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;
     }
 }