如何使用FileInputStream访问jar中的txt文件？

Question

我知道这个getResourceAsStream()方法,但解析器读取文件存在问题,整个结构实现为期望a FileInputStream()并getResourceAsStream()返回无法转换的输入流.对于这种情况,有没有简单的"修复"？

Answer 1

JAR文件中包含的资源本身不是文件,无法使用a读取FileInputStream.如果您有完全需要的代码FileInputStream,那么您需要使用数据提取getResourceAsStream(),将其复制到临时文件中,然后FileInputStream将该临时文件传递给您的代码.

当然,在将来,永远不要编写代码来期待具体的实现,比如InputStream,你总会后悔的.

Answer 2

我最近遇到了同样的问题.我们使用的第三方库从FileInputStream读取,但资源可以是JAR或远程中的任何位置.我们曾经写过临时文件,但是开销太大了.

一个更好的解决方案是编写一个包装InputStream的FileInputStream.这是我们使用的课程,

public class VirtualFileInputStream extends FileInputStream {

    private InputStream stream;

    public VirtualFileInputStream(InputStream stream) {
        super(FileDescriptor.in); // This will never be used
        this.stream = stream;
    }




    public int available() throws IOException {
        throw new IllegalStateException("Unimplemented method called");
    }


    public void close() throws IOException {
        stream.close();
    }


    public boolean equals(Object obj) {
        return stream.equals(obj);
    }


    public FileChannel getChannel() {
        throw new IllegalStateException("Unimplemented method called");
    }


    public int hashCode() {
        return stream.hashCode();
    }


    public void mark(int readlimit) {
        stream.mark(readlimit);
    }


    public boolean markSupported() {
        return stream.markSupported();
    }


    public int read() throws IOException {
        return stream.read();
    }


    public int read(byte[] b, int off, int len) throws IOException {
        return stream.read(b, off, len);
    }


    public int read(byte[] b) throws IOException {
        return stream.read(b);
    }


    public void reset() throws IOException {
        stream.reset();
    }


    public long skip(long n) throws IOException {
        return stream.skip(n);
    }


    public String toString() {
        return stream.toString();
    }

}