Clean sysouts from java project

Recently I was working in a project that had a lot of sysouts (System.out.println) peppered all over the code. I tried the usual sed approach find . -name '*.java' | xargs sed -i '/System.out.println/d' and that din't work out too well because of multiline sysouts. So, I decided to try the AST approach using the java parser from http://code.google.com/p/javaparser/. So, create a maven project add the javaparser repository and dependency in the pom.xml as given below

And the java code that creates the AST and looks for the System.out.println method call

Custom taglibs in Websphere

I spent the better part of an hour trying to figure out why

var v = "<mylib:my-tag attr="<%= request.getParameter("some_attr") %>" />";

wasn't compiling in WAS6 and was complaining that attribute value is not given for some_attr. But, this

<% String someAttr = request.getParameter("some_attr"); %>
var v = "<mylib:my-tag attr="<%= someAttr %>" />";

works just fine. Turns out if you need JSP evaluation inside you custom taglibs attribute you need to give inside single quotes instead of double quotes. Something about the twin double quotes trips up the WAS6 JSP compiler. Now, since I had to do this in a lot of places I simply opted for the simplest solution, use single quotes :)

var v = "<mylib:my-tag attr='<%= request.getParameter("some_attr") %>' />";

Works like a charm !!

JDBC debugging

Recently I had to muck through a whole bunch of code to fix a connection pooling issue because of which some partial results were getting committed into the database. While the actual problem turned out to be a commit getting issued deep in the custom framework code while querying for the nextval in an oracle sequence. As a by product of that investigation I wrote the following proxies to see which queries where executed by which connection. Usage is pretty simple. Just add the ConnectionInvocationHandler.createProxy(<your raw connection>) where ever you are getting the actual connection. The following classes only handle the most frequently occurring cases for me (for oracle).

package org.foo.sql;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.Statement;

public class ConnectionInvocationHandler implements InvocationHandler {
  
  Connection delegate = null;
  
  public static Connection createProxy(Connection conn) {
    return (Connection) Proxy.newProxyInstance(ConnectionInvocationHandler.class.getClassLoader(), new Class[]{ Connection.class }, new ConnectionInvocationHandler(conn));
  }
  
  ConnectionInvocationHandler(Connection original) {
    delegate = original;
  }

  public Object invoke(Object proxy, Method method, Object[] args)
      throws Throwable {
    Object result = method.invoke(delegate, args);
    String methodName = method.getName();
    if ( "prepareStatement".equals(methodName) ) {
      result = PreparedStatementInvocationHandler.createProxy((PreparedStatement) result, delegate.toString(), (String) args[0]);
    } else if ( "createStatement".equals(methodName) ) {
      result = StatementInvocationHandler.createProxy((Statement) result, delegate.toString());
    } else if ( "setAutoCommit".equals(methodName) ) {
      log("setAutoCommit(" + args[0] + ")");
    } else if ( "commit".equals(methodName) ) {
      log("commit()");
    } else if ( "rollback".equals(methodName) ) {
      log("rollback()");
    }
    return result;
  }
  
  private void log(String msg) {
    System.out.println("[" + delegate.toString() + "] " + msg);
  }
  
}

package org.foo.sql;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Statement;

public class StatementInvocationHandler implements InvocationHandler {

 String connId = null;
 Statement delegate = null;
  
  static Statement createProxy(Statement stmt, String connId) {
    return (Statement) Proxy.newProxyInstance(StatementInvocationHandler.class.getClassLoader(), new Class[]{ Statement.class }, new StatementInvocationHandler(stmt, connId));
  }
  
  StatementInvocationHandler(Statement stmt, String connId) {
    delegate = stmt;
    this.connId = connId;
  }
  
  public Object invoke(Object proxy, Method method, Object[] args)
      throws Throwable {
    Object result = method.invoke(delegate, args);
    String methodName = method.getName();
    if ( "executeQuery".equals(methodName) ) {
      log((String) args[0]);
    } else if ( "executeUpdate".equals(methodName) ) {
      log((String) args[0]);
    }
    return result;
  }
  
  private void log(String msg) {
    System.out.println("[" + connId + "][" + delegate.toString() + "] " + msg);
  }
}

package org.foo.sql;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.PreparedStatement;
import java.text.DecimalFormat;

public class PreparedStatementInvocationHandler implements InvocationHandler {
  
  String connId = null;
  StringBuilder query = null;
  PreparedStatement delegate = null;
  final DecimalFormat df = new DecimalFormat("0.#");
  
  static PreparedStatement createProxy(PreparedStatement pstmt, String connId, String query) {
    return (PreparedStatement) Proxy.newProxyInstance(PreparedStatementInvocationHandler.class.getClassLoader(), new Class[]{ PreparedStatement.class }, new PreparedStatementInvocationHandler(pstmt, connId, query));
  }
  
  PreparedStatementInvocationHandler(PreparedStatement original, String connId, String query) {
    delegate = original;
    this.connId = connId;
    this.query = new StringBuilder(query);
  }

  public Object invoke(Object proxy, Method method, Object[] args)
      throws Throwable {
    Object result = method.invoke(delegate, args);
    String methodName = method.getName();
    if ( "setInt".equals(methodName) ) {
      addParam(args[1].toString());
    } else if ( "setLong".equals(methodName) ) {
      addParam(args[1].toString());
    } else if ( "setDouble".equals(methodName) ) {
      addParam(df.format(((Double) args[1]).doubleValue()));
    } else if ( "setTimestamp".equals(methodName) ) {
      String dParam = args[1].toString();
      dParam = dParam.substring(dParam.indexOf('.')); // remove the ms
      addParam("to_date('" + dParam + "', 'yyyy-mm-dd hh24:mi:ss')");
    } else if ( "setString".equals(methodName) ) {
      addParam("'" + args[1].toString() + "'");
    } else if ( methodName.startsWith("set") ) {
      addParam("'<" + methodName.substring(3) + ">'");
    } else if ( "executeUpdate".equals(methodName) ) {
      log(query.toString());
    } else if ( "executeQuery".equals(methodName) ) {
      log(query.toString());
    }
    return result;
  }
  
  protected void addParam(String param) {
    int idx = query.indexOf("?");
    if ( idx > -1 ) {
      query.replace(idx, idx + 1, param);
    }
  }
  
  protected void log(String msg) {
    System.out.println("[" + connId + "][" + delegate.toString() + "] " + msg);
  }
}

Java Encryption

I was working on a project that required some encryption. So, I had some time to play around with the javax.crypto api. Here is a small utility which plays around with text files before encryption.

package org.foo.bar; 
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.StringWriter;
import java.security.SecureRandom;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;

import javax.crypto.Cipher;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;


public class FcUtil {
  private static final String UTF8 = "utf-8";
  private static SecretKey getKey(String alg, String pass) {
    try {
      KeyGenerator keyGen = KeyGenerator.getInstance("Rijndael");
      keyGen.init(new SecureRandom(pass.getBytes(UTF8)));
      return keyGen.generateKey();
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
  private static Cipher getCipher(String alg, String pass) {
    try {
      Cipher cipher = Cipher.getInstance(alg);
      cipher.init(Cipher.ENCRYPT_MODE, getKey(alg, pass));
      return cipher;
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
  private static void encrypt(Cipher cipher, InputStream is, OutputStream os) {
    try {
      byte[] buffer = new byte[1024 * 1024];
      CipherOutputStream cos = new CipherOutputStream(os, cipher);
      int read = -1;
      int count = 10;
      while ( (read = is.read(buffer) ) > 0 ) {
        cos.write(buffer, 0, read);
        if ( --count < 0 ) {
          count = 10;
          cos.flush();
        }
      } // endwhile
      is.close();
      cos.close();
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
  private static String rev(String str) {
    char[] chars = str.toCharArray();
    int l = chars.length, n = l >> 1;
    char c;
    for (int i = 0; i < n; i++ ) {
      c = chars[(b = l-i)];
      chars[b] = chars[i];
      chars[i] = c;
    }
    return new String(chars);
  }
  private static byte[] processText(File file) {
    try {
      BufferedReader br = new BufferedReader(
          new InputStreamReader(new FileInputStream(file), UTF8));
      ArrayList<String> list = new ArrayList<String>();
      StringBuilder b = new StringBuilder();
      String buf = null;
      while ( (buf = br.readLine()) != null ) {
        b.delete(0, b.length());
        list.add(b.insert(0, buf).reverse().toString());
      }
      Collections.reverse(list);
      br.close();
      int count = 10;
      StringWriter sw = new StringWriter();
      for (String s : list) {
        sw.write(s);
        sw.write('\n');
        if ( --count < 0 ) {
          count = 10;
          sw.flush();
        }
      }
      sw.close();
      return sw.getBuffer().toString().getBytes(UTF8);
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
  private static ByteArrayInputStream processText(InputStream is) {
    try {
      BufferedReader br = new BufferedReader(
          new InputStreamReader(is, UTF8));
      ArrayList<String> list = new ArrayList<String>();
      StringBuilder b = new StringBuilder();
      String buf = null;
      while ( (buf = br.readLine()) != null ) {
        b.delete(0, b.length());
        list.add(b.insert(0, buf).reverse().toString());
      }
      Collections.reverse(list);
      br.close();
      int count = 10;
      StringWriter sw = new StringWriter();
      for (String s : list) {
        sw.write(s);
        sw.write('\n');
        if ( --count < 0 ) {
          count = 10;
          sw.flush();
        }
      }
      sw.close();
      return new ByteArrayInputStream(sw.getBuffer().toString().getBytes(UTF8));
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
  private static ByteArrayInputStream readFully(File file) {
    try {
      FileInputStream fis = new FileInputStream(file);
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      byte[] buffer = new byte[1024 * 1024];
      int read = -1;
      while ( (read = fis.read(buffer)) > 0 ) {
        baos.write(buffer, 0, read);
      }
      fis.close();
      baos.close();
      return new ByteArrayInputStream(baos.toByteArray());
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
  private static void transferFully(InputStream is, OutputStream os) {
    try {
      byte[] buffer = new byte[1024 * 1024];
      int read = -1;
      int count = 10;
      while ( (read = is.read(buffer)) > 0 ) {
        os.write(buffer, 0, read);
        if ( --count < 0 ) {
          count = 10;
          os.flush();
        }
      }
      is.close();
      os.close();
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
  private static void process(Cipher cipher, File file) {
    if ( file.isDirectory() ) {
      return;
    }
    HashSet<String> textExt = new HashSet<String>() {{
      add("txt");
      add("java");
      add("properties");
      add("xml");
      add("bat");
      add("sh");
      add("jsp");
      add("html");
      add("tld");
      add("js");
      add("css");
      add("dtd");
      add("xsd");
      add("sql");
      add("ddl");
    }};
    try {
      String ext = file.getName().substring(file.getName().lastIndexOf('.')+1).toLowerCase();
      if ( textExt.contains(ext) ) {

        // encrypt
        ByteArrayInputStream bis = new ByteArrayInputStream(processText(file));
        encrypt(cipher, bis, new FileOutputStream(file));

        // decrypt
//        ByteArrayOutputStream baos = new ByteArrayOutputStream();
//        encrypt(cipher, readFully(file), baos);
//        transferFully(processText(new ByteArrayInputStream(
//            baos.toByteArray())), new FileOutputStream(file));
      } else {
        // encrypt & decrypt
        ByteArrayInputStream bis = readFully(file);
        encrypt(cipher, bis, new FileOutputStream(file));
      }
    } catch (Exception e) {
      throw new RuntimeException(e);
    }    
  }
  private static void handleDir(Cipher cipher, File dir) {
    long start = System.currentTimeMillis();
    FileFilter fileFilter = new FileFilter() {
      HashSet<String> encExt = new HashSet<String>() {{
        add("txt");
        add("java");
        add("properties");
        add("xml");
        add("bat");
        add("sh");
        add("jsp");
        add("html");
        add("tld");
        add("js");
        add("css");
        add("dtd");
        add("xsd");
        add("sql");
        add("ddl");
        
        add("doc");
        add("xls");
        add("ppt");
        add("pps");
        add("pdf");
        add("pst");
      }};
      public boolean accept(File pathname) {
        String ext = pathname.getName().substring(pathname.getName().lastIndexOf('.')+1).toLowerCase();
        return pathname.isFile() && encExt.contains(ext);
      }
    };
    FileFilter dirFilter = new FileFilter() {
      HashSet<String> exclude = new HashSet<String>() {{
        add(".svn");
        add("cvs");
        add(".hg");
      }};
      public boolean accept(File pathname) {
        return pathname.isDirectory() && !exclude.contains(pathname.getName().toLowerCase()) && pathname.getName().indexOf('.') != 0;
      }
      
    };
    File[] files = dir.listFiles(fileFilter);
    for (File file : files) {
//      System.out.println(file.getAbsolutePath());
      process(cipher, file);
    }
    File[] dirs = dir.listFiles(dirFilter);
    handleDirs(cipher, dirs);
//    System.out.println(dir.getAbsolutePath() + "[" + (System.currentTimeMillis() - start) + "ms]");
  }
  private static void handleDirs(Cipher cipher, File[] dirs) {
    for (File dir : dirs) {
      handleDir(cipher, dir);
    }
  }
  public static void main(String[] args) {
    final String alg = "Rijndael";
    if ( args.length != 2 ) {
      System.out.println("error");
      return;
    }
    final String key = args[0];
    
    try {
      Cipher cipher = getCipher(alg, key);
//      cipher.init(Cipher.DECRYPT_MODE, getKey(alg, key));
      final File file = new File(args[1]);
      handleDir(cipher, file);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}