Java Files copy()用法及代碼示例

java.nio.file.Files類的copy()方法用於將字節從文件複製到I /O流或從I /O流複製到文件。 I /O流是表示不同類型的源的輸入源或輸出目標，例如磁盤文件。

方法：根據傳遞的參數類型，Files類提供3種類型的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輸入，Path目標，CopyOption…選項)

此方法用於將所有字節從輸入流複製到文件。

參數：

in：將複製其數據的輸入流
目標：將數據複製到的文件的路徑
選項：描述數據複製方式的選項

返回類型：複製的字節數

異常：

IOException：如果在讀取或寫入時發生錯誤
FileAlreadyExistsException：如果目標文件已經存在並且不能被替換
DirectoryNotEmptyException：如果由於目標文件為非空目錄而無法替換目標文件
UnsupportedOperationException：如果不支持選項描述的應對方式
SecurityException：如果安全管理器拒絕對目標文件的寫訪問

實現方式：

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();
        }
    }
}

輸出：

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

方法2：使用copy(路徑源，OutputStream輸出)方法

此方法用於將所有字節從文件複製到輸出流。

參數：需要兩個

源：將要複製其數據的文件的路徑
out：將在其中寫入複製數據的輸出流

返回類型：複製的字節數

異常：

IOException：如果在讀取或寫入時發生錯誤
SecurityException：如果安全管理器拒絕對目標文件的讀取訪問

實現方式：

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();
        }
    }
}

輸出：

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

方法3：使用複製(路徑源，路徑目標，CopyOption…選項)

此方法用於將文件複製到目標文件。

參數：

源：將要複製其數據的文件的路徑
目標：將數據複製到的文件的路徑
選項：描述數據複製方式的選項

返回類型：複製數據的文件的路徑

異常：

IOException：如果在讀取或寫入時發生錯誤
FileAlreadyExistsException：如果目標文件已經存在並且不能被替換
DirectoryNotEmptyException：如果由於目標文件為非空目錄而無法替換目標文件
UnsupportedOperationException：如果不支持選項描述的應對方式
SecurityException：如果安全管理器拒絕對目標文件的寫訪問

實現方式：

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();
        }
    }
}

輸出：

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

相關用法

注：本文由純淨天空篩選整理自abhinavjain194大神的英文原創作品 Files copy() Method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。