56 lines
2.1 KiB
Markdown
56 lines
2.1 KiB
Markdown
# Protocol Buffers - Google's data interchange format
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Copyright 2008 Google Inc.
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https://developers.google.com/protocol-buffers/
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## Use Protobuf Java Lite Runtime
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Protobuf Java Lite runtime is separated from the main Java runtime because
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it's designed/implemented with different constraints. In particular, Java
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Lite runtime has a much smaller code size which makes it more suitable to
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be used on Android.
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Note that in order to achieve maximum performance and code size, we will
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NOT guarantee API/ABI stability for Java Lite. If this is not acceptable
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for your use-case, please use the full Java runtime instead. Note that
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the latest version of Java Lite is not compatible with the 3.0.0 version.
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You can generate Java Lite code for your .proto files:
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$ protoc --java_out=lite:${OUTPUT_DIR} path/to/your/proto/file
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Note that "optimize_for = LITE_RUNTIME" option in proto file is deprecated
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and will not have any effect any more.
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Include the generated Java files in your project and add a dependency on the
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protobuf Java runtime. If you are using Maven, use the following:
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```xml
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<dependency>
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<groupId>com.google.protobuf</groupId>
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<artifactId>protobuf-javalite</artifactId>
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<version>3.20.3</version>
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</dependency>
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```
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## R8 rule to make production app builds work
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The Lite runtime internally uses reflection to avoid generating hashCode/equals/(de)serialization methods.
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R8 by default obfuscates the field names, which makes the reflection fail causing exceptions of the form
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`java.lang.RuntimeException: Field {NAME}_ for {CLASS} not found. Known fields are [ {FIELDS} ]` in MessageSchema.java.
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There are open issues for this on the [protobuf Github project](https://github.com/protocolbuffers/protobuf/issues/6463) and [R8](https://issuetracker.google.com/issues/144631039).
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Until the issues is resolved you need to add the following line to your `proguard-rules.pro` file inside your project:
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```
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-keep class * extends com.google.protobuf.GeneratedMessageLite { *; }
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```
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## Older versions
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For the older version of Java Lite (v3.0.0), please refer to:
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https://github.com/protocolbuffers/protobuf/blob/javalite/java/lite.md
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