javaiodemo.java

精通java核心技术》随书源代码

// ==================== Program Discription =====================
// 程序名称：示例2-2 : JavaIODemo.java
// 程序目的：学习java io
// ==============================================================

import java.io.*;
import java.util.zip.*;
public class JavaIODemo
{
	String temp=new String();
	String t=new String();
	
	//从控制台获得输入
	public void readByLineFromConsoleAndPrint()
	{
		System.out.println("==从控制台获得输入==");
		try
		{
			BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
			System.out.println("请输入一行字符:");
			System.out.println(temp=in.readLine());
		}
		catch(IOException e)
		{
			e.printStackTrace();
		}
	}
	
	//从文件获得输入
	public void readByLineFromFileAndPrint()
	{
		System.out.println("==从文件获得输入==");	
		try
		{
			BufferedReader in=new BufferedReader(new FileReader("demo.out"));
			temp="";
			String s=new String();
			while((s=in.readLine())!=null)
			temp+=s+"\n";
			in.close();//关闭输入流
			System.out.println(temp);
		}
		catch(FileNotFoundException e)
		{
			e.printStackTrace();
		}
		catch(IOException e)
		{
			e.printStackTrace();
		}
	}
	
	//从内存获得输入
	public void readFromMemoryAndPrint()
	{
		System.out.println("==从内存获得输入==");
		try
		{
			StringReader stringReader=new StringReader(temp);
			int t;
			while((t=stringReader.read())!=-1)
				System.out.println((char)t);
	    }
	   	catch(IOException e)
		{
			e.printStackTrace();
		}
	}
	
	//文件输出流
	public void writeToFile()
	{
		System.out.println("==文件输出流==");
		try
		{
			BufferedReader in=new BufferedReader(new StringReader(temp));
			PrintWriter out=new PrintWriter(new BufferedWriter(new FileWriter("demo.out")));
			while((t=in.readLine())!=null)
				out.println(t);
			out.close();
		}
		catch(IOException e)
		{
			e.printStackTrace();
		}
	}
	
	//随机访问文件
	public void randomAccessFile()
	{
		try
		{
			System.out.println("==随机访问文件==");
			RandomAccessFile file=new RandomAccessFile("rand.out","rw");
			for(int i=0;i<10;i++)
				file.writeDouble(i*1.12);
			file.seek(100);
			file.writeDouble(577.4545);
			file.close();
			
			file=new RandomAccessFile("rand.out","r");	
			for(int i=0;i<10;i++)
				System.out.println("value "+i+"="+file.readDouble());
			file.seek(100);
			System.out.println(file.readDouble());			
			file.close();
		}
		catch(IOException e)
		{
			e.printStackTrace();
		}
	}
			
			
	//格式化数据输入输出
	public void formattedInputAndOutput()
	{
		System.out.println("==格式化数据输出==");
		try
		{			
			DataOutputStream out=new DataOutputStream(new BufferedOutputStream(new FileOutputStream("data.data")));
			out.writeDouble(54.7769);
			out.writeBytes("this is bytes\n");
			out.writeChars("this is chars\n");
			out.writeFloat(100.6f);
			out.writeUTF("this is utf encoding string\n");
			out.close();
			
			System.out.println("==格式化数据输入==");
			DataInputStream in=new DataInputStream(new BufferedInputStream(new FileInputStream("data.data")));
			BufferedReader reader=new BufferedReader(new InputStreamReader(in));
			System.out.println(in.readDouble());
			System.out.println(in.readLine());
			System.out.println(in.readLine());
			System.out.println(in.readFloat());
			System.out.println(in.readLine());
		}
		catch(EOFException e)
		{
			System.err.println("end of stream");
		}
		catch(IOException e)
		{
			e.printStackTrace();
		}
	}		
		
	//读写序列化对象
	public void readAndWriteSerialObject()
	{
		System.out.println("==读写序列化对象==");
		Test test=new Test("init value");
		try
		{
			
			ObjectOutputStream out=new ObjectOutputStream(new FileOutputStream("test.ser"));
			out.writeObject("保存序列化对象");
			out.writeObject(test);
			out.close();
			ObjectInputStream in=new ObjectInputStream(new FileInputStream("test.ser"));
			System.out.println(in.readObject());
			Test t=(Test)in.readObject();
			in.close();
			System.out.println(t.getValue());
		}	
		catch(IOException e)
		{
			e.printStackTrace();
		}
		catch(ClassNotFoundException e)
		{
			e.printStackTrace();
		}
	}
	
	//使用java压缩文件
	public void zipFile()
	{
		System.out.println("==使用java压缩文件==");
		try
		{
			FileOutputStream file=new FileOutputStream("demo.zip");
			CheckedOutputStream csum=new CheckedOutputStream(file,new Adler32());
			ZipOutputStream zip=new ZipOutputStream(new BufferedOutputStream(csum));
			zip.setComment("Zip 输出流测试");
			BufferedReader reader=new BufferedReader(new FileReader("Test.java"));
			zip.putNextEntry(new ZipEntry("Test.java"));
			int c;
			while((c=reader.read())!=-1)
				zip.write(c);
			zip.close();
		}
		catch(IOException e)
		{
			e.printStackTrace();
		}
	}
				
	public static void main(String[] args)
	{
		JavaIODemo demo=new JavaIODemo();
		demo.readByLineFromConsoleAndPrint();
		demo.readFromMemoryAndPrint();
		demo.writeToFile();
		demo.formattedInputAndOutput();
		demo.randomAccessFile();
		demo.readByLineFromFileAndPrint();
		demo.readAndWriteSerialObject();
		demo.zipFile();		
	}
}