JavaCompiler - Compiling source from a database

Question

Dear all,
I managed to compile some code on the fly using the javax.Tool package as shown underneath:
import javax.tools.*;
class CompilerExample {
    public static void main(String[] args) {
        String fileToCompile = "Program.java";
        JavaCompiler compiler =  ToolProvider.getSystemJavaCompiler();
        int compilationResult = compiler.run(null, null, null, fileToCompile);
        if (compilationResult == 0) {
            System.out.println("Compilation is successful");
        } else {
            System.out.println("Compilation Failed");
}However I'd like to get my code from a database rather than from a file. I know that the run method has an argument (the first) of type InputStream. I tried reading the stream but couldn't manage. Any hints please?
package compiler;
import javax.tools.*;
import java.sql.*;
import subpack.Data;
import java.io.*;
public class Main {
    public static void main(String[] args) throws Exception {
        Connection con = null;    
        PreparedStatement ps = null;
        ResultSet rs = null;
        try{
            Class.forName(Data.driver).newInstance();
            con = DriverManager.getConnection(Data.url + Data.db, Data.user, Data.pass);
        } catch (Exception e){
            System.out.println(e);
        ps = con.prepareStatement("SELECT source FROM source WHERE id = 156");
        rs = ps.executeQuery();
        while (rs.next()){
            InputStream in = rs.getBinaryStream("source");
            JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
            int compilationResult = compiler.run(in , null, null, "");
            if (compilationResult == 0) {
                System.out.println("Compilation is successful");
            } else {
                System.out.println("Compilation Failed");
}Thanks

Answer 1

I found some source code to compile code in memory and converted it into something I needed. Here goes:
package compiler;
import java.net.URI;
import java.util.Arrays;
import javax.tools.JavaCompiler.CompilationTask;
import javax.tools.JavaFileObject.Kind;
import javax.tools.*;
import java.sql.*;
import subpack.Data;
import java.io.*;
import java.util.StringTokenizer;
public class Main {
    public static void main(String[] args) throws Exception {
        Connection con = null;    
        PreparedStatement ps = null;
        ResultSet rs = null;
        try{
            Class.forName(Data.driver).newInstance();
            con = DriverManager.getConnection(Data.url + Data.db, Data.user, Data.pass);
        } catch (Exception e){
            System.out.println(e);
        ps = con.prepareStatement("SELECT source FROM source WHERE id = 156");
        rs = ps.executeQuery();
        if (rs.next()){
            String source = rs.getString("source");
            JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
            DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<JavaFileObject>();
            StringWriter writer = new StringWriter();
            PrintWriter out = new PrintWriter(writer);
            out.println(source);       
            out.close();
            StringTokenizer st = new StringTokenizer(source," ");
            String className = null;
            while (st.hasMoreTokens() && className == null){if (st.nextToken().equalsIgnoreCase("class")) className = st.nextToken(); }
            if (className.indexOf('{') > 0) className = className.replace('{', ' ');
            JavaFileObject file = new JavaSourceFromString(className.trim(), writer.toString());
            Iterable<? extends JavaFileObject> compilationUnits = Arrays.asList(file);
            CompilationTask task = compiler.getTask(null, null, diagnostics, null, null, compilationUnits);
            boolean success = task.call();
            if (success) {
                  System.out.println("Successful");
            } else {
                for (Diagnostic diagnostic : diagnostics.getDiagnostics()) {
                  System.out.println(diagnostic.getMessage(null));
class JavaSourceFromString extends SimpleJavaFileObject {
      final String code;
      JavaSourceFromString(String name, String code) {
        super(URI.create(name.replace('.','/') + Kind.SOURCE.extension),Kind.SOURCE);
            this.code = code;
      @Override
      public CharSequence getCharContent(boolean ignoreEncodingErrors) {
        return code;
}