Java IO操作的实例代码.doc

Java IO操作的实例代码2008-11-18 23:00215人阅读评论(0)收藏举报Java IO操作的实例代码（部分来自网络源码）/* 程序输出的时候会有乱码,原因是因为read()方法读取一个字节,中文字符* 是由两个字节构成,取一个字节(字符的一半)就转成一个字符,所以输出就会是乱码* author DaHai*/public class TestFileInputStreampublic static void main(String args)int b = 0;FileInputStream in = null;tryin = new FileInputStream(c:/TestFileInputStream.java);catch(FileNotFoundException e)System.out.println(找不到指定的文件);/终止当前正在运行的 Java 虚拟机。参数用作状态码；根据惯例，非零的状态码表示异常终止。 System.exit(-1); trylong num = 0;/只有读到文件的结尾才为-1while(b=in.read()!=-1)System.out.print(char)b);num+; in.close();System.out.println();System.out.println(共读取了+ num +个字节);catch(IOException e)System.out.println(文件读取错误);System.exit(-1);Java代码 复制文件import java.io.*; public class TestFileOutputStream public static void main(String args) int b = 0; FileInputStream in = null; FileOutputStream out = null; try in = new FileInputStream(c:/TestFileInputStream.java); /如果这个时候C盘下面还没有Test.java,那么new FileOutputStream会创建一个空的Test.java文件,但不会创建目录 out = new FileOutputStream(c:/Test.java); while(b = in.read()!=-1) out.write(b); in.close(); out.close(); catch(FileNotFoundException e) System.out.println(找不到指定文件); System.exit(-1); catch(IOException e) System.out.println(文件复制错误); System.exit(-1); System.out.println(文件已复制); 从文件里读取字符数据 Java代码 import java.io.*; public class TestFileReader public static void main(String args) FileReader fr = null; int c = 0; try fr = new FileReader(c:/TestFileReader.java); while(c = fr.read()!=-1) System.out.print(char)c); catch(FileNotFoundException e) System.out.println(系统找不到指定的文件); catch(IOException e) System.out.println(文件读取错误); 向文件里写字符数据 下面这个小程序可以写出全世界所有的字符Java代码 import java.io.*; public class TestFileWriter public static void main(String args) FileWriter fw = null; int b = 0; try fw = new FileWriter(c:/Unicode.dat); for(b=0;b65536;b+) fw.write(b);fw.flush();fw.close(); catch(FinleNotFoundException e) e.printStackTrace();System.out.println(e.getMessage();System.exit(0); catch(IOException e) e.printStackTrace();System.out.println(e.getMessage();System.exit(0); 带缓冲区功能的输入流 Java代码 import java.io.*; public class TestBufferStream public static void main(String args) try /一个字节的输入流并且不带缓冲区 FileInputStream fis = new FileInputStream(c:/TestFileInputStream.java); /相当于在上面的fis流上又套了一层管道,实际上读取的是一样的数据,但是它有了带缓冲区的功能 BufferedInputStream bis = new BufferedInputStream(fis); int c = 0; System.out.println(bis.read(); System.out.println(bis.read(); /mark一个标记,从第100个开始往外读 bis.mark(100); for(int i=0;i10 & (c=bis.read()!=-1;i+) System.out.print(char)c+ ); System.out.println(); /重置到上面的mark处 bis.reset(); for(int i=0;i=10 & (c=bis.read()!=-1;i+) System.out.print(char)c+ ); bis.close(); catch(IOException e) e.printStackTrace(); Java代码 修饰流的使用import java.io.*; public class TestBufferStream public static void main(String args) try /在FileWriter写出一个字符外面套层BufferedWriter管道 BufferedWriter bw = new BufferedWriter(new FileWriter(c:/write.txt); BufferedReader br = new BufferedReader(new FileReader(c:/write.txt); String s = null; for (int i = 0; i = 100; i+) s = String.valueOf(Math.random(); bw.write(s); bw.newLine(); bw.flush(); / readLine()方法为读一行数据 while (s = br.readLine() != null) System.out.println(s); bw.close(); br.close(); catch (IOException e) e.printStackTrace(); System.out.println(读取文件出错); Java代码 import java.io.*; public class TestTransForm2 public static void main(String args) /等待从键盘的输入,System.in可以理解为一根管道直接插在了键盘上 /System.in字节流输入一个字节,外面套层InputStreamReader转换流 InputStreamReader isr = new InputStreamReader(System.in); /isr转换流的外面又套层缓冲流,为了使用下面的readLine()方法,可以记取一行 BufferedReader br = new BufferedReader(isr); String s = null; try s = br.readLine(); while(s!=null) if(s.equalsIgnoreCase(exit) break; System.out.println(s.toUpperCase(); s = br.readLine(); br.close(); catch(IOException e) e.printStackTrace(); Java代码 import java.io.*; public class TestDataStream public static void main(String args) /在内存中定义了一个空间,同时一根管道插在了上面 ByteArrayOutputStream baos = new ByteArrayOutputStream(); /DataOutputStream直接写基础数据类型(boolean,double等),而且可以写UTF-8(省空间,网络上常用) DataOutputStream dos = new DataOutputStream(baos); try dos.writeDouble(Math.random(); dos.writeBoolean(true); ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray(); System.out.println(bais.available(); DataInputStream dis = new DataInputStream(bais); /输出按照先入先出的形式输出 System.out.println(dis.readDouble(); System.out.println(dis.readBoolean(); dos.close(); dis.close(); catch (IOException e) e.printStackTrace(); Java代码 import java.io.*; public class TestPrintStream1 public static void main(String args) PrintStream ps = null; try FileOutputStream fos = new FileOutputStream(d:/bak/log.dat); ps = new PrintStream(fos); catch (IOException e) e.printStackTrace(); if(ps != null) System.setOut(ps); int ln = 0; for(char c = 0; c =100) System.out.println(); ln = 0; Java代码 import java.io.*; public class TestPrintStream2 public static void main(String args) String filename = args0; if(filename!=null)list(filename,System.out); public static void list(String f,PrintStream fs) try BufferedReader br = new BufferedReader(new FileReader(f); String s = null; while(s=br.readLine()!=null) fs.println(s); br.close(); catch (IOException e) fs.println(无法读取文件); Java代码 import java.util.*; import java.io.*; public class TestPrintStream3 public static void main(String args) String s = null; BufferedReader br = new BufferedReader(new InputStreamReader(System.in); try FileWriter fw = new FileWriter(d:/bak/logfile.log, true); PrintWriter log = new PrintWriter(fw); while (s = br.readLine()!=null) if(s.equalsIgnoreCase(exit) break; System.out.println(s.toUpperCase(); log.println(-); log.println(s.toUpperCase(); log.flush(); log.println(=+new Date()+=); log.flush(); log.close(); catch (IOException e) e.printStackTrace(); Java代码 import java.io.*; public class TestObjectIO public static void main(String args) throws Exception T t = new T(); t.k = 8; FileOutputStream fos = new FileOutputStream(d:/share/ja