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impl: HttpHeaders.backedBy and HttpHeaders.copyOf to reduce ambiguity on the constructor.
Fixes spring-projects#34340
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-8
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2 files changed

+94
-8
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‎spring-web/src/main/java/org/springframework/http/HttpHeaders.java

+38
Original file line numberDiff line numberDiff line change
@@ -452,7 +452,9 @@ public HttpHeaders() {
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* headers map structures, primarily for internal use within the framework.
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* @param headers the headers map (expected to operate with case-insensitive keys)
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* @since 5.1
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* @deprecated Will be made private in favor of {@link #backedBy(MultiValueMap)} in a future release.
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*/
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@Deprecated
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public HttpHeaders(MultiValueMap<String, String> headers) {
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Assert.notNull(headers, "MultiValueMap must not be null");
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if (headers == EMPTY) {
@@ -477,6 +479,7 @@ else if (headers instanceof HttpHeaders httpHeaders) {
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* likely to be out of sync and should be discarded.
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* @param httpHeaders the headers to expose
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* @since 7.0
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* @deprecated Will be made private in favor of {@link #backedBy(HttpHeaders)} in a future release.
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*/
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public HttpHeaders(HttpHeaders httpHeaders) {
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Assert.notNull(httpHeaders, "HttpHeaders must not be null");
@@ -491,6 +494,41 @@ public HttpHeaders(HttpHeaders httpHeaders) {
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}
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}
493496

497+
/**
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* Construct a new {@code HttpHeaders} instance backed by an existing map.
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* <p>This constructor is available as an optimization for adapting to existing
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* headers map structures, primarily for internal use within the framework.
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* @param headers the headers map (expected to operate with case-insensitive keys)
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*/
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public static HttpHeaders backedBy(MultiValueMap<String, String> headers) {
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return new HttpHeaders(headers);
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}
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/**
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* Construct a new {@code HttpHeaders} instance by removing any read-only
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* wrapper that may have been previously applied around the given
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* {@code HttpHeaders} via {@link #readOnlyHttpHeaders(HttpHeaders)}.
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* <p>Once the writable instance is mutated, the read-only instance is
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* likely to be out of sync and should be discarded.
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* @param httpHeaders the headers to expose
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*/
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public static HttpHeaders backedBy(HttpHeaders httpHeaders) {
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return backedBy(httpHeaders.headers);
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}
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/**
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* Constructs a new {@code HttpHeaders} instance with the given headers.
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* @param headers
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*/
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public static HttpHeaders copyOf(MultiValueMap<String, String> headers) {
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HttpHeaders httpHeadersCopy = new HttpHeaders();
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headers.forEach((key, values) -> httpHeadersCopy.put(key, new ArrayList<>(values)));
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return httpHeadersCopy;
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}
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public static HttpHeaders copyOf(HttpHeaders httpHeaders) {
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return copyOf(httpHeaders.headers);
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}
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/**
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* Get the list of header values for the given header name, if any.

‎spring-web/src/test/java/org/springframework/http/HttpHeadersTests.java

+56-8
Original file line numberDiff line numberDiff line change
@@ -58,23 +58,71 @@ class HttpHeadersTests {
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final HttpHeaders headers = new HttpHeaders();
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@Test
61-
void constructorUnwrapsReadonly() {
61+
void backedByFactoryUnwrapsReadonly() {
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headers.setContentType(MediaType.APPLICATION_JSON);
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HttpHeaders readOnly = HttpHeaders.readOnlyHttpHeaders(headers);
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assertThat(readOnly.getContentType()).isEqualTo(MediaType.APPLICATION_JSON);
65-
HttpHeaders writable = new HttpHeaders(readOnly);
65+
HttpHeaders writable = HttpHeaders.backedBy(readOnly);
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writable.setContentType(MediaType.TEXT_PLAIN);
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// content-type value is cached by ReadOnlyHttpHeaders
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assertThat(readOnly.getContentType())
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.describedAs("readOnly HttpHeaders should NOT have updated content-type value")
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.isEqualTo(MediaType.APPLICATION_JSON);
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assertThat(writable.getContentType())
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.describedAs("writable HttpHeaders should have updated content-type value")
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.isEqualTo(MediaType.TEXT_PLAIN);
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assertThat(headers.getContentType())
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.describedAs("initial HttpHeaders should have updated content-type value")
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.isEqualTo(MediaType.TEXT_PLAIN);
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}
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@Test
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void backedByFactoryUnwrapsMultipleHeaders() {
82+
headers.setContentType(MediaType.APPLICATION_JSON);
83+
HttpHeaders readonlyOriginalExchangeHeaders = HttpHeaders.readOnlyHttpHeaders(headers);
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HttpHeaders firewallHeaders = HttpHeaders.backedBy(readonlyOriginalExchangeHeaders);
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HttpHeaders writeable = HttpHeaders.backedBy(firewallHeaders);
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writeable.setContentType(MediaType.TEXT_PLAIN);
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88+
// If readonly headers are unwrapped multiple times, the content-type value should be updated
89+
assertThat(writeable.getContentType()).isEqualTo(MediaType.TEXT_PLAIN);
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assertThat(firewallHeaders.getContentType()).isEqualTo(MediaType.TEXT_PLAIN);
91+
assertThat(readonlyOriginalExchangeHeaders.getContentType()).isEqualTo(MediaType.TEXT_PLAIN);
92+
assertThat(headers.getContentType()).isEqualTo(MediaType.TEXT_PLAIN);
93+
}
94+
95+
@Test
96+
void copyOfFactoryUnwrapsReadonly() {
97+
headers.setContentType(MediaType.APPLICATION_JSON);
98+
HttpHeaders readOnly = HttpHeaders.readOnlyHttpHeaders(headers);
6899
assertThat(readOnly.getContentType()).isEqualTo(MediaType.APPLICATION_JSON);
69-
assertThat(writable.getContentType()).isEqualTo(MediaType.TEXT_PLAIN);
100+
HttpHeaders writable = HttpHeaders.copyOf(readOnly);
101+
writable.setContentType(MediaType.TEXT_PLAIN);
102+
103+
assertThat(readOnly.getContentType())
104+
.describedAs("readOnly HttpHeaders should NOT have updated content-type value")
105+
.isEqualTo(MediaType.APPLICATION_JSON);
106+
assertThat(writable.getContentType())
107+
.describedAs("writable HttpHeaders should have updated content-type value")
108+
.isEqualTo(MediaType.TEXT_PLAIN);
109+
assertThat(headers.getContentType())
110+
.describedAs("initial HttpHeaders should have updated content-type value")
111+
.isEqualTo(MediaType.APPLICATION_JSON);
70112
}
71113

72114
@Test
73-
void writableHttpHeadersUnwrapsMultiple() {
74-
HttpHeaders originalExchangeHeaders = HttpHeaders.readOnlyHttpHeaders(new HttpHeaders());
75-
HttpHeaders firewallHeaders = new HttpHeaders(originalExchangeHeaders);
76-
HttpHeaders writeable = new HttpHeaders(firewallHeaders);
77-
writeable.setContentType(MediaType.APPLICATION_JSON);
115+
void copyOfFactoryUnwrapsMultipleHeaders() {
116+
headers.setContentType(MediaType.APPLICATION_JSON);
117+
HttpHeaders readonlyOriginalExchangeHeaders = HttpHeaders.readOnlyHttpHeaders(headers);
118+
HttpHeaders firewallHeaders = HttpHeaders.copyOf(readonlyOriginalExchangeHeaders);
119+
HttpHeaders writeable = HttpHeaders.copyOf(firewallHeaders);
120+
writeable.setContentType(MediaType.TEXT_PLAIN);
121+
122+
assertThat(writeable.getContentType()).isEqualTo(MediaType.TEXT_PLAIN);
123+
assertThat(firewallHeaders.getContentType()).isEqualTo(MediaType.APPLICATION_JSON);
124+
assertThat(readonlyOriginalExchangeHeaders.getContentType()).isEqualTo(MediaType.APPLICATION_JSON);
125+
assertThat(headers.getContentType()).isEqualTo(MediaType.APPLICATION_JSON);
78126
}
79127

80128
@Test

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