filerw.java

java方面较高级的程序设计源码 共十四个例子源码

//FileRW.java

import java.io.*;
import java.util.*;

public class FileRW
{
//需要输入的person数目。
	public static int NUMBER = 3;
	public static void main(String[] args)
	{
		Person[] people = new Person[NUMBER];
//暂时容纳输入数据的临时字符串数组。
		String[] field = new String[4];
//初始化field数组。
		for(int i = 0; i < 4; i++)
		{
			field[i] = "";
		}
//IO操作必须捕获IO异常。
		try
		{
//用于对field数组进行增加控制。
			int fieldcount = 0;

//先使用System.in构造InputStreamReader，再构造BufferedReader。
			BufferedReader stdin =
				new BufferedReader(new InputStreamReader(System.in));
			for(int i = 0; i < NUMBER; i++)
			{
				fieldcount = 0;
				System.out.println("The number " + (i + 1) + " person");
				System.out.println("Enter name,age,salary,married(optional), please separate fields by ':'");
//读取一行。
				String personstr = stdin.readLine();
//设置分隔符。
				StringTokenizer st = new StringTokenizer(personstr,":");
//判断是否还有分隔符可用。		
				while (st.hasMoreTokens())
				{
					field[fieldcount] = st.nextToken();
					fieldcount++;
				}
//如果输入married，则field[3]不为空，调用具有四个参数的Person构造函数。
				if(field[3] != "")
				{
					people[i] = new Person(field[0], Integer.parseInt(field[1]),
						Double.parseDouble(field[2]), field[3]);
//置field[3]为空，以备下次输入使用。
					field[3] = "";
				}
//如果未输入married，则field[3]为空，调用具有三个参数的Person构造函数。
				else
				{
					people[i] = new Person(field[0], Integer.parseInt(field[1]),
						Double.parseDouble(field[2]));
				}
			}

//将输入的数据保存至“people.dat”文本文件中。
			PrintWriter out = new PrintWriter( new BufferedWriter(new
				FileWriter("people.dat")));
			writeData(people, out);
//关闭流。
			out.close();

//从文件“people.dat”读取数据。
			BufferedReader in = new BufferedReader(new
				FileReader("people.dat"));
			Person[] inPeople = readData(in);
//关闭流。
			in.close();

//输出从文件中读入的数据。
			for (int i = 0; i < inPeople.length; i++)
				System.out.println(inPeople[i]);
		}
		catch(IOException exception)
		{
			System.err.println("IOException");
		}
	}

//将所有数据写入输出流。
	static void writeData(Person[] p, PrintWriter out) 
		throws IOException
	{
//写入记录条数，即人数。
		out.println(p.length);
		for (int i = 0; i < p.length; i++)
			p[i].writeData(out);
	}

//将所有数据从输入流中读出。
	static Person[] readData(BufferedReader in)
		throws IOException
	{
//获取记录条数，即人数。
		int n = Integer.parseInt(in.readLine());

		Person[] p = new Person[n];
		for (int i = 0; i < n; i++)
		{
			p[i] = new Person();
			p[i].readData(in);
		}
		return p;
	}
}

class Person
{
	private String name;
	private int age;
	private double salary;
	private String married;

	public Person()
	{
	}

	public Person(String n, int a, double s)
	{
		name = n;
		age = a;
		salary = s;
		married = "F";
	}

	public Person(String n, int a, double s, String m)
	{
		name = n;
		age = a;
		salary = s;
		married = m;
	}

	public String getName()
	{
		return name;
	}

	public int getAge()
	{
		return age;
	}

	public double getSalary()
	{
		return salary;
	}

	public String getMarried()
	{
		return married;
	}

//设置输出格式。
	public String toString()
	{
		return getClass().getName() + "[name=" + name
			+ ",age=" + age
			+ ",salary=" + salary
			+ ",married=" + married
			+ "]";
	}

//写入一条记录，即一个人的数据到输出流。
	public void writeData(PrintWriter out) throws IOException
	{
//格式化输出。
		out.println(name + ":"
			+ age + ":"
			+ salary + ":"
			+ married);
	}

//从输入流读入一条记录，即一个人的数据。
	public void readData(BufferedReader in) throws IOException
	{
		String s = in.readLine();
		StringTokenizer t = new StringTokenizer(s, ":");
		name = t.nextToken();
		age = Integer.parseInt(t.nextToken());
		salary = Double.parseDouble(t.nextToken());
		married = t.nextToken();
	}
}