Add ability to add resources to jars

Previously Meson lacked the ability to add resources to jar files.

Fixes #9945

docs/markdown/snippets/jar-resources.md

@@ -0,0 +1,34 @@
+## JAR Resources
+
+The ability to add resources to a JAR has been added. Use the `java_resources`
+keyword argument. It takes a `sturctured_src` object.
+
+```meson
+jar(
+  meson.project_name(),
+  sources,
+  main_class: 'com.mesonbuild.Resources',
+  java_resources: structured_sources(
+    files('resources/resource1.txt'),
+    {
+      'subdir': files('resources/subdir/resource2.txt'),
+    }
+  )
+)
+```
+
+To access these resources in your Java application:
+
+```java
+try (InputStreamReader reader = new InputStreamReader(
+        Resources.class.getResourceAsStream("/resource1.txt"),
+        StandardCharsets.UTF_8)) {
+    // ...
+}
+
+try (InputStreamReader reader = new InputStreamReader(
+        Resources.class.getResourceAsStream("/subdir/resource2.txt"),
+        StandardCharsets.UTF_8)) {
+    // ...
+}
+```

docs/yaml/functions/jar.yaml

@@ -14,3 +14,7 @@ kwargs:
   main_class:
     type: str
     description: Main class for running the built jar
+  java_resources:
+    type: structured_src
+    since: 0.62.0
+    description: Resources to be added to the jar

mesonbuild/backend/ninjabackend.py

@@ -1231,10 +1231,11 @@ class NinjaBackend(backends.Backend):
         elem = NinjaBuildElement(self.all_outputs, 'PHONY', 'phony', '')
         self.add_build(elem)
 
-    def generate_jar_target(self, target):
+    def generate_jar_target(self, target: build.Jar):
         fname = target.get_filename()
         outname_rel = os.path.join(self.get_target_dir(target), fname)
         src_list = target.get_sources()
+        resources = target.get_java_resources()
         class_list = []
         compiler = target.compilers['java']
         c = 'c'
@@ -1280,6 +1281,9 @@ class NinjaBackend(backends.Backend):
         commands += ['-C', self.get_target_private_dir(target), '.']
         elem = NinjaBuildElement(self.all_outputs, outname_rel, jar_rule, [])
         elem.add_dep(class_dep_list)
+        if resources:
+            # Copy all resources into the root of the jar.
+            elem.add_orderdep(self.__generate_sources_structure(Path(self.get_target_private_dir(target)), resources)[0])
         elem.add_item('ARGS', commands)
         self.add_build(elem)
         # Create introspection information
@@ -1663,11 +1667,10 @@ class NinjaBackend(backends.Backend):
         elem.add_orderdep(instr)
         self.add_build(elem)
 
-    def __generate_compile_structure(self, target: build.BuildTarget) -> T.Tuple[T.List[str], T.Optional[str]]:
+    def __generate_sources_structure(self, root: Path, structured_sources: build.StructuredSources) -> T.Tuple[T.List[str], T.Optional[str]]:
         first_file: T.Optional[str] = None
         orderdeps: T.List[str] = []
-        root = Path(self.get_target_private_dir(target)) / 'structured'
+        for path, files in structured_sources.sources.items():
-        for path, files in target.structured_sources.sources.items():
             for file in files:
                 if isinstance(file, File):
                     out = root / path / Path(file.fname).name
@@ -1706,7 +1709,8 @@ class NinjaBackend(backends.Backend):
         main_rust_file = None
         if target.structured_sources:
             if target.structured_sources.needs_copy():
-                _ods, main_rust_file = self.__generate_compile_structure(target)
+                _ods, main_rust_file = self.__generate_sources_structure(Path(
+                    self.get_target_private_dir(target)) / 'structured', target.structured_sources)
                 orderdeps.extend(_ods)
             else:
                 # The only way to get here is to have only files in the "root"

mesonbuild/build.py

@@ -36,7 +36,7 @@ from .mesonlib import (
     extract_as_list, typeslistify, stringlistify, classify_unity_sources,
     get_filenames_templates_dict, substitute_values, has_path_sep,
     OptionKey, PerMachineDefaultable,
-    MesonBugException,
+    MesonBugException
 )
 from .compilers import (
     Compiler, is_object, clink_langs, sort_clink, lang_suffixes,
@@ -122,7 +122,7 @@ known_exe_kwargs = known_build_target_kwargs | {'implib', 'export_dynamic', 'pie
 known_shlib_kwargs = known_build_target_kwargs | {'version', 'soversion', 'vs_module_defs', 'darwin_versions'}
 known_shmod_kwargs = known_build_target_kwargs | {'vs_module_defs'}
 known_stlib_kwargs = known_build_target_kwargs | {'pic', 'prelink'}
-known_jar_kwargs = known_exe_kwargs | {'main_class'}
+known_jar_kwargs = known_exe_kwargs | {'main_class', 'java_resources'}
 
 @lru_cache(maxsize=None)
 def get_target_macos_dylib_install_name(ld) -> str:
@@ -2712,6 +2712,7 @@ class Jar(BuildTarget):
         self.filename = self.name + '.jar'
         self.outputs = [self.filename]
         self.java_args = kwargs.get('java_args', [])
+        self.java_resources: T.Optional[StructuredSources] = kwargs.get('java_resources', None)
 
     def get_main_class(self):
         return self.main_class
@@ -2722,6 +2723,9 @@ class Jar(BuildTarget):
     def get_java_args(self):
         return self.java_args
 
+    def get_java_resources(self) -> T.Optional[StructuredSources]:
+        return self.java_resources
+
     def validate_install(self, environment):
         # All jar targets are installable.
         pass

test cases/java/10 resources/meson.build

@@ -0,0 +1,7 @@
+project('resources', ['java'])
+
+if meson.backend() != 'ninja'
+  error('MESON_SKIP_TEST: only valid on backends which support jar()')
+endif
+
+subdir('src')

test cases/java/10 resources/src/com/mesonbuild/Resources.java

@@ -0,0 +1,26 @@
+package com.mesonbuild;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+
+public class Resources {
+    public static void main(String[] args) throws IOException {
+        try (InputStreamReader reader = new InputStreamReader(
+                Resources.class.getResourceAsStream("/resource1.txt"),
+                StandardCharsets.UTF_8)) {
+            final BufferedReader buffered = new BufferedReader(reader);
+
+            assert buffered.readLine() == "1";
+        }
+
+        try (InputStreamReader reader = new InputStreamReader(
+                Resources.class.getResourceAsStream("/subdir/resource2.txt"),
+                StandardCharsets.UTF_8)) {
+            final BufferedReader buffered = new BufferedReader(reader);
+
+            assert buffered.readLine() == "2";
+        }
+    }
+}

test cases/java/10 resources/src/meson.build

@@ -0,0 +1,13 @@
+sources = files('com/mesonbuild/Resources.java')
+
+resources = jar(
+  meson.project_name(),
+  sources,
+  main_class: 'com.mesonbuild.Resources',
+  java_resources: structured_sources(
+    files('resources/resource1.txt'),
+    {
+      'subdir': files('resources/subdir/resource2.txt'),
+    }
+  )
+)

test cases/java/10 resources/src/resources/resource1.txt

@@ -0,0 +1 @@
+1

test cases/java/10 resources/src/resources/subdir/resource2.txt

@@ -0,0 +1 @@
+2