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
| 1234567891011121314151617181920212223242526 | try{ File inputFile = newFile(args[0]); if(!inputFile.exists()) { System.out.println("源文件不存在，程序终止"); System.exit(1); } File outputFile = newFile(args[1]); InputStream in = newFileInputStream(inputFile); OutputStream out = newFileOutputStream(outputFile); bytedate[] = newbyte[1024]; inttemp = 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(); } |
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
try {
BufferedReader in = new BufferedReader(new FileReader(file));
line = in.readLine();
while (line != null) {
char[] ch = line.toCharArray();
for (int a=0;a<ch.length;a++) {
if (Character.isLetter(ch[a])) {//统计字母
i++;
} else if (Character.isDigit(ch[a])) {//统计数字
j++;
} else if (Character.isWhitespace(ch[a])) {//统计空格
f++;
}
}
line = in.readLine();//统计行数
k++;
}
in.close();
System.out.println("字母有：" + i + " 数字有：" + j + " 空格有：" + f + " 行数：" + k);
System.out.println("aa一共出现了" + check("D://a.txt") + "次");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
| 12345678910111213141516171819202122232425262728293031 | String fileName = "D:/date.java.bak"; // String fileName = "D:/test.qqq"; String line; inti = 0, j = 0, f = 0, k = 0; try{ BufferedReader in = newBufferedReader(newFileReader(fileName)); line = in.readLine(); while(line != null) { // System.out.println(line); charc[] = line.toCharArray(); for(inti1 = 0; i1 < c.length; i1++) { // 如果是字母 if(Character.isLetter(c[i1])) i++; // 如果是数字 elseif(Character.isDigit(c[i1])) j++; // 是空格 elseif(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
int count = 0;
try {
BufferedReader in = new BufferedReader(new FileReader(file));
StringBuilder sb = new StringBuilder();
while (true) {
String str = in.readLine();
if (str == null)
break;
sb.append(str);
}
Pattern p = Pattern.compile("aa");
Matcher m = p.matcher(sb);
while (m.find()) {
count ++;
}
System.out.println("aa一共出现了" + count + "次");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
| 1234567891011121314151617181920212223 | try{ BufferedReader br = newBufferedReader(newFileReader( "D:\\test.txt")); StringBuilder sb = newStringBuilder(); while(true) { String str = br.readLine(); if(str == null) break; sb.append(str); } Pattern p = Pattern.compile("aa"); Matcher m = p.matcher(sb); intcount = 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(); } |
| 123456789101112131415161718192021222324252627282930 | try{ BufferedReader br = newBufferedReader(newFileReader(newFile( "d:\\2.txt"))); StringBuffer sb = newStringBuffer(); while(true) { String str = br.readLine(); if(str == null) { break; } sb.append(str + "、"); } String str = sb.toString(); String s[] = str.split("、"); doubled[] = newdouble[s.length]; for(inti = 0; i < s.length; i++) { d[i] = Double.parseDouble(s[i]); } for(inti = 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(); } |
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2013-2-17 9:54:34 |
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