如何在 v8 Javascript 中跨多个函数使用相同的上下文?
How to use the same context across multiple functions in v8 Javascript?
我是 V8 的新手,正在尝试在我的 C++ 和 JS 代码之间创建一些绑定。问题是我无法跨不同的 Javascript 函数访问全局 Javascript 变量。原因是因为每个 Javascript 函数调用了我不同的 C++ 函数。我想我的代码的问题是我在每个 C++ 函数中创建了一个新的本地上下文。
我的JS代码:
var test = [];
function f1()
{
var obj = {};
obj.name = "Testing";
test.push(obj);
}
function f2()
{
var value = test[0].name;
}
我的 C++ 代码:
class Test
{
v8::Persistent<v8::Script> compiledScript;
v8::Local<v8::Value> result;
v8::Isolate* isolate;
v8::Persistent<v8::Context> context;
Test(filePath) {
// Create and allocate isolate
v8::Locker isolateLocker(isolate);
v8::Isolate::Scope isolate_scope(isolate);
v8::HandleScope handle_scope(isolate);
// Create some bindings
v8::Local<v8::Context> con = v8::Context::New(isolate, nullptr, binding_template);
con->SetAlignedPointerInEmbedderData(0, &binder);
context.Reset(isolate, con);
v8::Context::Scope context_scope(con);
std::string source_file = LoadFile(filePath);
v8::Local<v8::String> sourceScript = v8::String::NewFromUtf8(isolate, source_file.c_str(), v8::NewStringType::kNormal).ToLocalChecked();
v8::Local<v8::Script> script = v8::Script::Compile(con, sourceScript).ToLocalChecked();
compiledScript.Reset(isolate, script);
}
void function1()
{
v8::Locker isolateLocker(isolate);
v8::Isolate::Scope isolate_scope(isolate);
v8::HandleScope handle_scope(isolate);
v8::Local<v8::Context> con= v8::Local<v8::Context>::New(isolate, context);
v8::Local<v8::Script> script = v8::Local<v8::Script>::New(isolate, compiledScript);
v8::Context::Scope context_scope(con);
// Code to call the Javascript function f1
result = script->Run(con).ToLocalChecked();
v8::Local<v8::Object> global = con->Global();
v8::Local<v8::Value> function_value1 = global->Get(v8::String::NewFromUtf8(isolate, "f1"));
v8::Local<v8::Function> function1 = v8::Local<v8::Function>::Cast(function_value1);
v8::Local<v8::Value> js_result1;
js_result1 = function1->Call(con, global, 0, nullptr).ToLocalChecked();
}
void function2()
{
v8::Locker isolateLocker(isolate);
v8::Isolate::Scope isolate_scope(isolate);
v8::HandleScope handle_scope(isolate);
v8::Local<v8::Context> con = v8::Local<v8::Context>::New(isolate, context);
v8::Local<v8::Script> script = v8::Local<v8::Script>::New(isolate, compiledScript);
v8::Context::Scope context_scope(con);
// Code to call the Javascript function f2
result = script->Run(con).ToLocalChecked();
v8::Local<v8::Object> global = con->Global();
v8::Local<v8::Value> function_value2 = global->Get(v8::String::NewFromUtf8(isolate, "f2"));
v8::Local<v8::Function> function2 = v8::Local<v8::Function>::Cast(function_value2);
v8::Local<v8::Value> js_result2;
js_result2 = function2->Call(con, global, 0, nullptr).ToLocalChecked();
}
};
void main(int argcs, char* argvs[])
{
V8::InitializeICUDefaultLocation(argvs[0]);
V8::InitializeExternalStartupData(argvs[0]);
Platform* platform = platform::CreateDefaultPlatform();
V8::InitializePlatform(platform);
V8::Initialize();
Test test(jsFile);
test.function1();
test.function2();
}
当执行上面的 JS 代码时,我得到一个错误,说 name is a 属性 of undefined。我的理解是变量 test 在第二个函数中未被识别可能是因为每个函数都在不同的上下文中执行。如果是这样,我如何让它们在相同的上下文中执行?如果没有,有人可以帮助我理解并解决问题吗?
任何帮助将不胜感激:)
我想通了。错误是我在所有函数中每次都 运行ning 脚本。相反,我应该像编译一样在构造函数中只 运行 一次。
我是 V8 的新手,正在尝试在我的 C++ 和 JS 代码之间创建一些绑定。问题是我无法跨不同的 Javascript 函数访问全局 Javascript 变量。原因是因为每个 Javascript 函数调用了我不同的 C++ 函数。我想我的代码的问题是我在每个 C++ 函数中创建了一个新的本地上下文。
我的JS代码:
var test = [];
function f1()
{
var obj = {};
obj.name = "Testing";
test.push(obj);
}
function f2()
{
var value = test[0].name;
}
我的 C++ 代码:
class Test
{
v8::Persistent<v8::Script> compiledScript;
v8::Local<v8::Value> result;
v8::Isolate* isolate;
v8::Persistent<v8::Context> context;
Test(filePath) {
// Create and allocate isolate
v8::Locker isolateLocker(isolate);
v8::Isolate::Scope isolate_scope(isolate);
v8::HandleScope handle_scope(isolate);
// Create some bindings
v8::Local<v8::Context> con = v8::Context::New(isolate, nullptr, binding_template);
con->SetAlignedPointerInEmbedderData(0, &binder);
context.Reset(isolate, con);
v8::Context::Scope context_scope(con);
std::string source_file = LoadFile(filePath);
v8::Local<v8::String> sourceScript = v8::String::NewFromUtf8(isolate, source_file.c_str(), v8::NewStringType::kNormal).ToLocalChecked();
v8::Local<v8::Script> script = v8::Script::Compile(con, sourceScript).ToLocalChecked();
compiledScript.Reset(isolate, script);
}
void function1()
{
v8::Locker isolateLocker(isolate);
v8::Isolate::Scope isolate_scope(isolate);
v8::HandleScope handle_scope(isolate);
v8::Local<v8::Context> con= v8::Local<v8::Context>::New(isolate, context);
v8::Local<v8::Script> script = v8::Local<v8::Script>::New(isolate, compiledScript);
v8::Context::Scope context_scope(con);
// Code to call the Javascript function f1
result = script->Run(con).ToLocalChecked();
v8::Local<v8::Object> global = con->Global();
v8::Local<v8::Value> function_value1 = global->Get(v8::String::NewFromUtf8(isolate, "f1"));
v8::Local<v8::Function> function1 = v8::Local<v8::Function>::Cast(function_value1);
v8::Local<v8::Value> js_result1;
js_result1 = function1->Call(con, global, 0, nullptr).ToLocalChecked();
}
void function2()
{
v8::Locker isolateLocker(isolate);
v8::Isolate::Scope isolate_scope(isolate);
v8::HandleScope handle_scope(isolate);
v8::Local<v8::Context> con = v8::Local<v8::Context>::New(isolate, context);
v8::Local<v8::Script> script = v8::Local<v8::Script>::New(isolate, compiledScript);
v8::Context::Scope context_scope(con);
// Code to call the Javascript function f2
result = script->Run(con).ToLocalChecked();
v8::Local<v8::Object> global = con->Global();
v8::Local<v8::Value> function_value2 = global->Get(v8::String::NewFromUtf8(isolate, "f2"));
v8::Local<v8::Function> function2 = v8::Local<v8::Function>::Cast(function_value2);
v8::Local<v8::Value> js_result2;
js_result2 = function2->Call(con, global, 0, nullptr).ToLocalChecked();
}
};
void main(int argcs, char* argvs[])
{
V8::InitializeICUDefaultLocation(argvs[0]);
V8::InitializeExternalStartupData(argvs[0]);
Platform* platform = platform::CreateDefaultPlatform();
V8::InitializePlatform(platform);
V8::Initialize();
Test test(jsFile);
test.function1();
test.function2();
}
当执行上面的 JS 代码时,我得到一个错误,说 name is a 属性 of undefined。我的理解是变量 test 在第二个函数中未被识别可能是因为每个函数都在不同的上下文中执行。如果是这样,我如何让它们在相同的上下文中执行?如果没有,有人可以帮助我理解并解决问题吗?
任何帮助将不胜感激:)
我想通了。错误是我在所有函数中每次都 运行ning 脚本。相反,我应该像编译一样在构造函数中只 运行 一次。