13477940/servlet-async-framework

It's a servlet implement for processing asynchronous http request task simple framework instance.

Servlet-Async-Framework

It's a tomcat(or jetty) webapp for processing asynchronous http request task simple framework instance.

Features

＊非同步處理每個連結至 Servlet 的 HttpRequest（AsyncHttpServlet）
＊可自定義擴充伺服器功能的 RequestHandler 與責任鏈模式架構（Chain Of Responsibility Pattern）
＊檔案上傳處理（Easy File Upload）
＊伺服器端檔案瀏覽及下載（File Explore & Download）
＊HTTP Parameters 封裝處理，方便調用（Easy to use HTTP Parameters）
＊實作類似於 Android Handler 功能處理後端非同步任務（Android Handler Instance for Servlet AsyncTask）
＊簡易型的 JDK HttpClient 功能（Simplified JDK HttpClient）

Require

• Java OpenJDK 8+(recommend use LTS version or Latest version)
  • Eclipse Temurin JDK
  • Microsoft OpenJDK
• Apache Tomcat 8.5+ or Jetty ( attention JDBC use )
  • Tomcat
  • Jetty (recommend)
• Google Gson
  • google/gson
  • Gson Jar
• Apache Tika Core
  • Apache Tika Core
• Elopteryx/upload-parser ( now integrated src, just need to know )
  • Elopteryx/upload-parser
• kotlin-stdlib -> for kotlin coroutines ( wating for JDK 19 Virtual Threads (Preview) alternative plan )
  • kotlin-stdlib
• kotlinx-coroutines-core-jvm -> for kotlin coroutines
  • kotlinx-coroutines-core-jvm

Optional

• Database JDBC
  • MariaDB
  • MySQL
  • PostgreSQL
  • MSSQL
• OkHttp（need Kotlin Standard Library）- for use HttpClient
  • Kotlin Standard Library
  • OkHttp
  • OkIO
• Jakarta Mail API
  • Jakarta Mail
• Bouncy Castle Provider ( for AES, SHA, Base64, Base32, etc... )
  • Bouncy Castle Provider
• ZXing Core ( for QRCode )
  • ZXing Core
  • ZXing Java SE Extensions

Getting Started

放置檔案內容到 tomcat/webapps/testasync 之中，並進行編譯，編譯完成後，即可啟動 Tomcat。
complie src/java after put source code file to tomcat/webapps/testasync.
if compile done to startup tomcat.

＊Index(Form-Data Request Test):

http://ip:port/testasync/

＊Page Request(Parameters Test):

http://ip:port/testasync/service?page=test

＊File Request(File Explore & Download):

http://ip:port/testasync/service?file=value

Compile Command

Windows OS:

cd tomcat\webapps\testasync\WEB-INF\
javac -cp ..\..\..\tomcat\lib\*;.\lib\*;.\classes\; -d .\classes -encoding utf-8 .\src\*\*.java

Unix / Linux / Mac OS:

cd tomcat/webapps/testasync/WEB-INF/
javac -cp ../../../tomcat/lib/*:./lib/*:./classes/: -d ./classes -encoding utf-8 ./src/*/*.java

RequestHandler Example

A RequestHandler can handle a http request task or a type of task.
Create a complete website MicroService or API with multiple RequestHandlers.

package app.handler;

import framework.file.FileFinder;
import framework.observer.Bundle;
import framework.observer.Handler;
import framework.observer.Message;
import framework.setting.AppSetting;
import framework.web.context.AsyncActionContext;
import framework.web.handler.RequestHandler;

import javax.servlet.http.HttpServletResponse;
import java.io.File;

public class PageHandler extends RequestHandler {

    private AsyncActionContext requestContext;

    @Override
    public void startup(AsyncActionContext asyncActionContext) {
        if(checkIsMyJob(asyncActionContext)) {
            this.requestContext = asyncActionContext;
            processRequest();
        } else {
            this.passToNext(asyncActionContext);
        }
    }

    @Override
    protected boolean checkIsMyJob(AsyncActionContext asyncActionContext) {
        if(asyncActionContext.isFileAction()) return false;
        if(null != asyncActionContext.getResourceExtension()) return false; // 排除資源類請求
        if("page".equals(asyncActionContext.getParameters().get("page"))) return true;
        return asyncActionContext.getParameters().size() == 0;
    }

    private void processRequest() {
        String dirSlash = new AppSetting.Builder().build().getDirSlash();
        switch (requestContext.getUrlPath()) {
            case "/":
            case "/index": {
                outputPage(dirSlash + "index.html");
            } break;
            default: {
                response404();
            } break;
        }
    }

    // 指定檔案路徑後輸出該頁面檔案，如果仍然不具有檔案則回傳 404
    private void outputPage(String path) {
        outputPage(path, new Handler(){
            @Override
            public void handleMessage(Message m) {
                super.handleMessage(m);
                requestContext.complete();
            }
        });
    }
    private void outputPage(String path, Handler handler) {
        File file = getPageFile(path);
        if(null != file && file.exists()) {
            requestContext.outputFileToResponse(file, file.getName(), "text/html", false, handler);
        } else {
            response404(handler);
        }
    }

    private File getPageFile(String path) {
        File appDir = new FileFinder.Builder().build().find("WEB-INF").getParentFile();
        File res = new File(appDir.getPath() + path);
        if(!res.exists()) return null;
        return res;
    }

    private void response404() {
        response404(new Handler(){
            @Override
            public void handleMessage(Message m) {
                super.handleMessage(m);
                requestContext.complete();
            }
        });
    }

    private void response404(Handler handler) {
        try {
            requestContext.getHttpResponse().sendError(HttpServletResponse.SC_NOT_FOUND);
            if(null != handler) {
                Bundle b = new Bundle();
                b.putString("status", "fail");
                b.putString("error_code", "404");
                b.putString("msg_zht", "沒有正確的指定頁面網址");
                Message m = handler.obtainMessage();
                m.setData(b);
                m.sendToTarget();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

Use WebAppServicePool build a Chain Of Responsibility

package app.listener;

import app.handler.*;
import framework.web.executor.WebAppServicePoolStatic;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class AppContextListener implements ServletContextListener {

    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        WebAppServicePoolStatic.getInstance().addHandler(new PageHandler());
        WebAppServicePoolStatic.getInstance().addHandler(new ResourceFileHandler());
        WebAppServicePoolStatic.getInstance().addHandler(new FileHandler());
        WebAppServicePoolStatic.getInstance().addHandler(new UploadHandler());
        WebAppServicePoolStatic.getInstance().addHandler(new ParameterHandler());
        // etc...
    }

    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {}

}

Build a database connection pool

package app.database;

import framework.database.datasource.TomcatDataSource;
import framework.database.interfaces.ConnectionPool;

public class MyConnectionPoolStatic {

    private static ConnectionPool instance = null;

    public static ConnectionPool getInstance() {
        if(null == instance) {
            try {
                instance = new TomcatDataSource.Builder()
                        .setIP("db_ip")
                        .setPort("db_port")
                        .setDatabaseType("mysql") // mariadb, mysql, postgresql or mssql
                        .setAccount("db_acc")
                        .setPassword("db_pwd")
                        .setDatabaseName("db_name")
                        .setUseSSL(true)
                        .build();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return instance;
    }

}

How To Use Database Functions

// build a database action
DatabaseAction dbAct = new DatabaseAction.Builder()
        .setConnection(MyConnectionPoolStatic.getInstance().getConnection())
        .setSQL("your_sql_command")
        .setParameters(ArrayList<String> params) // not necessary
        .build();

// dbAct.query(), dbAct.update() ... etc
dbAct.execute();

// close ConnectionPool
MyConnectionPoolStatic.getInstance().shutdown();