BufferedInputStream与BufferedOutputStream用法简介

      BufferedInputStream是带缓冲区的输入流，默认缓冲区大小是8M，能够减少访问磁盘的次数，提高文件读取性能；BufferedOutputStream是带缓冲区的输出流，能够提高文件的写入效率。BufferedInputStream与BufferedOutputStream分别是FilterInputStream类和FilterOutputStream类的子类，实现了装饰设计模式。

       BufferedInputStream类的例子如下：

import java.io.File;
import java.io.InputStream;
import java.io.FileInputStream;
import java.io.BufferedInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class BufferedInputStreamDemo01{

	// 声明常量
        public static final int SIZE=1024;

	public static void main(String[] args){
	   //变量声明
           File f=null;
	   InputStream input=null;
	   BufferedInputStream bis=null;
           StringBuilder strBuild=null;
	   SimpleDateFormat sdf=null;
	   Date d=null;
           long start=0L;
	   long end=0L; 

          try{
		  sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
		  
		  strBuild=new StringBuilder();
                  start=System.currentTimeMillis();
		  d=new Date();
		  if(d!=null){
                  d.setTime(start);
	     }
          System.out.println("程序开始执行时间:"+sdf.format(d));

	  f=new File("d:"+File.separator+"demo.txt");
          input=new FileInputStream(f);
          // 指定文件带缓冲区的读取流且指定缓冲区大小为2KB
	  bis=new BufferedInputStream(input,2*SIZE);
          int bisLength=bis.available();
          int readLength=0;
          byte[] byteArray=new byte[SIZE];
          int tmp=0;
          while((tmp=bis.read(byteArray))!=-1){ 
                strBuild.append(new String(byteArray,0,tmp));
		System.out.println("每次读取字节数量:"+tmp);
		System.out.println("文件中剩余字节数:"+input.available());
	 }
          
          System.out.println(String.format("文件的大小:%d,缓冲区读取流返回的大小:%d",f.length(),bisLength));
	  System.out.println("文件的内容："+strBuild.toString());
	  System.out.println("字符串长度:"+strBuild.toString().length());
	  char[] cTmp=strBuild.toString().toCharArray();
	  System.out.println("字符串->字符数组长度:"+cTmp.length);

	  end=System.currentTimeMillis();
	  d=new Date();
	  if(d!=null){ 
	     d.setTime(end);
	  }
	  System.out.println("程序执行的结束时间:"+sdf.format(d));
	  System.out.println("<-------------******************---------------->");
	  System.out.println("程序执行时间(ms):"+(end-start)+"毫秒");

       }catch(FileNotFoundException ex){
          ex.printStackTrace();
       }catch(IOException ex){
          ex.printStackTrace();
       }finally{
         try{
               if(input!=null){
		 input.close();
		}
	       if(bis!=null){
		 bis.close(); 
	       }
         }catch(IOException ex){
           ex.printStackTrace();
         }
      }
   }
}

   BufferedOutputStream类的例子如下：

import java.io.File;
import java.io.OutputStream;
import java.io.FileOutputStream;
import java.io.BufferedOutputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class BufferedOutputStreamDemo01{
        public static final int SIZE=1024;
        public static final String DRIVERNAME="oracle.jdbc.driver.OracleDriver";
        public static final String DBURL="jdbc:oracle:thin:@IP:1521:DB名称";
	public static final String USERNAME="用户名";
	public static final String PASSWORD="密码";
    
	static{
	   try{
	        // 加载驱动程序
	        Class.forName(DRIVERNAME);
	      }catch(ClassNotFoundException ex){
	        ex.printStackTrace();
	    }
	}

	public static void main(String[] args){
	   // 变量声明
	   File f=null;
	   OutputStream output=null; 
	   BufferedOutputStream bos=null;
           Connection con=null;
	   PreparedStatement pst=null;
           ResultSet rs=null;
	   StringBuilder strBuild=null;
 
           try{
		  String sql=" select vendor_no,vendor_name,address,phone,email,zipcode from VENDOR";
		   
		  con=new BufferedOutputStreamDemo01().getConnection();
                  // 获得数据库操作类
                  pst=new BufferedOutputStreamDemo01().getPst(con,sql);
                  // 获得结果集
		  rs=pst.executeQuery();

		  f=new File("F:"+File.separator+"tmp.txt");
		  output=new FileOutputStream(f,false);
		  bos=new BufferedOutputStream(output,SIZE*4);
          
		  while(rs.next()){
                        strBuild=new StringBuilder();
            
			// 店号
			strBuild.append(rs.getString("vendor_no"));
			strBuild.append(",");

                        // 店名
			strBuild.append(rs.getString("vendor_name"));
			strBuild.append(",");
            
			// 地址
			strBuild.append(rs.getString("address"));
			strBuild.append(",");
            
			// 电话
			strBuild.append(rs.getString("phone"));
			strBuild.append(",");

                        // 邮件
			strBuild.append(rs.getString("email"));
			strBuild.append(",");

                        // 邮政编码
			strBuild.append(rs.getString("zipcode"));
			strBuild.append("\n");
            
                        bos.write(strBuild.toString().getBytes("utf-8"));
		  }

           }catch(IOException ex1){
               ex1.printStackTrace();
	   }catch(SQLException ex){
	       ex.printStackTrace();
	   }finally{
               try{
			 // 关闭流
			 if(output!=null){
			   output.close(); 
			 }
			 if(bos!=null){
                            bos.close();
			 } 
			 //关闭数据库连接
			 if(rs!=null){
                            rs.close();
			 }
                         if(pst!=null){
                            pst.close();
			 }
                         if(con!=null){
			   con.close();
			 }
                 }catch(IOException ex){
	            ex.printStackTrace();
                 }catch(SQLException ex){
                    ex.printStackTrace();
	         }
	     }
	}
    
	/**
        **获得数据库连接
	**
	**/
	public static Connection getConnection(){
	   Connection con=null;
	   try{
	       // 获得数据库连接
	       con=DriverManager.getConnection(DBURL,USERNAME,PASSWORD);
	   }catch(SQLException ex){
	       ex.printStackTrace();
	   } 

	   return con;
	}
    
	/**
        **获得数据库操作类
	**/
	public static PreparedStatement getPst(Connection con,String sql){
            PreparedStatement pst=null;
	    try{
		  pst=con.prepareStatement(sql);
	       }catch(SQLException ex){
		  ex.printStackTrace();
	       } 

	    return pst;
	}
}

以上带缓冲区的输入输出流实例希望对初学者有所帮助，望批评指正！