java 数据流DataOutputStream和DataInputstream

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应用实例

import java.io.*;

public class DataStreamDemo
{
public static void main(String[] args)
  {
try 
    {
DataOutputStream out=new DataOutputStream(new FileOutputStream("F:\\workspace\\JavaPrj\\test.txt"));
double[] prices={18.99,9.22,14.22,5.22,4.21};
int[] units={10,10,20,39,40};
String[] descs={"bike","book","boat","boot","bus"};
for(int i=0;i<prices.length;i++)
      {
try 
        {
out.writeDouble(prices[i]);
out.writeChar('\t');
out.writeInt(units[i]);
out.writeChar('\t');
out.writeChars(descs[i]);
out.writeChar('\n');
        } 
catch (IOException e) 
        {
// TODO Auto-generated catch block
e.printStackTrace();
        }

      }
try 
      {
out.close();
      } 
catch (IOException e) 
      {
// TODO Auto-generated catch block
e.printStackTrace();
      }
    } 
catch (FileNotFoundException e) 
    {
// TODO Auto-generated catch block
e.printStackTrace();
    }

try 
    {
DataInputStream in=new DataInputStream(new FileInputStream("F:\\workspace\\JavaPrj\\test.txt"));
double prices;
int num;
StringBuffer name;
char chr;
int len;

try 
      {
while(true)
        {
len=5;
name=new StringBuffer();
prices=in.readDouble();
in.readChar();
num=in.readInt();
in.readChar();
while((chr=in.readChar())!='\n')
          {
name.append(chr);
          }
//double类型转String类型以及加入空格对齐的方法
System.out.println("产品名称："+name+"\t价格："+prices+getBlanks(len-Double.toString(prices).length())+"\t数量："+num);
        } 
      }
catch (IOException e) 
      {
// TODO Auto-generated catch block
e.printStackTrace();
      }
    } 
catch (FileNotFoundException e) 
    {
// TODO Auto-generated catch block
e.printStackTrace();
    }
  }
//加入空格进行对齐操作
public static String getBlanks(int n)
  {
String str="";
while(n>0)
    {
str+=" ";
n--;
    }
return str;
  }
}