spring OnClassCondition 源码
springboot OnClassCondition 代码
文件路径:/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/OnClassCondition.java
/*
* Copyright 2012-2021 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.boot.autoconfigure.condition;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.springframework.boot.autoconfigure.AutoConfigurationImportFilter;
import org.springframework.boot.autoconfigure.AutoConfigurationMetadata;
import org.springframework.boot.autoconfigure.condition.ConditionMessage.Style;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.core.type.AnnotatedTypeMetadata;
import org.springframework.util.MultiValueMap;
import org.springframework.util.StringUtils;
/**
* {@link Condition} and {@link AutoConfigurationImportFilter} that checks for the
* presence or absence of specific classes.
*
* @author Phillip Webb
* @see ConditionalOnClass
* @see ConditionalOnMissingClass
*/
@Order(Ordered.HIGHEST_PRECEDENCE)
class OnClassCondition extends FilteringSpringBootCondition {
@Override
protected final ConditionOutcome[] getOutcomes(String[] autoConfigurationClasses,
AutoConfigurationMetadata autoConfigurationMetadata) {
// Split the work and perform half in a background thread if more than one
// processor is available. Using a single additional thread seems to offer the
// best performance. More threads make things worse.
if (autoConfigurationClasses.length > 1 && Runtime.getRuntime().availableProcessors() > 1) {
return resolveOutcomesThreaded(autoConfigurationClasses, autoConfigurationMetadata);
}
else {
OutcomesResolver outcomesResolver = new StandardOutcomesResolver(autoConfigurationClasses, 0,
autoConfigurationClasses.length, autoConfigurationMetadata, getBeanClassLoader());
return outcomesResolver.resolveOutcomes();
}
}
private ConditionOutcome[] resolveOutcomesThreaded(String[] autoConfigurationClasses,
AutoConfigurationMetadata autoConfigurationMetadata) {
int split = autoConfigurationClasses.length / 2;
OutcomesResolver firstHalfResolver = createOutcomesResolver(autoConfigurationClasses, 0, split,
autoConfigurationMetadata);
OutcomesResolver secondHalfResolver = new StandardOutcomesResolver(autoConfigurationClasses, split,
autoConfigurationClasses.length, autoConfigurationMetadata, getBeanClassLoader());
ConditionOutcome[] secondHalf = secondHalfResolver.resolveOutcomes();
ConditionOutcome[] firstHalf = firstHalfResolver.resolveOutcomes();
ConditionOutcome[] outcomes = new ConditionOutcome[autoConfigurationClasses.length];
System.arraycopy(firstHalf, 0, outcomes, 0, firstHalf.length);
System.arraycopy(secondHalf, 0, outcomes, split, secondHalf.length);
return outcomes;
}
private OutcomesResolver createOutcomesResolver(String[] autoConfigurationClasses, int start, int end,
AutoConfigurationMetadata autoConfigurationMetadata) {
OutcomesResolver outcomesResolver = new StandardOutcomesResolver(autoConfigurationClasses, start, end,
autoConfigurationMetadata, getBeanClassLoader());
return new ThreadedOutcomesResolver(outcomesResolver);
}
@Override
public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
ClassLoader classLoader = context.getClassLoader();
ConditionMessage matchMessage = ConditionMessage.empty();
List<String> onClasses = getCandidates(metadata, ConditionalOnClass.class);
if (onClasses != null) {
List<String> missing = filter(onClasses, ClassNameFilter.MISSING, classLoader);
if (!missing.isEmpty()) {
return ConditionOutcome.noMatch(ConditionMessage.forCondition(ConditionalOnClass.class)
.didNotFind("required class", "required classes").items(Style.QUOTE, missing));
}
matchMessage = matchMessage.andCondition(ConditionalOnClass.class)
.found("required class", "required classes")
.items(Style.QUOTE, filter(onClasses, ClassNameFilter.PRESENT, classLoader));
}
List<String> onMissingClasses = getCandidates(metadata, ConditionalOnMissingClass.class);
if (onMissingClasses != null) {
List<String> present = filter(onMissingClasses, ClassNameFilter.PRESENT, classLoader);
if (!present.isEmpty()) {
return ConditionOutcome.noMatch(ConditionMessage.forCondition(ConditionalOnMissingClass.class)
.found("unwanted class", "unwanted classes").items(Style.QUOTE, present));
}
matchMessage = matchMessage.andCondition(ConditionalOnMissingClass.class)
.didNotFind("unwanted class", "unwanted classes")
.items(Style.QUOTE, filter(onMissingClasses, ClassNameFilter.MISSING, classLoader));
}
return ConditionOutcome.match(matchMessage);
}
private List<String> getCandidates(AnnotatedTypeMetadata metadata, Class<?> annotationType) {
MultiValueMap<String, Object> attributes = metadata.getAllAnnotationAttributes(annotationType.getName(), true);
if (attributes == null) {
return null;
}
List<String> candidates = new ArrayList<>();
addAll(candidates, attributes.get("value"));
addAll(candidates, attributes.get("name"));
return candidates;
}
private void addAll(List<String> list, List<Object> itemsToAdd) {
if (itemsToAdd != null) {
for (Object item : itemsToAdd) {
Collections.addAll(list, (String[]) item);
}
}
}
private interface OutcomesResolver {
ConditionOutcome[] resolveOutcomes();
}
private static final class ThreadedOutcomesResolver implements OutcomesResolver {
private final Thread thread;
private volatile ConditionOutcome[] outcomes;
private ThreadedOutcomesResolver(OutcomesResolver outcomesResolver) {
this.thread = new Thread(() -> this.outcomes = outcomesResolver.resolveOutcomes());
this.thread.start();
}
@Override
public ConditionOutcome[] resolveOutcomes() {
try {
this.thread.join();
}
catch (InterruptedException ex) {
Thread.currentThread().interrupt();
}
return this.outcomes;
}
}
private static final class StandardOutcomesResolver implements OutcomesResolver {
private final String[] autoConfigurationClasses;
private final int start;
private final int end;
private final AutoConfigurationMetadata autoConfigurationMetadata;
private final ClassLoader beanClassLoader;
private StandardOutcomesResolver(String[] autoConfigurationClasses, int start, int end,
AutoConfigurationMetadata autoConfigurationMetadata, ClassLoader beanClassLoader) {
this.autoConfigurationClasses = autoConfigurationClasses;
this.start = start;
this.end = end;
this.autoConfigurationMetadata = autoConfigurationMetadata;
this.beanClassLoader = beanClassLoader;
}
@Override
public ConditionOutcome[] resolveOutcomes() {
return getOutcomes(this.autoConfigurationClasses, this.start, this.end, this.autoConfigurationMetadata);
}
private ConditionOutcome[] getOutcomes(String[] autoConfigurationClasses, int start, int end,
AutoConfigurationMetadata autoConfigurationMetadata) {
ConditionOutcome[] outcomes = new ConditionOutcome[end - start];
for (int i = start; i < end; i++) {
String autoConfigurationClass = autoConfigurationClasses[i];
if (autoConfigurationClass != null) {
String candidates = autoConfigurationMetadata.get(autoConfigurationClass, "ConditionalOnClass");
if (candidates != null) {
outcomes[i - start] = getOutcome(candidates);
}
}
}
return outcomes;
}
private ConditionOutcome getOutcome(String candidates) {
try {
if (!candidates.contains(",")) {
return getOutcome(candidates, this.beanClassLoader);
}
for (String candidate : StringUtils.commaDelimitedListToStringArray(candidates)) {
ConditionOutcome outcome = getOutcome(candidate, this.beanClassLoader);
if (outcome != null) {
return outcome;
}
}
}
catch (Exception ex) {
// We'll get another chance later
}
return null;
}
private ConditionOutcome getOutcome(String className, ClassLoader classLoader) {
if (ClassNameFilter.MISSING.matches(className, classLoader)) {
return ConditionOutcome.noMatch(ConditionMessage.forCondition(ConditionalOnClass.class)
.didNotFind("required class").items(Style.QUOTE, className));
}
return null;
}
}
}
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- 本文标签: Java Spring Spring Boot
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