FileReader/FileWriter複製文件(分別按字符和字符數組複製)

package unittest;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

/**

• @author Dylaniou

• 讀取字符數組的效率顯然要比讀取字符效率高很多
  */
  public class CopyFile {
  public static void main(String[] args) throws IOException {
  FileReader fr = new FileReader(“E:\a\b\copyfrom.txt”);
  FileWriter fw = new FileWriter(“E:\a\b\copyto.txt”);

   FileReader fr1 = new FileReader("E:\\a\\b\\copyfrom1.txt");
   FileWriter fw1 = new FileWriter("E:\\a\\b\\copyto1.txt");
   
   FileReader fr2 = new FileReader("E:\\a\\b\\copyfrom2.txt");
   FileWriter fw2 = new FileWriter("E:\\a\\b\\copyto2.txt");
   
   FileReader fr3 = new FileReader("E:\\a\\b\\copyfrom3.txt");
   FileWriter fw3 = new FileWriter("E:\\a\\b\\copyto3.txt");
   
   method1(fr, fw);//一次讀取一個字符
   method2(fr1, fw1);//一次讀取一個字符數組
   method3(fr2, fw2);//緩衝區字符讀寫
   method4(fr3, fw3);//緩衝區字符數組讀寫
   fr.close();
   fw.close();
  

  }

  /**

  • 一次讀取一個字符
  • @param fr
  • @param fw
  • @throws IOException
    */
    private static void method1(FileReader fr, FileWriter fw) throws IOException {
    // TODO Auto-generated method stub
    long t1 = System.currentTimeMillis();
    int ch;
    while((ch = fr.read())!=-1){
    fw.write(ch);
    }
    fw.flush();
    long t2 = System.currentTimeMillis();
    getTime(“File字符”,t1,t2);
    }

  /**

  • 一次讀取一個字符數組
  • @param fr
  • @param fw
  • @throws IOException
    */
    private static void method2(FileReader fr, FileWriter fw) throws IOException {
    // TODO Auto-generated method stub
    long t1 = System.currentTimeMillis();
    char[] ch = new char[1024];
    int len;
    while((len = fr.read(ch))!=-1){
    fw.write(ch,0,len);
    }
    fw.flush();
    long t2 = System.currentTimeMillis();
    getTime(“File字符數組”,t1,t2);
    }

  /**

  • 緩衝區字符讀寫
  • @param fr
  • @param fw
  • @throws IOException
    */
    private static void method3(FileReader fr, FileWriter fw) throws IOException {
    // TODO Auto-generated method stub
    long t1 = System.currentTimeMillis();
    BufferedReader br = new BufferedReader(fr);
    BufferedWriter bw = new BufferedWriter(fw);
    int c;
    while((c = br.read())!=-1){
    bw.write©;
    }
    bw.flush();
    long t2 = System.currentTimeMillis();
    getTime(“Buffered字符”,t1,t2);
    }

  /**

  • 緩衝區字符數組讀寫
  • @param fr
  • @param fw
  • @throws IOException
    */
    private static void method4(FileReader fr, FileWriter fw) throws IOException {
    // TODO Auto-generated method stub
    long t1 = System.currentTimeMillis();
    BufferedReader br = new BufferedReader(fr);
    BufferedWriter bw = new BufferedWriter(fw);
    char[] ch = new char[1024];
    int len;
    while((len = br.read(ch))!=-1){
    bw.write(ch,0,len);
    }
    bw.flush();
    long t2 = System.currentTimeMillis();
    getTime(“Buffered字符數組”,t1,t2);
    }

  private static void getTime(String methodName,long t1, long t2){
  System.out.println(methodName+ “耗時：” + (t2-t1) + “ms”);
  }

}