脚本和Java Servlets

Question

我正在开发一款网络应用程序，旨在帮助运输公司管理非紧急旅行。服务器端是Jboss Web，它是Tomcat6的修改版本。我工作的公司最近的任务是为特定客户添加一些自定义功能。

该应用程序能够从第三方公司导入CSV文件。CSV包含一个旅行清单，公司可以将其导入我们的软件中，然后从那里管理旅行。我们的一些客户一直要求的是一项功能，即根据CSV中的预约时间，每条记录默认预定的收件时间和送货时间。然而，我们所有的客户都有不同的方法来估计这些时间。我想，我可以实现这个自定义功能与一些简短的脚本添加每个公司。然而，我希望能够从脚本访问数据库。我真正想要的是能够将现有的连接对象从java servlet传递到脚本本身。如果我可以这样做，那么我就不需要在CSV中打开/关闭每个记录的连接。我不会从脚本本身在数据库中设置任何数据。我只是在数据库中查找数值来辅助计算。

所以，在解释完所有这些之后，这就是我想知道的。有没有脚本语言可以让我从java servlet传入和返回原生java对象？

Answer 1

Servlet是HTTP侦听器。它们要求您传递HTTP请求和响应。它们既不知道也不关心Java对象。您必须将Java对象编组为String，并对它们进行适当编码。

Answer 2

我终于想通了。显然，我想要的一切都内置到了java中。Java具有将java对象传递到javascript调用中的能力，并且这些对象可以像本地java对象一样被使用。我能够在javascript调用中设置一个全局java.sql.Connection，并像在java中一样读取数据库。此外，我还能够修改传入的对象，并将它们返回给调用java的代码。以下是运行正常的代码。

Java源文件。

import java.io.FileNotFoundException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class JSTest {

    public static void main(String[] args) {
        new JSTest().go();
    }

    public void go(){
        Connection db = null;
        try {
            //Initialize all of the built in Java script parsing classes
            ScriptEngineManager manager = new ScriptEngineManager();
            ScriptEngine engine = manager.getEngineByName("javascript");
            db = login("127.0.0.1", "3306", "testdb", "user", "password");
            //set the database connection as a global variable for the javascript object.
            engine.put("g_connection",db);
            engine.eval(new java.io.FileReader("/home/scripts/testScript.js"));
            Invocable inv = (Invocable) engine;

            //Put together some sample data for the script to manipulate
            Calendar cal = Calendar.getInstance();
            cal.setTimeInMillis(0);
            cal.set(2014, 6, 20, 10, 30, 0);
            Date apptTime = cal.getTime();

            TripLeg tripLeg = new TripLeg();
            tripLeg.setLegSequence("A");
            tripLeg.setAppointmentTime(apptTime);
            tripLeg.setProjectedMiles(5);
            Trip trip = new Trip();
            trip.setClientID(5);//This is the id of the client record. I need to look it up in the script.
            tripLeg = (TripLeg) inv.invokeFunction("modifyTripLeg", trip, tripLeg);

            SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            if (tripLeg.getScheduledPUTime() != null)
                System.out.println(format.format(tripLeg.getScheduledPUTime()));
            else
                System.out.println("PU time not set.");
            if (tripLeg.getScheduledDOTime() != null)
                System.out.println(format.format(tripLeg.getScheduledDOTime()));
            else
                System.out.println("DO time not set.");
        } catch (ScriptException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } finally {
            try {
                if (db != null)
                    db.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    public Connection login (String server, String port, String database, String userName, String password)
    {
        Connection  db = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = String.format("jdbc:mysql://%s:%s/%s", server, port, database);
            db = DriverManager.getConnection(url, userName, password);      
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            return null;
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
        return db;
    }
    //Sample trip and trip leg classes stripped down to the bare minimum stuff that I need to access.
    public class Trip{
        private  int clientID;
        public int getClientID() {
            return clientID;
        }
        public void setClientID(int clientID) {
            this.clientID = clientID;
        }
    }
    public class TripLeg{
        private Date scheduledPUTime;
        private Date scheduleDOTime;
        private Date appointmentTime;
        private String legSequence;
        private double projectedMiles;

        public Date getScheduledPUTime() {
            return scheduledPUTime;
        }
        public void setScheduledPUTime(Date scheduledPUTime) {
            this.scheduledPUTime = scheduledPUTime;
        }
        public Date getScheduledDOTime() {
            return scheduleDOTime;
        }
        public void setScheduledDOTime(Date scheduleDOTime) {
            this.scheduleDOTime = scheduleDOTime;
        }
        public Date getAppointmentTime() {
            return appointmentTime;
        }
        public void setAppointmentTime(Date appointmentTime) {
            this.appointmentTime = appointmentTime;
        }
        public String getLegSequence() {
            return legSequence;
        }
        public void setLegSequence(String legSequence) {
            this.legSequence = legSequence;
        }
        public double getProjectedMiles() {
            return projectedMiles;
        }
        public void setProjectedMiles(double projectedMiles) {
            this.projectedMiles = projectedMiles;
        }
    }
}

这里是javascript源文件。(/home/scripts/testScript.js)

function modifyTrip(trip, tripLeg){
    return trip;
};
function modifyTripLeg(trip, tripLeg){
    var importFormat = getClientImportFormat(trip.getClientID());
    var legSequence = tripLeg.getLegSequence();
    var scheduledPUTime = tripLeg.getScheduledPUTime();
    var scheduledDOTime = tripLeg.getScheduledDOTime();
    var appointmentTime = tripLeg.getAppointmentTime();
    var projectedMiles = tripLeg.getProjectedMiles();

    if (importFormat == "TESTER_CLIENT"){
        if (legSequence == "A"){
            if (isEmptyDate(scheduledPUTime) && !isEmptyDate(appointmentTime) && !isEmptyDouble(projectedMiles))
                scheduledPUTime = new Date(appointmentTime.getTime() - ((projectedMiles + 45) * 60 *1000));
            if (isEmptyDate(scheduledDOTime) && !isEmptyDate(appointmentTime))
                scheduledDOTime = new Date(appointmentTime.getTime() - (15 * 60 *1000));
        }

        if (legSequence == "B"){
            if (scheduledPUTime == null && appointmentTime != null && (projectedMiles != null && projectedMiles > 0.00))
                scheduledPUTime = new Date(appointmentTime.getTime() - ((projectedMiles + 45) * 60 *1000));
            if (scheduledDOTime == null && appointmentTime != null)
                scheduledPUTime = new Date(appointmentTime.getTime() - (15 * 60 *1000));
        }
    }
    tripLeg.setScheduledPUTime(scheduledPUTime);
    tripLeg.setScheduledDOTime(scheduledDOTime);
    return tripLeg;
};
function getClientImportFormat(clientID){
    var sql = "select ImportFormat from Client where id = ?";
    var stmt = g_connection.prepareStatement(sql);
    stmt.setInt(1, clientID);
    var rs = stmt.executeQuery();
    var importFormat = "";
    if (rs.next()){
        importFormat = rs.getString(1);
    }
    rs.close();
    return importFormat;    
}
function isEmptyDate(testDate){
    if (!testDate)
        return true;
    if (testDate == null)
        return true;
    return false;
};
function isEmptyDouble(testDouble){
    if (!testDouble)
        return true;
    if (testDouble == null)
        return true;
    if (testDouble <= 0.0)
        return true;
    return false;
}

让我明白这一切的两个页面：http://docs.oracle.com/javase/8/docs/technotes/guides/scripting/prog_guide/api.html http://javalandscape.blogspot.com/2008/12/scripting-in-jdk6-jsr-223-part-2.html

另外，我的公司还在使用java6，所以我不能使用nashorn引擎。每当我在代码中请求引擎时，我使用"javascript“代替，对于我需要做的有限的事情，它工作得很好。在java servlet中，这一切都能完美地工作。

希望这能帮助其他正在寻找类似东西的人。