accedendo a javascript da dentro java

Question

So che ci sono molti esempi là fuori su questo, ma si sentono tutti un po 'datati (anche i documenti del sole) quindi sto chiedendo qui per assicurarsi che quello che sto facendo sia aggiornato. Come potrei parlare di javascript dall'interno di un'applet Java? Qualcosa di semplice come come chiamare alert () è tutto ciò che sto cercando. Punti bonus per un modo per verificare se il browser ha javascript abilitato (questa applet può essere utilizzata in un ambiente scolastico in cui avere javascript disattivato è una possibilità reale). Tutto l'aiuto è molto apprezzato, grazie in anticipo ...

Codice:

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import netscape.javascript.JSObject;

public class TeamProject extends Applet implements ActionListener, MouseListener {
    char[][] charValues = new char[10][10];
    Table aTable;
    boolean allowUserInput = false;
    Button BtnStart;
    Button randomChangeBtn;
    boolean guessMode;
    JSObject jso;

    public void init() {
        //setup buttons
        BtnStart = new Button("add row/column");
        BtnStart.addActionListener((ActionListener)this);   //cast
        randomChangeBtn = new Button("change one value");
        randomChangeBtn.addActionListener((ActionListener)this);
        //add button
        this.add(BtnStart);
        //add image to Image objects
        Image imgO = getImage(getCodeBase(), "images/not.gif");
        Image imgX= getImage(getCodeBase(), "images/cross.gif");
        //setup table
        aTable = new Table(100, 100, 75, 55, 5, 5, imgX, imgO);
        //setBackground(Color.LIGHT_GRAY);
        super.resize(700, 700);
        //add mouse listener
        addMouseListener(this);
        //initially guessMode will be false
        guessMode = false;
        //to talk to javascript
        jso = JSObject.getWindow(this);
    }

    public void paint(Graphics g) {
        g.setColor(Color.black);
        aTable.draw(g);
    }

    //Mouse listener methods
    public void mousePressed (MouseEvent e) {
        if(!guessMode){
            if ((allowUserInput)) { //&&(aTable.isDrawable(e.getX(), e.getY())))
                aTable.swapSquareValue(e.getX(), e.getY());
                repaint();
            }
        } else {
            System.out.println("guessed row = " + e.getY() + " guessed col = " + e.getX());
            aTable.checkGuess(e.getX(), e.getY());
            //repaint();
        }
    }

    public void mouseClicked (MouseEvent e) {}
    public void mouseEntered (MouseEvent e) {}
    public void mouseReleased (MouseEvent e) {}
    public void mouseExited (MouseEvent e) {}

    //Button action listener
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == BtnStart) {
            aTable.addRow();
            aTable.addColumn();
            this.remove(BtnStart);
            this.add(randomChangeBtn);
            repaint();
        } else if (e.getSource() == randomChangeBtn) {
            //aTable.addRow();
            aTable.randomChangeFunc();
            repaint();
            guessMode = true;
        }
        allowUserInput = true;
        System.out.println(aTable.toString());
    }
}

e la mia classe Table:

import java.awt.*;
import java.util.Random;

public class Table {
    private char[][]values = new char[10][10];  //probably better to use array of integer values(0 or 1)
    Image imgO;
    Image imgX;
    private int Rows;
    private int Columns;
    private int BoxWidth ;
    private int BoxHeight;
    public Point Pos = new Point();

    private int tableHeight;
    private int tableWidth;

    private int changedRow;
    private int changedCol;

    //constructor
    public Table(int x, int y, int width, int height, int col, int rows, Image X, Image O) {
        Rows = rows;
        Columns = col;
        BoxWidth = width;
        BoxHeight = height;
        Pos.x = x;
        Pos.y = y;

        imgX = X;
        imgO = O;

        tableHeight = Rows*BoxHeight;
        tableWidth = Columns*BoxWidth;
        this.setValues();
    }

    //draw table
    public void draw(Graphics g) {
        //draw vertical table lines
        for (int i = 0 ; i <= Columns ; i++)
            g.drawLine(i*BoxWidth + Pos.x, Pos.y, i*BoxWidth + Pos.x, tableHeight+Pos.y);

        //draw horizontal table line
        for(int i = 0 ; i <= Rows ; i++)
            g.drawLine(Pos.x, i*BoxHeight + Pos.y, tableWidth+Pos.x, i*BoxHeight + Pos.y);

        //draw values
        drawValues(g);
    }

    public void swapSquareValue(int x, int y) {
        if (this.isDrawable(x, y)) {
            int col = this.getColumn(x)-1;
            int row = this.getRow(y)-1;

            if(values[row][col] == 'X')
                values[row][col] = 'O';
            else if(values[row][col] == 'O')
                values[row][col] = 'X';
            else
                System.out.println("ERROR SWAPPING SQUARE VALUE");
        } else
            System.out.println("says not drawable");
    }

    public char getValue(int col, int row) {
        return values[row][col];
    }

    //return true if (x,y) is a point in the table
    public boolean isDrawable(int x, int y) {
        if((this.getRow(y)!=-1)||(this.getColumn(x)!=-1))
            return true;
        else
            return false;
    }

    public void addRow() {
        Rows++;
        tableHeight = (Rows*BoxHeight);
        int numOfXs = 0;
        for (int c=0; c < Columns; c++) {
            numOfXs = 0;
            for(int r = 0; r < Rows - 1; r++) {
                if(values[r][c] == 'X'){
                    numOfXs++;
                    System.out.println("in column " + c + "new x found at " + r + " " + c + ", numOfXs = " + numOfXs);
                }
                if(numOfXs % 2 == 0) {
                    values[Rows - 1][c] = 'O';
                } else{
                    values[Rows - 1][c] = 'X';
                }
            }//end inner for
            System.out.println("end of column " + c);
        }//end outer for
    }// end function

    public void addColumn() {
        Columns++;
        tableWidth = (Columns*BoxWidth);
        int numOfXs = 0;

        for (int r=0; r < Rows; r++) {
            numOfXs = 0;
            for(int c = 0; c < Columns - 1; c++) {
                if(values[r][c] == 'X') {
                    numOfXs++;
                    System.out.println("in row " + r + "new x found at " + r + " " + c + ", numOfXs = " + numOfXs);
                }
                if(numOfXs % 2 == 0) {
                    values[r][Columns - 1] = 'O';
                }
                else {
                    values[r][Columns - 1] = 'X';
                }
            }//end inner for
            System.out.println("end of row " + r);
        }
    }

    //does not add or remove values
    public void setColumn(int col) {
        Columns = col;
        tableWidth = (Columns*BoxWidth);
    }

    //does not add or remove values
    public void setRows(int row) {
        Rows = row;
        tableHeight = (row*BoxHeight);
    }

    public String toString() {
        String ValueString = "Displaying charValues[" + Rows + "][" + Columns + "]\n";
        for (int r=0; r < Rows; r++) {
            for (int c=0; c < Columns; c++) {
                ValueString += (char)values[r][c];
            }
            ValueString += "\n";        //next line
        }
        return ValueString;
    }

    private void drawValues(Graphics g) {
        Point drawPoint = new Point();
        for (int r=0; r < Rows; r++)
            for (int c=0; c < Columns; c++) {
                drawPoint.x = Pos.x+BoxWidth*c;
                drawPoint.y = Pos.y+BoxHeight*r;
                //g.setColor(Color.white);
                //g.fillRect(drawPoint.x+1, drawPoint.y+1, BoxWidth-1, BoxHeight-1);
                if (values[r][c] == 'X') {
                    g.drawImage(imgX,drawPoint.x+1, drawPoint.y+1, BoxWidth-1, BoxHeight-1, null);
                } else {
                    g.drawImage(imgO,drawPoint.x+1, drawPoint.y+1, BoxWidth-1, BoxHeight-1, null);
                }
                //System.out.print((char)values[r][c]);
            }
        g.setColor(Color.black);
    }

    //fills array with random values
    private void setValues() {
        for (int r=0; r < Rows; r++)
            for (int c=0; c < Columns; c++) {
                values[r][c] = this.randomChar();
            }
    }

    //randomly return 'X' or 'O'
    private char randomChar() {
        char randomValue;
        Random RandomGen = new Random();

        if (RandomGen.nextInt(2)==0)
            randomValue = 'O';
        else
            randomValue ='X';
        return randomValue;
    }

    private int getColumn(int x) {
        int offsetx=0;
        for (int i = 0 ; i < Columns ; i++) {
            offsetx = i*BoxWidth;
            if((x>Pos.x+offsetx)&& (x<Pos.x+offsetx+BoxWidth))
                return i+1;
        }
        return -1;
    }

    private int getRow(int y) {
        int offsety=0;
        for (int i = 0 ; i < Rows ; i++) {
            offsety = i*BoxHeight;
            if((y>Pos.y+offsety)&& (y<Pos.x+offsety+BoxHeight))
                return i+1;
        }
        return -1;
    }

    public void randomChangeFunc() {
        //get random row and column
        Random rand=new Random();

        int randRow = rand.nextInt(Rows);
        int randCol = rand.nextInt(Columns);

        System.out.println("randRow = " + randRow + " randCol = " + randCol);
        /*THIS SHOULD BE HANDLED BY swapSquareValue(randCol,randRow)
        /*BUT GETTING ERRORS (notDrawable). THE FOLLOWING CODE IS A WORK-AROUND
        */
        if(values[randRow][randCol] == 'X')
            values[randRow][randCol] = 'O';
        else if(values[randRow][randCol] == 'O')
            values[randRow][randCol] = 'X';
        else
            System.out.println("ERROR SWAPPING SQUARE VALUE");
        //set globals
        changedRow = randRow;
        changedCol = randCol;
    }

    public void checkGuess(int guessCol, int guessRow){
        int gCol = this.getColumn(guessCol)-1;
        int gRow = this.getRow(guessRow)-1;
        System.out.println("gCol = " + gCol + " gRow = " + gRow);
        if(gCol == changedCol && gRow == changedRow) {
            System.out.println("CORRECT!!!");
        } else
            System.out.println("incorrect :(");
    }
}

Modifica del mio comando javac in:

javac -classpath /usr/lib/Java6u1/jre/lib/plugin.jar TeamProject.java

ignora la mia " Tabella " classe e ricevo errori quando lo menziono. Qualche idea?

Answer 1

Guarda questo articolo . Se provi a chiamare JS dall'applet in questa pagina funziona sicuramente, perché ci sono eccezioni js dopo l'azione di aggiornamento dall'applet :)

importa netscape.javascript.JSObject

public void init ()     {         jso = JSObject.getWindow (questo);     }

 public void actionPerformed(ActionEvent e) {
     if(jso != null )
         try {
                jso.call("updateWebPage", new String[] {txt.getText()});
             }
             catch (Exception ex) {
                 ex.printStackTrace();
             }
 }

Modifica Per il problema del percorso di classe devi aggiungere plugin.jar al tuo percorso di classe che si trova in% JAVA_HOME% \ jre \ lib \ plugin.jar

EDIT2:
Penso che il tuo problema sia che una classe Table non sia compilata troppo:

prova javac -classpath /usr/lib/Java6u1/jre/lib/plugin.jar TeamProject.java Table.java o usa caratteri jolly come * .java .

Forse dovresti prendere in considerazione l'uso dell'IDE come Eclipse o Netbeans per compilare ed eseguire progetti invece di lottare con gli strumenti da riga di comando.

Answer 2

Come richiesto, un campione che richiama avviso sulla pagina in cui è incorporato (testato in Opera 10.01, FF 3.5.4, IE6).

Nota il MAYSCRIPT nel tag dell'applet, questo DEVE essere presente per abilitare la comunicazione java-javascript. Come da impostazione predefinita, l'accesso a JSObject è disabilitato per motivi di sicurezza.

HTML:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
  "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
  <title>Test</title>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
  <applet code="HelloWWW.class" width="300px" height="100px"  MAYSCRIPT></applet>
</body>
</html>

Java (compilare con javac -cp.; [pathtojre] /jre/lib/plugin.jar HelloWWW.java )

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import netscape.javascript.*;

public class HelloWWW extends Applet implements ActionListener {
  Button runButton;
  public void init() {
    runButton = new Button("Run: alert(\"Hello WWW\")");
    add(runButton);
    runButton.addActionListener(this);
  }
  public void actionPerformed(ActionEvent evt) {
    if (evt.getSource() == runButton) {
      try {
        //get JSOBject
        JSObject jso = JSObject.getWindow(this);
        //call alert with parameter passed as Object array
        jso.call("alert", new Object[]{"Hello WWW"});
      } catch (JSException e) {
        e.printStackTrace();
      }
      runButton.setLabel("Did it!");
      repaint();
    }
  } 
}

Controlla anche Java-to-Javascript Comunicazione e Mozilla Dev: JSObject per ulteriori informazioni.