Struct Util 权威指南 - 通过 SPI 实现自定义扩展

1
void handleDefinitionFile(String dir, ClassLoader classLoader, List<ExtensionDefinition> output) throws IOException {
2
    String fileName = dir + this.service.getName();
3
    Enumeration<URL> urls = classLoader != null
4
            ? classLoader.getResources(fileName)
5
            : ClassLoader.getSystemResources(fileName);
6
    while (urls.hasMoreElements()) {
7
        URL url = urls.nextElement();
8
        try (BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream(), StandardCharsets.UTF_8))) {
9
            String line = null;
10
            while (null != (line = reader.readLine())) {
11
                line = line.trim();
12
                if (line.length() > 0) {
13
                    try {
14
                        output.add(this.createExtensionDefinition(line, classLoader));
15
                    } catch (LinkageError | ClassNotFoundException e) {
16
                        LOGGER.warn("load [{}] class failure. {}", line, e.getMessage());
17
                    }
18
                }
19
            }
20
        } catch (Throwable e) {
21
            LOGGER.warn("handle extension definition file error.", e);
22
        }
23
    }
24
}
25

26
ExtensionDefinition createExtensionDefinition(String clzName, ClassLoader loader) throws ClassNotFoundException {
27
    Class<?> clzOfService = Class.forName(clzName, true, loader);
28
    String name = null;
29
    int order = 0;
30
    SPI anno = AnnotationUtils.findAnnotation(SPI.class, clzOfService);
31
    if (anno != null) {
32
        name = anno.name();
33
        order = anno.order();
34
    }
35
    return new ExtensionDefinition(name, clzOfService, order);
36
}

1
public class StringToArrayConverter implements Converter {
2

3
    @Override
4
    public Object convert(Object originValue, Class<?> targetType) {
5
        if (!targetType.isArray() || String.class != originValue.getClass()) {
6
            return null;
7
        }
8
        String content = (String) originValue;
9
        Class<?> componentType = targetType.getComponentType();
10
        String[] data = content.split(separator);
11
        if (exceptBlank) {
12
            data = Arrays.stream(data)
13
                    .map(String::trim)
14
                    .filter(s -> !s.isEmpty())
15
                    .toArray(String[]::new);
16
        }
17
        Object array = Array.newInstance(componentType, data.length);
18
        for (int i = 0; i < data.length; i++) {
19
            Array.set(array, i, ConverterUtil.covert(data[i], componentType));
20
        }
21
        return array;
22
    }
23
}