2020.8.3第二十八天

1.今天学习缓冲流

缓冲流的原理是将数据先缓冲起来，然后-起写入或读取出来，使用缓冲流读写文件非常高效，常用的缓冲流有以下几种: BufferedReader BufferedWriter. BufferedInputStream和BufferedOuputStream.1. 1.BufferedReader 与BufferedWriter

BufferedReader属于字符流,如果要想使用BufferedReader就需要将一个字节流变成字符流，为了解决这样的问题，在Java中提供了以下两个转换类。

#将输入的字节流变为字符流: InputStreamReader.
#将输出的字符流变为字节流: OutputStreamWriter.
在BufferedReader类中提供了一个专门的读取操作。

public String readLine() throws IOException

使用BufferedReader读取内容

 1 import java.io.BufferedReader;
 2 import java.io.FileInputStream;
 3 import java.io. IOException;
 4 import java.io. InputStreamReader;
 5 public class BufferedReaderDemo{
 6 public static void main(String[] args) throws IOException {
 7 read() ;
 8 }
 9 public static void read() throws IOException {
10 BufferedReader read = new BufferedReader (new InputStreamReader(
11 new FileInputStream ("D:/Hello.txt")));
12 String line=null;
13 while ((line=read.readLine())!=null) {
14 System.out.println(line) ;
15 }
16 read.close() ;
17 }
18 }

使用BufferedWriter读取内容

 1 import java.io.BufferedWriter;
 2 import java.io.FileOutputStream;
 3 import java.io.IOException;
 4 import java.io.OutputStreamWriter;
 5 public class BufferedWriterDemo {
 6 public static void main(String[] args) throws IOException {
 7 write () ;
 8 }
 9 public static void write() throws IOException{
10 BufferedWriter w=new BufferedWriter (new OutputStreamWriter (
11 new FileOutputStream ("D:/Hello.txt")));
12 w.write("Hello");
13 w.write ("Java") ;
14 w.close() ;
15 }
16 }

2.BufferedinputStream与BufferedoutputStream

读取或写入影像数据

 1 import java.io.BufferedInputStream;
 2 import java.io.BufferedOutputStream;
 3 import java.io.FileInputStream;
 4 import java.io.FileOutputStream;
 5 import java.io.IOException;
 6 public class BufferedInputOutput {
 7 public static void main(String[] args) throws IOException{
 8 outIn();
 9 }
10 public static void outIn() throws IOException {
11 BufferedInputStream in = new BufferedInputStream (new FileInputStream(
12 "D:\\test.png"));
13 BufferedOutputStream out = new BufferedOutputStream (
14 new FileOutputStream("D:\\test2.png"));
15 byte[] buf=new byte [1024];
16 int len = -1;
17 while ((len=in.read (buf))!=-1) {
18 out.write (buf,0, len);
19 }
20 out.close();
21 in.close();
22 }
23 }