InjectProvider.java:
package geektime.tdd.di;
import jakarta.inject.Inject;
import java.lang.reflect.*;
import java.util.*;
import java.util.function.BiFunction;
import java.util.stream.Stream;
import static java.util.Arrays.stream;
import static java.util.stream.Stream.concat;
class InjectionProvider<T> implements ContextConfig.ComponentProvider<T> {
private Constructor<T> injectConstructor;
private List<Field> injectFields;
private List<Method> injectMethods;
public InjectionProvider(Class<T> component) {
if (Modifier.isAbstract(component.getModifiers())) throw new IllegalComponentException();
this.injectConstructor = getInjectConstructor(component);
this.injectFields = getInjectFields(component);
this.injectMethods = getInjectMethods(component);
if (injectFields.stream().anyMatch(f -> Modifier.isFinal(f.getModifiers())))
throw new IllegalComponentException();
if (injectMethods.stream().anyMatch(m -> m.getTypeParameters().length != 0))
throw new IllegalComponentException();
}
@Override
public T get(Context context) {
try {
T instance = injectConstructor.newInstance(toDependencies(context, injectConstructor));
for (Field field : injectFields) field.set(instance, toDependency(context, field));
for (Method method : injectMethods) method.invoke(instance, toDependencies(context, method));
return instance;
} catch (InvocationTargetException | InstantiationException | IllegalAccessException e) {
throw new RuntimeException(e);
}
}
@Override
public List<Context.Ref> getDependencies() {
return concat(concat(stream(injectConstructor.getParameters()).map(Parameter::getParameterizedType),
injectFields.stream().map(Field::getGenericType)),
injectMethods.stream().flatMap(m -> stream(m.getParameters()).map(Parameter::getParameterizedType)))
.map(Context.Ref::of).toList();
}
private static <T> List<Method> getInjectMethods(Class<T> component) {
List<Method> injectMethods = traverse(component, (methods, current) -> injectable(current.getDeclaredMethods())
.filter(m -> isOverrideByInjectMethod(methods, m))
.filter(m -> isOverrideByNoInjectMethod(component, m)).toList());
Collections.reverse(injectMethods);
return injectMethods;
}
private static <T> List<Field> getInjectFields(Class<T> component) {
return traverse(component, (fields, current) -> injectable(current.getDeclaredFields()).toList());
}
private static <Type> Constructor<Type> getInjectConstructor(Class<Type> implementation) {
List<Constructor<?>> injectConstructors = injectable(implementation.getConstructors()).toList();
if (injectConstructors.size() > 1) throw new IllegalComponentException();
return (Constructor<Type>) injectConstructors.stream().findFirst().orElseGet(() -> defaultConstructor(implementation));
}
private static <Type> Constructor<Type> defaultConstructor(Class<Type> implementation) {
try {
return implementation.getDeclaredConstructor();
} catch (NoSuchMethodException e) {
throw new IllegalComponentException();
}
}
private static <T> List<T> traverse(Class<?> component, BiFunction<List<T>, Class<?>, List<T>> finder) {
List<T> members = new ArrayList<>();
Class<?> current = component;
while (current != Object.class) {
members.addAll(finder.apply(members, current));
current = current.getSuperclass();
}
return members;
}
private static <T extends AnnotatedElement> Stream<T> injectable(T[] declaredFields) {
return stream(declaredFields).filter(f -> f.isAnnotationPresent(Inject.class));
}
private static boolean isOverride(Method m, Method o) {
return o.getName().equals(m.getName()) && Arrays.equals(o.getParameterTypes(), m.getParameterTypes());
}
private static <T> boolean isOverrideByNoInjectMethod(Class<T> component, Method m) {
return stream(component.getDeclaredMethods()).filter(m1 -> !m1.isAnnotationPresent(Inject.class)).noneMatch(o -> isOverride(m, o));
}
private static boolean isOverrideByInjectMethod(List<Method> injectMethods, Method m) {
return injectMethods.stream().noneMatch(o -> isOverride(m, o));
}
private static Object[] toDependencies(Context context, Executable executable) {
return stream(executable.getParameters()).map(p -> toDependency(context, p.getParameterizedType())).toArray(Object[]::new);
}
private static Object toDependency(Context context, Field field) {
return toDependency(context, field.getGenericType());
}
private static Object toDependency(Context context, Type type) {
return context.get(Context.Ref.of(type)).get();
}
}
Context.java:
package geektime.tdd.di;
import java.lang.annotation.Annotation;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Objects;
import java.util.Optional;
public interface Context {
<ComponentType> Optional<ComponentType> get(Ref<ComponentType> ref);
class Ref<ComponentType> {
public static <ComponentType> Ref<ComponentType> of(Class<ComponentType> component) {
return new Ref(component, null);
}
public static <ComponentType> Ref<ComponentType> of(Class<ComponentType> component, Annotation qualifier) {
return new Ref(component, qualifier);
}
public static Ref of(Type type) {
return new Ref(type, null);
}
private Type container;
private Class<ComponentType> component;
private Annotation qualifier;
Ref(Type type, Annotation qualifier) {
init(type);
this.qualifier = qualifier;
}
protected Ref() {
Type type = ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
init(type);
}
private void init(Type type) {
if (type instanceof ParameterizedType container) {
this.container = container.getRawType();
this.component = (Class<ComponentType>) container.getActualTypeArguments()[0];
} else
this.component = (Class<ComponentType>) type;
}
public Type getContainer() {
return container;
}
public Class<?> getComponent() {
return component;
}
public boolean isContainer() {
return container != null;
}
public Annotation getQualifier() {
return qualifier;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Ref ref = (Ref) o;
return Objects.equals(container, ref.container) && component.equals(ref.component);
}
@Override
public int hashCode() {
return Objects.hash(container, component);
}
}
}
ContextConfig.java:
package geektime.tdd.di;
import jakarta.inject.Provider;
import java.lang.annotation.Annotation;
import java.util.*;
public class ContextConfig {
private Map<Class<?>, ComponentProvider<?>> providers = new HashMap<>();
private Map<Component, ComponentProvider<?>> components = new HashMap<>();
public <Type> void bind(Class<Type> type, Type instance) {
providers.put(type, (ComponentProvider<Type>) context -> instance);
}
public <Type> void bind(Class<Type> type, Type instance, Annotation... qualifiers) {
for (Annotation qualifier : qualifiers)
components.put(new Component(type, qualifier), context -> instance);
}
record Component(Class<?> type, Annotation qualifiers) {
}
public <Type, Implementation extends Type>
void bind(Class<Type> type, Class<Implementation> implementation) {
providers.put(type, new InjectionProvider<>(implementation));
}
public <Type, Implementation extends Type>
void bind(Class<Type> type, Class<Implementation> implementation, Annotation... qualifiers) {
for (Annotation qualifier : qualifiers)
components.put(new Component(type, qualifier), new InjectionProvider<>(implementation));
}
public Context getContext() {
providers.keySet().forEach(component -> checkDependencies(component, new Stack<>()));
return new Context() {
@Override
public <ComponentType> Optional<ComponentType> get(Ref<ComponentType> ref) {
if (ref.getQualifier() != null) {
return Optional.ofNullable(components.get(new Component(ref.getComponent(), ref.getQualifier()))).map(provider -> (ComponentType) provider.get(this));
}
if (ref.isContainer()) {
if (ref.getContainer() != Provider.class) return Optional.empty();
return (Optional<ComponentType>) Optional.ofNullable(providers.get(ref.getComponent()))
.map(provider -> (Provider<Object>) () -> provider.get(this));
}
return Optional.ofNullable(providers.get(ref.getComponent())).map(provider -> (ComponentType) provider.get(this));
}
};
}
private void checkDependencies(Class<?> component, Stack<Class<?>> visiting) {
for (Context.Ref dependency : providers.get(component).getDependencies()) {
if (!providers.containsKey(dependency.getComponent()))
throw new DependencyNotFoundException(component, dependency.getComponent());
if (!dependency.isContainer()) {
if (visiting.contains(dependency.getComponent())) throw new CyclicDependenciesFoundException(visiting);
visiting.push(dependency.getComponent());
checkDependencies(dependency.getComponent(), visiting);
visiting.pop();
}
}
}
interface ComponentProvider<T> {
T get(Context context);
default List<Context.Ref> getDependencies() {
return List.of();
}
}
}
荧光笔
直线
曲线
枫中的刀剑当对未来重构后的代码结构有清楚的认识同时又有足够的测试覆盖时，可以不比严格按照TDD的节奏来进行重构。 好处是可以节省大量的平行实现。 这相当于你对这块代码有足够的信心，可以加大前进步伐。即使出问题也在可控范围之内。 因此我们在使用TDD时并不是始终保持一个不变的节奏，实际情况下根据你对当前情况的认知会做出相应的调整，信心充分就可以加大步伐，信心不足就严格执行，小步前进。这是非常灵活的。2022-05-293
aoe少了30多个测试项目链接 https://github.com/wyyl1/geektime-tdd-di-container/branches2022-05-22
张铁林跟着做了2小时，已经完成，在master分支上有代码。2022-05-17
