SL4A 之实现原理解析

# Copyright (C) 2009 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy of
# the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations under
# the License.
 
__author__ = 'Damon Kohler <[email protected]>'
 
import collections
import json
import os
import socket
import sys
 
PORT = os.environ.get('AP_PORT')
HOST = os.environ.get('AP_HOST')
HANDSHAKE = os.environ.get('AP_HANDSHAKE')
Result = collections.namedtuple('Result', 'id,result,error')
 
class Android(object):
 
  def __init__(self, addr=None):
    if addr is None:
      addr = HOST, PORT
    self.conn = socket.create_connection(addr)
    self.client = self.conn.makefile()
    self.id = 0
    if HANDSHAKE is not None:
      self._authenticate(HANDSHAKE)
 
  def _rpc(self, method, *args):
    data = {'id': self.id,
            'method': method,
            'params': args}
    request = json.dumps(data)
    self.client.write(request+'\n')
    self.client.flush()
    response = self.client.readline()
    self.id += 1
    result = json.loads(response)
    if result['error'] is not None:
      print result['error']
    # namedtuple doesn't work with unicode keys.
    return Result(id=result['id'], result=result['result'],
                  error=result['error'], )
 
  def __getattr__(self, name):
    def rpc_call(*args):
      return self._rpc(name, *args)
    return rpc_call

// Copyright (C) 2009 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
 
import org.json.*;
 
Android() {
  String AP_PORT = System.getenv().get("AP_PORT");
  String AP_HOST = System.getenv().get("AP_HOST");
  String AP_HANDSHAKE = System.getenv().get("AP_HANDSHAKE");
  Socket conn = new Socket(AP_HOST, Integer.decode(AP_PORT));
  BufferedReader in = new BufferedReader(
      new InputStreamReader(conn.getInputStream(), "8859_1"), 1 << 13);
  OutputStream out_stream = new BufferedOutputStream(
      conn.getOutputStream(), 1 << 13);
  PrintWriter out = new PrintWriter(
      new OutputStreamWriter(out_stream, "8859_1"), true);
  int id = 0;
 
  call(String method, JSONArray params) {
    JSONObject request = new JSONObject();
    request.put("id", id);
    request.put("method", method);
    request.put("params", params);
    out.write(request.toString() + "\n");
    out.flush();
    String data = in.readLine();
    if (data == null) {
      return null;
    }
    return new JSONObject(data);
  }
 
  call(String method) {
    JSONArray args = new JSONArray();
    call(method, args);
  }
 
  call(String method, Object arg1) {
    JSONArray args = new JSONArray();
    args.put(arg1);
    call(method, args);
  }
 
  call(String method, Object arg1, Object arg2) {
    JSONArray args = new JSONArray();
    args.put(arg1);
    args.put(arg2);
    call(method, args);
  }
 
  call(String method, Object arg1, Object arg2, Object arg3) {
    JSONArray args = new JSONArray();
    args.put(arg1);
    args.put(arg2);
    args.put(arg3);
    call(method, args);
  }
 
  call(String method, Object arg1, Object arg2, Object arg3, Object arg4) {
    JSONArray args = new JSONArray();
    args.put(arg1);
    args.put(arg2);
    args.put(arg3);
    args.put(arg4);
    call(method, args);
  }
 
  JSONArray handshake = new JSONArray();
  handshake.put(AP_HANDSHAKE);
  call("_authenticate", handshake);
 
  return this;
}

/* * Copyright 2009 Brice Lambson * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. */
 
var AP_PORT = java.lang.System.getenv("AP_PORT");
var AP_HOST = java.lang.System.getenv("AP_HOST");
var AP_HANDSHAKE = java.lang.System.getenv("AP_HANDSHAKE");
 
load('/sdcard/com.googlecode.rhinoforandroid/extras/rhino/json2.js');
 
function Android() {
 
  this.connection = new java.net.Socket(String(AP_HOST), AP_PORT),
  this.input = new java.io.BufferedReader(
      new java.io.InputStreamReader(this.connection.getInputStream(), "8859_1"),
                                    1 << 13),
  this.output = new java.io.PrintWriter(new java.io.OutputStreamWriter(
      new java.io.BufferedOutputStream(this.connection.getOutputStream(),
                                       1 << 13),
      "8859_1"), true),
  this.id = 0,
 
  this.rpc = function(method, args) {
    this.id += 1;
    var request = JSON.stringify({'id': this.id, 'method': method,
                                  'params': args});
    this.output.write(request + '\n');
    this.output.flush();
    var response = this.input.readLine();
    return eval("(" + response + ")");
  },
 
  this.__noSuchMethod__ = function(id, args) {
    var response = this.rpc(id, args);
    if (response.error != null) {
      throw response.error;
    }
    return response.result;
  }
 
  this._authenticate(String(AP_HANDSHAKE));
}

// Released into the public domain, 15 August 2010
 
// This program demonstrates how a C application can access some of the Android
// API via the SL4A (Scripting Languages for Android, formerly "ASE", or Android
// Scripting Environment) RPC mechanism. It works either from a host computer
// or as a native binary compiled with the NDK (rooted phone required, I think)
 
// SL4A is a neat Android app that provides support for many popular scripting
// languages like Python, Perl, Ruby and TCL. SL4A exposes a useful subset of
// the Android API in a clever way: by setting up a JSON RPC server. That way,
// each language only needs to implement a thin RPC client layer to access the
// whole SL4A API.
 
// The Android NDK is a C compiler only intended for writing optimized
// subroutines of "normal" Android apps written in Java. So it doesn't come
// with any way to access the Android API.
 
// This program uses the excellent "Jansson" JSON library to talk to SL4A's
// RPC server, effectively adding native C programs to the list of languages
// supported by SL4A.
 
// To try it, first install SL4A: http://code.google.com/p/android-scripting/
//
// Start a private server with View->Interpreters->Start Server
//
// Note the port number the server is running on by pulling down the status
// bar and tapping "SL4A service". 
 
// This program works just fine as either a native Android binary or from a
// host machine.
 
// ------------
 
// To compile on an ordinary linux machine, first install libjansson. Then:
 
// $ gcc -ljansson ndk-to-sl4a.c -o ndk-to-sl4a
 
// To access SL4A on the phone use "adb forward tcp:XXXXX tcp:XXXXX" to port
// forward the SL4A server port from your host to the phone. See this
// page for more details:
// http://code.google.com/p/android-scripting/wiki/RemoteControl
 
// ------------
 
// To compile using the NDK:
// 1. Make sure you can compile "Hello, world" using the NDK. See:
// http://credentiality2.blogspot.com/2010/08/native-android-c-program-using-ndk.html
//
// 2. If you followed the above instructions, you have a copy of the agcc.pl
// wrapper that calls the NDK's gcc compiler with the right options for
// standalone apps.
//
// 3. Unpack a fresh copy of the jansson sources. Tell configure to build for
// Android:
//
// $ CC=agcc.pl ./configure --host=arm
// $ make
//
// 4. Cross your fingers and go! (I'm quite certain there's a more elegant
// way to do this)
//
// $ agcc.pl -I/path/to/jansson-1.3/src -o ndk-to-sl4a-arm ndk-to-sl4a.c /path/to/jansson-1.3/src/*.o
//
// 5. Copy to the phone and run it with the port of the SL4A server!
 
#include <stdio.h>
#include <jansson.h>
#include <unistd.h>
#include <string.h>
 
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> 
 
// This mimics SL4A's android.py, constructing a JSON RPC object and
// sending it to the SL4A server.
int sl4a_rpc(int socket_fd, char *method, json_t *params) {
  static int request_id = 0; // monotonically increasing counter
 
  json_t *root = json_object();
 
  json_object_set(root, "id", json_integer(request_id));
  request_id++;
 
  json_object_set(root, "method", json_string(method));
 
  if (params == NULL) {
    params = json_array();
    json_array_append(params, json_null());
  }
 
  json_object_set(root, "params", params);
 
  char *command = json_dumps(root, JSON_PRESERVE_ORDER | JSON_ENSURE_ASCII);
  printf("command string:'%s'\n", command);
 
  write(socket_fd, command, strlen(command));
  write(socket_fd, "\n", strlen("\n"));
 
  // At this point we just print the response, but really we should buffer it
  // up into a single string, then pass it to json_loads() for decoding.
  printf("Got back:\n");
  while (1) {
    char c;
    read(socket_fd, &c, 1);
    printf("%c", c);
    if (c == '\n') {
      break;
    }
  }
  fflush(stdout);
  return 0;
}
 
// This function is just boilerplate TCP socket setup code
int init_socket(char *hostname, int port) {
  int socket_fd = socket(AF_INET, SOCK_STREAM, 0);
  if (socket_fd == -1) {
    perror("Error creating socket");
    return 0;
  }
 
  struct hostent *host = gethostbyname(hostname);
  if (host == NULL) {
    perror("No such host");
    return -1;
  }
 
  struct sockaddr_in socket_address;
 
  int i;
  for (i=0; i < sizeof(socket_address); i++) {
    ((char *) &socket_address)[i] = 0;
  }
 
  socket_address.sin_family = AF_INET;
 
  for (i=0; i < host->h_length; i++) {
    ((char *) &socket_address.sin_addr.s_addr)[i] = ((char *) host->h_addr)[i];
  }
 
  socket_address.sin_port = htons(port);
 
  if (connect(socket_fd, (struct sockaddr *) &socket_address, sizeof(socket_address)) < 0) {
    perror("connect() failed");
    return -1;
  }
 
  return socket_fd;
}
 
main(int argc, char **argv) {
  int port = 0;
  if (argc != 2) {
    printf("Usage: %s port\n", argv[0]);
    return 1;
  }
  port = atoi(argv[1]);
 
  int socket_fd = init_socket("localhost", port);
  if (socket_fd < 0) return 2;
 
  json_t *params = json_array();
  json_array_append(params, json_string("w00t!"));
  sl4a_rpc(socket_fd, "makeToast", params);
}