Springboot如何设置外部目录为classpath？

[风云扬]

普通的jar包：
通过java读取classpath下的properties配置文件内容，如下“代码段一”；此时，命令行通过
java -classpath ./testClasspath.jar:./test.properties com.devin.TestClasspath指定外部的classpath，代码依然能读取test.properties的配置内容, test.properties可以放到任意位置，只要在-classpath指定该路径就可以

Springboot jar包运行模式：
假设此时springboot的工程依赖上面提到的testClasspath.jar包，需要把springboot打成jar包，通过java -jar springboot.jar的方式启动服务；但springboot不支持设置-classpath，所以无法为testClasspath.jar指定外部test.properties文件的路径

问题是：springboot是否有什么方式可以设置外部目录成为classpath，让其依赖的其它jar包能读取到classpath下的配置文件？
之所以有这个问题，是因为有些配置文件不是springboot项目维护的（比如YARN的core-site.xml）,只能通过指定classpath的方式为hadoop的jar包读取文件的目录


代码段一：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Properties;
import java.util.Set;

public class TestClasspath{
    private static String keyValueSeparators = "=: \t\r\n\f";
    private static String strictKeyValueSeparators = "=:";
    private static String specialSaveChars = "=: \t\r\n\f#!";
    private static String whiteSpaceChars = " \t\r\n\f";

    public static void main(String[] args){
        try
        {
            InputStream is = TestClasspath.class.getClassLoader().getResourceAsStream("test.properties");
            Properties testProperties = new Properties();
            load(testProperties, is, "utf-8");

            Set<Entry<Object, Object>> propertiesSet = testProperties.entrySet();
            for (Map.Entry<Object, Object> entry : propertiesSet)
            {
                String sparkConfKey = entry.getKey().toString();
                String sparkConfValue = entry.getValue().toString();

                System.out.println(sparkConfKey + " = " + sparkConfValue);
            }

        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

    }

    public static void load(Properties properties, InputStream inStream, String encoding)
            throws IOException
    {
        InputStreamReader reader = new InputStreamReader(inStream, encoding);

        load(properties, reader);
    }

    public static void load(Properties properties, Reader reader) throws IOException
    {
        BufferedReader in = new BufferedReader(reader);

        while (true)
        {
            // Get next line
            String line = in.readLine();

            if (line == null)
            {
                return;
            }

            if (line.length() > 0)
            {
                // Find start of key
                int len = line.length();
                int keyStart;

                for (keyStart = 0; keyStart < len; keyStart++)
                {
                    if (whiteSpaceChars.indexOf(line.charAt(keyStart)) == -1)
                    {
                        break;
                    }
                }

                // Blank lines are ignored
                if (keyStart == len)
                {
                    continue;
                }

                // Continue lines that end in slashes if they are not comments
                char firstChar = line.charAt(keyStart);

                if ((firstChar != '#') && (firstChar != '!'))
                {
                    while (continueLine(line))
                    {
                        String nextLine = in.readLine();

                        if (nextLine == null)
                        {
                            nextLine = "";
                        }

                        String loppedLine = line.substring(0, len - 1);

                        // Advance beyond whitespace on new line
                        int startIndex;

                        for (startIndex = 0; startIndex < nextLine.length(); startIndex++)
                        {
                            if (whiteSpaceChars.indexOf(nextLine.charAt(startIndex)) == -1)
                            {
                                break;
                            }
                        }

                        nextLine = nextLine.substring(startIndex, nextLine.length());
                        line = new String(loppedLine + nextLine);
                        len = line.length();
                    }

                    // Find separation between key and value
                    int separatorIndex;

                    for (separatorIndex = keyStart; separatorIndex < len; separatorIndex++)
                    {
                        char currentChar = line.charAt(separatorIndex);

                        if (currentChar == '\\')
                        {
                            separatorIndex++;
                        }
                        else if (keyValueSeparators.indexOf(currentChar) != -1)
                        {
                            break;
                        }
                    }

                    // Skip over whitespace after key if any
                    // test
                    int valueIndex;

                    for (valueIndex = separatorIndex; valueIndex < len; valueIndex++)
                    {
                        if (whiteSpaceChars.indexOf(line.charAt(valueIndex)) == -1)
                        {
                            break;
                        }
                    }

                    // Skip over one non whitespace key value separators if any
                    if (valueIndex < len)
                    {
                        if (strictKeyValueSeparators.indexOf(line.charAt(valueIndex)) != -1)
                        {
                            valueIndex++;
                        }
                    }

                    // Skip over white space after other separators if any
                    while (valueIndex < len)
                    {
                        if (whiteSpaceChars.indexOf(line.charAt(valueIndex)) == -1)
                        {
                            break;
                        }

                        valueIndex++;
                    }

                    String key = line.substring(keyStart, separatorIndex);
                    String value = (separatorIndex < len) ? line.substring(valueIndex, len) : "";

                    // Convert then store key and value
                    key = loadConvert(key);
                    value = loadConvert(value);
                    properties.put(key, value);
                }
            }
        }
    }

    private static boolean continueLine(String line)
    {
        int slashCount = 0;
        int index = line.length() - 1;

        while ((index >= 0) && (line.charAt(index--) == '\\'))
        {
            slashCount++;
        }

        return ((slashCount % 2) != 0);
    }

    private static String loadConvert(String theString)
    {
        char aChar;
        int len = theString.length();
        StringBuffer outBuffer = new StringBuffer(len);

        for (int x = 0; x < len; )
        {
            aChar = theString.charAt(x++);

            if (aChar == '\\')
            {
                aChar = theString.charAt(x++);

                if (aChar == 'u')
                {
                    // Read the xxxx
                    int value = 0;

                    for (int i = 0; i < 4; i++)
                    {
                        aChar = theString.charAt(x++);

                        switch (aChar)
                        {
                            case '0':
                            case '1':
                            case '2':
                            case '3':
                            case '4':
                            case '5':
                            case '6':
                            case '7':
                            case '8':
                            case '9':
                                value = ((value << 4) + aChar) - '0';
                                break;

                            case 'a':
                            case 'b':
                            case 'c':
                            case 'd':
                            case 'e':
                            case 'f':
                                value = ((value << 4) + 10 + aChar) - 'a';
                                break;

                            case 'A':
                            case 'B':
                            case 'C':
                            case 'D':
                            case 'E':
                            case 'F':
                                value = ((value << 4) + 10 + aChar) - 'A';
                                break;

                            default:
                                throw new IllegalArgumentException("Malformed \\uxxxx encoding.");
                        }
                    }

                    outBuffer.append((char) value);
                }
                else
                {
                    if (aChar == 't')
                    {
                        aChar = '\t';
                    }
                    else if (aChar == 'r')
                    {
                        aChar = '\r';
                    }
                    else if (aChar == 'n')
                    {
                        aChar = '\n';
                    }
                    else if (aChar == 'f')
                    {
                        aChar = '\f';
                    }

                    outBuffer.append(aChar);
                }
            }
            else
            {
                outBuffer.append(aChar);
            }
        }

        return outBuffer.toString();
    }
}

[风云扬]

基于整个帖子： https://stackoverflow.com/questions/46728122/add-an-external-xml-file-containing-passwords-to-class-path-in-spring-boot 问题已经解决了，结贴。 补充2点： 1、经过试验，不需要在读取文件的时候前面加/（“you need to call getResourceAsStream("/myxml.xml") with a slash in the path.”） 2、如果需要配置对个外部目录，通过逗号分隔即可：java -Dloader.path="/myhomet/bb,/myhome/cc" -jar testclass-1.0.0.jar