目录总结
本文讲述如何利用v8::TryCatch捕捉js代码中发生的异常。
首先，声明TryCatch对象。
v8::TryCatch trycatch( isolate );
然后，定义抛出异常的函数：
void ThrowException( const v8::FunctionCallbackInfo<v8::Value>& info ) { v8::Isolate* isolate = info.GetIsolate(); v8::HandleScope scope( isolate ); v8::Local<v8::Value> exc = v8::Local<v8::Value>::New( info.GetIsolate(), v8::Exception::Error( v8::String::NewFromUtf8( isolate, "throw an exception" ).ToLocalChecked() ) ); info.GetIsolate()->ThrowException( exc );}
设置访问器访问C++函数：
v8::Local<v8::ObjectTemplate> global = v8::ObjectTemplate::New( isolate );global->Set( isolate, "throwException", v8::FunctionTemplate::New( isolate, ThrowException ) );
因为异常发生在执行js文件期间，所以需要在Run函数后判断是否有异常发生。这里Run的结果没有继续调用ToLocalChecked()，因为result为NULL。
// Run the script to get the result.v8::MaybeLocal<v8::Value> result = script->Run( context );if ( trycatch.HasCaught() ) { v8::Local<v8::Message> message = trycatch.Message(); ResolveMessage( message ); return -1;}
这样就可以在js文件中使用C++函数抛出异常，并解析异常信息。
main.cpp
// Copyright 2015 the V8 project authors. All rights reserved.// Use of this source code is governed by a BSD-style license that can be// found in the LICENSE file.#include <stdio.h>#include <stdlib.h>#include <string.h>#include "include/libplatform/libplatform.h"#include "include/v8.h"#include "point.h"using namespace std;using namespace v8;const std::string fileName = "file.js";// Reads a file into a v8 string.MaybeLocal<String> ReadFile( Isolate* isolate, const string& name ) { FILE* file = fopen( name.c_str(), "rb" ); if ( file == NULL ) return MaybeLocal<String>(); fseek( file, 0, SEEK_END ); size_t size = ftell( file ); rewind( file ); std::unique_ptr<char> chars( new char[size + 1] ); chars.get()[size] = '\0'; for ( size_t i = 0; i < size;) { i += fread( &chars.get()[i], 1, size - i, file ); if ( ferror( file ) ) { fclose( file ); return MaybeLocal<String>(); } } fclose( file ); MaybeLocal<String> result = String::NewFromUtf8( isolate, chars.get(), NewStringType::kNormal, static_cast<int>(size) ); return result;}void ThrowException( const v8::FunctionCallbackInfo<v8::Value>& info ) { v8::Isolate* isolate = info.GetIsolate(); v8::HandleScope scope( isolate ); v8::Local<v8::Value> exc = v8::Local<v8::Value>::New( info.GetIsolate(), v8::Exception::Error( v8::String::NewFromUtf8( isolate, "throw an exception" ).ToLocalChecked() ) ); info.GetIsolate()->ThrowException( exc );}void ResolveMessage( v8::Local<v8::Message> message ) { v8::Isolate* isolate = message->GetIsolate(); v8::Local<v8::Context> context = isolate->GetCurrentContext(); int lineNum = message->GetLineNumber( context ).ToChecked(); v8::String::Utf8Value err_msg( isolate, message->Get() ); v8::String::Utf8Value err_src( isolate, message->GetSourceLine( context ).ToLocalChecked() ); printf( "line %d, [error] %s, [error source] %s", lineNum, *err_msg, *err_src );}int main( int argc, char* argv[] ) { // Initialize V8. v8::V8::InitializeICUDefaultLocation( argv[0] ); v8::V8::InitializeExternalStartupData( argv[0] ); std::unique_ptr<v8::Platform> platform = v8::platform::NewDefaultPlatform(); v8::V8::InitializePlatform( platform.get() ); v8::V8::Initialize(); // Create a new Isolate and make it the current one. v8::Isolate::CreateParams create_params; create_params.array_buffer_allocator = v8::ArrayBuffer::Allocator::NewDefaultAllocator(); v8::Isolate* isolate = v8::Isolate::New( create_params ); { v8::Isolate::Scope isolate_scope( isolate ); // Create a stack-allocated handle scope. v8::HandleScope handle_scope( isolate ); v8::TryCatch trycatch( isolate ); v8::Local<v8::ObjectTemplate> global = v8::ObjectTemplate::New( isolate ); global->Set( isolate, "throwException", v8::FunctionTemplate::New( isolate, ThrowException ) ); // Create a new context. v8::Local<v8::Context> context = v8::Context::New( isolate, nullptr, global ); // Enter the context for compiling and running the hello world script. v8::Context::Scope context_scope( context ); { // Create a string containing the JavaScript source code. v8::Local<v8::String> source; if ( !ReadFile( isolate, fileName ).ToLocal( &source ) ) { fprintf( stderr, "Error reading '%s'.\n", fileName.c_str() ); return -1; } // Compile the source code. v8::Local<v8::Script> script = v8::Script::Compile( context, source ).ToLocalChecked(); // Run the script to get the result. v8::MaybeLocal<v8::Value> result = script->Run( context ); if ( trycatch.HasCaught() ) { v8::Local<v8::Message> message = trycatch.Message(); ResolveMessage( message ); return -1; } } } // Dispose the isolate and tear down V8. isolate->Dispose(); v8::V8::Dispose(); v8::V8::ShutdownPlatform(); delete create_params.array_buffer_allocator; return 0;}
file.js
throwException();
运行结果：
总结
本篇文章就到这里了，希望能给你带来帮助，也希望您能够多多关注的更多内容!
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