JS/CSS压缩工具 YUI Compressor

YUI Compressor 是一个用来压缩 JS 和 CSS 文件的工具，采用Java开发。

使用方法：

//压缩JS
java -jar yuicompressor-2.4.2.jar --type js --charset utf-8 -v src.js > packed.js
//压缩CSS
java -jar yuicompressor-2.4.2.jar --type css --charset utf-8 -v src.css > packed.css

网上搜索的 YUI Compressor 都是直接调用Java命令使用的或者通过文件流输入和文件流输出直接压缩js和css。

没有直接是字符串输入，压缩后 字符串输出的，没有办法自己研究吧，以下是研究后的成果，给大家共享下：

在线使用地址：http://www.aiisen.com/jscompress.html

1、先下载 yuicompressor.jar（此版本是2.4.2，如果需要下载最新的请到http://yuilibrary.com/download/#yuicompressor 下载）

在java上使用例子（主要是利用 ByteArrayInputStream 和 ByteArrayOutputStream）：

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;

import org.mozilla.javascript.ErrorReporter;
import org.mozilla.javascript.EvaluatorException;

import com.yahoo.platform.yui.compressor.CssCompressor;
import com.yahoo.platform.yui.compressor.JavaScriptCompressor;
/**
 * @author [email protected]
 * @version 2013-06-15
 */
public class YUICompressor {
	public static void main(String args[]) {
		String content = "function aiisen(stringA,stringB){\nvar stringA=\"你好爱森\";\nalert(\"hello world\"\n)};";
		System.out.println(content);
		String com = YUICompressor.compress("js", content, -1, true);
		System.out.println(com);
	}

	private static StringBuffer errs = null;

	/**
	 * @param type: js/css
	 * @param content
	 * @param linebreakpos 字节换行
	 * @param munge ture/false JS标识符混淆
	 */
	public static String compress(String type, String content, int linebreakpos, boolean munge) {
		Reader in = null;
		Writer out = null;
		ByteArrayOutputStream byteOut = null;
		ByteArrayInputStream byteIn = null;
		String dcontent = null;
		try {
			String charset = "UTF-8";
			if (type == null) {
				return  "type can not be null";
			}
			if (!type.equalsIgnoreCase("js") && !type.equalsIgnoreCase("css")) {
				return  "type can only be 'js' or 'css'";
			}
			byteIn = new ByteArrayInputStream(content.getBytes(charset));
			in = new InputStreamReader(byteIn, charset);
			byteOut = new ByteArrayOutputStream(1024000);
			if (type.equalsIgnoreCase("js")) {
				// 只在压缩JS的时候才实例化
				errs = new StringBuffer();
				try {
					JavaScriptCompressor compressor = new JavaScriptCompressor(in, new ErrorReporter() {
						public void warning(String message, String sourceName, int line, String lineSource,
								int lineOffset) {
							if (line < 0) {
								logErr("\n[ERROR] " + message);
							} else {
								logErr("\n[ERROR] " + line + ':' + lineOffset + ':' + message);
							}
						}

						public void error(String message, String sourceName, int line, String lineSource, int lineOffset) {
							if (line < 0) {
								logErr("\n[ERROR] " + message);
							} else {
								logErr("\n[ERROR] " + line + ':' + lineOffset + ':' + message);
							}
						}

						public EvaluatorException runtimeError(String message, String sourceName, int line,
								String lineSource, int lineOffset) {
							error(message, sourceName, line, lineSource, lineOffset);
							return new EvaluatorException(message);
						}
					});
					out = new OutputStreamWriter(byteOut, charset);
					boolean preserveAllSemiColons = false;
					boolean disableOptimizations = false;
					compressor.compress(out, linebreakpos, munge, false, preserveAllSemiColons, disableOptimizations);
					out.flush();
					dcontent = byteOut.toString(charset);
				} catch (EvaluatorException e) {
					e.printStackTrace();
					return (errs == null ? "" : errs.toString()) + e.getMessage();

				}
			} else if (type.equalsIgnoreCase("css")) {
				CssCompressor compressor = new CssCompressor(in);
				out = new OutputStreamWriter(byteOut, charset);
				compressor.compress(out, linebreakpos);
				out.flush();
				dcontent = byteOut.toString(charset);
			}

		} catch (IOException e) {
			e.printStackTrace();
			return e.getMessage();
		} finally {
			if (in != null) {
				try {
					in.close();
				} catch (IOException e) {
					e.printStackTrace();
					return e.getMessage();
				}
			}
			if (out != null) {
				try {
					out.close();
				} catch (IOException e) {
					e.printStackTrace();
					return e.getMessage();
				}
			}
			if (byteIn != null) {
				try {
					byteIn.close();
				} catch (IOException e) {
					e.printStackTrace();
					return e.getMessage();
				}
			}
			if (byteOut != null) {
				try {
					byteOut.close();
				} catch (IOException e) {
					e.printStackTrace();
					return e.getMessage();
				}
			}
		}
		return dcontent;
	}

	private static void logErr(String msg) {
		if (errs != null) {
			errs.append(msg);
		}
	}

	public static boolean isUTF8(byte[] data) {
		int count_good_utf = 0;
		int count_bad_utf = 0;
		byte current_byte = 0x00;
		byte previous_byte = 0x00;
		for (int i = 1; i < data.length; i++) {
			current_byte = data[i];
			previous_byte = data[i - 1];
			if ((current_byte & 0xC0) == 0x80) {
				if ((previous_byte & 0xC0) == 0xC0) {
					count_good_utf++;
				} else if ((previous_byte & 0x80) == 0x00) {
					count_bad_utf++;
				}
			} else if ((previous_byte & 0xC0) == 0xC0) {
				count_bad_utf++;
			}
		}
		return (count_good_utf > count_bad_utf);
	}

}