Java tutorial
package com.googlecode.htmlcompressor.compressor; /* * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.io.IOException; import java.io.InputStream; import java.io.StringWriter; import java.util.ArrayList; import java.util.List; import java.util.logging.Level; import java.util.zip.ZipEntry; import java.util.zip.ZipInputStream; import com.google.common.collect.Lists; import com.google.common.io.LimitInputStream; import com.google.javascript.jscomp.CompilationLevel; import com.google.javascript.jscomp.Compiler; import com.google.javascript.jscomp.CompilerOptions; import com.google.javascript.jscomp.JSSourceFile; import com.google.javascript.jscomp.Result; import com.google.javascript.jscomp.WarningLevel; /** * Basic JavaScript compressor implementation using <a href="http://code.google.com/closure/compiler/">Google Closure Compiler</a> * that could be used by {@link HtmlCompressor} for inline JavaScript compression. * * @author <a href="mailto:serg472@gmail.com">Sergiy Kovalchuk</a> * * @see HtmlCompressor#setJavaScriptCompressor(Compressor) * @see <a href="http://code.google.com/closure/compiler/">Google Closure Compiler</a> */ public class ClosureJavaScriptCompressor implements Compressor { public static final String COMPILATION_LEVEL_SIMPLE = "simple"; public static final String COMPILATION_LEVEL_ADVANCED = "advanced"; public static final String COMPILATION_LEVEL_WHITESPACE = "whitespace"; //Closure compiler default settings private CompilerOptions compilerOptions = new CompilerOptions(); private CompilationLevel compilationLevel = CompilationLevel.SIMPLE_OPTIMIZATIONS; private Level loggingLevel = Level.SEVERE; private WarningLevel warningLevel = WarningLevel.DEFAULT; private boolean customExternsOnly = false; private List<JSSourceFile> externs = null; public ClosureJavaScriptCompressor() { } public ClosureJavaScriptCompressor(CompilationLevel compilationLevel) { this.compilationLevel = compilationLevel; } @Override public String compress(String source) { StringWriter writer = new StringWriter(); //prepare source List<JSSourceFile> input = new ArrayList<JSSourceFile>(); input.add(JSSourceFile.fromCode("source.js", source)); //prepare externs List<JSSourceFile> externsList = new ArrayList<JSSourceFile>(); if (compilationLevel.equals(CompilationLevel.ADVANCED_OPTIMIZATIONS)) { //default externs if (!customExternsOnly) { try { externsList = getDefaultExterns(); } catch (IOException e) { e.printStackTrace(); } } //add user defined externs if (externs != null) { for (JSSourceFile extern : externs) { externsList.add(extern); } } //add empty externs if (externsList.size() == 0) { externsList.add(JSSourceFile.fromCode("externs.js", "")); } } else { //empty externs externsList.add(JSSourceFile.fromCode("externs.js", "")); } Compiler.setLoggingLevel(loggingLevel); Compiler compiler = new Compiler(); compiler.disableThreads(); compilationLevel.setOptionsForCompilationLevel(compilerOptions); warningLevel.setOptionsForWarningLevel(compilerOptions); Result result = compiler.compile(externsList, input, compilerOptions); if (result.success) { writer.write(compiler.toSource()); } else { writer.write(source); } return writer.toString(); } //read default externs from closure.jar private List<JSSourceFile> getDefaultExterns() throws IOException { InputStream input = ClosureJavaScriptCompressor.class.getResourceAsStream("/externs.zip"); ZipInputStream zip = new ZipInputStream(input); List<JSSourceFile> externs = Lists.newLinkedList(); for (ZipEntry entry = null; (entry = zip.getNextEntry()) != null;) { LimitInputStream entryStream = new LimitInputStream(zip, entry.getSize()); externs.add(JSSourceFile.fromInputStream(entry.getName(), entryStream)); } return externs; } /** * Returns level of optimization that is applied when compiling JavaScript code. * * @return <code>CompilationLevel</code> that is applied when compiling JavaScript code. * * @see <a href="http://closure-compiler.googlecode.com/svn/trunk/javadoc/com/google/javascript/jscomp/CompilationLevel.html">CompilationLevel</a> */ public CompilationLevel getCompilationLevel() { return compilationLevel; } /** * Sets level of optimization that should be applied when compiling JavaScript code. * If none is provided, <code>CompilationLevel.SIMPLE_OPTIMIZATIONS</code> will be used by default. * * <p><b>Warning:</b> Using <code>CompilationLevel.ADVANCED_OPTIMIZATIONS</code> could * break inline JavaScript if externs are not set properly. * * @param compilationLevel Optimization level to use, could be set to <code>CompilationLevel.ADVANCED_OPTIMIZATIONS</code>, <code>CompilationLevel.SIMPLE_OPTIMIZATIONS</code>, <code>CompilationLevel.WHITESPACE_ONLY</code> * * @see <a href="http://code.google.com/closure/compiler/docs/api-tutorial3.html">Advanced Compilation and Externs</a> * @see <a href="http://code.google.com/closure/compiler/docs/compilation_levels.html">Closure Compiler Compilation Levels</a> * @see <a href="http://closure-compiler.googlecode.com/svn/trunk/javadoc/com/google/javascript/jscomp/CompilationLevel.html">CompilationLevel</a> */ public void setCompilationLevel(CompilationLevel compilationLevel) { this.compilationLevel = compilationLevel; } /** * Returns options that are used by the Closure compiler. * * @return <code>CompilerOptions</code> that are used by the compiler * * @see <a href="http://closure-compiler.googlecode.com/svn/trunk/javadoc/com/google/javascript/jscomp/CompilerOptions.html">CompilerOptions</a> */ public CompilerOptions getCompilerOptions() { return compilerOptions; } /** * Sets options that will be used by the Closure compiler. * If none is provided, default options constructor will be used: <code>new CompilerOptions()</code>. * * @param compilerOptions <code>CompilerOptions</code> that will be used by the compiler * * @see <a href="http://closure-compiler.googlecode.com/svn/trunk/javadoc/com/google/javascript/jscomp/CompilerOptions.html">CompilerOptions</a> */ public void setCompilerOptions(CompilerOptions compilerOptions) { this.compilerOptions = compilerOptions; } /** * Returns logging level used by the Closure compiler. * * @return <code>Level</code> of logging used by the Closure compiler */ public Level getLoggingLevel() { return loggingLevel; } /** * Sets logging level for the Closure compiler. * * @param loggingLevel logging level for the Closure compiler. * * @see java.util.logging.Level */ public void setLoggingLevel(Level loggingLevel) { this.loggingLevel = loggingLevel; } /** * Returns <code>JSSourceFile</code> used as a reference during the compression * at <code>CompilationLevel.ADVANCED_OPTIMIZATIONS</code> level. * * @return <code>JSSourceFile</code> used as a reference during compression */ public List<JSSourceFile> getExterns() { return externs; } /** * Sets external JavaScript files that are used as a reference for function declarations if * <code>CompilationLevel.ADVANCED_OPTIMIZATIONS</code> compression level is used. * * <p>A number of default externs defined inside Closure's jar will be used besides user defined ones, * to use only user defined externs set {@link #setCustomExternsOnly(boolean) setCustomExternsOnly(true)} * * <p><b>Warning:</b> Using <code>CompilationLevel.ADVANCED_OPTIMIZATIONS</code> could * break inline JavaScript if externs are not set properly. * * @param externs <code>JSSourceFile</code> to use as a reference during compression * * @see #setCompilationLevel(CompilationLevel) * @see #setCustomExternsOnly(boolean) * @see <a href="http://code.google.com/closure/compiler/docs/api-tutorial3.html">Advanced Compilation and Externs</a> * @see <a href="http://closure-compiler.googlecode.com/svn/trunk/javadoc/com/google/javascript/jscomp/JSSourceFile.html">JSSourceFile</a> */ public void setExterns(List<JSSourceFile> externs) { this.externs = externs; } /** * Returns <code>WarningLevel</code> used by the Closure compiler * * @return <code>WarningLevel</code> used by the Closure compiler */ public WarningLevel getWarningLevel() { return warningLevel; } /** * Indicates the amount of information you want from the compiler about possible problems in your code. * * @param warningLevel <code>WarningLevel</code> to use * * @see <a href="http://code.google.com/closure/compiler/docs/api-ref.html"> */ public void setWarningLevel(WarningLevel warningLevel) { this.warningLevel = warningLevel; } /** * Returns <code>true</code> if default externs defined inside Closure's jar are ignored * and only user defined ones are used. * * @return <code>true</code> if default externs defined inside Closure's jar are ignored * and only user defined ones are used */ public boolean isCustomExternsOnly() { return customExternsOnly; } /** * If set to <code>true</code>, default externs defined inside Closure's jar will be ignored * and only user defined ones will be used. * * @param customExternsOnly <code>true</code> to skip default externs and use only user defined ones * * @see #setExterns(List) * @see #setCompilationLevel(CompilationLevel) */ public void setCustomExternsOnly(boolean customExternsOnly) { this.customExternsOnly = customExternsOnly; } }