accedendo a javascript da dentro java
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05-07-2019 - |
Domanda
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?
Soluzione
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.
Altri suggerimenti
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.