Java中IO流操作文件总结

IO流操作文件总结

拷贝文件

package com.cloud.day1;
import Java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class Demo1 {
   public static void main(String[] args) {
      try {
         File inputFile = new File("E:/baidu.html");
         if(!inputFile.exists()){
            System.out.println("源文件不存在！");
            System.exit(1);
         }
         File outputFile = new File("E:/test.html");
         FileInputStream inputStream = new FileInputStream(inputFile);
         FileOutputStream outputStream = new FileOutputStream(outputFile);
         byte data[]=new byte[1024];
         int temp = 0;
         while((temp=inputStream.read(data))!=-1){
            outputStream.write(data);
         }
         inputStream.close();
         outputStream.close();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

文件内容查找

package com.cloud.day1;
import java.io.BufferedReader;
import java.io.FileReader;
public class Demo2 {
   public static void main(String[] args) {
      String fileName = "E:/test.txt";
      String line;
      int num=0,space=0,str=0;
      try {
         BufferedReader reader = new BufferedReader(new FileReader(fileName));
         while((line=reader.readLine())!=null){
            char[] ch = line.toCharArray();
            for(int i=0;i<ch.length;i++){
                if(Character.isLetter(ch[i])){
                   str++;
                }else if(Character.isWhitespace(ch[i])){
                   space++;
                }else if(Character.isDigit(ch[i])){
                   num++;
                }
            }
         }
         reader.close();
         System.out.println("num="+num+";space="+space+";str="+str);
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

文件内容搜索

package com.cloud.day1;
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Demo3 {
   public static void main(String[] args) {
      try {
         StringBuffer stringBuffer = new StringBuffer();
         BufferedReader reader = new BufferedReader(new FileReader("E:/test.txt"));
         while(true){
            String str = reader.readLine();
            if(str==null){break;}
            stringBuffer.append(str);
         }
         Pattern p = Pattern.compile("he");
         Matcher m = p.matcher(stringBuffer);
         int count = 0;
         while(m.find()){
            count++;
         }
         System.out.println("count="+count);
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

文件读取方式

package com.cloud.day1;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.InputStream;
import java.io.Reader;
/**
 * 文件读取的三种方式
 */
public class Demo4 {
   public static void main(String[] args) {
      try {
         File file = new File("E:/test.txt");
         //第一种读取方式
         InputStream inputStream = new FileInputStream(file);
         byte[] b = new byte[Integer.parseInt(file.length()+"")];
         inputStream.read(b);
         inputStream.close();
         System.out.println("b="+b);
         //第二种读取方式
         Reader reader = new FileReader(file);
         char[] r = new char[(int)file.length()];
         reader.read(r);
         System.out.println(new String(r));
         r.clone();
         //第三种读取方式
         BufferedReader bufferedReader = new BufferedReader(new FileReader("E:/test.txt"));
         StringBuffer buffer = new StringBuffer();
         String str;
         while(true){
            str = bufferedReader.readLine();
            if(str==null){break;}
            buffer.append(str);
         }
         System.out.println(buffer);
         bufferedReader.close();
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

文件写入方式

package com.cloud.day1;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.OutputStream;
import java.io.PrintWriter;
public class Demo5 {
   public static void main(String[] args) {
      try {
         File file = new File("E:/test.txt");
         OutputStream outputStream = new FileOutputStream(file);
         BufferedWriter writer = new BufferedWriter(new FileWriter(file));
         PrintWriter printWriter = new PrintWriter(file);
         //方式一
         outputStream.write("hello".getBytes());
         //方式二
         writer.write("AnHui");
         //方式三
         printWriter.write("Hello,AnHui");
         printWriter.close();
         writer.close();
         outputStream.close();
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

边读边写

package com.cloud.day1;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
public class Demo6 {
   public static void main(String[] args) {
      try{
         File inputfile = new File("E:/test.txt");
         File outputfile = new File("E:/test1.txt");
         BufferedReader bufferedReader = new BufferedReader(new FileReader(inputfile));
         BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(outputfile));
         String str = null;
         while((str=bufferedReader.readLine())!=null){
            bufferedWriter.write(str);
         }
         bufferedWriter.close();
         bufferedReader.close();
      } catch(Exception e){
         e.printStackTrace();
      }
   }
}