A standalone program that reads a list of classes and builds a database of packages, classes, and class fields and methods : BufferedReader « File Input Output « Java

A standalone program that reads a list of classes and builds a database of packages, classes, and class fields and methods

 * Copyright (c) 2004 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 3nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose,
 * including teaching and use in open-source projects.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book, 
 * please visit http://www.davidflanagan.com/javaexamples3.

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileReader;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

 * This class is a standalone program that reads a list of classes and builds a
 * database of packages, classes, and class fields and methods.
public class MakeAPIDB {
  public static void main(String args[]) {
    Connection c = null; // The connection to the database
    try {
      // Read the classes to index from a file specified by args[0]
      ArrayList classnames = new ArrayList();
      BufferedReader in = new BufferedReader(new FileReader(args[0]));
      String name;
      while ((name = in.readLine()) != null)

      // Now determine the values needed to set up the database
      // connection The program attempts to read a property file named
      // "APIDB.props", or optionally specified by args[1]. This
      // property file (if any) may contain "driver", "database", "user",
      // and "password" properties that specify the necessary values for
      // connecting to the db. If the properties file does not exist, or
      // does not contain the named properties, defaults will be used.
      Properties p = new Properties(); // Empty properties
      try {
        p.load(new FileInputStream(args[1])); // Try to load properties
      } catch (Exception e1) {
        try {
          p.load(new FileInputStream("APIDB.props"));
        } catch (Exception e2) {

      // Read values from Properties file
      String driver = p.getProperty("driver");
      String database = p.getProperty("database");
      String user = p.getProperty("user", "");
      String password = p.getProperty("password", "");

      // The driver and database properties are mandatory
      if (driver == null)
        throw new IllegalArgumentException("No driver specified!");
      if (database == null)
        throw new IllegalArgumentException("No database specified!");

      // Load the driver. It registers itself with DriverManager.

      // And set up a connection to the specified database
      c = DriverManager.getConnection(database, user, password);

      // Create three new tables for our data
      // The package table contains a package id and a package name.
      // The class table contains a class id, a package id, and a name.
      // The member table contains a class id, a member name, and an bit
      // that indicates whether the class member is a field or a method.
      Statement s = c.createStatement();
      s.executeUpdate("CREATE TABLE package " + "(id INT, name VARCHAR(80))");
      s.executeUpdate("CREATE TABLE class " + "(id INT, packageId INT, name VARCHAR(48))");
      s.executeUpdate("CREATE TABLE member " + "(classId INT, name VARCHAR(48), isField BIT)");

      // Prepare some statements that will be used to insert records into
      // these three tables.
      insertpackage = c.prepareStatement("INSERT INTO package VALUES(?,?)");
      insertclass = c.prepareStatement("INSERT INTO class VALUES(?,?,?)");
      insertmember = c.prepareStatement("INSERT INTO member VALUES(?,?,?)");

      // Now loop through the list of classes and use reflection
      // to store them all in the tables
      int numclasses = classnames.size();
      for (int i = 0; i < numclasses; i++) {
        try {
          storeClass((String) classnames.get(i));
        } catch (ClassNotFoundException e) {
          System.out.println("WARNING: class not found: " + classnames.get(i) + "; SKIPPING");
    } catch (Exception e) {
      if (e instanceof SQLException)
        System.err.println("SQLState: " + ((SQLException) e).getSQLState());
      System.err.println("Usage: java MakeAPIDB " + "<classlistfile> <propfile>");
    // When we're done, close the connection to the database
    finally {
      try {
      } catch (Exception e) {

   * This hash table records the mapping between package names and package id.
   * This is the only one we need to store temporarily. The others are stored in
   * the db and don't have to be looked up by this program
  static Map package_to_id = new HashMap();

  // Counters for the package and class identifier columns
  static int packageId = 0, classId = 0;

  // Some prepared SQL statements for use in inserting
  // new values into the tables. Initialized in main() above.
  static PreparedStatement insertpackage, insertclass, insertmember;

   * Given a fully-qualified classname, this method stores the package name in
   * the package table (if it is not already there), stores the class name in
   * the class table, and then uses the Java Reflection API to look up all
   * methods and fields of the class, and stores those in the member table.
  public static void storeClass(String name) throws SQLException, ClassNotFoundException {
    String packagename, classname;

    // Dynamically load the class.
    Class c = Class.forName(name);

    // Display output so the user knows that the program is progressing
    System.out.println("Storing data for: " + name);

    // Figure out the packagename and the classname
    int pos = name.lastIndexOf('.');
    if (pos == -1) {
      packagename = "";
      classname = name;
    } else {
      packagename = name.substring(0, pos);
      classname = name.substring(pos + 1);

    // Figure out what the package id is. If there is one, then this
    // package has already been stored in the database. Otherwise, assign
    // an id, and store it and the packagename in the db.
    Integer pid;
    pid = (Integer) package_to_id.get(packagename); // Check hashtable
    if (pid == null) {
      pid = new Integer(++packageId); // Assign an id
      package_to_id.put(packagename, pid); // Remember it
      insertpackage.setInt(1, packageId); // Set statement args
      insertpackage.setString(2, packagename);
      insertpackage.executeUpdate(); // Insert into package db

    // Now, store the classname in the class table of the database.
    // This record includes the package id, so that the class is linked to
    // the package that contains it. To store the class, we set arguments
    // to the PreparedStatement, then execute that statement
    insertclass.setInt(1, ++classId); // Set class identifier
    insertclass.setInt(2, pid.intValue()); // Set package identifier
    insertclass.setString(3, classname); // Set class name
    insertclass.executeUpdate(); // Insert the class record

    // Now, get a list of all non-private methods of the class, and
    // insert those into the "members" table of the database. Each
    // record includes the class id of the containing class, and also
    // a value that indicates that these are methods, not fields.
    Method[] methods = c.getDeclaredMethods(); // Get a list of methods
    for (int i = 0; i < methods.length; i++) { // For all non-private
      if (Modifier.isPrivate(methods[i].getModifiers()))
      insertmember.setInt(1, classId); // Set the class id
      insertmember.setString(2, methods[i].getName()); // Set method name
      insertmember.setBoolean(3, false); // It is not a field
      insertmember.executeUpdate(); // Insert into db

    // Do the same thing for the non-private fields of the class
    Field[] fields = c.getDeclaredFields(); // Get a list of fields
    for (int i = 0; i < fields.length; i++) { // For each non-private
      if (Modifier.isPrivate(fields[i].getModifiers()))
      insertmember.setInt(1, classId); // Set the class id
      insertmember.setString(2, fields[i].getName()); // Set field name
      insertmember.setBoolean(3, true); // It is a field
      insertmember.executeUpdate(); // Insert the record


Related examples in the same category

1.Create BufferedReader from System.in
2.Create BufferedReader from InputStreamReader
3.Create BufferedReader from StringReader
4.Create BufferedReader out of FileReader
5.Create BufferedReader from URL
6.Create BufferedReader from FileReader and Read / display lines from file
7.Create BufferedReader from InputStreamReader and System.in, read console input
8.Use BufferedReader to Read and process lines from console
9.Tab filter: Convert tab to space characters
10.List of lines in a file with BufferedReader
11.Use BufferedReader to read line by line
12.A simple FilterReader that strips HTML tags out of a stream of characters
13.Using BufferedReader to read input number from user
14.Read lines of text from a file with the BufferedReader class
15.Read from a file using a BufferedReader
16.Read each line in a comma separated file into an array
17.Read content of a file
18.Reading Text from a File
19.Read a text file
20.Call the static method PressAnykey to keep to "DOS" window open.
21.ReadLines: read file to list of strings
22.The AsciiReader can read ascii data files
23.Count the number of lines in the buffer