文件读取，写入与遇到的问题

package com.java.test;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class FileTest {
    
    private static String path = "D:\\";

    
    public static void main(String[] args) {
        String fileContent = readFile();
        writeFile(fileContent);
    }
    
    public static String readFile(){
        String fileContent = "";
        FileInputStream fileInputStream = null;
        InputStreamReader  inputStreamReader = null;
        BufferedReader bufferedReader = null;
        File file = null;
        try {
            file = isExitFile("x","txt");
        } catch (IOException e1) {
            System.out.println("创建文件失败");
            e1.printStackTrace();
        }
        try {
            fileInputStream = new FileInputStream(file);
            inputStreamReader = new InputStreamReader(fileInputStream,"utf-8");
            bufferedReader = new BufferedReader(inputStreamReader);
            String readLine = null;
            while ((readLine = bufferedReader.readLine())!=null) {
                fileContent  += readLine;
            }
        } catch (Exception e) {
            System.out.println("读取错误");
        }finally {
            try {
                fileInputStream.close();
                inputStreamReader.close();
                bufferedReader.close();
            } catch (IOException e) {
                System.out.println("关闭失败");
                e.printStackTrace();
            }
        }
        return fileContent;
    }
    
    public static void writeFile(String fileContent){
        File file = null;
        FileOutputStream fileOutputStream = null;
        OutputStreamWriter outputStreamWriter = null;
        BufferedWriter bufferedWriter = null;
        
        try {
            file = isExitFile("y", "txt");
        } catch (IOException e) {
            System.out.println("创建文件失败");
            e.printStackTrace();
        }
        
        try {
            fileOutputStream = new FileOutputStream(file);
            outputStreamWriter = new OutputStreamWriter(fileOutputStream, "utf-8");
            bufferedWriter = new BufferedWriter(outputStreamWriter);
            bufferedWriter.write(fileContent);
            bufferedWriter.flush();
        } catch (Exception e) {
            System.out.println("写入文件失败");
        }finally{
            try {
                fileOutputStream.close();
                outputStreamWriter.close();
                bufferedWriter.close();
            } catch (IOException e) {
                System.out.println("关闭失败");
                e.printStackTrace();
            }
        }
        
    }
    
    //判断文件是否存在，若不存在则创建
    public static File isExitFile(String fileName,String fileType) throws IOException{
        String filePath = path+fileName+"."+fileType;
        File file = null;
        file = new File(filePath);
        if(!file.exists()){
            System.out.println("文件名为"+fileName+"不存在");
            file.createNewFile();
        }else{
            System.out.println("文件名为"+fileName+"存在");
        }
        return file;
    }
}
　　

 

    1.path变量中用\\的原因：
        是将\转义，如使用\回报编译的错误
        


    2.编码不同，文件也不同，若文件夹中有ISO-8859-1的文件
      
        File file = new File("D:\\test.txt","UTF-8");
        这样定义会报如下错误
        java.io.IOException: 系统找不到指定的路径。

    3.将内容读入文件中时读不进去
       bufferedWriter.write(fileContent);
       需要在结尾时关闭流或对流进行刷新
  
注：关闭流会先刷新流，再关闭