如何在Java中指定的开始和结束行中删除文本

Question

I am writing scripts to a text file with comments using java. Inside the comment, my sql script is written. I am writing my scripts within the comment actions starts and actions ends and I want the script within this comment to be replaced by some other scripts later. How can I remove the script which is available inside the specified comment and add new script .

--
-- `actions` starts
--
CREATE TABLE IF NOT EXISTS `actions` (
  `aid` varchar(255) NOT NULL DEFAULT '0' COMMENT 'Primary Key: Unique actions ID.',
  `type` varchar(32) NOT NULL DEFAULT '' COMMENT 'The object  acts on ',
  PRIMARY KEY (`aid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='Stores action.';
--
-- `actions` ends
--

--
-- `operations` starts
--
CREATE TABLE IF NOT EXISTS `operations` (
  `type` varchar(32) NOT NULL DEFAULT '' COMMENT 'The object that that action acts on ',
  `callback` varchar(255) NOT NULL DEFAULT '' COMMENT 'The callback ',
  `parameters` longblob NOT NULL COMMENT 'Parameters to be passed to .',
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='Stores operations.';
--
-- `operations` ends
--

Answer 1

I found the solution. Solutions is to use indexOf method to identify the starting and ending blocks. The code that i used is,

private static final String VARIABLE_FIELD = "variable";
private static final String END_MODULE_END_TAG = "' ends";
private static final String START_MODULE_END_TAG = "' starts";
private static final String MODULE_START_TAG = "-- '";
private static final String DOUBLE_HYPHEN = "--";
private static final String VALUE_FIELD = "value";
private static final String NAME_FIELD = "name";
private static final String SQL_VARIABLE_SEP = "`,`";
private static final String SQL_VALUE_SEP = "','";
private static final String SINGLE_QUOTE = "'";
private static final String LINE_BREAK = "\n";
private static final String EQUAL = "=";

File scriptFile = new File(versionFile + File.separator + fileName);
StringBuffer sb = new StringBuffer();
if (scriptFile.isFile()) {
    // if script file is available need to replace the content
    buff = new BufferedReader(new FileReader(scriptFile));
    String readBuff = buff.readLine();
    String sectionStarts = MODULE_START_TAG + moduleName + START_MODULE_END_TAG;
    String sectionEnds = MODULE_START_TAG + moduleName + END_MODULE_END_TAG;

    while (readBuff != null) {
        sb.append(readBuff);
        sb.append(LINE_BREAK);
        readBuff = buff.readLine();
    }

    int cnt1 = sb.indexOf(sectionStarts);
    int cnt2 = sb.indexOf(sectionEnds);
    if (cnt1 != -1 || cnt2 != -1) {
        sb.replace(cnt1 + sectionStarts.length(), cnt2, LINE_BREAK + queryString + LINE_BREAK);
    } else {
        // if this module is not added already in the file and need to add this config alone
        sb.append(LINE_BREAK + DOUBLE_HYPHEN + LINE_BREAK);
        sb.append(MODULE_START_TAG + moduleName + START_MODULE_END_TAG + LINE_BREAK);
        sb.append(queryString);
        sb.append(LINE_BREAK);
        sb.append(MODULE_START_TAG + moduleName + END_MODULE_END_TAG + LINE_BREAK);
        sb.append(DOUBLE_HYPHEN + LINE_BREAK);
    }
}

The key code is

int cnt1 = sb.indexOf(sectionStarts); int cnt2 = sb.indexOf(sectionEnds); if (cnt1 != -1 || cnt2 != -1) { sb.replace(cnt1 + sectionStarts.length(), cnt2, LINE_BREAK + queryString + LINE_BREAK); }

int cnt1 = sb.indexOf(sectionStarts); it identifies the starting tag and int cnt2 = sb.indexOf(sectionEnds); identifies the ending tag.

It will find the block and will replace the content with new one.