FileWriter和jar文件 - 找不到资源

Question

我最近写了一个程序.文件处理类是下一个:

package smartest.eu;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class Processor {
    private BufferedWriter out;
    private BufferedReader in;

    // this method opens the file for reading!
    public void openWriter() throws Exception {
        if (out == null) {
            try {
                out = new BufferedWriter(new FileWriter(new File("src/personaldata.txt")));
            }
            catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        else {
            throw new Exception("Writer opened already");
        }
    }

    // this method opens the reader
    public void readWriter() throws Exception {
        if (in == null) {
            try {
                in = new BufferedReader(new FileReader("src/personaldata.txt"));
                in.mark(65538);
            }
            catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        else {
            throw new Exception("Reader already opened");
        }
    }

    // this method reads the file line by line outputting a string as the result
    public String readText() throws Exception {
        String answer1 = "";
        if (in != null) {
            try {
                if ((answer1 = in.readLine()) != null) {
                    answer1 += "\n";
                }
                else {
                    answer1 = "No more data!\nThe stream will be read from the beginning!\n";
                }
            }
            catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        else {
            throw new Exception("Open file for reading at first");
        }

        return answer1;
    }

    // this method writes the given string to a file
    public void writeText(String a) throws Exception {
        if (out != null) {
            out.write(a);
            out.flush();
        }
        else {
            throw new Exception("Open file for writing at first");
        }
    }

    public void resitStream() {
        try {
            in.reset();
        }
        catch (Exception ex) {
            ex.printStackTrace();
        }
    }

}

目录结构processor.jar:

1) manifest
2) personaldata.txt
3) smartest/eu/*.class

但是当我制作jar文件时,它无法找到该文件(提供"File not found exception").我该怎么办呢？PS你能不能提一下这个问题的内容 - 为什么.jar文件在罐子里面不可用？

Answer 1

这条线

new FileReader("src/personaldata.txt")

尝试在当前目录personaldata.txt的子目录src中打开该文件.当前目录是在命令提示符中启动java命令时的目录.因此,如果您进入c:\并启动java -jar the/path/to/myJar.jar,它将在c:\ src\personaldata.txt中搜索该文件.

因此,文件用于访问文件系统.jar里面没有资源.要从类路径加载资源,必须使用

Processor.class.getResourceAsStream("/personaldata.txt")

查看此方法的javadoc以了解其工作原理.

请注意,写入jar中的文件是不可能的.