go.mobile/example/libhello: make example self-contained

This example now uses the pre-L build system.
A gradle-based example will follow as soon as
I am testing on Android L devices.

LGTM=adonovan
R=adonovan
CC=golang-codereviews
https://golang.org/cl/143900043

example/libhello/AndroidManifest.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+Copyright 2014 The Go Authors. All rights reserved.
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file.
+-->
+<manifest
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	package="com.example.hello"
+	android:versionCode="1"
+	android:versionName="1.0">
+
+	<application android:label="Hello">
+		<activity android:name="com.example.hello.MainActivity"
+			android:label="Hello"
+			android:exported="true">
+			<intent-filter>
+				<action android:name="android.intent.action.MAIN" />
+				<category android:name="android.intent.category.LAUNCHER" />
+			</intent-filter>
+		</activity>
+	</application>
+</manifest> 

example/libhello/README

@@ -0,0 +1,42 @@
+The libhello app demonstrates calling Go code from a primarily Java app.
+
+Starting in Java lets you program against Android's extensive UI
+libraries in their native language and call into Go for library code
+(business logic, code shared with a Go server, portable code).
+
+The Java entry point to the program is the file
+src/com/example/hello/MainActivity.java, where the statement
+
+	Hi.Hello("world");
+
+is a call into Go code.
+
+The Go code is in a package called hi, the file is hi/hi.go, and it
+contains the function Hello:
+
+	func Hello(name string) {
+		fmt.Printf("Hello, %s!\n", name)
+	}
+
+Java language bindings are generated for this package using the gobind
+tool. There is a user guide for gobind at 
+
+	http://godoc.org/code.google.com/p/go.mobile/cmd/gobind
+
+The generated source has been included in the distribution. If you
+modify the exported interface of package hi, you have to run gobind
+manually before calling all.bash.
+
+Along with the gobind generated source, the app includes a main.go file
+to define the app entry point.
+
+make.bash builds the app, all.bash deploys it.
+
+The first step in building the app is to build the native shared
+library out of the Go code, and place it in
+libs/armeabi-v7a/libgojni.so.
+
+The second step is building the app with the standard Android build
+system by calling ant debug (also done in make.bash). Two extra Java
+files are included in the build by make.bash to support the language
+bindings. This produces an apk ready for running on a device.

example/libhello/all.bash

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+# Copyright 2014 The Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+# Script to build and launch the app on an android device.
+
+set -e
+
+./make.bash
+
+adb install -r bin/hello-debug.apk
+
+adb shell am start -a android.intent.action.MAIN \
+	-n com.example.hello/com.example.hello.MainActivity

example/libhello/build.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+Copyright 2014 The Go Authors. All rights reserved.
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file.
+-->
+<project name="Hello" default="help">
+	<property name="target" value="android-19" />
+	<property environment="env" />
+	<condition property="sdk.dir" value="${env.ANDROID_HOME}">
+		<isset property="env.ANDROID_HOME" />
+	</condition>
+	<fail message="missing ANDROID_HOME env variable" unless="sdk.dir" />
+	<import file="${sdk.dir}/tools/ant/build.xml" />
+</project>

example/libhello/main.go

@@ -2,14 +2,19 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// This is the Go entry point for the libhello app.
+// It is invoked from Java.
+//
+// See README for details.
 package main
 
 import (
 	"code.google.com/p/go.mobile/app"
 
+	_ "code.google.com/p/go.mobile/bind/java"
 	_ "code.google.com/p/go.mobile/example/libhello/hi/go_hi"
 )
 
 func main() {
-	app.Run()
+	app.Run(app.Callbacks{})
 }

example/libhello/make.bash

@@ -9,17 +9,13 @@ if [ ! -f make.bash ]; then
 	echo 'make.bash must be run from $GOPATH/src/code.google.com/p/go.mobile/example/libhello'
 	exit 1
 fi
-if [ -z "$ANDROID_APP" ]; then
-	echo 'ERROR: Environment variable ANDROID_APP is unset.'
-	exit 1
-fi
-ANDROID_APP=$(cd $ANDROID_APP; pwd)
 
-mkdir -p $ANDROID_APP/src/main/jniLibs/armeabi \
-	$ANDROID_APP/src/main/java/go/hi
-(cd ../.. && ln -sf $PWD/app/*.java $ANDROID_APP/src/main/java/go)
-(cd ../.. && ln -sf $PWD/bind/java/*.java $ANDROID_APP/src/main/java/go)
-ln -sf $PWD/hi/*.java $ANDROID_APP/src/main/java/go/hi
+mkdir -p libs/armeabi-v7a src/go/hi
+ANDROID_APP=$PWD
+(cd ../.. && ln -sf $PWD/app/*.java $ANDROID_APP/src/go)
+(cd ../.. && ln -sf $PWD/bind/java/Seq.java $ANDROID_APP/src/go)
+ln -sf $PWD/hi/*.java src/go/hi
 CGO_ENABLED=1 GOOS=android GOARCH=arm GOARM=7 \
 	go build -ldflags="-shared" .
-mv -f libhello $ANDROID_APP/src/main/jniLibs/armeabi/libgojni.so
+mv -f libhello libs/armeabi-v7a/libgojni.so
+ant debug

example/libhello/src/com/example/hello/MainActivity.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2014 The Go Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+
+package com.example.hello;
+
+import go.Go;
+import go.hi.Hi;
+import android.app.Activity;
+import android.os.Bundle;
+
+/*
+ * MainActivity is the entry point for the libhello app.
+ *
+ * From here, the Go runtime is initialized and a Go function is
+ * invoked via gobind language bindings.
+ *
+ * See example/libhello/README for details.
+ */
+public class MainActivity extends Activity {
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        Go.init(getApplicationContext());
+        Hi.Hello("world");
+    }
+}