net.contextfw.web.application.internal.servlet.ResourceServlet Maven / Gradle / Ivy

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package net.contextfw.web.application.internal.servlet;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.regex.Pattern;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.contextfw.web.application.WebApplicationException;
import net.contextfw.web.application.internal.util.ResourceEntry;
import net.contextfw.web.application.internal.util.ResourceScanner;

import org.apache.commons.io.IOUtils;

public abstract class ResourceServlet extends HttpServlet {

    private static final long serialVersionUID = -1979474932427776224L;

    private volatile String content = null;

    public void clean() {
        content = null;
    }
    
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        if (clear()) {
            clean();
        }

        if (content == null) {
            synchronized (this) {
                if (content == null) {
                    StringBuilder contentBuilder = new StringBuilder();
                    List files = ResourceScanner.findResources(getRootPaths(), getAcceptor());
                    for (ResourceEntry file : files) {
                        addContent(contentBuilder, file);
                    }
                    content = contentBuilder.toString();
                }
            }
        }

        resp.getWriter().print(content);
        resp.getWriter().close();
    }

    private void addContent(StringBuilder contentBuilder, ResourceEntry file) {
        try {
            InputStream stream = file.getInputStream();
            contentBuilder.append(IOUtils.toString(stream));
            if (contentBuilder.charAt(contentBuilder.length() - 1) != '\n') {
            	contentBuilder.append("\n");
            }
            stream.close();
        } catch (FileNotFoundException e) {
            throw new WebApplicationException(e);
        } catch (IOException e) {
            throw new WebApplicationException(e);
        }
    }

    public abstract boolean clear();

    protected abstract Pattern getAcceptor();

    protected abstract List getRootPaths();
}