java字节流深入研究

1、1字节流读取中文的问题filelnuptstreamdemo.javapackage cn.itcast_01;import java.io.filel nputstream;import java.i 0oexcepti on;/*字节流读取中文可能出现的小问题：*/public class filelnputstreamdemo public static void main(string args) throws loexception /创建字节输入流对象filelnputstream fis = new filelnputstream(”a.txt”);/读取数据/ int by =

2、 0;/ while (by = fis.read() != -1) / system.out.print(char) by);/byte bys = new byte1024;int len = 0;while (len = fis.read(bys) != -1) system.out.print(new string(bys, 0, len);/释放资源fis.close();stringdemo.javapackage cn.itcast_o1;import java.io.unsupportedencodingexception;import java.util.arrays;/*

3、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*举例：谍战片(发电报，接电报)*码表:小本子*字符数值要发送一段文字: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*编码问题简单，只要编码解码的格式是一致的。*/public class s

4、tringdemo public static void main(string args) throws unsupportedencodingexception string s = ”你好”；/ string - bytebyte bys = s.getbytes(); / -60, -29, -70, -61/ byte bys = s.getbytes(”gbk”); -60, -29, -70, -61/ byte bys = s.getbytes(nutf-8h);/ -28, -67, -96, -27, -91, -67system.out.pri ntln (arrays.

5、tostring(bys);/ byte - stringstring ss = new string(bys); / 你好/ string ss = new string(bys, ”gbk”)； 你好/ string ss = new string(bys, ”utf8”)； / ?system.out.println(ss);3默认编码转字符流inputstreamreader.javapackage cn.itcast_02;import java.io.filel nputstream;import java.i 0oexception;import java.io.inputstr

6、eamreader;/* lnputstreamreader(lnputstream is):用默认的编码读取数据* lnputstreamreader(lnputstream is,string charsetname):用指定的编码读取数据*/public class inputstreamreaderdemo public static void main(string args) throws loexception /创建对象/ inputstreamreader isr = new inputstreamreader(newfilelnputstream(/ "osw.t

7、xt");/ inputstreamreader isr = new lnputstreamreader(new filelnputstream(/ “osw.txt”)，”gbk“)；inputstreamreader isr = new lnputstreamreader(newfilelnputstream(“osw.txt”)，”utf8”)；/读取数据 / 一次读取一个字符 int ch = 0;while (ch = isr.read() != -1) system.out.print(char) ch);/释放资源isr.close();outputstreamwrit

8、er.javapackage cn.itcast_02;import java.io.fileoutputstream;import java.i 0oexception;import java.io.outputstreamwriter;/* outputstreamwriter(outputstream out):根据默认编码把字节流的数据转换为字符 流* outputstreamwriter(outputstream out,string charsetname):根据指定编码把字节 流数据转换为字符流*把字节流转换为字符流。*字符流=字节流+编码表。*/public class out

9、putstreamwriterdemo public static void main(string args) throws loexception /创建对象/ outputstreamwriter osw = new outputstreamwriter(newfileoutputstream(”osw.txt”)； 默认 gbk/ outputstreamwriter osw = new outputstreamwriter(new fileoutputstream(/ "osw.txt'1), “gbk”)； / 指定 gbkoutputstreamwriter o

10、sw = new outputstreamwriter(newfileoutputstream(“osw.txt”)，"utf-8h); / 指定 utf-8/写数据 osw.write(h 中国”);/释放资源 osw.close();4 i n putst ream readerinputstreamreader.javapackage cn.itcast_03;import java.io.filel nputstream;import java.i 0oexcepti on;import java.io.inputstreamreader;/* inputstreamread

11、er 的方法：* int read():次读取一个字符* int read(char chs):次读取一个字符数组public class inputstreamreaderdemo public static void main(string args) throws loexception /创建对象inputstreamreader isr = new inputstreamreader(newfilelnputstream(hstringdemo.java");/ 一次读取一个字符/ int ch = 0;/ while (ch = isr.read() != -1) / s

12、ystem.out.print(char) ch);/ 一次读取一个字符数组char chs = new char1024;int len = 0;while (len = isr.read(chs) != -1) system.out.print(new string(chs, 0, len);/释放资源isr.close();outputstreamwriter.javapackage cn.itcast_03;import java.io.fileoutputstream;import java.i ooexception;import java.io.ouipuisireamwriie

13、c* ou-outsireamwsersbfj 讯-* pub=c void wme(ini 0-呦->+塑* pub=c void wmeohaecbufhjlflt苹薯肾* pub=c void wmeohar 口 cbuf5-i off5-i _enjn->+苹tffis喪®* pub=c void wme(smng 住2胡->+羽册* pub-ic void wme(sming ssini off5-i -en)丽->苹册3_* 剧醫-coseosf-ushos冈型 7* aooseo來s湧訂w®制冷型苹为越-&冈。來swdn 曲7。

14、* b_ush()>a>a型举爾-&冈.型卷 2311、pub-ic c_ass ouipuismeamwriierdemo 宀 pub-ic ss-hc void main(smn吕 args) throws -oexcepiion 宀 二些®誇b ou-outsireamwmer osw n new ouipuisireamwriiesewfi-eouipuisiream(osw21x3)二二 pub_ic void wse(i2.cjjfl->+苹二 osw.wriiera.)二 osw.wme(97)- 二甘亠十卜磬施那niltk讯富？原因是：字符=

15、2字节 /文件中数据存储的基本单位是字节。/ void flush()/ public void write(char cbuf):写一个字符数组/ char chs = 'a'/bvc'/dve'/ osw.write(chs);/ public void write(char cbuf,int off,int len):写一个字符数组的一咅b 分/ osw.write(chs,1,3);/ public void write(string str):写一个字符串/ osw.write(”我爱林青霞”);/ public void write(string s

16、tr,int off,int len):写一个字符串的一部分osw.write(”我爱林青霞”,2, 3);/刷新缓冲区osw.flush();/ osw.write(”我爱林青霞”,2, 3);/释放资源osw.close();/ java.iooexception: stream closed/ osw.write(”我爱林青霞”,2, 3);5文本内容复制到当前目录下copyfiledemo.javapackage cn.itcast_04;import java.io.filelnputstream;import java.io.fileoutputstream;import java

17、.i 0oexceptio n;import java.i on putstreamreader;import java.io.outputstreamwriter;/数据源：* a.txt -读取数据-字符转换流-inputstreamreader*目的地：* b.txt -写出数据-字符转换流-outputstreamwriter*/public class copyfiledemo public static void main(string args) throws loexception /封装数据源inputstreamreader isr = new inputstreamrea

18、der(newfilelnputstream(“a.txt”)；封装目的地*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outputstreamwriter osw = new outputstreamwriter(new fileoutputstream(” b.txt”)；/读写数据/方式1/ int ch = 0;/ while (ch = isr.read() != -1) / osw.write(ch);/方式2char chs = new char1024;int len = 0;while (len = isr.read(chs) != -1) osw

19、.write(chs, 0, len);/ osw.flush();/释放资源osw.close();isr.close();copyfiledemo2.javapackage cn.itcast_04;import java.io.filereader;import java.io.filewriter;import java.i 0oexception;/*由于我们常见的操作都是使用本地默认编码，所以，不用指定编码。*而转换流的名称有点长，所以，java就提供了其子类供我们使用。* outputstreamwriter = fileoutputstream + 编码表(gbk)* file

20、writer = fileoutputstream + 编码表(gbk)* inputstreamreader = filelnputstream + 编码表(gbk)* filereader = filelnputstream + 编码表(gbk)*/*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*目的地：* b.txt -写出数据-字符转换流-outputstreamwriter - filewriter*/public class copyfilede

21、mo2 public static void main(string args) throws loexception /封装数据源filereader fr = new filereader(”a.txt”)；封装目的地filewriter fw = new filewriter(,b.txtn);/ 一次一个字符i i int ch = 0;/ while (ch = fr.read() != -1) / fw.write(ch);/ 一次_个字符数组char chs = new char1024;int len = 0;while (len = fr.read(chs) != -1) f

22、w.write(chs, 0, len); fw.flush();/释放资源fw.close();fr.close();copyfiledemo3 .javapackage cn.itcast_04;import java.io.filereader;import java.io.filewriter;import java.iooexception;/*需求:把c:xa.txt内容复制到d:xb.txt中数据源:c:xa.txt - filereader*目的地：*d:xb.txt - filewriter*/public class copyfiledemo3 public static

23、void main(string args) throws loexception /封装数据源filereader fr = new filereader("c:wa.txt");封装目的地filewriter fw = new filewriter(”d:b.txt“)；/读写数据/ int ch = 0;int ch;while (ch = fr.read() != -1) fw.write(ch);释放资源fw.close();fr.close();6字符缓冲流buffered demo.javaimport java.io.bufferedreader;impor

24、t java.io.bufferedwriter;import java.io.filereader;import java.io.filewriter;import java.i 0oexception;/*字符缓冲流的特殊方法：* bufferedwriter:* public void newline():根据系统来决定换行符* bufferedreader:* public string readline():次读取一行数据* 包含该行内容的字符串，不包含任何行终止符，如果已到达流末尾，则返回null*/public class buffereddemo public static v

25、oid main(string args) throws loexception / write();read();private static void read() throws loexception /创建字符缓冲输入流对象bufferedreader br = new bufferedreader(new filereader(”bw2.txt”);/ public string readline():次读取一行数据/ string line = br.readline();/ system.out.println(line);/line = br.readline();/ syst

26、em.out.println(line);/最终版代码string line = null;while (line = br.readline() != null) system.out.pri ntln(line);w放资源br.close(); private static void write() throws loexception /创建字符缓冲输出流对象bufferedwriter bw = new bufferedwriter(new filewriter(”bw2.txt”); for (int x = 0; x < 10; x+) bw. write(” hello”

27、+ x);/ bw.write(rn);bw.newline();bw.flush();bw.close();ufferedreaderdemo.javaimport java.io.bufferedreader;import java.io.filereader;import java.i 0oexception;* bufferedreader*从字符输入流中读取文本，缓冲各个字符，从而实现字符、数组和行的高效读取。*可以指定缓冲区的大小，或者可使用默认的大小。大多数情况下，默认值就足够大 了。* bufferedreader(reader in)*/public class buffer

28、edreaderdemo public static void main(string args) throws loexception /创建字符缓冲输入流对象bufferedreader br = new bufferedreader(new filereader("bw.txt"):方式1/ int ch = 0;/ while (ch = br.read() != -1) / system.out.print(char) ch);/方式2char chs = new char1024;int len = 0;while (len = br.read(chs) !=

29、-1) system.out.print(new string(chs, 0, len);/释放资源br.close();bufferwriterdemo.javapackage cn.itcast_05;import java.io.bufferedwriter;import java.io.filewriter;import java.i0oexception;/可以指定缓冲区的大小，或者接受默认的大小。在大多数情况下，默认值就足够大 了。*/public class bufferedwriterdemo public static void main(string args) throw

30、s loexception / bufferedwriter(writer out)/ bufferedwriter bw = new bufferedwriter(new outputstreamwriter(/ new fileoutputstream (hbw.txth);*字符流为了高效读写，也提供了对应的字符缓冲流。* buffered writer:字符缓冲输出流* bufferedreader:字符缓冲输入流* bufferedwriter:字符缓冲输出流*将文本写入字符输出流，缓冲各个字符，从而提供单个字符、数组和字符串的高效 写入。bufferedwser bw h new

31、bufferedwriiersew fi_ewriier(bwix3)_bwwme(=he-_o)八 bwwme(.wor-ct)_ bw.wme(.java) bwf-ush()；bwb-osesrcopyf 二 edemo java package cnicasl06import java.io.bufferedreadecimport java.io.bufferedwriiecimport java.io.fi-ereadecimporl java.io.fi-ewriiecimport java.p-oexcepiiom* i - 皿划 t3a.es-吻m世里味玛日mjim别 tsb

32、.ixi 召* -* a.ixi ; i料対磐甫 gs-npuisireamreader : fi-ereader.bufferedreader* ml-b.txt -写出数据-字符转换流-outputstreamwriter - filewriter -bufferedwriter*/public class copyfiledemo public static void main(string args) throws loexception /封装数据源bufferedreader br = new bufferedreader(new filereaderc'a.txt&quo

33、t;);封装目的地bufferedwriter bw = new bufferedwriter(new filewriter(”b.txt”)；/两种方式其中的一种一次读写一个字符数组 char chs = new char1024;int len = 0;while (len = br.read(chs) != -1) bw.write(chs, 0, len);bw.flush();/释放资源bw.close(); br.close();copyfiledemo2.javapackage cn.itcast_06;import java.io.bufferedreader; import

34、java.io.bufferedwriter;import java.io.filereader;import java.io.filewriter;import java.i 0oexception;/*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 一 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

35、copyfiledemo2 public static void main(string args) throws loexception /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”)；/读写数据string line = null;while (line = br.readline() != null) bw.write(li ne);bw.new

36、li ne();bw.flush();/释放资源bw.close();br.close();编码package cn.itcast_o1;import java.io.unsupportede ncodi ngexceptio n;import java.util.arrays;/举例：谍战片(发电报，接电报)*码表：小本子字符数值* 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*编码问题简单，只要编码解码的格式是一致的。*/public class stringdemo public static void main(string args) throws unsupportedencodingexception string s = ”你好”；/ string - bytebyt