java之 20天 PrintWriter 和PrintStream(三)

打印流
文件的分割 与合并

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.SequenceInputStream;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.Vector;

/**
 * 打印流:
 * 该流提供了打印的方法,可以将各种数据类型的数据都原样打印.
 * 
 * 字节打印流
 * printStream
 *   构造函数可以接受的参数类型:
 *   1.file对象:  File
 *   2.字符串路径:  String
 *   3.字符输出流:  OutputStream
 *   
 * 
 * 字符打印流
 * PrintWriter
 *   构造函数可以接收的参数类型
 *   1.file对象  File
 *   2.字符串路径   String
 *   3.字节输出流    OutputStream
 *   4.字符输出流: Writer
 *   
 *   
 * 练习 ----合并多个文件------------
 *     SequenceInputStream
 *
 * 练习-----切割文件--------------
 * 
 */
public class PrintDemo {

	public static void main(String[] args) throws IOException {
		
		//	method();
		//System.out.println("========将多个读取流变成一个读取流============");
		//sequenceDemo();
		//System.out.println("=========将一个大的文件分割成多个文件==============");
		//splitFileDemo();
		System.out.println("=========将上面的多个碎片文件变成一个文件============");
		merge();
	}
	//合并上面 分割的文件
	public static void merge() throws IOException{
		List<FileInputStream> list=new ArrayList<FileInputStream>();

		for(int x=1;x<=19;x++){
			list.add(new FileInputStream("E:\\splitFile\\"+x+".part"));
		}
		
		final Iterator<FileInputStream> it=list.iterator();
		
		Enumeration<FileInputStream> en=new Enumeration<FileInputStream>(){

			@Override
			public boolean hasMoreElements() {
				// TODO Auto-generated method stub
				return it.hasNext();
			}

			@Override
			public FileInputStream nextElement() {
				// TODO Auto-generated method stub
				return it.next();
			}};
			
	   SequenceInputStream sis=new SequenceInputStream(en);
	   
	   FileOutputStream fos=new FileOutputStream("E:\\cMeger.pdf");
		
	   byte[] buf=new byte[1024];
	   int len=0;
	   while((len=sis.read(buf))!=-1){
		  fos.write(buf,0,len);
	   }
	   fos.close();
	   sis.close();
		
		
	}
	
	//切割文件
	public static void splitFileDemo() throws IOException{
		FileInputStream fis=new FileInputStream("E:\\c.pdf");
		
		FileOutputStream fos=null;
		byte[] buf=new byte[1024*1024]; //1M
		int len=0;
		int count=1;
		while((len=fis.read(buf))!=-1){
			fos=new FileOutputStream("E:\\splitFile\\"+(count++)+".part");
			fos.write(buf,0,len);
			fos.close();
		}
		fis.close();
		
	}
	
	
	//合并流   (不会自动换行哦)
	public static void sequenceDemo() throws IOException{
		
		Vector<FileInputStream> v=new Vector<FileInputStream>();
		v.add(new FileInputStream("E:\\1.txt"));
		v.add(new FileInputStream("E:\\2.txt"));
		v.add(new FileInputStream("E:\\3.txt"));
		
		SequenceInputStream sis=new SequenceInputStream(v.elements());
		
		FileOutputStream fos=new FileOutputStream("E:\\4.txt");
		byte[] buf=new byte[1024];
		int len=0;
		while((len=sis.read(buf))!=-1){
			fos.write(buf,0,len);
		}
		fos.close();
		sis.close();
		
	}
	
	
	//字符打印流
	public static void method() throws IOException{
		BufferedReader bufr=new BufferedReader(new InputStreamReader(System.in));

		//true 刷新 只对流而言的 
		//PrintWriter out=new PrintWriter(System.out,true);
		//输出到文件中 不能自动刷行 
		//PrintWriter out=new PrintWriter("a.txt");
		//这样文件 封装成  字符流的后就可以自动刷新了
		//PrintWriter out=new PrintWriter(new FileWriter("a.txt"),true);
		//发现效率不高,提高效率
		PrintWriter out=new PrintWriter(new BufferedWriter(new FileWriter("a.txt")),true);
		
		
		
		String line=null;
		while((line=bufr.readLine())!=null){
			if("over".equals(line))
				break;
			out.println(line.toUpperCase());
			//out.flush();
		}
		
		out.close();
		bufr.close();
	}

}