Java压缩JavaScript代码实例

这篇文章主要讲解了Java压缩javascript代码实例，内容清晰明了，对此有兴趣的小伙伴可以学习一下，相信大家阅读完之后会有帮助。

通过移除空行和注释来压缩 JavaScript 代码

public class JavaScriptCompressor {private static final char LINE_FEED = \'\\n\';private static final char CARRIAGE_RETURN = \'\\r\';private static final char SPACE = \' \';private static final char TAB = \'\\t\';public static String compress(String script) {JavaScriptCompressor jsc = new JavaScriptCompressor(script);return jsc.outputBuffer.toString();}private String script;private StringBuffer outputBuffer;private int pos;private char ch;private char lastAppend;private Boolean endReached;private Boolean contentAppendedAfterLastIdentifier = true;private JavaScriptCompressor(String script) {this.script = script;outputBuffer = new StringBuffer(script.length());nextchar();while (!endReached) {if (Character.isJavaidentifierStart(ch)) {renderIdentifier();} else if (ch == \' \') {skipWhiteSpace();} else if (isWhitespace()) {// Compress whitespaceskipWhiteSpace();} else if ((ch == \'\"\') || (ch == \'\\\'\')) {        // Handle strings        renderString();      } else if (ch == \'/\') {        // Handle comments        nextChar();        if (ch == \'/\') {          nextChar();          skipLineComment();        } else if (ch == \'*\') {          nextChar();          skipBlockComment();        } else {          append(\'/\');        }      } else {        append(ch);        nextChar();      }    }  }    private void append(char ch) {    lastAppend = ch;    outputBuffer.append(ch);    contentAppendedAfterLastIdentifier = true;  }    private boolean isWhitespace() {    return ch == CARRIAGE_RETURN || ch == SPACE || ch == TAB || ch == LINE_FEED;      }    private void nextChar() {    if (!endReached) {      if (pos < script.length()) {        ch = script.charAt(pos++);      } else {        endReached = true;        ch = 0;      }    }  }    private void renderIdentifier() {    if (!contentAppendedAfterLastIdentifier)      append(SPACE);    append(ch);    nextChar();    while (Character.isJavaIdentifierPart(ch)) {      append(ch);      nextChar();    }    contentAppendedAfterLastIdentifier = false;  }    private void renderString() {    char startCh = ch; // Save quote char    append(ch);    nextChar();    while (true) {      if ((ch == LINE_FEED) || (ch == CARRIAGE_RETURN) || (endReached)) {        // JavaScript error: string not terminated        return;      } else {        if (ch == \'\\\\\') {          append(ch);          nextChar();          if ((ch == LINE_FEED) || (ch == CARRIAGE_RETURN) || (endReached)) {            // JavaScript error: string not terminated            return;          }          append(ch);          nextChar();        } else {          append(ch);          if (ch == startCh) {            nextChar();            return;          }          nextChar();        }      }    }  }    private void skipLineComment() {    while ((ch != CARRIAGE_RETURN) && (ch != LINE_FEED)) {      if (endReached) {        return;      }      nextChar();    }  }    private void skipBlockComment() {    while (true) {      if (endReached) {        return;      }      if (ch == \'*\') {        nextChar();        if (ch == \'/\') {          nextChar();          return;        }      } else        nextChar();    }  }    private void renderNewLine() {    if (lastAppend != \'\\n\' && lastAppend != \'\\r\') {      append(\'\\n\');    }  }    private void skipWhiteSpace() {    if (ch == LINE_FEED || ch == CARRIAGE_RETURN) {      renderNewLine();    } else {      append(ch);    }    nextChar();    while (ch == LINE_FEED || ch == CARRIAGE_RETURN || ch == SPACE || ch == TAB) {      if (ch == LINE_FEED || ch == CARRIAGE_RETURN) {        renderNewLine();      }      nextChar();    }  }}