cocos2d多语言互调之一---lua调java

打开如图位置的luaj.lua文件

 1 local luaj = {}
 2 
 3 local callJavaStaticMethod = LuaJavaBridge.callStaticMethod
 4 
 5 local function checkArguments(args, sig)
 6     if type(args) ~= "table" then args = {} end
 7     if sig then return args, sig end
 8 
 9     sig = {"("}
10     for i, v in ipairs(args) do
11         local t = type(v)
12         if t == "number" then
13             sig[#sig + 1] = "F"
14         elseif t == "boolean" then
15             sig[#sig + 1] = "Z"
16         elseif t == "function" then
17             sig[#sig + 1] = "I"
18         else
19             sig[#sig + 1] = "Ljava/lang/String;"
20         end
21     end
22     sig[#sig + 1] = ")V"
23 
24     return args, table.concat(sig)
25 end
26 
27 function luaj.callStaticMethod(className, methodName, args, sig)
28     local args, sig = checkArguments(args, sig)
29     --echoInfo("luaj.callStaticMethod(\"%s\",\n\t\"%s\",\n\targs,\n\t\"%s\"", className, methodName, sig)
30     return callJavaStaticMethod(className, methodName, args, sig)
31 end
32 
33 return luaj

luaj.callStaticMethod 方法就是调JAVA的函数
我们再看方法最后返回的东西

return callJavaStaticMethod(className, methodName, args, sig)

而文件开始就写了

local callJavaStaticMethod = LuaJavaBridge.callStaticMethod

callJavaStaticMethod 是一个函数类型，再查LuaJavaBridge到底是什么,我们用sublime ctrl+p 搜索一下

这是一个头文件，LuaJavaBridge 就是这个C++写的类,再看它下面的方法

再打开它的

LuaJavaBridge.cpp源文件查看源代码

int LuaJavaBridge::callJavaStaticMethod(lua_State *L)
{
    if (!lua_isstring(L, -4) || !lua_isstring(L, -3)  || !lua_istable(L, -2) || !lua_isstring(L, -1))
    {
        lua_pushboolean(L, 0);
        lua_pushinteger(L, LUAJ_ERR_INVALID_SIGNATURES);
        return 2;
    }

    LOGD("%s", "LuaJavaBridge::callJavaStaticMethod(lua_State *L)");

    const char *className  = lua_tostring(L, -4);
    const char *methodName = lua_tostring(L, -3);
    const char *methodSig  = lua_tostring(L, -1);

    CallInfo call(className, methodName, methodSig);

    // check args
    lua_pop(L, 1);                                                    /* L: args */
    int count = fetchArrayElements(L, -1);                          /* L: args e1 e2 e3 e4 ... */
    jvalue *args = NULL;
    if (count > 0)
    {
        args = new jvalue[count];
        for (int i = 0; i < count; ++i)
        {
            int index = -count + i;
            switch (call.argumentTypeAtIndex(i))
            {
                case TypeInteger:
                    if (lua_isfunction(L, index))
                    {
                        args[i].i = retainLuaFunction(L, index, NULL);
                    }
                    else
                    {
                        args[i].i = (int)lua_tonumber(L, index);
                    }
                    break;

                case TypeFloat:
                    args[i].f = lua_tonumber(L, index);
                    break;

                case TypeBoolean:
                    args[i].z = lua_toboolean(L, index) != 0 ? JNI_TRUE : JNI_FALSE;
                    break;

                case TypeString:
                default:
                    args[i].l = call.getEnv()->NewStringUTF(lua_tostring(L, index));
                    break;
            }
        }
        lua_pop(L, count);                                           /* L: args */
    }

    bool success = args ? call.executeWithArgs(args) : call.execute();
    if (args) delete []args;

    if (!success)
    {
        LOGD("LuaJavaBridge::callJavaStaticMethod(\"%s\", \"%s\", args, \"%s\") EXECUTE FAILURE, ERROR CODE: %d",
                className, methodName, methodSig, call.getErrorCode());

        lua_pushboolean(L, 0);
        lua_pushinteger(L, call.getErrorCode());
        return 2;
    }

    LOGD("LuaJavaBridge::callJavaStaticMethod(\"%s\", \"%s\", args, \"%s\") SUCCESS",
            className, methodName, methodSig);

    lua_pushboolean(L, 1);
    return 1 + call.pushReturnValue(L);
}

细心观察LuaJavaBridge.cpp，文件开头的地方include了jni的头文件

#include "platform/android/jni/JniHelper.h"

 

再观察 LuaJavaBridge.h 文件开头的地方

extern "C" {
#include "lua.h"
}

可以发现LuaJavaBridge.cpp也是一层中间代码，负责把lua和java粘合起来

注：在c里面调用了lua.h头文件即可用C调用LUA。后续继续写JAVA调用LUA以及LUA与C++之间的互调