上一篇:Java (二)基于Eclipse配置Commons IO的环境
例1:查看文件、文件夹的长度(大小)。
1 import java.io.File;
2
3 import org.apache.commons.io.FileUtils;
4
5 public class Main {
6
7 public static void main(String[] args) {
8 long length = FileUtils.sizeOf(new File("J:/PrtSc/20190321/1.png"));
9 System.out.println(length);
10
11 length = FileUtils.sizeOf(new File("J:/PrtSc/20190321"));
12 System.out.println(length);
13
14 length = FileUtils.sizeOfDirectory(new File("J:/PrtSc/20190321"));
15 System.out.println(length);
16 }
17 }
控制台的输出:
23415
1015221
1015221
例2:列出指定目录下的非空文件。
1 import java.io.File;
2 import java.util.Collection;
3
4 import org.apache.commons.io.FileUtils;
5 import org.apache.commons.io.filefilter.EmptyFileFilter;
6
7 public class Main {
8
9 public static void main(String[] args) {
10 System.out.println(System.getProperty("user.dir") + "\n");
11
12 Collection<File> files1 = FileUtils.listFiles(new File(System.getProperty("user.dir")), EmptyFileFilter.NOT_EMPTY, null);
13 for (File file: files1) {
14 System.out.println(file.getAbsolutePath());
15 }
16
17 System.out.println("\n" + new File("empty.txt").length() + " bytes");
18 }
19 }
因为empty.txt是一个空文件,所以不会被列出来。
控制台的输出:
I:\Java\mycode\CommonsIOI:\Java\mycode\CommonsIO\.classpath
I:\Java\mycode\CommonsIO\.project0 bytes
如果向empty.txt写入内容,再次运行程序,empty.txt就会被列出。因为此时empty.txt不是一个空文件。
控制台的输出:
I:\Java\mycode\CommonsIOI:\Java\mycode\CommonsIO\.classpath
I:\Java\mycode\CommonsIO\.project
I:\Java\mycode\CommonsIO\empty.txt47 bytes
例3:列出指定目录,以及其子目录下的非空文件。
1 import java.io.File;
2 import java.util.Collection;
3
4 import org.apache.commons.io.FileUtils;
5 import org.apache.commons.io.filefilter.DirectoryFileFilter;
6 import org.apache.commons.io.filefilter.EmptyFileFilter;
7
8 public class Main {
9
10 public static void main(String[] args) {
11 System.out.println(System.getProperty("user.dir") + "\n");
12
13 Collection<File> files1 = FileUtils.listFiles(new File(System.getProperty("user.dir")), EmptyFileFilter.NOT_EMPTY, DirectoryFileFilter.INSTANCE);
14 for (File file: files1) {
15 System.out.println(file.getAbsolutePath());
16 }
17 }
18 }
控制台的输出:
I:\Java\mycode\CommonsIOI:\Java\mycode\CommonsIO\.classpath
I:\Java\mycode\CommonsIO\.project
I:\Java\mycode\CommonsIO\.settings\org.eclipse.jdt.core.prefs
I:\Java\mycode\CommonsIO\bin\com\mk\Main.class
I:\Java\mycode\CommonsIO\lib\commons-io-2.6-sources.jar
I:\Java\mycode\CommonsIO\lib\commons-io-2.6.jar
I:\Java\mycode\CommonsIO\src\com\mk\Main.java
例4.1:列出指定目录下,指定后缀的文件。
1 import java.io.File;
2 import java.util.Collection;
3
4 import org.apache.commons.io.FileUtils;
5 import org.apache.commons.io.filefilter.DirectoryFileFilter;
6 import org.apache.commons.io.filefilter.SuffixFileFilter;
7
8 public class Main {
9
10 public static void main(String[] args) {
11 System.out.println(System.getProperty("user.dir") + "\n");
12
13 Collection<File> files1 = FileUtils.listFiles(new File(System.getProperty("user.dir")), new SuffixFileFilter("java"), DirectoryFileFilter.INSTANCE);
14 for (File file: files1) {
15 System.out.println(file.getAbsolutePath());
16 }
17 }
18 }
控制台的输出:
I:\Java\mycode\CommonsIOI:\Java\mycode\CommonsIO\src\com\mk\Main.java
例4.2:列出指定目录下,指定后缀的文件。
1 import java.io.File;
2 import java.util.Collection;
3
4 import org.apache.commons.io.FileUtils;
5 import org.apache.commons.io.filefilter.DirectoryFileFilter;
6 import org.apache.commons.io.filefilter.FileFilterUtils;
7 import org.apache.commons.io.filefilter.SuffixFileFilter;
8
9 public class Main {
10
11 public static void main(String[] args) {
12 System.out.println(System.getProperty("user.dir") + "\n");
13
14 Collection<File> files1 = FileUtils.listFiles(new File(System.getProperty("user.dir")), FileFilterUtils.or(new SuffixFileFilter("java"), new SuffixFileFilter("class")), DirectoryFileFilter.INSTANCE);
15 for (File file: files1) {
16 System.out.println(file.getAbsolutePath());
17 }
18 }
19 }
控制台的输出:
I:\Java\mycode\CommonsIOI:\Java\mycode\CommonsIO\bin\com\mk\Main.class
I:\Java\mycode\CommonsIO\src\com\mk\Main.java
例4.3:列出指定目录下,指定后缀的文件。
1 import java.io.File;
2 import java.util.Collection;
3
4 import org.apache.commons.io.FileUtils;
5 import org.apache.commons.io.filefilter.DirectoryFileFilter;
6 import org.apache.commons.io.filefilter.EmptyFileFilter;
7 import org.apache.commons.io.filefilter.FileFilterUtils;
8 import org.apache.commons.io.filefilter.SuffixFileFilter;
9
10 public class Main {
11
12 public static void main(String[] args) {
13 System.out.println(System.getProperty("user.dir") + "\n");
14
15 Collection<File> files1 = FileUtils.listFiles(new File(System.getProperty("user.dir")), FileFilterUtils.or(new SuffixFileFilter("java"), new SuffixFileFilter("class"), EmptyFileFilter.EMPTY), DirectoryFileFilter.INSTANCE);
16 for (File file: files1) {
17 System.out.println(file.getAbsolutePath());
18 }
19 }
20 }
控制台的输出:
I:\Java\mycode\CommonsIOI:\Java\mycode\CommonsIO\bin\com\mk\Main.class
I:\Java\mycode\CommonsIO\empty.txt
I:\Java\mycode\CommonsIO\src\com\mk\Main.java
例5.1:读取文本文档的内容。
1 import java.io.File;
2 import java.io.IOException;
3
4 import org.apache.commons.io.FileUtils;
5
6 public class Main {
7
8 public static void main(String[] args) throws IOException {
9 System.out.println(System.getProperty("user.dir") + "\n");
10
11 String message = FileUtils.readFileToString(new File("empty.txt"), "GBK");
12 System.out.println(message);
13 System.out.println();
14
15 byte[] bytes = FileUtils.readFileToByteArray(new File("empty.txt"));
16 System.out.println(bytes.length + " bytes");
17 System.out.println(new String(bytes));
18 }
19 }
控制台的输出:
I:\Java\mycode\CommonsIO锄禾日当午
码农真辛苦
一段小字符
一写一下午46 bytes
锄禾日当午
码农真辛苦
一段小字符
一写一下午
例5.2:逐行读取文本文档的内容。
1 import java.io.File;
2 import java.io.IOException;
3 import java.util.List;
4
5 import org.apache.commons.io.FileUtils;
6
7 public class Main {
8
9 public static void main(String[] args) throws IOException {
10 System.out.println(System.getProperty("user.dir") + "\n");
11
12 List<String> strings = FileUtils.readLines(new File("empty.txt"), "GBK");
13 for (String str: strings) {
14 System.out.println(str);
15 }
16 }
17 }
控制台的输出:
I:\Java\mycode\CommonsIO锄禾日当午
码农真辛苦
一段小字符
一写一下午
例5.3:逐行读取文本文档的内容。
1 import java.io.File;
2 import java.io.IOException;
3
4 import org.apache.commons.io.FileUtils;
5 import org.apache.commons.io.LineIterator;
6
7 public class Main {
8
9 public static void main(String[] args) throws IOException {
10 System.out.println(System.getProperty("user.dir") + "\n");
11
12 LineIterator lineIterator = FileUtils.lineIterator(new File("empty.txt"), "GBK");
13 while (lineIterator.hasNext()) {
14 System.out.println(lineIterator.nextLine());
15 }
16 }
17 }
控制台的输出:
I:\Java\mycode\CommonsIO锄禾日当午
码农真辛苦
一段小字符
一写一下午
例6.1:写内容到文件。
1 import java.io.File;
2 import java.io.IOException;
3
4 import org.apache.commons.io.FileUtils;
5
6 public class Main {
7
8 public static void main(String[] args) throws IOException {
9 System.out.println(System.getProperty("user.dir") + "\n");
10
11 FileUtils.write(new File("text.txt"), "Where ", "GBK", true);
12 FileUtils.writeStringToFile(new File("text.txt"), "are ", "GBK", true);
13 FileUtils.writeByteArrayToFile(new File("text.txt"), "we?".getBytes("GBK"), true);
14 }
15 }
运行程序,在工程目录下生成一个文件text.txt,内容:
Where are we?
例6.2:写内容到文件。
1 import java.io.File;
2 import java.io.IOException;
3 import java.util.ArrayList;
4 import java.util.List;
5
6 import org.apache.commons.io.FileUtils;
7
8 public class Main {
9
10 public static void main(String[] args) throws IOException {
11 System.out.println(System.getProperty("user.dir") + "\n");
12
13 List<String> str = new ArrayList<String>();
14 str.add("Bruce Wayne: I've had training.");
15 str.add("Ducard: The training is nothing! Will is everything! The will to act.");
16
17 FileUtils.writeLines(new File("text.txt"), str, "\r\n", false);
18 }
19 }
运行程序,在工程目录下生成一个文件text.txt,内容:
Bruce Wayne: I've had training.
Ducard: The training is nothing! Will is everything! The will to act.