try to support typesafe config (#5)

* try to support typesafe config

* scalafmt

build.sbt

@@ -250,7 +250,8 @@ lazy val `play-jsonJVM` = `play-json`.jvm
           specs2(scalaVersion.value).map(_.exclude("org.scala-lang.modules", "scala-xml_2.13"))
         else
           specs2(scalaVersion.value)
-      } :+ (
+      } ++ Seq(
+        "com.typesafe"   % "config"          % "1.4.3",
         "ch.qos.logback" % "logback-classic" % "1.3.15" % Test
       ),
     Test / unmanagedSourceDirectories ++= (docsP / PlayDocsKeys.scalaManualSourceDirectories).value,

play-json/jvm/src/main/resources/reference.conf

@@ -0,0 +1,10 @@
+play.json {
+  jackson {
+    read {
+      # see https://www.javadoc.io/static/com.fasterxml.jackson.core/jackson-core/2.17.3/com/fasterxml/jackson/core/StreamReadConstraints.html
+      # these defaults are the same as the defaults in `StreamReadConstraints`
+      max-nesting-depth = 1000
+      max-string-length = 20000000
+    }
+  }
+}

play-json/jvm/src/main/scala/play/api/libs/json/JsonConfig.scala

@@ -5,6 +5,7 @@
 package play.api.libs.json
 
 import com.fasterxml.jackson.core.StreamReadConstraints
+import com.typesafe.config.ConfigFactory
 
 import play.api.libs.json.JsonConfig.defaultMaxPlain
 import play.api.libs.json.JsonConfig.defaultMinPlain
@@ -187,6 +188,10 @@ object JsonConfig {
    */
   val preserveZeroDecimalProperty: String = "play.json.serializer.preserveZeroDecimal"
 
+  private val playJsonConfig = ConfigFactory
+    .load()
+    .getConfig("play.json.jackson")
+
   private[json] def loadScaleLimit: Int = prop(scaleLimitProperty, defaultScaleLimit)(_.toInt)
 
   private[json] def loadDigitsLimit: Int = prop(digitsLimitProperty, defaultDigitsLimit)(_.toInt)
@@ -198,10 +203,10 @@ object JsonConfig {
   private[json] def loadMaxPlain: BigDecimal = prop(maxPlainProperty, defaultMaxPlain)(BigDecimal.exact)
 
   private[json] def loadMaxNestingDepth: Int =
-    prop(maxNestingDepth, StreamReadConstraints.DEFAULT_MAX_DEPTH)(Integer.parseInt)
+    prop(maxNestingDepth, playJsonConfig.getInt("read.max-nesting-depth"))(Integer.parseInt)
 
   private[json] def loadMaxStringLength: Int =
-    prop(maxStringLength, StreamReadConstraints.DEFAULT_MAX_STRING_LEN)(Integer.parseInt)
+    prop(maxStringLength, playJsonConfig.getInt("read.max-string-length"))(Integer.parseInt)
 
   private[json] def loadPreserveZeroDecimal: Boolean =
     prop(preserveZeroDecimalProperty, defaultPreserveZeroDecimal)(_.toBoolean)