JAVA 编译器 API - 无法找到外部类文件

Question

我有一个简单的代码来制作Java代码编译器

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import javax.tools.*;
import java.io.*;
import java.util.*;

public class Compiler extends JFrame
{
    String loc="D:\\java";
    File file=null,
         dir=null;
    boolean success;
    public Compiler()
    {
        super("Highlight example");
        try 
        {
            UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
        } 
        catch (Exception evt) {}
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new GridLayout(1,2));

        JTextPane textPane = new JTextPane();
        JTextArea debug=new JTextArea();
        JButton comp=new JButton("Compile"),
                browse=new JButton("...");

        JTextArea location=new JTextArea();

        JPanel right=new JPanel(),
               up=new JPanel();

        up.setLayout(new BorderLayout());
        up.add(new JScrollPane(location),"Center");
        up.add(browse,"East");

        right.setLayout(new BorderLayout(2,1));
        right.add(up,BorderLayout.NORTH);
        right.add(new JScrollPane(textPane), "Center");
        right.add(comp,"South");
        add(right);
        add(new JScrollPane(debug));
        setSize(800, 400);
        setVisible(true);

        browse.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                success=false;
                UIManager.put("FileChooser.readOnly", Boolean.TRUE);
                JFileChooser fc = new JFileChooser(loc);
                int status = fc.showOpenDialog(new JFrame());
                if (status==JFileChooser.APPROVE_OPTION)
                {
                    debug.setText("");
                    file = fc.getSelectedFile();
                    dir = fc.getCurrentDirectory();
                    try
                    {
                        textPane.read(new FileReader(file), null);
                    }
                    catch(Exception ex)
                    {

                    }
                }
            }
        });

        comp.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                try
                    {   
                        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
                        DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<JavaFileObject>();
                        StandardJavaFileManager fileManager = compiler.getStandardFileManager(diagnostics, null, null);
                        Iterable<? extends JavaFileObject> compilationUnits = fileManager.getJavaFileObjectsFromStrings(Arrays.asList(file+""));
                        String[] option=new String[]{"-g","-parameters"};
                        Iterable<String> options = Arrays.asList(option);
                        JavaCompiler.CompilationTask task=null;

                        fileManager.setLocation(javax.tools.StandardLocation.CLASS_OUTPUT, Arrays.asList(dir));

                        task = compiler.getTask(null, fileManager, diagnostics, options, null, compilationUnits);
                        success = task.call();

                        fileManager.close();
                 //     System.out.println("Success: " + success);
                        if(success==true)
                        {
                            debug.setText("Success");
                        }
                        else
                        {
                            int i=1;
                            for (Diagnostic diagnostic : diagnostics.getDiagnostics())
                                if(diagnostic.getLineNumber()!=-1)
                                    debug.append("Error on line "+diagnostic.getLineNumber()+" in "+ diagnostic+"\n");
                        }
                    }
                    catch(Exception ex)
                    {

                    }
            }
        });
    }

    public static void main(String[]args)
    {
        new Compiler();
    }
}

我不知道为什么编译器找不到以前的代码结果。我不知道如何解决这个问题。

有关更多详细信息，我做了一个示例:

1. 选择A.java

2. A.java的内容

3. 然后我选择了 B.java。看看A.java已经用create A.class编译好了

4. B.java 无法编译，因为找不到 class A

并且在包文件夹中也找不到类。

这里是示例 2:

A.java已使用创建文件夹 <path>\a\b 进行编译

并使用导入访问类

我有一些尝试

来自:

fileManager.setLocation(javax.tools.StandardLocation.CLASS_OUTPUT, Arrays.asList(dir));

至:

fileManager.setLocation(javax.tools.StandardLocation.CLASS_PATH, Arrays.asList(dir));

但它不起作用

Answer 1

除了设置 javax.tools.StandardLocation.CLASS_OUTPUT 之外，您还需要设置 javax.tools.StandardLocation.CLASS_PATH 以包含之前放置的相同位置输出:

fileManager.setLocation(javax.tools.StandardLocation.CLASS_OUTPUT, Arrays.asList(dir));
// Set dirClassPath to include dir, and optionally other locations
fileManager.setLocation(javax.tools.StandardLocation.CLASS_PATH, Arrays.asList(dirClassPath));