package com.jiajia.filedemo;

 import java.io.BufferedReader;

 import java.io.BufferedWriter;

 import java.io.File;

 import java.io.FileInputStream;

 import java.io.FileOutputStream;

 import java.io.FileReader;

 import java.io.FileWriter;

 import java.io.InputStreamReader;

 import java.io.OutputStreamWriter;

 public class Demo_1 {

         public static void main(String[] args) throws Exception{

         String filename_input = "/Users/fanjiajia/Desktop/temp";

         String filename_output = "/Users/fanjiajia/Desktop/temp2.txt";//若temp1不存在，他会自己给你创建一个

         String str = read_1(filename_input);

         System.out.println(str);

         writer_2(str, filename_output);

     }

     /**

      *文件读取方法一

      * @param filename

      * @return

      * @throws Exception

      */

     public static String read_1(String filename) throws Exception{

         File f = new File(filename);

         FileInputStream f_in = new FileInputStream(f);

         InputStreamReader isr = new InputStreamReader(f_in);

         BufferedReader buf_reader = new BufferedReader(isr);

         String s;

         StringBuilder sb = new StringBuilder();

         while((s=buf_reader.readLine())!=null){

             sb.append(s+"\n");

         }

         buf_reader.close();

         isr.close();

         f_in.close();

         return sb.toString();

     }

     /**

      * 文件读取方法二

      * @param filename

      * @return

      * @throws Exception

      */

     public static String read_2(String filename) throws Exception {

         FileReader filereader = new FileReader(filename);

         BufferedReader in = new BufferedReader(filereader);

         String s ;

         StringBuilder sb = new StringBuilder();

         while((s=in.readLine())!=null){

             sb.append(s+"\n");

         }

         in.close();

         filereader.close();

         return sb.toString();

     }

     /**

      * 文件写入方法一

      * @param str

      * @param filename

      * @throws Exception

      */

     public static void writer_1(String str,String filename    ) throws Exception{

         //将给定的字符串输出到filename文件中

         FileWriter f_writer = new FileWriter(filename);

         BufferedWriter buf_writer = new BufferedWriter(f_writer);

         buf_writer.write(str);

         buf_writer.close();

         f_writer.close();

     }

     /**

      * 文件写入方法二

      * @param str

      * @param filename

      * @throws Exception

      */

     public static void writer_2(String str,String filename) throws Exception{

         File f = new File(filename);

         FileOutputStream f_os = new FileOutputStream(f);

         OutputStreamWriter os  = new OutputStreamWriter(f_os);

         BufferedWriter buf_writer = new BufferedWriter(os);

         buf_writer.write(str);

         buf_writer.close();

         os.close();

         f_os.close();

     }

 }