在前面的回答,我概述瞭如何Config4*能夠滿足您的需求。我決定吃我自己的狗食,所以我敲了一個現成的編譯和運行CONFIG4 *的應用程序,將你想要做什麼。我在這個答案中提供內聯代碼。與其通過StackOverview網頁閱讀代碼,您可能會發現將代碼複製並粘貼到文件中更容易,因此您可以使用文本編輯器查看代碼。
首先,我們需要定義三個變量配置文件:
下面是這樣一個文件的例子(複製並粘貼到這一點templates.cfg
):
deploymentType ?= ""; # specified with a command-line argument
files = [
# template file output file
# ----------------------------------------------------
"log4j-template.properties", "log4j.properties",
"hello-template.sh", "hello.sh",
];
@if (deploymentType == "dev") {
searchAndReplace = [
"${db.host}", "localhost",
"${db.user}", "guest",
"${db.log.level}", "2",
];
} @elseIf (deploymentType == "staging") {
searchAndReplace = [
"${db.host}", exec("hostname"),
"${db.user}", getenv("USERNAME"),
"${db.log.level}", "0",
];
} @elseIf (deploymentType == "prod") {
searchAndReplace = [
"${db.host}", "production.example.com",
"${db.user}", getenv("USERNAME"),
"${db.log.level}", "0",
];
} @else {
@error "deploymentType must be 'dev', 'staging' or 'prod'";
}
這裏是應用程序的主行。你應該削減正以下內容粘貼到InstantiateTemplateFiles.java
:
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import org.config4j.Configuration;
import org.config4j.SchemaValidator;
import org.config4j.ConfigurationException;
public class InstantiateTemplateFiles
{
public static void main(String[] args)
{
Configuration cfg = Configuration.create();
SchemaValidator sv = new SchemaValidator();
String[] searchAndReplace;
String[] files;
String contents;
String modifiedContents;
String templateFile;
String outputFile;
int i;
String[] schema = new String[] {
"deploymentType = string",
"searchAndReplace=table[string,search, string,replace]",
"files=table[string,template-file, string,output-file]",
};
if (args.length != 2) {
System.err.println("\nusage: java InstantiateTemplateFiles"
+ " meta-config-file.cfg deploymentType\n");
System.exit(1);
}
try {
//--------
// Parse the configuration file, perform schema validation
// and retrieve the required configuration variables.
//--------
cfg.insertString("", "deploymentType", args[1]);
cfg.parse(args[0]);
sv.parseSchema(schema);
sv.validate(cfg, "", "");
searchAndReplace = cfg.lookupList("", "searchAndReplace");
files = cfg.lookupList("", "files");
//--------
// Do the real work
//--------
for (i = 0; i < files.length; i += 2) {
Util.searchAndReplaceInFile(files[i + 0], files[i + 1],
searchAndReplace);
}
} catch(IOException ex) {
System.err.println("\n" + ex.getMessage() + "\n");
System.exit(1);
} catch(ConfigurationException ex) {
System.err.println("\n" + ex.getMessage() + "\n");
System.exit(1);
}
}
}
最後,這裏是執行搜索和替換的文件的代碼。此代碼獨立於Config4 *,因此即使您決定構建基於非Config4 *的實用程序,也可能會發現它很有用。你應該削減正將此代碼粘貼到Util.java
:
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
public class Util
{
public static void searchAndReplaceInFile(
String inputFile,
String outputFile,
String[] searchAndReplacePairs) throws IOException
{
String contents;
String modifiedContents;
contents = Util.readTextFile(inputFile);
modifiedContents = Util.replace(contents, searchAndReplacePairs);
Util.writeTextFile(outputFile, modifiedContents);
}
public static String readTextFile(String fileName) throws IOException
{
BufferedReader in;
StringBuffer result;
String line;
result = new StringBuffer();
in = new BufferedReader(new FileReader(fileName));
while ((line = in.readLine()) != null) {
result.append(line).append("\n");
}
in.close();
return result.toString();
}
public static void writeTextFile(String fileName, String contents)
throws IOException
{
PrintWriter out;
StringBuffer result;
String line;
out = new PrintWriter(new BufferedWriter(new FileWriter(fileName)));
out.print(contents);
out.close();
}
public static String replace(
String origStr,
String searchStr,
String replacementStr)
{
StringBuffer result;
int origStrLen;
int searchStrLen;
int currStart;
int pIndex;
result = new StringBuffer();
origStrLen = origStr.length();
searchStrLen = searchStr.length();
currStart = 0;
pIndex = origStr.indexOf(searchStr, currStart);
while (pIndex != -1) {
result.append(origStr.substring(currStart, pIndex));
result.append(replacementStr);
currStart = pIndex + searchStrLen;
pIndex = origStr.indexOf(searchStr, currStart);
}
result.append(origStr.substring(currStart));
return result.toString();
}
public static String replace(
String origStr,
String[] searchAndReplacePairs)
{
int i;
int currIndex;
String subStr;
String replaceStr;
StringBuffer result;
SearchAndReplacePair[] pairs;
SearchAndReplacePair nextPair;
pairs = new SearchAndReplacePair[searchAndReplacePairs.length/2];
for (i = 0; i < searchAndReplacePairs.length; i += 2) {
pairs[i/2] = new SearchAndReplacePair(origStr,
searchAndReplacePairs[i + 0],
searchAndReplacePairs[i + 1]);
}
result = new StringBuffer();
currIndex = 0;
nextPair = findNextPair(origStr, currIndex, pairs);
while (nextPair != null) {
subStr = origStr.substring(currIndex, nextPair.indexOf);
result.append(subStr);
result.append(nextPair.replace);
currIndex = nextPair.indexOf + nextPair.length;
for (i = 0; i < pairs.length; i++) {
pairs[i].findNext(currIndex);
}
nextPair = findNextPair(origStr, currIndex, pairs);
}
subStr = origStr.substring(currIndex);
result.append(subStr);
return result.toString();
}
private static SearchAndReplacePair findNextPair(
String origStr,
int currIndex,
SearchAndReplacePair[] pairs)
{
int i;
SearchAndReplacePair bestSoFar;
SearchAndReplacePair item;
bestSoFar = null;
for (i = 0; i < pairs.length; i++) {
item = pairs[i];
if (item.indexOf == -1) {
continue;
}
if (bestSoFar == null) {
bestSoFar = item;
continue;
}
if (bestSoFar.indexOf < item.indexOf) {
continue;
}
if (bestSoFar.indexOf > item.indexOf) {
bestSoFar = item;
continue;
}
if (bestSoFar.length < item.length) {
bestSoFar = item;
}
}
return bestSoFar;
}
}
class SearchAndReplacePair
{
String source;
String search;
String replace;
int length;
int indexOf;
int sourceLength;
public SearchAndReplacePair(String source, String search, String replace)
{
this.source = source;
this.sourceLength = source.length();
this.search = search;
this.replace = replace;
this.length = search.length();
this.indexOf = source.indexOf(search);
}
public void findNext(int fromIndex)
{
if (indexOf == -1 || indexOf + 1 == sourceLength) {
indexOf = -1;
} else {
indexOf = source.indexOf(search, fromIndex);
}
}
}
假設你已經下載並安裝Config4J(從Config4*網站),你可以編譯程序有以下:
CLASSPATH=.:/path/to/config4j.jar;
export CLASSPATH
javac -classpath .:/ag/projects/config4j/lib/config4j.jar *.java
這裏是運行它的一個例子:
java InstantiateTemplateFiles templates.cfg prod
如果文件hello-template.sh
樣子:
#!/bin/sh
DB_HOST=${db.host}
DB_USER=${db.user}
DB_LOG_LEVEL=${db.log.level}
echo Hello from $DB_USER at log level $DB_LOG_LEVEL on host $DB_HOST
然後將生成的文件hello.sh
的樣子:
#!/bin/sh
DB_HOST=production.example.com
DB_USER=cjmchale
DB_LOG_LEVEL=0
echo Hello from $DB_USER at log level $DB_LOG_LEVEL on host $DB_HOST