我的顶级Java工具名单

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：

StringUitls

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"    

StringUtils.isEmpty(null) && StringUtils.isEmpty(""); // true StringUtils.isBlank(" \n\t"); // true StringUtils.substringAfterLast("foo.bar.baz", "."); // "baz" StringUtils.substringBeforeLast("foo.bar.baz", "."); // "foo.bar" StringUtils.split("foo.bar.baz", '.'); // { "foo", "bar", "baz" } StringUtils.split("foo, bar,baz", ", "); // { "foo", "bar", "baz" } 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);  

File file1; File file2; InputStream inputStream; OutputStream outputStream; // copy one file into another FileUtils.copyFile(file1, file2); IOUtils.copy(inputStream, outputStream); // read a file into a String String s1 = FileUtils.readFileToString(file1); String s2 = IOUtils.toString(inputStream); // read a file into a list of Strings, one item per line List<String> l1 = FileUtils.readLines(file1); List<String> l2 = IOUtils.readLines(inputStream); // put this in your finally() clause after manipulating streams IOUtils.closeQuietly(inputStream); // return the list of xml and text files in the specified folder and any subfolders Collection<File> c1 = FileUtils.listFiles(file1, { "xml", "txt" }, true); // copy one folder and its contents into another FileUtils.copyDirectoryToDirectory(file1, file2); // delete one folder and its contents 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 }  

// create an ArrayList with three arguments List<String> list = Lists.newArrayList("foo", "bar", "baz"); // notice that there is no generics or class cast, // and still this line does not generate a warning. Set<String> s = Sets.newConcurrentHashSet(); // intersect and union are basic features of a Set, if you ask me Set<String> s = Sets.intersect(s1, s2); // Example of multiple values in a Map ListMultimap<String, Validator> validators = new ArrayListMultimap<String, Validator>(); validators.put("save", new RequiredValidator()); validators.put("save", new StringValidator()); validators.put("delete", new NumberValidator()); validators.get("save"); // { RequiredValidator, StringValidator } validators.get("foo"); // empty List (not null) 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>();  

// a map that may be modified (by the same or different thread) while being iterated Map<String, Something> repository = new ConcurrentHashMap<String, Something>(); // same with lists. This one is only available with Java 6 List<Something> list = new CopyOnWriteArrayList<Something>();

你有好的工具推荐吗？欢迎留言。
来自：java.dzone.com