通过javascript杀死小程序 [英] Killing applet through javascript
问题描述
我创建了一个小程序，它需要执行以下代码:
I have created an applet which has a necessity to execute the following code:
public class Example extends JApplet {
private ServerSocket ss ;
private Socket socket;
private boolean closed;
@Override
public void init(){
try {
new Example().initialize();
} catch (IOException ex) {
Logger.getLogger(Example.class.getName()).log(Level.SEVERE, null,ex);
}
}
public void closed(){
System.out.println("Inside close");
this.closed=true;
}
public void initialize() throws IOException{
ss =new ServerSocket(5002);
while(!closed){
System.out.println("Waiting to accept request");
socket = ss.accept();
System.out.println("Request accepted");
}
}}
HTML
执行小程序的 HTML 文件片段:
HTML
Fragment of HTML file to execute applet:
<script type="text/javascript" >
function closeCall(){
document.app.closed();
}
</script>
<body>
<applet id="app" code="example.Example" archive="Example.jar" height="300" width="300">
</applet>
<input type="button" value="go" onClick="closeCall()" />
问题:在单击 Go 时，我的浏览器停止响应，并且 javascript 代码中也没有错误.有没有办法调用document.app.closed();方法?
Problem: On clicking Go my browser stops responding and there is no error in javascript code as well. Is there any way to call the document.app.closed(); method?
推荐答案
只有在将该代码转换为 SSCCE1许多问题变得清晰:
It was only after turning that code into an SSCCE1 that the many problems became clear:
- 这段代码对我来说失败了，没有任何 JS 的迹象.这向我表明这与 JS 没有有关！
- 调用
initialize()的Example的实例与小程序的实例不一样！UI 是否检测到 JS 并不重要，它不会停止正在运行的实例. accept()阻止了 EDT.- 将
closed设置为true直到下一个客户端连接并且代码循环检查closed<的值后才会生效./code> 属性.我通过调用ss.close()实现了它(这使得closed属性变得多余 BTW - 但我把它留在了).
- This code failed for me without any sign of JS. That indicates to me that this has nothing to do with JS!
- The instance of
Exampleon whichinitialize()was called was not the same as that which was the applet! It did not matter if the UI ever detected the JS, it would not have stopped the running instance. - The
accept()was blocking the EDT. - Setting
closedtotruewas not about to have an effect until after the next client connected and the code looped around to check the value of theclosedattribute again. I achieved it by callingss.close()(which makes theclosedattribute redundant BTW - but I left it in).
- 请考虑在未来发布 SSCCE.
代码
试试这个版本:
// <applet code='Example' width=400 height=100></applet>
import java.awt.event.*;
import javax.swing.*;
import java.net.*;
import java.io.*;
import java.util.logging.*;
public class Example extends JApplet {
private ServerSocket ss ;
private Socket socket;
private boolean closed;
@Override
public void init(){
JButton stop = new JButton("Stop!");
stop.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent ae) {
closed();
}
});
add( stop );
validate();
Runnable r = new Runnable() {
public void run() {
try {
initialize();
} catch (IOException ex) {
ex.printStackTrace();
}
}
};
Thread t = new Thread(r);
t.start();
}
public void closed() {
System.out.println("Inside close");
closed=true;
try {
ss.close();
} catch(Exception e) {
e.printStackTrace();
}
}
public void initialize() throws IOException {
ss =new ServerSocket(5002);
while(!closed){
System.out.println("Waiting to accept request");
socket = ss.accept();
System.out.println("Request accepted");
}
}
}
运行
我在此版本中添加了一个按钮，以便您可以在没有 JavaScript 的情况下检查它是否按预期工作(在将 JS 加入混合之前，您应该使用自己的代码进行检查).AppletVewer 使用源代码顶部的单行注释将代码显示在屏幕上.像这样使用它:
Run
I have added a button to this version so that you can check it works as expected without JavaScript (which you should have checked with your own code before tossing JS into the mix). The single line comment at the top of the source is used by AppletVewer to put the code on-screen. Use it like this:
prompt> appletviewer Example.java
典型输出
Waiting to accept request
Inside close
java.net.SocketException: socket closed
at java.net.PlainSocketImpl.socketAccept(Native Method)
at java.net.PlainSocketImpl.accept(PlainSocketImpl.java:408)
at java.net.ServerSocket.implAccept(ServerSocket.java:462)
at java.net.ServerSocket.accept(ServerSocket.java:430)
at Example.initialize(Example.java:51)
at Example$2.run(Example.java:27)
at java.lang.Thread.run(Thread.java:662)
Tool completed successfully
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