Java Web论坛小程序在小程序查看器中工作，但在浏览器中不工作_Java_Html_File_Security_Applet

Java Web论坛小程序在小程序查看器中工作，但在浏览器中不工作

java html file security

Java Web论坛小程序在小程序查看器中工作，但在浏览器中不工作,java,html,file,security,applet,Java,Html,File,Security,Applet,我在一个嵌入式小程序上遇到了问题，我已经工作了一段时间了。小程序的jar已签名，所有权限都已授予，并且在小程序查看器中运行良好。当加载到浏览器中时，只有一个带有错误标志的空白框，我的小程序应该在这个框中。单击时返回“java.lang.invocationtargetexception”。我使用基本的HTML格式嵌入小程序。下面是我用来显示它的HTML代码： <html> <body background="BG.png"> <a href="index.htm

我在一个嵌入式小程序上遇到了问题，我已经工作了一段时间了。小程序的jar已签名，所有权限都已授予，并且在小程序查看器中运行良好。当加载到浏览器中时，只有一个带有错误标志的空白框，我的小程序应该在这个框中。单击时返回“java.lang.invocationtargetexception”。我使用基本的HTML格式嵌入小程序。下面是我用来显示它的HTML代码：

<html>
<body background="BG.png">

<a href="index.html">Back to the index</a>

<center><h1>Web Forum</h1></center>
<center><table border = "0">

<tr>
<td><center><h3>Forums</h3></center></td>
<td width = 25></td>
<td width = 225><center><h3>Chatbox</h3></center></td>
</tr>

<tr>
<td><center><applet
code=Topics.class
archive=Topics.jar
width=750
height=1000 ><PARAM name="permissions" value="sandbox"></PARAM>
</applet></center></td>

<td width = 25></td>

<td width = 225 bgcolor = #00FF00><center><h3>Coming Soon</h3></center></td>
</tr>

</table></center>
</Body>
</Html>

以下是已签名jar的清单：

Manifest-Version: 1.0

Name: .classpath
SHA-256-Digest: IhqMeyTH+t/Wtxr+NP6B1f5GapLwQ67HJhYQ7UM+kA0=

Name: .project
SHA-256-Digest: Lw9C+yAb3p1vC6m2pwcjhv8TB1ET8xOYjM2sFlgIjIw=

Permissions: all-permissions
Codebase: http://25.2.202.42/

我看不出代码本身会导致错误的原因，但这里只是以防万一：

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

import java.applet.*;
import java.io.*;


@SuppressWarnings("serial")
public class Topics extends Applet {

String name;
String topics;
String paragraphs;
//reading file for existing posts
String fileread = "Topics.txt";
static String line = null;
{
try {
    FileReader fileReader = 
        new FileReader(fileread);

    BufferedReader bufferedReader = 
        new BufferedReader(fileReader);

    while((line = bufferedReader.readLine()) != null) {
        System.out.println(line);
    }   

    bufferedReader.close();         
}
catch(FileNotFoundException ex) {
    System.out.println(
        "Unable to open file '" + 
        fileread + "'");                
}
catch(IOException ex1) {
    System.out.println(
        "Error reading file '" 
        + fileread + "'");                  

}
}
static String display = line;

JPanel topicPanel;
JLabel title, username, topic, paragraph, topicsTitle, dtopicsTitle;
JTextField nameField, topicField;
JButton submitButton, topicrefreshButton;
JTextArea paragraphArea, topicArea;


public void init() {
    final JPanel topicGUI = new JPanel();
    topicGUI.setLayout(null);

    setBackground(Color.GREEN);

    setVisible(true);

    // JLabels

    JLabel title = new JLabel("                                                                           Make A Post                                                                           ");
    title.setSize(150, 25);
    title.setFont(new Font("Serif", Font.PLAIN, 25));
    title.setHorizontalAlignment(0);
    add(title);


    JLabel username = new JLabel("Username: ");
    username.setSize(70, 15);
    username.setHorizontalAlignment(0);
    add(username);

    // JTextField

    nameField = new JTextField(8);
    nameField.setSize(150, 18);
    add(nameField);

    // JLabel

    JLabel topic = new JLabel("Topic: ");
    topic.setSize(40, 15);
    topic.setHorizontalAlignment(0);
    add(topic);

    // JTextField

    topicField = new JTextField(8);
    topicField.setSize(180, 18);
    add(topicField);


    //JLabel

    JLabel paragraph = new JLabel("                                                                                          Paragraph:                                                                                          ");
    paragraph.setSize(70, 15);
    paragraph.setHorizontalAlignment(0);
    add(paragraph);

    // JTextAreas

    paragraphArea = new JTextArea(8, 5);
    paragraphArea.setSize(700, 100);
    paragraphArea.setLineWrap(true);
    paragraphArea.setEditable(true);
    add(paragraphArea);


    // JButton

    JButton submitButton = new JButton("SUBMIT");
    submitButton.setSize(100, 30);
    submitButton.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {

            name = nameField.getText();
            topics = topicField.getText();
            paragraphs = paragraphArea.getText();



            display ="\n" + "\t" + name + " - " + "\n" + "\t" + topics + " : " + "\n" + paragraphs + display + "\n";

            topicField.setText("");
            paragraphArea.setText("");

            //writing new info to file
            String fileName = "Topics.txt";

            try {
                FileWriter fileWriter =
                    new FileWriter(fileName);

                BufferedWriter bufferedWriter =
                    new BufferedWriter(fileWriter);

                bufferedWriter.write(display);

                bufferedWriter.close();
            }
            catch(IOException ex) {
                System.out.println(
                    "Error writing to file '"
                    + fileName + "'");
            }
            topicArea.setText(display);
        }
     });


add(submitButton);
JLabel dtopicsTitle = new JLabel("                                                                           Topics:                                                                           ");
dtopicsTitle.setLocation(170, 3);
dtopicsTitle.setSize(150,30);
dtopicsTitle.setFont(new Font("Serif", Font.PLAIN, 25));
dtopicsTitle.setHorizontalAlignment(0);
add(dtopicsTitle);


topicrefreshButton = new JButton("Refresh Topics");
topicrefreshButton.setLocation(250, 30);
topicrefreshButton.setSize(100, 30);
topicrefreshButton.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {

        topicArea.setText(display);

    }
});
add(topicrefreshButton);    


        topicArea = new JTextArea(40, 64);
        topicArea.setSize(650, 430);
        topicArea.setLineWrap(true);
        topicArea.setEditable(false);
        topicArea.setText(display);
        add(topicArea);
        JScrollPane topicScroll = new JScrollPane(topicArea);
        topicScroll.setSize(650,430);
        add(topicScroll);


}
}

感谢您提供的支持。

Applet

和

File

像油和水一样混合（即“不”）

不仅任何

文件

对象都不会指向您期望的位置（它们指向用户的本地文件系统，而不是服务器），而且小程序在使用文件之前需要经过数字签名和信任

小程序通常通过URL访问资源。如果URL可以相对于小程序的代码库、文档库或类路径形成，则它可以保持沙盒状态并仍然工作。否则，它将需要信任

其他提示

确保配置为显示小程序和JWS应用程序。如果默认级别没有输出，请提高该级别并重试

将形式为

catch（异常e）{..

的代码更改为

catch（异常e）{e.printStackTrace（）；//非常有用！。

Java GUI可能必须在多个平台上工作，在不同的屏幕分辨率和使用不同的PLAF。因此，它们不利于组件的精确放置。要为一个健壮的GUI组织组件，请使用布局管理器，或者与布局填充和边框配合使用

不要将Swing组件与AWT组件混用。（使用

JApplet

而不是

Applet

）

顺便说一句-现在浏览一下“代码之外的任何内容”，我注意到小程序确实是经过签名和信任的。但是无论如何都要使用

URL

。权限

和Codebase
不应该在主部分而不是它们自己的单独部分吗？（即，将其上移到清单版本，前面没有空行。）
import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

import java.applet.*;
import java.io.*;


@SuppressWarnings("serial")
public class Topics extends Applet {

String name;
String topics;
String paragraphs;
//reading file for existing posts
String fileread = "Topics.txt";
static String line = null;
{
try {
    FileReader fileReader = 
        new FileReader(fileread);

    BufferedReader bufferedReader = 
        new BufferedReader(fileReader);

    while((line = bufferedReader.readLine()) != null) {
        System.out.println(line);
    }   

    bufferedReader.close();         
}
catch(FileNotFoundException ex) {
    System.out.println(
        "Unable to open file '" + 
        fileread + "'");                
}
catch(IOException ex1) {
    System.out.println(
        "Error reading file '" 
        + fileread + "'");                  

}
}
static String display = line;

JPanel topicPanel;
JLabel title, username, topic, paragraph, topicsTitle, dtopicsTitle;
JTextField nameField, topicField;
JButton submitButton, topicrefreshButton;
JTextArea paragraphArea, topicArea;


public void init() {
    final JPanel topicGUI = new JPanel();
    topicGUI.setLayout(null);

    setBackground(Color.GREEN);

    setVisible(true);

    // JLabels

    JLabel title = new JLabel("                                                                           Make A Post                                                                           ");
    title.setSize(150, 25);
    title.setFont(new Font("Serif", Font.PLAIN, 25));
    title.setHorizontalAlignment(0);
    add(title);


    JLabel username = new JLabel("Username: ");
    username.setSize(70, 15);
    username.setHorizontalAlignment(0);
    add(username);

    // JTextField

    nameField = new JTextField(8);
    nameField.setSize(150, 18);
    add(nameField);

    // JLabel

    JLabel topic = new JLabel("Topic: ");
    topic.setSize(40, 15);
    topic.setHorizontalAlignment(0);
    add(topic);

    // JTextField

    topicField = new JTextField(8);
    topicField.setSize(180, 18);
    add(topicField);


    //JLabel

    JLabel paragraph = new JLabel("                                                                                          Paragraph:                                                                                          ");
    paragraph.setSize(70, 15);
    paragraph.setHorizontalAlignment(0);
    add(paragraph);

    // JTextAreas

    paragraphArea = new JTextArea(8, 5);
    paragraphArea.setSize(700, 100);
    paragraphArea.setLineWrap(true);
    paragraphArea.setEditable(true);
    add(paragraphArea);


    // JButton

    JButton submitButton = new JButton("SUBMIT");
    submitButton.setSize(100, 30);
    submitButton.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {

            name = nameField.getText();
            topics = topicField.getText();
            paragraphs = paragraphArea.getText();



            display ="\n" + "\t" + name + " - " + "\n" + "\t" + topics + " : " + "\n" + paragraphs + display + "\n";

            topicField.setText("");
            paragraphArea.setText("");

            //writing new info to file
            String fileName = "Topics.txt";

            try {
                FileWriter fileWriter =
                    new FileWriter(fileName);

                BufferedWriter bufferedWriter =
                    new BufferedWriter(fileWriter);

                bufferedWriter.write(display);

                bufferedWriter.close();
            }
            catch(IOException ex) {
                System.out.println(
                    "Error writing to file '"
                    + fileName + "'");
            }
            topicArea.setText(display);
        }
     });


add(submitButton);
JLabel dtopicsTitle = new JLabel("                                                                           Topics:                                                                           ");
dtopicsTitle.setLocation(170, 3);
dtopicsTitle.setSize(150,30);
dtopicsTitle.setFont(new Font("Serif", Font.PLAIN, 25));
dtopicsTitle.setHorizontalAlignment(0);
add(dtopicsTitle);


topicrefreshButton = new JButton("Refresh Topics");
topicrefreshButton.setLocation(250, 30);
topicrefreshButton.setSize(100, 30);
topicrefreshButton.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {

        topicArea.setText(display);

    }
});
add(topicrefreshButton);    


        topicArea = new JTextArea(40, 64);
        topicArea.setSize(650, 430);
        topicArea.setLineWrap(true);
        topicArea.setEditable(false);
        topicArea.setText(display);
        add(topicArea);
        JScrollPane topicScroll = new JScrollPane(topicArea);
        topicScroll.setSize(650,430);
        add(topicScroll);


}
}