【IT168 资讯】
Ignacio Coloma说道：作为一个软件开发者，缺乏想象力是最严重的罪过之一。我们经常把事情重复做一遍又一遍，但是我们很少改变这种方式，至少我是这样。经过这些年开发，在我的工具箱里面有了一些每个项目我都需要用到的工具，烦人的重复工作不再是我的事。
下面这些工具也许你已经用到，让我来仔细介绍它们：
StringUtils
这是象面包和奶油一样必须的通用语言库，这个实用工具类包括一些很早以前在String中未包含的重要方法。
Java代码
1 StringUtils.isEmpty(null) && StringUtils.isEmpty(""); // true
2 StringUtils.isBlank(" \n\t"); // true
3 StringUtils.substringAfterLast("foo.bar.baz", "."); // "baz"
4 StringUtils.substringBeforeLast("foo.bar.baz", "."); // "foo.bar"
5 StringUtils.split("foo.bar.baz", '.'); // { "foo", "bar", "baz" }
6 StringUtils.split("foo, bar,baz", ", "); // { "foo", "bar", "baz" }
7 StringUtils.leftPad("1", 3, '0'); // "001"
2 StringUtils.isBlank(" \n\t"); // true
3 StringUtils.substringAfterLast("foo.bar.baz", "."); // "baz"
4 StringUtils.substringBeforeLast("foo.bar.baz", "."); // "foo.bar"
5 StringUtils.split("foo.bar.baz", '.'); // { "foo", "bar", "baz" }
6 StringUtils.split("foo, bar,baz", ", "); // { "foo", "bar", "baz" }
7 StringUtils.leftPad("1", 3, '0'); // "001"
IOUtils and FileUtils
在一种当你需要手动操作多个文件罕见情况下必须具备的工具，这两个工具很相似(FileUtils操作文件，IOUtils操作InputStream和Reader classes)，和捆绑常用IO.
Java代码
1 File file1;
2 File file2;
3 InputStream inputStream;
4 OutputStream outputStream;
5
6 // copy one file into another
7 FileUtils.copyFile(file1, file2);
8 IOUtils.copy(inputStream, outputStream);
9
10 // read a file into a String
11 String s1 = FileUtils.readFileToString(file1);
12 String s2 = IOUtils.toString(inputStream);
13
14 // read a file into a list of Strings, one item per line
15 List<String> l1 = FileUtils.readLines(file1);
16 List<String> l2 = IOUtils.readLines(inputStream);
17
18 // put this in your finally() clause after manipulating streams
19 IOUtils.closeQuietly(inputStream);
20
21 // return the list of xml and text files in the specified folder and any subfolders
22 Collection<File> c1 = FileUtils.listFiles(file1, { "xml", "txt" }, true);
23
24 // copy one folder and its contents into another
25 FileUtils.copyDirectoryToDirectory(file1, file2);
26
27 // delete one folder and its contents
28 FileUtils.deleteDirectory(file1);
2 File file2;
3 InputStream inputStream;
4 OutputStream outputStream;
5
6 // copy one file into another
7 FileUtils.copyFile(file1, file2);
8 IOUtils.copy(inputStream, outputStream);
9
10 // read a file into a String
11 String s1 = FileUtils.readFileToString(file1);
12 String s2 = IOUtils.toString(inputStream);
13
14 // read a file into a list of Strings, one item per line
15 List<String> l1 = FileUtils.readLines(file1);
16 List<String> l2 = IOUtils.readLines(inputStream);
17
18 // put this in your finally() clause after manipulating streams
19 IOUtils.closeQuietly(inputStream);
20
21 // return the list of xml and text files in the specified folder and any subfolders
22 Collection<File> c1 = FileUtils.listFiles(file1, { "xml", "txt" }, true);
23
24 // copy one folder and its contents into another
25 FileUtils.copyDirectoryToDirectory(file1, file2);
26
27 // delete one folder and its contents
28 FileUtils.deleteDirectory(file1);
Google collections
这是我所知道的最好的扩展实现包，其中一些被社区叫嚣着要加入JDK：
Java代码
1 // create an ArrayList with three arguments
2 List<String> list = Lists.newArrayList("foo", "bar", "baz");
3
4 // notice that there is no generics or class cast,
5 // and still this line does not generate a warning.
6 Set<String> s = Sets.newConcurrentHashSet();
7
8 // intersect and union are basic features of a Set, if you ask me
9 Set<String> s = Sets.intersect(s1, s2);
10
11 // Example of multiple values in a Map
12 ListMultimap<String, Validator> validators = new ArrayListMultimap<String, Validator>();
13 validators.put("save", new RequiredValidator());
14 validators.put("save", new StringValidator());
15 validators.put("delete", new NumberValidator());
16
17 validators.get("save"); // { RequiredValidator, StringValidator }
18 validators.get("foo"); // empty List (not null)
19 validators.values(); // { RequiredValidator, StringValidator, NumberValidator }
2 List<String> list = Lists.newArrayList("foo", "bar", "baz");
3
4 // notice that there is no generics or class cast,
5 // and still this line does not generate a warning.
6 Set<String> s = Sets.newConcurrentHashSet();
7
8 // intersect and union are basic features of a Set, if you ask me
9 Set<String> s = Sets.intersect(s1, s2);
10
11 // Example of multiple values in a Map
12 ListMultimap<String, Validator> validators = new ArrayListMultimap<String, Validator>();
13 validators.put("save", new RequiredValidator());
14 validators.put("save", new StringValidator());
15 validators.put("delete", new NumberValidator());
16
17 validators.get("save"); // { RequiredValidator, StringValidator }
18 validators.get("foo"); // empty List (not null)
19 validators.values(); // { RequiredValidator, StringValidator, NumberValidator }
java.util.concurrent
不是每个人都需要这么重的java.util.concurrent，但是很好用:
Java代码
1 // a map that may be modified (by the same or different thread) while being iterated
2 Map<String, Something> repository = new ConcurrentHashMap<String, Something>();
3
4 // same with lists. This one is only available with Java 6
5 List<Something> list = new CopyOnWriteArrayList<Something>();
2 Map<String, Something> repository = new ConcurrentHashMap<String, Something>();
3
4 // same with lists. This one is only available with Java 6
5 List<Something> list = new CopyOnWriteArrayList<Something>();
