标签：读数 高效 字符编码 blog form stack 文件流 nts err
一.文件流（字节流，字符流）
1.字节流
package com.zijie; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; public class TestFileInputStream { public static void main(String[] args) { int b = 0; FileInputStream in = null; try{ in = new FileInputStream("e:\\go\\file.txt"); } catch(FileNotFoundException e) { System.out.println("找不到指定的文件"); System.exit(-1); } try{ long num = 0; // 返回-1的话就表示已经读到了文件的结尾 while((b = in.read()) != -1) { System.out.print((char)b); num++; } in.close(); System.out.println("\n\n共读取了" + num + "个字节"); } catch(IOException e1) { System.out.println("读取文件时出现异常"); System.exit(-1); } } }
package com.zijie; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; public class TestFileOutputStream { public static void main(String[] args) { int b = 0; FileInputStream in = null; FileOutputStream out = null; try { in = new FileInputStream("e:\\go\\file.txt"); // OutputStream有这个文件就往这个文件里面写, 没有的话就自动创建一个 out = new FileOutputStream("e:\\go\\fileNew.txt"); // 一边读, 一边写 while ((b = in.read()) != -1) { out.write(b); } } catch (FileNotFoundException e) { System.out.println("找不到指定文件"); System.exit(-1); } catch (IOException e) { System.out.println("文件复制出错"); System.exit(-1); } System.out.println("文件成功复制"); } }
2.字符流
package com.zifu; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; public class TestFileReader { public static void main(String[] args) { FileReader fr = null; int c = 0; try { fr = new FileReader("e:\\go\\file.txt"); while ((c = fr.read()) != -1) { System.out.print((char) c); } fr.close(); } catch (FileNotFoundException e) { System.out.println("文件未找到"); System.exit(-1); } catch (IOException e) { System.out.println("读取文件时出现异常"); System.exit(-1); } } }
package com.zifu; import java.io.FileWriter; import java.io.IOException; public class TestFileWriter { public static void main(String[] args) { FileWriter fw = null; try { fw = new FileWriter("e:\\go\\unicode000.dat"); for (int i = 1; i <= 50000; i++) { fw.write(i); } } catch (IOException e) { System.out.println("写入文件出错 !"); System.exit(-1); } } }
二.缓冲流
package com.buffer; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; public class TestBufferRW { public static void main(String[] args) { try { BufferedWriter bw = new BufferedWriter(new FileWriter("e:\\go\\bwrite.txt")); BufferedReader br = new BufferedReader(new FileReader("e:\\go\\bwrite.txt")); String s = null; for (int i = 0; i < 100; i++) { s = "" + Math.random(); //bw.write(s); bw.append(s); bw.newLine(); } bw.flush(); // 特别好用的方法, readLine while((s = br.readLine()) != null) { System.out.println(s); } br.close(); bw.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }
package com.buffer; import java.io.BufferedInputStream; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; public class TestBufferStream { public static void main(String[] args) { try { FileInputStream fis = new FileInputStream("e:\\go\\bufferedfile.txt"); BufferedInputStream bis = new BufferedInputStream(fis); int c = 0; System.out.println((char)bis.read()); System.out.println((char)bis.read()); /* while((c = bis.read()) != -1) { System.out.print((char)c+", "); }*/ // 标记到第30的位置再开始读数据 bis.mark(100); for (int i = 0; i <= 10 && (c = bis.read()) != -1; i++) { System.out.print((char)c); } System.out.println(); // 回到mark标记的那个地方 bis.reset(); for (int i = 0; i <= 10 && (c = bis.read()) != -1; i++) { System.out.print((char)c); } bis.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }
三.转换流
转换流是指将字节流与字符流之间的转换，包含两个类：InputStreamReader和OutputStreamWriter。
转换流的出现方便了对文件的读写，她在字符流与字节流之间架起了一座桥梁，使原本毫无关联的两种流操作能够进行转化，提高了程序的灵活性。
package com.convert; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.OutputStreamWriter; import java.io.UnsupportedEncodingException; public class TestTranForm1 { public static void main(String[] args) { OutputStreamWriter osw = null; try { osw = new OutputStreamWriter(new FileOutputStream("e:\\go\\newreader.txt")); osw.write("山东淄博"); // 默认使用当前系统的字符编码 System.out.println(osw.getEncoding()); osw.close(); // FileOutputStream加第二个参数true表示追加内容 osw = new OutputStreamWriter(new FileOutputStream("e:\\go\\newreader.txt", true), "utf-8"); osw.write("qwerttttt"); System.out.println(osw.getEncoding()); osw.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }
标签：读数 高效 字符编码 blog form stack 文件流 nts err
原文地址：http://www.cnblogs.com/bekeyuan123/p/6931358.html
