Character stream
(1) Operation byte stream data is not particularly convenient Chinese, so there have been converted stream.
Role is to convert the flow of the byte stream into a stream of characters to use.
(2) converting the stream is actually a character stream
= + Character stream code table byte stream
(3) code table
A: is a numeric value corresponding to the characters and a table consisting of
B: common coding table
ASCII
ISO-8859-1
GB2312
GBK
GB18030
UTF-8
C: coding problem string
Code: to become able to understand not read
String -- byte[]
Decoding: can not read into the can understand
byte[] -- String
/*
* String(byte[] bytes, String charsetName):通过指定的字符集解码字节数组
* byte[] getBytes(String charsetName):使用指定的字符集合把字符串编码为字节数组
*
* 编码:把看得懂的变成看不懂的
* String -- byte[]
*
* 解码:把看不懂的变成看得懂的
* byte[] -- String
*
* 要发送一段文字：
* 今天晚上在老地方见
*
* 发送端：今 -- 数值 -- 二进制 -- 发出去
* 接收端：接收 -- 二进制 -- 十进制 -- 数值 -- 字符 -- 今
*
* 今天晚上在老地方见
*/
public class StringDemo {
public static void main(String[] args) throws UnsupportedEncodingException {
String s = "你好";
//String-byte[]
byte[] bys = s.getBytes(); // [-60, -29, -70, -61]
System.out.println(Arrays.toString(bys));
// byte[] -- String
String ss = new String(bys); // 你好
System.out.println(ss);
}
}
(4) IO issues and stream encoding method
A:OutputStreamWriter
OutputStreamWriter (OutputStream os): The default encoding, GBK converting data character stream is a stream of bytes
OutputStreamWriter (OutputStream os, String charsetName): according to the specified coding. Converting data character stream is a stream of bytes
method:
public void write (int c): write a character
public void write (char [] cbuf): Write an array of characters
Part of writing a character array: public void write (char [] cbuf, int off, int len)
public void write (String str): write a string
public void write (String str, int off, int len): Write part of a string
Interview questions: the difference between close () and flush () is?
A: close () Closes the stream object, but first refresh buffer. After closing, the flow must not continue to be used again.
B: flush () only flushes the buffer after the refresh, the stream object can continue to use.
B:InputStreamReader
InputStreamReader (InputStream is): the default encoding, GBK
InputStreamReader (InputStream is, String charsetName): specify the encoding
method:
int read (): reads one character
int read (char [] chs): reads one character array
C: coding problem is very simple
As long as you can encode the same
(5) the character stream
Reader
|--InputStreamReader
|--FileReader
|--BufferedReader
public String readLine (): read a line of data: a string that contains the contents of the line, not including any line terminator, if the end of the stream is
null
Writer
|--OutputStreamWriter
|--FileWriter
|--BufferedWriter
public void newLine (): The system determines newline
(6) Copy the text file
/*
* 需求：把当前项目目录下的a.txt内容复制到当前项目目录下的b.txt中
*
* 数据源：
* a.txt -- 读取数据 -- 字符转换流 -- InputStreamReader -- FileReader -- BufferedReader
* 目的地：
* b.txt -- 写出数据 -- 字符转换流 -- OutputStreamWriter -- FileWriter -- BufferedWriter
*/
public class CopyFileDemo2 {
public static void main(String[] args) throws IOException {
// 封装数据源
BufferedReader br = new BufferedReader(new FileReader("a.txt"));
// 封装目的地
BufferedWriter bw = new BufferedWriter(new FileWriter("b.txt"));
// 方式1:一次读写一个字符数组
//char[] chs = new char[1024];
//int len = 0;
//while ((len = br.read(chs)) != -1) {
//bw.write(chs, 0, len);
//bw.flush();
//}
//方式2：一次读取一行数据
String line = null;
while ((line = br.readLine()) != null) {
bw.write(line);
bw.newLine();
bw.flush();
}
// 释放资源
bw.close();
br.close();
}
}
