Apache Commons Library: I agree when I use it!

Document directory

• 1. commons-io
• 2. commons-cli
• 3. commons-Lang
• 4. commons-Configuration

Recently I wrote a program and found that the Apache commons (http://commons.apache.org/) Library is really good, can simplify a lot of tedious tasks in Java, helped us create a lot of wheels.

1. commons-io

I/O-related tool methods.

 

Example 1: Disable a stream

Bufferedwriter out = NULL; <br/> try {<br/> out = new bufferedwriter (...); <br/> out. write (...); <br/>... <br/>}< br/> catch (ioexception e) {<br/> E. printstacktrace (); <br/>}< br/> finally {<br/> If (OUT! = NULL) {<br/> try {out. Close () ;}catch (ioexception e) {}< br/>}< br/>}

In Finally, the general method of closing the stream is used. You only need to write ioutils as follows:

Ioutils. closequietly (out );

 

Example 2: read an object

List <string> = fileutils. readlines (File); // read the file content in the list by row. <br/> byte [] = fileutils. readfiletobytearray (File); // You can also read the byte array.

It can also be read directly from inputstream.

 

Example 3: traverse a directory

 

Commons-io provides directorywalker for Recursive directory traversal. Your program only needs to inherit directorywalker and then implement some methods. "Directory loader", the name is cool

2. commons-cli

Commons-CLI can help you parse command line parameters.

 

All you need to write is code like this:

// Options is used to hold all parameters. <br/> options Options = new options (); </P> <p> // Add parameters, specify parameter attributes <br/> options. addoption ("T", false, "display current time"); </P> <p> // resolution parameter <br/> commandlineparser parser = new posixparser (); <br/> CommandLine cmd = parser. parse (options, argS); </P> <p> // read the parsing result <br/> If (CMD. hasoption ("T") {<br/>... <br/>}< br/> else {<br/>... <br/>}

Helpformatter also helps you automatically generate a command line option, which is very considerate.

3. commons-Lang

Provides many basic tools and methods to enhance the classes in the Java. lang package. String processing is usually used, that is, stringutils and stringescapeutils.

I used stringescapeutils. escapehtml (string): to replace the special HTML characters (<> ", etc.) in the string with HTML entities.

 

Also, strtokenizer can perform more complex Syntax Parsing than stringtokenizer.

 

4. commons-Configuration

No, but it looks good. Provides a unified interface to read configurations from various places, such as properties files, Windows INI files, XML documents, and applet/servlet parameters.

PS. In addition, commons-Pool provides a general object pool implementation, which I will introduce in another article.