datatest.java

java应用开发详解

import java.io.*;

public class dataTest
{
	public static void main(String[] args) throws IOException 
	{
		// 将数据写入某一种载体
        	DataOutputStream out = new DataOutputStream(new
				   FileOutputStream("invoice1.txt"));

        	//价格
        	double[] prices = { 19.99, 9.99, 15.99, 3.99, 4.99 };
        	//数目
        	int[] units = { 12, 8, 13, 29, 50 };
        	//描述
        	String[] descs = { "Java T-shirt",
			   	   "Java Mug",
			   	   "Duke Juggling Dolls",
			           "Java Pin",
			           "Java Key Chain" };
        
        	//向数据过滤流写入主要类型
        	for (int i = 0; i < prices.length; i ++) 
        	{
            		//写入价格
            		//注意为了明了起见，使用tab隔开数据
            		out.writeDouble(prices[i]);
            		out.writeChar('\t');
            		//写入数目
            		out.writeInt(units[i]);
            		out.writeChar('\t');
            		//写入描述
            		//行尾加入换行符
            		out.writeChars(descs[i]);
            		out.writeChar('\n');
        	}
        	out.close();

        	// 将数据读出
        	DataInputStream in = new DataInputStream(new
				 FileInputStream("invoice1.txt"));

        	double price;
        	int unit;
        	StringBuffer desc;
        	double total = 0.0;

        	try 
        	{
            		//当文本被全部读出以后会抛出EOFException例外，中断循环
            		while (true) 
            		{
                		//读出价格
                		price = in.readDouble();
                		//跳过tab
                		in.readChar();       
                		//读出数目
                		unit = in.readInt();
                		//跳过tab
                		in.readChar();      
				char chr;
				//读出描述
				desc = new StringBuffer();
				
				while ((chr = in.readChar()) != '\n')
		    			desc.append(chr);

                		System.out.println("You've ordered " +
				    	unit + " units of " +
				    	desc + " at $" + price);
                		total = total + unit * price;
            		}
        	}
        	catch (EOFException e) 
        	{
        		System.out.println("For a TOTAL of: $" + total);
        	}
        	in.close();
    	}
}