JavaSPI 机制学习笔记

package autocomplete;

import java.util.Iterator;
import java.util.ServiceLoader;

/**
 * Created by lovesqcc on 16-2-29.
 */
public class PrefixMatcherTest {

    public static void main(String[] args) {
        ServiceLoader matcher = ServiceLoader.load(PrefixMatcher.class);
        Iterator matcherIter = matcher.iterator();
        while (matcherIter.hasNext()) {
            PrefixMatcher wordMatcher = matcherIter.next();
            System.out.println(wordMatcher.getClass().getName());
            String[] prefixes = new String[] {"a", "b", "c", "d", "e", "f", "g", "i",
                    "l", "n", "p", "r", "s", "t", "v", "w", "do", "finally"};
            for (String prefix: prefixes) {
                System.out.println(wordMatcher.obtainMatchedWords(prefix));
            }
        }

    }
}

package autocomplete;

import java.io.*;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by lovesqcc on 16-2-29.
 * A very Simple JavaSPI implementation using java reflection
 */
public class SimpleServiceLoader {

    private static final String PREFIX = "/META-INF/services/";

    public static  List load(Class cls) {
        List<String> implClasses = readServiceFile(cls);
        List implList = new ArrayList();
        for (String implClass : implClasses) {
            Class c = null;
            try {
                c = (Class) Class.forName(implClass);
                implList.add(c.newInstance());
            } catch (Exception e) {
                return new ArrayList();
            }
        }
        return implList;
    }

    private static List<String> readServiceFile(Class cls) {
        String infName = cls.getCanonicalName();
        String fileName = cls.getResource(PREFIX+infName).getPath();
        try {
            BufferedReader br = new BufferedReader(new FileReader(new File(fileName)));
            String line = "";
            List<String> implClasses = new ArrayList<String>();
            while ((line = br.readLine()) != null) {
                implClasses.add(line);
            }
            return implClasses;
        } catch (FileNotFoundException fnfe) {
            System.out.println("File not found: " + fileName);
            return new ArrayList<String>();
        } catch (IOException ioe) {
            System.out.println("Read file failed: " + fileName);
            return new ArrayList<String>();
        }
    }

    public static void main(String[] args) {
        List implList = load(PrefixMatcher.class);
        if (implList != null && implList.size() >0) {
            for (PrefixMatcher matcher: implList) {
                System.out.println(matcher.obtainMatchedWords("sh"));
            }
        }
    }
}