java io 操作

IO是JAVASE中非常重要的一块，是面向对象的完美体现，深入学习IO，你将可以领略到很多面向对象的思想。
在公司没活干，复习了一下IO，发现很多都忘记了，所以写的不好，只够初学用。我把我复习过程中写的代码贴出来，大家共同学习，并请多指教指教哈。顺便一起讨论IO
1、文件拷贝

Java code

try {            File inputFile = new File(args[0]);            if (!inputFile.exists()) {                System.out.println("源文件不存在，程序终止");                System.exit(1);            }            File outputFile = new File(args[1]);            InputStream in = new FileInputStream(inputFile);            OutputStream out = new FileOutputStream(outputFile);            byte date[] = new byte[1024];            int temp = 0;            while ((temp = in.read(date)) != -1) {                out.write(date);            }            in.close();            out.close();        } catch (FileNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }

2、java读文件:实现统计某一目录下每个文件中出现的字母个数、数字个数、空格个数及行数，除此之外没有其他字符

Java code

 String fileName = "D:/date.java.bak";        // String fileName = "D:/test.qqq";        String line;        int i = 0, j = 0, f = 0, k = 0;        try {            BufferedReader in = new BufferedReader(new FileReader(fileName));            line = in.readLine();            while (line != null) {                // System.out.println(line);                char c[] = line.toCharArray();                for (int i1 = 0; i1 < c.length; i1++) {                    // 如果是字母                    if (Character.isLetter(c[i1]))                        i++;                    // 如果是数字                    else if (Character.isDigit(c[i1]))                        j++;                    // 是空格                    else if (Character.isWhitespace(c[i1]))                        f++;                }                line = in.readLine();                k++;            }            in.close();            System.out                    .println("字母:" + i + ",数字:" + j + ",空格:" + f + ",行数:" + k);        } catch (IOException e) {            e.printStackTrace();        }

3、 从文件（d:\test.txt）中查出字符串”aa”出现的次数

Java code

try {            BufferedReader br = new BufferedReader(new FileReader(                    "D:\\test.txt"));            StringBuilder sb = new StringBuilder();            while (true) {                String str = br.readLine();                if (str == null)                    break;                sb.append(str);            }            Pattern p = Pattern.compile("aa");            Matcher m = p.matcher(sb);            int count = 0;            while (m.find()) {                count++;            }            System.out.println("\"aa\"一共出现了" + count + "次");        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }

4、 三种方法读取文件

Java code

 try {            // 方法一            BufferedReader br = new BufferedReader(new FileReader(new File(                    "D:\\1.xls")));            // StringBuilder bd = new StringBuilder();            StringBuffer bd = new StringBuffer();            while (true) {                String str = br.readLine();                if (str == null) {                    break;                }                System.out.println(str);                bd.append(str);            }            br.close();            // System.out.println(bd.toString());            // 方法二            InputStream is = new FileInputStream(new File("d:\\1.xls"));            byte b[] = new byte[Integer.parseInt(new File("d:\\1.xls").length()                    + "")];            is.read(b);            System.out.write(b);            System.out.println();            is.close();            // 方法三            Reader r = new FileReader(new File("d:\\1.xls"));            char c[] = new char[(int) new File("d:\\1.xls").length()];            r.read(c);            String str = new String(c);            System.out.print(str);            r.close();        } catch (RuntimeException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (FileNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }

5、三种方法写文件

Java code

 try {            PrintWriter pw = new PrintWriter(new FileWriter("d:\\1.txt"));            BufferedWriter bw = new BufferedWriter(new FileWriter(new File(                    "d:\\1.txt")));            OutputStream os = new FileOutputStream(new File("d:\\1.txt"));            // 1            os.write("ffff".getBytes());            // 2            // bw.write("ddddddddddddddddddddddddd");            // 3            // pw.print("你好sssssssssssss");            bw.close();            pw.close();            os.close();        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }

6、读取文件，并把读取的每一行存入double型数组中

Java code

try {            BufferedReader br = new BufferedReader(new FileReader(new File(                    "d:\\2.txt")));            StringBuffer sb = new StringBuffer();            while (true) {                String str = br.readLine();                if (str == null) {                    break;                }                sb.append(str + "、");            }            String str = sb.toString();            String s[] = str.split("、");            double d[] = new double[s.length];            for (int i = 0; i < s.length; i++) {                d[i] = Double.parseDouble(s[i]);            }            for (int i = 0; i < d.length; i++) {                System.out.println(d[i]);            }            br.close();        } catch (FileNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }