如何在现有文件中附加字符串？（How to append a string in an existing file?）

问题描述 (Problem Description)

如何将一个文件复制到另一个文件？

解决方案 (Solution)

此示例显示如何使用BufferedWriter类的读写方法将一个文件的内容复制到另一个文件中。

import java.io.*;
public class Main {
   public static void main(String[] args) throws Exception {
      BufferedWriter out1 = new BufferedWriter(new FileWriter("srcfile"));
      out1.write("string to be copied\n");
      out1.close();
      InputStream in = new FileInputStream(new File("srcfile"));
      OutputStream out = new FileOutputStream(new File("destnfile"));
      byte[] buf = new byte[1024];
      int len;
      while ((len = in.read(buf)) > 0) {
         out.write(buf, 0, len);
      }
      in.close();
      out.close();
      BufferedReader in1 = new BufferedReader(new FileReader("destnfile"));
      String str;
      while ((str = in1.readLine()) != null) {
         System.out.println(str);
      }
      in.close();
   }
}

结果 (Result)

上面的代码示例将产生以下结果。

string to be copied

以下是将一个文件复制到java中的另一个文件的另一个示例示例

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class CopyExample {
   public static void main(String[] args) {
      FileInputStream ins = null;
      FileOutputStream outs = null;
      try {
         File infile =new File("C:\\Users\\xnip7\\Desktop\\abc.txt");
         File outfile =new File("C:\\Users\\xnip7\\Desktop\\bbc.txt");
         ins = new FileInputStream(infile);
         outs = new FileOutputStream(outfile);
         byte[] buffer = new byte[1024];
         int length;
         while ((length = ins.read(buffer)) > 0) {
            outs.write(buffer, 0, length);
         } 
         ins.close();
         outs.close();
         System.out.println("File copied successfully!!");
      } catch(IOException ioe) {
         ioe.printStackTrace();
      } 
   }
}

上面的代码示例将产生以下结果。

File copied successfully!!