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Immutable Resource[Resolver|Transformer]Chains

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Issue: SPR-16862
This commit is contained in:
Rossen Stoyanchev
2018-05-22 15:33:17 -04:00
parent 5207672b3f
commit f121aa5e31
7 changed files with 185 additions and 172 deletions
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81
spring-webmvc/src/main/java/org/springframework/web/servlet/resource/DefaultResourceResolverChain.java
View File

@@ -17,7 +17,9 @@
package org.springframework.web.servlet.resource;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.ListIterator;
import javax.servlet.http.HttpServletRequest;
import org.springframework.core.io.Resource;
@@ -25,72 +27,63 @@ import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* A default implementation of {@link ResourceResolverChain} for invoking a list
* of {@link ResourceResolver}s.
* Default immutable implementation of {@link ResourceResolverChain}.
*
* @author Jeremy Grelle
* @author Rossen Stoyanchev
* @author Sam Brannen
* @since 4.1
*/
class DefaultResourceResolverChain implements ResourceResolverChain {
private final List<ResourceResolver> resolvers = new ArrayList<>();
@Nullable
private final ResourceResolver resolver;
private int index = -1;
@Nullable
private final ResourceResolverChain nextChain;
public DefaultResourceResolverChain(@Nullable List<? extends ResourceResolver> resolvers) {
if (resolvers != null) {
this.resolvers.addAll(resolvers);
resolvers = resolvers != null ? resolvers : Collections.emptyList();
DefaultResourceResolverChain chain = initChain(new ArrayList<>(resolvers));
this.resolver = chain.resolver;
this.nextChain = chain.nextChain;
}
private static DefaultResourceResolverChain initChain(ArrayList<? extends ResourceResolver> resolvers) {
DefaultResourceResolverChain chain = new DefaultResourceResolverChain(null, null);
ListIterator<? extends ResourceResolver> itr = resolvers.listIterator(resolvers.size());
while (itr.hasPrevious()) {
chain = new DefaultResourceResolverChain(itr.previous(), chain);
}
return chain;
}
private DefaultResourceResolverChain(@Nullable ResourceResolver resolver,
@Nullable ResourceResolverChain chain) {
Assert.isTrue((resolver == null && chain == null) || (resolver != null && chain != null),
"Both resolver and resolver chain must be null, or neither is");
this.resolver = resolver;
this.nextChain = chain;
}
@Override
@Nullable
public Resource resolveResource(
@Nullable HttpServletRequest request, String requestPath, List<? extends Resource> locations) {
@SuppressWarnings("ConstantConditions")
public Resource resolveResource(@Nullable HttpServletRequest request, String requestPath,
List<? extends Resource> locations) {
ResourceResolver resolver = getNext();
if (resolver == null) {
return null;
}
try {
return resolver.resolveResource(request, requestPath, locations, this);
}
finally {
this.index--;
}
return this.resolver != null ?
this.resolver.resolveResource(request, requestPath, locations, this.nextChain) : null;
}
@Override
@Nullable
@SuppressWarnings("ConstantConditions")
public String resolveUrlPath(String resourcePath, List<? extends Resource> locations) {
ResourceResolver resolver = getNext();
if (resolver == null) {
return null;
}
try {
return resolver.resolveUrlPath(resourcePath, locations, this);
}
finally {
this.index--;
}
}
@Nullable
private ResourceResolver getNext() {
Assert.state(this.index <= this.resolvers.size(),
"Current index exceeds the number of configured ResourceResolvers");
if (this.index == (this.resolvers.size() - 1)) {
return null;
}
this.index++;
return this.resolvers.get(this.index);
return this.resolver != null ?
this.resolver.resolveUrlPath(resourcePath, locations, this.nextChain) : null;
}
}

65
spring-webmvc/src/main/java/org/springframework/web/servlet/resource/DefaultResourceTransformerChain.java
View File

@@ -18,7 +18,9 @@ package org.springframework.web.servlet.resource;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.ListIterator;
import javax.servlet.http.HttpServletRequest;
import org.springframework.core.io.Resource;
@@ -26,8 +28,7 @@ import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* A default implementation of {@link ResourceTransformerChain} for invoking
* a list of {@link ResourceTransformer}s.
* Default immutable implementation of {@link ResourceTransformerChain}.
*
* @author Rossen Stoyanchev
* @since 4.1
@@ -36,9 +37,11 @@ class DefaultResourceTransformerChain implements ResourceTransformerChain {
private final ResourceResolverChain resolverChain;
private final List<ResourceTransformer> transformers = new ArrayList<>();
@Nullable
private final ResourceTransformer transformer;
private int index = -1;
@Nullable
private final ResourceTransformerChain nextChain;
public DefaultResourceTransformerChain(ResourceResolverChain resolverChain,
@@ -46,9 +49,33 @@ class DefaultResourceTransformerChain implements ResourceTransformerChain {
Assert.notNull(resolverChain, "ResourceResolverChain is required");
this.resolverChain = resolverChain;
if (transformers != null) {
this.transformers.addAll(transformers);
transformers = transformers != null ? transformers : Collections.emptyList();
DefaultResourceTransformerChain chain = initTransformerChain(resolverChain, new ArrayList<>(transformers));
this.transformer = chain.transformer;
this.nextChain = chain.nextChain;
}
private DefaultResourceTransformerChain initTransformerChain(ResourceResolverChain resolverChain,
ArrayList<ResourceTransformer> transformers) {
DefaultResourceTransformerChain chain = new DefaultResourceTransformerChain(resolverChain, null, null);
ListIterator<? extends ResourceTransformer> itr = transformers.listIterator(transformers.size());
while (itr.hasPrevious()) {
chain = new DefaultResourceTransformerChain(resolverChain, itr.previous(), chain);
}
return chain;
}
public DefaultResourceTransformerChain(ResourceResolverChain resolverChain,
@Nullable ResourceTransformer transformer, @Nullable ResourceTransformerChain chain) {
Assert.isTrue((transformer == null && chain == null) || (transformer != null && chain != null),
"Both transformer and transformer chain must be null, or neither is");
this.resolverChain = resolverChain;
this.transformer = transformer;
this.nextChain = chain;
}
@@ -58,30 +85,10 @@ class DefaultResourceTransformerChain implements ResourceTransformerChain {
@Override
@SuppressWarnings("ConstantConditions")
public Resource transform(HttpServletRequest request, Resource resource) throws IOException {
ResourceTransformer transformer = getNext();
if (transformer == null) {
return resource;
}
try {
return transformer.transform(request, resource, this);
}
finally {
this.index--;
}
}
@Nullable
private ResourceTransformer getNext() {
Assert.state(this.index <= this.transformers.size(),
"Current index exceeds the number of configured ResourceTransformers");
if (this.index == (this.transformers.size() - 1)) {
return null;
}
this.index++;
return this.transformers.get(this.index);
return transformer != null ?
this.transformer.transform(request, resource, this.nextChain) : resource;
}
}

24
spring-webmvc/src/main/java/org/springframework/web/servlet/resource/ResourceHttpRequestHandler.java
View File

@@ -111,6 +111,12 @@ public class ResourceHttpRequestHandler extends WebContentGenerator
private final List<ResourceTransformer> resourceTransformers = new ArrayList<>(4);
@Nullable
private ResourceResolverChain resolverChain;
@Nullable
private ResourceTransformerChain transformerChain;
@Nullable
private ResourceHttpMessageConverter resourceHttpMessageConverter;
@@ -324,6 +330,10 @@ public class ResourceHttpRequestHandler extends WebContentGenerator
initAllowedLocations();
// Initialize immutable resolver and transformer chains
this.resolverChain = new DefaultResourceResolverChain(this.resourceResolvers);
this.transformerChain = new DefaultResourceTransformerChain(this.resolverChain, this.resourceTransformers);
if (this.resourceHttpMessageConverter == null) {
this.resourceHttpMessageConverter = new ResourceHttpMessageConverter();
}
@@ -525,15 +535,13 @@ public class ResourceHttpRequestHandler extends WebContentGenerator
return null;
}
ResourceResolverChain resolveChain = new DefaultResourceResolverChain(getResourceResolvers());
Resource resource = resolveChain.resolveResource(request, path, getLocations());
if (resource == null || getResourceTransformers().isEmpty()) {
return resource;
}
Assert.notNull(this.resolverChain, "ResourceResolverChain not initialized.");
Assert.notNull(this.transformerChain, "ResourceTransformerChain not initialized.");
ResourceTransformerChain transformChain =
new DefaultResourceTransformerChain(resolveChain, getResourceTransformers());
resource = transformChain.transform(request, resource);
Resource resource = this.resolverChain.resolveResource(request, path, getLocations());
if (resource != null) {
resource = this.transformerChain.transform(request, resource);
}
return resource;
}