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com.github.henryco.injector.meta.Injector Maven / Gradle / Ivy
package com.github.henryco.injector.meta;
import com.github.henryco.injector.meta.annotations.Component;
import com.github.henryco.injector.meta.annotations.Inject;
import com.github.henryco.injector.meta.annotations.Provide;
import com.github.henryco.injector.meta.annotations.Singleton;
import java.lang.reflect.*;
import java.util.Collection;
/**
* @author Henry on 17/12/17.
*/
public final class Injector {
private static final class NULL_MARKER {
private static final NULL_MARKER instance = new NULL_MARKER();
private NULL_MARKER() {}
}
private static final NULL_MARKER NULL = NULL_MARKER.instance;
@SuppressWarnings("unchecked")
public static T findOrInstanceByType(Class type, ModuleStruct struct) {
T o = findInSingletonsByType(type, struct);
if (o != null) return o;
T byMethod = findInMethodsByType(type, struct);
if (byMethod != null) return byMethod;
T nested = findInNestedByType(type, struct);
if (nested != null) return nested;
T component = findInComponentsByType(type, struct);
if (component != null) return component;
return null;
}
@SuppressWarnings("unchecked")
public static T findOrInstanceByName(String name, ModuleStruct struct) {
T o = findInSingletonsByName(name, struct);
if (o != null) return o;
T byMethod = findInMethodsByName(name, struct);
if (byMethod != null) return byMethod;
T nested = findInNestedByName(name, struct);
if (nested != null) return nested;
T component = findInComponentsByName(name, struct);
if (component != null) return component;
return null;
}
private static T findInComponentsByName(String name, ModuleStruct struct) {
return findInComponents(name, null, struct);
}
private static T findInComponentsByType(Class type, ModuleStruct struct) {
return findInComponents(null, type, struct);
}
@SuppressWarnings("unchecked")
private static T findInComponents(String name, Class type, ModuleStruct struct) {
assertNameAndType(name, type);
for (ModuleStruct moduleStruct : struct.included) {
for (Class component : moduleStruct.components) {
Component ca = component.getDeclaredAnnotation(Component.class);
if (name != null) {
String compName = ca.value();
if (compName.trim().isEmpty() || !compName.trim().equals(name))
continue;
}
if (type != null) {
if (!Helper.checkType(component, type))
continue;
}
T dependency = instanceDependencyFromConstructor(component, struct);
if (dependency != null) {
if (component.getDeclaredAnnotation(Singleton.class) != null) {
String svName = ca.value().isEmpty() ? component.getSimpleName() : ca.value();
moduleStruct.singletons.put(svName, dependency);
}
return dependency;
}
return null;
}
}
return null;
}
private static T findInNestedByName(String name, ModuleStruct struct) {
for (ModuleStruct moduleStruct : struct.included) {
T o = findOrInstanceByName(name, moduleStruct);
if (o != null) return o;
}
return null;
}
private static T findInNestedByType(Class type, ModuleStruct struct) {
for (ModuleStruct moduleStruct : struct.included) {
T o = findOrInstanceByType(type, moduleStruct);
if (o != null) return o;
}
return null;
}
@SuppressWarnings("unchecked")
private static T findInSingletonsByName(String name, ModuleStruct struct) {
for (ModuleStruct moduleStruct : struct.included) {
Object o = moduleStruct.singletons.get(name);
if (o != null) return (T) moduleStruct.singletons.get(name);
}
return null;
}
@SuppressWarnings("unchecked")
private static T findInSingletonsByType(Class type, ModuleStruct struct) {
if (type == null) return null;
for (ModuleStruct moduleStruct : struct.included) {
Collection values = moduleStruct.singletons.values();
for (Object value : values) {
if (Helper.checkType(value.getClass(), type))
return (T) value;
}
}
return null;
}
private static T findInMethodsByName(String name, ModuleStruct struct) {
return findInMethods(name, null, struct);
}
private static T findInMethodsByType(Class type, ModuleStruct struct) {
return findInMethods(null, type, struct);
}
private static T findInMethods(String name, Class type, ModuleStruct struct) {
assertNameAndType(name, type);
for (ModuleStruct moduleStruct : struct.included) {
if (moduleStruct.module == null) continue;
Method[] methods = moduleStruct.module.getDeclaredMethods();
for (Method method : methods) {
Provide provide = method.getDeclaredAnnotation(Provide.class);
if (provide == null)
continue;
if (name == null) {
if (!Helper.checkType(method.getReturnType(), type))
continue;
}
if (type == null) {
String compName = provide.value();
if (compName.trim().isEmpty() || !compName.trim().equals(name))
continue;
}
try {
T dependency = instanceDependencyFromMethod(moduleStruct.module.newInstance(), struct, method);
if (dependency != null) {
if (method.getDeclaredAnnotation(Singleton.class) != null) {
String svName = provide.value().isEmpty() ? method.getName() : provide.value();
moduleStruct.singletons.put(svName, dependency);
}
return dependency;
}
} catch (InstantiationException | IllegalAccessException e) {
e.printStackTrace();
}
}
}
return null;
}
@SuppressWarnings("unchecked")
private static T instanceDependencyFromConstructor(Class component, ModuleStruct struct) {
Constructor[] constructors = component.getDeclaredConstructors();
if (constructors.length == 0)
throw new RuntimeException("Component must have at least one constructor");
Constructor constructor = null;
for (Constructor c : constructors) {
Inject ia = c.getDeclaredAnnotation(Inject.class);
if (ia != null) {
if (constructor != null)
throw new RuntimeException("Only once constructor can possess @Inject annotation");
constructor = c;
}
}
if (constructor == null)
constructor = constructors[0];
Parameter[] parameters = constructor.getParameters();
Object[] arguments = instanceDependencyArguments(parameters, struct);
T instance;
try {
instance = (T) constructor.newInstance(arguments);
} catch (InstantiationException | IllegalAccessException | InvocationTargetException e) {
throw new RuntimeException("Cannot instance via constructor", e);
} catch (IllegalArgumentException ex) {
throw new RuntimeException("Cannot instance via constructor," +
" check providable dependencies", ex);
}
return injectDependenciesToInstance(instance, struct);
}
public static T injectDependenciesToInstance(T instance,
ModuleStruct struct,
Object ... componentsToInject) {
Field[] fields = instance.getClass().getDeclaredFields();
Object[] fieldValues = instanceDependencyFields(fields, instance.getClass(), struct, componentsToInject);
for (int i = 0; i < fields.length; i++) {
if (fieldValues[i] == NULL) continue;
Helper.setValue(fields[i], instance, fieldValues[i]);
}
return instance;
}
@SuppressWarnings("unchecked")
private static T instanceDependencyFromMethod(Object moduleInstance,
ModuleStruct struct,
Method method) {
if (method.getParameterCount() == 0) try {
return (T) method.invoke(moduleInstance);
} catch (Exception e) {
e.printStackTrace();
}
Parameter[] parameters = method.getParameters();
Object[] args = instanceDependencyArguments(parameters, struct);
try {
return (T) method.invoke(moduleInstance, args);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
private static Object[] instanceDependencyFields(Field[] fields,
Class instance,
ModuleStruct struct,
Object ... componentsToInject) {
Object[] fieldValues = new Object[fields.length];
for (int i = 0; i < fields.length; i++) {
Inject inject = fields[i].getDeclaredAnnotation(Inject.class);
if (inject == null) {
try {
String setterName = Helper.createSetterName(fields[i].getName());
Method declaredMethod = instance.getDeclaredMethod(setterName, fields[i].getType());
inject = declaredMethod.getDeclaredAnnotation(Inject.class);
} catch (NoSuchMethodException e) {
inject = null;
}
if (inject == null) {
fieldValues[i] = NULL;
continue;
}
}
if (!containsComponent(inject, fields[i], componentsToInject)) {
fieldValues[i] = NULL;
continue;
}
if (inject.value().trim().isEmpty()) {
fieldValues[i] = findOrInstanceByType(fields[i].getType(), struct);
}
else {
fieldValues[i] = findOrInstanceByName(inject.value(), struct);
}
}
return fieldValues;
}
private static Object[] instanceDependencyArguments(Parameter[] parameters, ModuleStruct struct) {
Object[] args = new Object[parameters.length];
for (int i = 0; i < args.length; i++) {
Parameter param = parameters[i];
Inject inject = param.getDeclaredAnnotation(Inject.class);
if (inject != null && !inject.value().trim().isEmpty())
args[i] = findOrInstanceByName(inject.value(), struct);
else
args[i] = findOrInstanceByType(param.getType(), struct);
}
return args;
}
private static void assertNameAndType(String name, Class type) {
if ((name != null && type != null))
throw new RuntimeException("Cannot find by NAME and TYPE in the same time!");
if (name == null && type == null)
throw new RuntimeException("NAME and TYPE cannot be NULL in the same time!");
}
private static boolean containsComponent(Inject inject, Field field, Object[] componentsToInject) {
if (componentsToInject.length == 0) return true;
for (Object cti : componentsToInject) {
if (cti instanceof String) {
boolean b = cti.equals(inject.value()) || cti.equals(field.getName());
if (b) return true;
} else if (cti instanceof Class) {
boolean b = Helper.checkType((Class) cti, field.getType());
if (b) return true;
}
}
return false;
}
}
