Java文件复制失败

要解决Java文件复制失败的问题，可以尝试以下方法：

1. 使用Java的标准库提供的文件复制方法：

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;

public class FileCopyExample {
    public static void main(String[] args) {
        File sourceFile = new File("source.txt");
        File destinationFile = new File("destination.txt");

        try {
            Files.copy(sourceFile.toPath(), destinationFile.toPath(), StandardCopyOption.REPLACE_EXISTING);
            System.out.println("File copied successfully.");
        } catch (IOException e) {
            System.err.println("Failed to copy file: " + e.getMessage());
        }
    }
}

2. 检查源文件和目标文件是否存在：

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;

public class FileCopyExample {
    public static void main(String[] args) {
        File sourceFile = new File("source.txt");
        File destinationFile = new File("destination.txt");

        if (!sourceFile.exists()) {
            System.err.println("Source file does not exist.");
            return;
        }

        try {
            Files.copy(sourceFile.toPath(), destinationFile.toPath(), StandardCopyOption.REPLACE_EXISTING);
            System.out.println("File copied successfully.");
        } catch (IOException e) {
            System.err.println("Failed to copy file: " + e.getMessage());
        }
    }
}

3. 检查文件读取和写入权限：

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;

public class FileCopyExample {
    public static void main(String[] args) {
        File sourceFile = new File("source.txt");
        File destinationFile = new File("destination.txt");

        if (!sourceFile.canRead()) {
            System.err.println("No read permission for source file.");
            return;
        }

        if (!destinationFile.canWrite()) {
            System.err.println("No write permission for destination file.");
            return;
        }

        try {
            Files.copy(sourceFile.toPath(), destinationFile.toPath(), StandardCopyOption.REPLACE_EXISTING);
            System.out.println("File copied successfully.");
        } catch (IOException e) {
            System.err.println("Failed to copy file: " + e.getMessage());
        }
    }
}

请根据您的具体情况选择适合的解决方法，并确保源文件存在、目标文件可写，并具有正确的读取和写入权限。