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

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io. IOException;
import java.io. InputStreamReader;
public class BufferedReaderDemo{
public static void main(String[] args) throws IOException {
read() ;
}
public static void read() throws IOException {
BufferedReader read = new BufferedReader (new InputStreamReader(
new FileInputStream ("D:/Hello.txt")));
String line=null;
while ((line=read.readLine())!=null) {
System.out.println(line) ;
}
read.close() ;
}
}

 使用BufferedWriter读取内容

import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
public class BufferedWriterDemo {
public static void main(String[] args) throws IOException {
write () ;
}
public static void write() throws IOException{
BufferedWriter w=new BufferedWriter (new OutputStreamWriter (
new FileOutputStream ("D:/Hello.txt")));
w.write("Hello");
w.write ("Java") ;
w.close() ;
}
}

 2.BufferedinputStream与BufferedoutputStream

读取或写入影像数据

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class BufferedInputOutput {
public static void main(String[] args) throws IOException{
outIn();
}
public static void outIn() throws IOException {
BufferedInputStream in = new BufferedInputStream (new FileInputStream(
"D:\test.png"));
BufferedOutputStream out = new BufferedOutputStream (
new FileOutputStream("D:\test2.png"));
byte[] buf=new byte [1024];
int len = -1;
while ((len=in.read (buf))!=-1) {
out.write (buf,0, len);
}
out.close();
in.close();
}
}

 2.遇到的问题：没有弄清楚各种流的关系。

3.明天继续学习第12章。