FindReplace";

Our backup location would be D:\FindReplace\backup. And I am assuming that even CSV is loacted in same folder i.e., D:\FindReplace and now our utlity will output the replaced files in D:\FindReplace\ReplacedFiles.

String sourceFolderPath = "D:\\FindReplace";
String destFolderPath = sourceFolderPath + "\\ReplacedFiles";
String findReplaceCSV = sourceFolderPath + "\\findReplace.csv";

Now let us start our backup creation. To create a backup we need to iterate over each file and copy the file into sourceFolderPath\backup folder with same filename and .bak extension. Below is the snippet for the same action

System.out.println("*****Backup Intialized******");

  if(file.isFile()) { 
     String sourceFilePath = file.getAbsolutePath(); 
     String bakFilePath = sourceFilePath.substring(0,sourceFilePath.lastIndexOf(File.separator)) +
                          "\\backup\\" + 
                          file.getName().replace(sourceFilePath.substring(sourceFilePath.lastIndexOf("."), 
                          sourceFilePath.length()), ".bak");   
     File backupFile = new File(bakFilePath);   
     createBackup(file, backupFile);      
  } 
}   
System.out.println("****Backup Completed*****");         

The above code calls the 'createBackup()' method which actually does the copy action. This method takes in two File arguments, one is source and other will be target. Below is the code snippet for the method.

public static void createBackup(File source, File target) throws IOException{
        InputStream in = new FileInputStream(source);
        OutputStream out = new FileOutputStream(target);
       
          byte[] buf = new byte[1024];
          int len;
     
          while ((len = in.read(buf)) > 0) {
              out.write(buf, 0, len);
          }
     
          in.close();
          out.close();
    }

This Completes the first module. Now let us see find and replace map creation from .CSV file

FindReplace Map

We need to create a map collection from CSV file which contain find and replace string. Here we will store find strings in CSV a key in map and corresponding replace string will be stored as value for the key. Below is the snippet for the action

Map<String, String> findReplaceMap = new HashMap<String, String>();
        
        System.out.println("****Find Replace Map Creation Started****");
        
        findReplaceMap = createReplaceMap(findReplaceCSV);
        
        System.out.println("****Find Replace Map Created!*****");        

The above snippet calls createReplaceMap() method which takes in string parameter as argument, this string will be CSV file location and this method reads in CSV and creates map and returns the map collection.

public static Map<String, String> createReplaceMap(String csvfileName){
        Map<String, String> _findReplaceMap = new HashMap<String, String>();
        BufferedReader br = null;
        try {
            String line = "";
            String cvsSplitBy = ",";
            br = new BufferedReader(new FileReader(csvfileName));
            while ((line = br.readLine()) != null) {
                
                // use comma as separator
                String[] findReplace = line.split(cvsSplitBy);

                _findReplaceMap.put(findReplace[0], findReplace[1]);

            }
            br.close();
        
        }
        catch(Exception e){
            e.printStackTrace();
        }
        return _findReplaceMap;
        
    }

System.out.println("*****Find Replace in Files Intialized******");
System.out.print("Find Replace in progress");
for(File file:listOfFiles){
    if(file.isFile()){

        System.out.print(".");

        File convFile = new File(destFolderPath + @"\" + file.getName());
        try {
            convFile.createNewFile();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        findReplace(file, convFile, findReplaceMap);
    }
}
System.out.println("");
System.out.println("****Find Replace Action Completed******");

The above code call a method findReplace() for the actual action this method takes in three arguments, first two will be file arguments, source file and converted file, the third argument will be findReplace map. Below the snippet for the method.

public static Map<String, String> createReplaceMap(String csvfileName){
    Map<String, String> _findReplaceMap = new HashMap<String, String>();
    BufferedReader br = null;
    try {
        String line = "";
        String cvsSplitBy = ",";
        br = new BufferedReader(new FileReader(csvfileName));
        while ((line = br.readLine()) != null) {

            // use comma as separator
            String[] findReplace = line.split(cvsSplitBy);

            _findReplaceMap.put(findReplace[0], findReplace[1]);

        }
        br.close();

    }
    catch(Exception e){
        e.printStackTrace();
    }

    return _findReplaceMap;
}

History

This is the first revision of the article.