合并文件

package file.spilt.merge;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.SequenceInputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.Properties;

public class MergeFile {
   public static void main(String[] args) throws IOException {
      //读取多个拆分后的文件(inputs：所有输入流的集合)
      /*List<FileInputStream> inputs = new ArrayList<>();
      for(int i=1;i<=8;i++) {
         inputs.add( new FileInputStream("E:\\splitDir\\"+i+".part"));
      }
      //指定合并后的文件输出流
      OutputStream out = new FileOutputStream("e:\\myMusic.mp3");
      
      //将多个 输入流 依次读入内存，最后再一次性输出到 myMusic.mp3
      byte[]  buf = new byte[1024*1024] ;
      
      for(FileInputStream in:inputs) {
         int len = in.read(buf) ;
         out.write(buf, 0, len);
      }
      out.close(); 
      
      for(FileInputStream in:inputs) {
         in.close();
      }
      */
      
      //文件合并，方法二：
      //指定拆分后的文件位置
      File splitDir = new File("E:\\splitDir");
      mergeFile(splitDir);
   }
   
   public static Properties getProperties() throws FileNotFoundException, IOException {
      //找到配置文件的位置
      String configFileName = "E:\\splitDir\\conf.properties" ;
      Properties prop = new Properties();
      prop.load( new FileInputStream(configFileName )     );
      return prop ;
   }
   
   //文件合并
   public static void mergeFile(File splitDir) throws IOException {
      //合并之前，先读取配置信息
      Properties prop = getProperties();
      String fileName = prop.getProperty("filename") ;
      int partCount = Integer.parseInt(prop.getProperty("partcount") )  ;
      
      List<FileInputStream> inputs = new ArrayList<>();
      for(int i=1;i<=partCount;i++) {
         inputs.add( new FileInputStream("E:\\splitDir\\"+i+".part"));
      }
      Enumeration<FileInputStream>  en = Collections.enumeration(inputs );//List-->Enumeration
      //多个流->1个流
      SequenceInputStream sin = new SequenceInputStream(en);
      
      //指定合并后的文件输出流
      OutputStream out = new FileOutputStream("e:\\"+fileName);
      //sin -输出 (类似文件复制)
      byte[] buf = new byte[1024];
      int len = -1 ; 
      while((len=sin.read(buf))!=-1 ) {
         out.write(buf, 0, len);
      }
      out.close(); 
      sin.close(); 
   }
   
   
   
   
   
   
   
   
   
   
   
   
   
}