Java Files copy()用法及代码示例

java.nio.file.Files类的copy()方法用于将字节从文件复制到I /O流或从I /O流复制到文件。 I /O流是表示不同类型的源的输入源或输出目标，例如磁盘文件。

方法：根据传递的参数类型，Files类提供3种类型的copy()方法。

使用copy(InputStream in, Path target, CopyOption… options)方法
使用copy(Path source, OutputStream out)方法
使用copy(Path source, Path target, CopyOption… options)方法

方法1：使用copy(InputStream输入，Path目标，CopyOption…选项)

此方法用于将所有字节从输入流复制到文件。

参数：

in：将复制其数据的输入流
目标：将数据复制到的文件的路径
选项：描述数据复制方式的选项

返回类型：复制的字节数

异常：

IOException：如果在读取或写入时发生错误
FileAlreadyExistsException：如果目标文件已经存在并且不能被替换
DirectoryNotEmptyException：如果由于目标文件为非空目录而无法替换目标文件
UnsupportedOperationException：如果不支持选项描述的应对方式
SecurityException：如果安全管理器拒绝对目标文件的写访问

实现方式：

示例

Java


// Impoerting classes from java.nio package as
// this package is responsible for network linking
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
  
// Main Class
public class GFG {
  
    // Main driver method
    public static void main(String[] args)
    {
        // Input custom string
        String text = "geeksforgeeks";
  
        // Path of the file where data is to be copied
        Path path = (Path)Paths.get("/usr", "local", "bin",
                                    "fileIn.txt");
  
        System.out.println("Path of target file:"
                           + path.toString());
  
        // Byte stream whose data is to be copied
        InputStream in
            = new ByteArrayInputStream(text.getBytes());
  
        // Try block to check for exceptions
        try {
  
            // Printing number of copied bytes
            System.out.println(
                "Number of bytes copied:"
                + Files.copy(
                    in, path,
                    StandardCopyOption.REPLACE_EXISTING));
        }
  
        // Catch block to handle the exceptions
        catch (IOException e) {
  
            // Print the line number where exception occured
            e.printStackTrace();
        }
    }
}

输出：

Path of target file:/usr/local/bin/fileIn.txt
Number of bytes copied:13

方法2：使用copy(路径源，OutputStream输出)方法

此方法用于将所有字节从文件复制到输出流。

参数：需要两个

源：将要复制其数据的文件的路径
out：将在其中写入复制数据的输出流

返回类型：复制的字节数

异常：

IOException：如果在读取或写入时发生错误
SecurityException：如果安全管理器拒绝对目标文件的读取访问

实现方式：

示例

Java


// Impoerting classes from java.nio package as
// this package is responsible for network linking
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
  
// Main Class
public class GFG {
  
    // Main driver method
    public static void main(String[] args)
    {
  
        // Path of file whose data is to be copied
        Path path = (Path)Paths.get("/usr", "local", "bin",
                                    "fileOut.txt");
  
        // Getting the path of source file
        System.out.println("Path of source file:"
                           + path.toString());
  
        // Output stream where data is to written
        OutputStream out = new ByteArrayOutputStream();
  
        // Try block to check for exceptions
        try {
            // Printing number of copied bytes
            System.out.println("Number of bytes copied:"
                               + Files.copy(path, out));
        }
  
        // Catch block to handle the exception
        catch (IOException e) {
  
            // Print the line number where exception occured
            e.printStackTrace();
        }
    }
}

输出：

Path of source file:/usr/local/bin/fileOut.txt
Number of bytes copied:13

方法3：使用复制(路径源，路径目标，CopyOption…选项)

此方法用于将文件复制到目标文件。

参数：

源：将要复制其数据的文件的路径
目标：将数据复制到的文件的路径
选项：描述数据复制方式的选项

返回类型：复制数据的文件的路径

异常：

IOException：如果在读取或写入时发生错误
FileAlreadyExistsException：如果目标文件已经存在并且不能被替换
DirectoryNotEmptyException：如果由于目标文件为非空目录而无法替换目标文件
UnsupportedOperationException：如果不支持选项描述的应对方式
SecurityException：如果安全管理器拒绝对目标文件的写访问

实现方式：

示例

Java


// Impoerting classes from java.nio package as
// this package is responsible for network linking
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
  
// Main Class
public class GFG {
  
    // Main driver method
    public static void main(String[] args)
    {
        // Path of file where data is to copied
        Path pathIn = (Path)Paths.get("/usr", "local",
                                      "bin", "fileIn.txt");
        // Path of file whose data is to be copied
        Path pathOut = (Path)Paths.get(
            "/usr", "local", "bin", "fileOut.txt");
  
        System.out.println("Path of target file:"
                           + pathIn.toString());
  
        System.out.println("Path of source file:"
                           + pathOut.toString());
  
        // Try block to check for exceptions
        try {
  
            // Printing number of bytes copied
            System.out.println(
                "Number of bytes copied:"
                + Files.copy(
                    pathOut, pathIn,
                    StandardCopyOption.REPLACE_EXISTING));
        }
  
        // Catch block to handle the exceptions
        catch (IOException e) {
  
            // Print the line number where exception occured
            e.printStackTrace();
        }
    }
}

输出：

Path of target file:/usr/local/bin/fileIn.txt
Path of source file:/usr/local/bin/fileOut.txt
Number of bytes copied:13

相关用法

注：本文由纯净天空筛选整理自abhinavjain194大神的英文原创作品 Files copy() Method in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。