java _io_文件读取标准步骤

Posted 2022-05-06

File f =new File("~"); //创建源
InputStream is =new FileInputStream(f); //选择流
is.read() 读取单个数据，并使游标下移 //操作(读取)
is.close() //释放资源,输入流读取后必须释放资源

public class test

public static void main(String[]args) 

    //创建源
    File f=new File("C:/Users/10853/eclipse-workspace/hell/src/hell/abc");
    InputStream is =null;//提升is的作用域，避免在try中声明后，作用域
                        //只在try，finally中语句无法执行
    //选择流
    try 
         is =new FileInputStream(f);
    //操作(读取)    
        int temp;
        while((temp=is.read())!=-1) //temp=is.read()表达式整体的值就是temp的值
                                   //is.read()会读取单个数据，当数据读取完毕时，返回-1
            System.out.println((char)temp);
        

     catch (FileNotFoundException e) 
        // TODO Auto-generated catch block
        e.printStackTrace();
     catch (IOException e) 
        // TODO Auto-generated catch block
        e.printStackTrace();
    finally
    
        try 
            if(null!=is)//当is创建成功时才执行关闭
            
                is.close();
            
         catch (IOException e) 
            // TODO Auto-generated catch block
            e.printStackTrace();