AbstractLazyContent.java

/*
 * GovWay - A customizable API Gateway 
 * https://govway.org
 * 
 * Copyright (c) 2005-2025 Link.it srl (https://link.it). 
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 3, as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package org.openspcoop2.message.rest;

import java.io.FileInputStream;
import java.io.InputStream;
import java.io.OutputStream;

import org.openspcoop2.message.exception.MessageException;
import org.openspcoop2.utils.Utilities;
import org.openspcoop2.utils.io.DumpByteArrayOutputStream;

/**
 * AbstractLazyContent
 *
 * @author Andrea Poli (poli@link.it)
 * @author $Author$
 * @version $Rev$, $Date$
 */
public abstract class AbstractLazyContent<T> {

    public static boolean BUILD_LAZY = true;
    
    protected T content;
    protected DumpByteArrayOutputStream contentBuffer;
    protected byte[] contentByteArray; // inefficiente, viene memorizzato due volte, se e' attivo anche il contentBuffer, usare anzi quel costruttore
    protected String contentType;
    
    protected AbstractLazyContent() {}
    public void init(InputStream is, String contentType) throws MessageException {
        try{
            this.contentType = contentType;
            this.contentByteArray = Utilities.getAsByteArray(is);
        }catch(Exception e){
            throw new MessageException(e.getMessage(),e);
        }
    }
    public void init(DumpByteArrayOutputStream contentBuffer, String contentType) throws MessageException {
        try{
            this.contentType = contentType;
            this.contentBuffer = contentBuffer;
        }catch(Exception e){
            throw new MessageException(e.getMessage(),e);
        }
    }
    public void init(T content) {
        this.content = content;
    }
    
    public abstract T buildContent(InputStream is) throws MessageException;
    public abstract T buildContent(byte[] c) throws MessageException;
    public abstract void writeContentTo(OutputStream os, boolean consume) throws MessageException;
    
    public void buildContent() throws MessageException {
        if(this.content==null) {
            if(this.contentBuffer!=null) {
                try{
                    if(this.contentBuffer.isSerializedOnFileSystem()) {
                        try(InputStream is = new FileInputStream(this.contentBuffer.getSerializedFile())){
                            this.content = buildContent(is);
                        }
                    }
                    else {
                        this.content = buildContent(this.contentBuffer.toByteArray());
                    }
                    this.contentBuffer = null;
                }catch(Exception e){
                    throw new MessageException(e.getMessage(),e);
                }
            }
            else if(this.contentByteArray!=null) {
                try{
                    this.content = buildContent(this.contentByteArray);
                    this.contentByteArray = null;
                }catch(Exception e){
                    throw new MessageException(e.getMessage(),e);
                }
            }
        }
    }
    public T getContent() throws MessageException {
        if(this.content==null) {
            buildContent();
        }
        return this.content;
    }
    
    public void writeTo(OutputStream os, boolean consume) throws MessageException {
        writeTo(true, os, consume);
    }
    protected void writeTo(boolean checkContent, OutputStream os, boolean consume) throws MessageException {
        try{
            if(checkContent && this.content!=null) {
                this.writeContentTo(os, consume);
                if(consume) {
                    this.content=null;
                }
            }
            else if(this.contentBuffer!=null) {
                this.contentBuffer.writeTo(os);
                if(consume) {
                    this.contentBuffer=null;
                }
            }
            else if(this.contentByteArray!=null) {
                os.write(this.contentByteArray);
                if(consume) {
                    this.contentByteArray=null;
                }
            }
        }catch(Exception e){
            throw new MessageException(e.getMessage(),e);
        }
    }
    
}