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class ContainerImpl implements Container {
// ... 省略n行代码
/**
* Field and method injectors.
*/
final Map<Class<?>, List<Injector>> injectors =
new ReferenceCache<Class<?>, List<Injector>>() {
@Override
protected List<Injector> create(Class<?> key) {
List<Injector> injectors = new ArrayList<Injector>();
// 拿class当做key,查询所有带有@Inject注解的class,添加到injectors
addInjectors(key, injectors);
return injectors;
}
};
// ... 省略n行代码
/**
* Recursively adds injectors for fields and methods from the given class to
* the given list. Injects parent classes before sub classes.
*/
void addInjectors(Class clazz, List<Injector> injectors) {
if (clazz == Object.class) {
return;
}
// Add injectors for superclass first.
addInjectors(clazz.getSuperclass(), injectors);
// TODO (crazybob): Filter out overridden members.
addInjectorsForFields(clazz.getDeclaredFields(), false, injectors);
addInjectorsForMethods(clazz.getDeclaredMethods(), false, injectors);
}
// ... 省略n行代码
void addInjectorsForMethods(Method[] methods, boolean statics,
List<Injector> injectors) {
addInjectorsForMembers(Arrays.asList(methods), statics, injectors,
new InjectorFactory<Method>() {
public Injector create(ContainerImpl container, Method method,
String name) throws MissingDependencyException {
return new MethodInjector(container, method, name);
}
});
}
// ... 省略n行代码
void addInjectorsForFields(Field[] fields, boolean statics,
List<Injector> injectors) {
addInjectorsForMembers(Arrays.asList(fields), statics, injectors,
new InjectorFactory<Field>() {
public Injector create(ContainerImpl container, Field field,
String name) throws MissingDependencyException {
return new FieldInjector(container, field, name);
}
});
}
// ... 省略n行代码
// 核心代码
<M extends Member & AnnotatedElement> void addInjectorsForMembers(
List<M> members, boolean statics, List<Injector> injectors,
InjectorFactory<M> injectorFactory) {
for (M member : members) {
if (isStatic(member) == statics) {
Inject inject = member.getAnnotation(Inject.class);
if (inject != null) {
try {
injectors.add(injectorFactory.create(this, member, inject.value()));
} catch (MissingDependencyException e) {
if (inject.required()) {
throw new DependencyException(e);
}
}
}
}
}
}
// ... 省略n行代码
// 调用Container的inject方法时实施依赖注入
void inject(Object o, InternalContext context) {
List<Injector> injectors = this.injectors.get(o.getClass());
for (Injector injector : injectors) {
injector.inject(context, o);
}
}
// ... 省略n行代码
// 对添加@Inject注解的方法，实施依赖注入
static class MethodInjector implements Injector {
final Method method;
final ParameterInjector<?>[] parameterInjectors;
public MethodInjector(ContainerImpl container, Method method, String name)
throws MissingDependencyException {
// 注入的方法名
this.method = method;
if (!method.isAccessible()) {
SecurityManager sm = System.getSecurityManager();
try {
if (sm != null) sm.checkPermission(new ReflectPermission("suppressAccessChecks"));
method.setAccessible(true);
} catch(AccessControlException e) {
throw new DependencyException("Security manager in use, could not access method: "
+ name + "(" + method.getName() + ")", e);
}
}
Class<?>[] parameterTypes = method.getParameterTypes();
if (parameterTypes.length == 0) {
throw new DependencyException(
method + " has no parameters to inject.");
}
parameterInjectors = container.getParametersInjectors(
method, method.getParameterAnnotations(), parameterTypes, name);
}
public void inject(InternalContext context, Object o) {
try {
// 给加@Inject注解的方法传参, 如我们的ActionSupport类setContainer方法
method.invoke(o, getParameters(method, context, parameterInjectors));
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
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