java文件操作

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1.读文件

 <span style="color:#FF0000;">File file = new File("d:/test.txt");  </span>    <span style="color:#FF0000;"> InputStream in = null;  </span>        try {              System.out.println("以字节为单位读取文件内容，一次读一个字节：");              // 一次读一个字节             <span style="color:#FF0000;"> in = new FileInputStream(file); </span>             int tempbyte;              <span style="color:#FF0000;">while ((tempbyte = in.read()) != -1) {                  System.out.println(tempbyte);              }              in.close();  </span>        } catch (IOException e) {              e.printStackTrace();              return;          }

2.写文件

 <span style="color:#FF0000;"> File file = new File("d:/test.txt");                           String str = "亲爱的小南瓜！";          byte bt[] = new byte[1024];          bt = str.getBytes();  </span>        try {            <span style="color:#FF0000;">  FileOutputStream in = new FileOutputStream(file);  </span>            try {                <span style="color:#FF0000;">  in.write(bt);                  in.close();                 </span> // boolean success=true;                  // System.out.println("写入文件成功");              } catch (IOException e) {                  // TODO Auto-generated catch block                  e.printStackTrace();              }          } catch (FileNotFoundException e) {              // TODO Auto-generated catch block              e.printStackTrace();          }

3.判断文件是否存在，如果不存在创建新文件

   <span style="color:#FF0000;"> File file=new File(path+filename); </span>          if(<span style="color:#FF0000;">!file.exists()</span>)           {               try {                  <span style="color:#FF0000;"> file.createNewFile(); </span>              } catch (IOException e) {                   // TODO Auto-generated catch block                   e.printStackTrace();               }           }

4.判断文件夹是否存在，如果不存在创建新文件夹

    <span style="color:#FF0000;">File file =new File(path+filename);   </span>    //如果文件夹不存在则创建       if  (<span style="color:#FF0000;">!file .exists()</span>)         {            <span style="color:#FF0000;"> file .mkdir();  </span>     }

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