net.jmatrix.db.schema.data.v1.GenericSchemaHasher Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of jsql Show documentation
SQL Utilities including simple command line, schema management.
There is a newer version: 1.2.8
package net.jmatrix.db.schema.data.v1;

import java.security.MessageDigest;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import net.jmatrix.db.common.DBUtils;
import net.jmatrix.db.common.Hex;
import net.jmatrix.db.common.console.SysConsole;
import net.jmatrix.db.common.console.TextConsole;

/**
 * Generic hasher based on datbase metadata from jdbc.
 * 
 * 
 */
public class GenericSchemaHasher implements SchemaHasher {
   static TextConsole console=SysConsole.getConsole();

   Connection con=null;
   
   List configTables=null;
   
   List tables=null;
   
   public GenericSchemaHasher(Connection c) {
      con=c;
      reset();
   }
   
   @Override
   public String calculateSchemaHash() throws Exception {
      String hash=null;
      
      long start=System.currentTimeMillis();
      try {
         MessageDigest digest=MessageDigest.getInstance("MD5");
         digest.reset();
         
         add(con, digest, new String[]{"TABLE", "VIEW"});
         
         if (configTables != null) {
            for (String tablename:configTables) {
               addRows(con, digest, tablename);
            }
         }
         
         hash=Hex.asHex(digest.digest());
      } finally {
         long et=System.currentTimeMillis()-start;
         console.info("Calculated schema hash '"+hash+"' in "+et+"ms");
      }
      
      return hash;
   }
   
   void reset() {
      tables=new ArrayList();
   }
   
   boolean ignoreTable(String tablename) {
      if (tablename == null)
         return true;
      if (tablename.toUpperCase().matches("^DBM"))
         return true;
      return false;
   }
   
   private void add(Connection con, MessageDigest digest, String types[]) throws SQLException {
      DatabaseMetaData dbmd=con.getMetaData();
      
      ResultSet rs=null;
      
      try {
         con.getSchema();
         
         rs=dbmd.getTables(null, con.getSchema(), null, types);
         
         while (rs.next()) {
            String tableName=rs.getString("table_name");
            
            if (!ignoreTable(tableName)) {
               tables.add(tableName.toUpperCase());
               
               ResultSet rs2=null;
               console.info("Hashing Table Schema: "+tableName);
               try {
                  rs2=dbmd.getColumns(null, con.getSchema(), tableName, null);
                  // column name, type, size
                  while(rs2.next()) {
                     String cname=rs2.getString("column_name");
                     String tname=rs2.getString("type_name");
                     String size=rs2.getString("column_size");
                     digest.update(cname.getBytes());
                     digest.update(tname.getBytes());
                     digest.update(size.getBytes());
                  }
               } finally {
                  DBUtils.close(rs2);
               }
            } else {
               console.info("Ignoring "+tableName);
            }
         }
      } finally {
         DBUtils.close(rs);
      }
   }
   
   private void addRows(Connection con, MessageDigest digest, String tablename) throws SQLException {
      if (!tables.contains(tablename.toUpperCase())) {
         console.warn("Cannot find table '"+tablename+"' in known schema tables: "+tables);
         
         digest.update("TABLE_DOES_NOT_EXIST".getBytes());
         return;
      }
      String sql="select * from "+tablename;
      
      console.info("hashing table "+tablename);
      
      Statement state=null;
      ResultSet rs=null;
      try {
         state=con.createStatement();
         rs=state.executeQuery(sql);
         
         ResultSetMetaData rsmd=rs.getMetaData();
         int cols=rsmd.getColumnCount();
         
         digest.update((""+cols).getBytes());
         
         int count=0;
         while (rs.next()) {
            count++;
            for (int i=1; i<=cols; i++) {
               String val=rs.getString(i);
               
               if (val == null)
                  digest.update("NULLVALUE".getBytes());
               else
                  digest.update(val.getBytes());
            }
         }
         console.info("Updated hash with "+count+" rows x "+cols+" cols");
      } finally {
         
      }
   }
   


   public List getConfigTables() {
      return configTables;
   }

   public void setConfigTables(List configTables) {
      this.configTables = configTables;
   }
}