Question

因此，我正在学习节点，尝试自己编写简单的服务器。将数据写入响应时，它将无法正常工作。我将数据转换为String，我尝试将数据显示到控制台，并且benn正常显示，但是当我将其传递给response.write（）时，页面上没有任何变化。我在poems / lorem目录中创建了名为“ lorem”的文件，并将此路径写入浏览器中的链接。如您所见，我正在编写一些调试资料，但是我删除了大部分。

var http = require('http');
var fs   = require('fs');
var path = require('path');

var port = process.argv[2];

var readFileContent = (filePath) => 
{
    var readData = '';

    fs.readFile(path.normalize(process.cwd() + filePath), 'utf-8', (err, data) => 
    {
        let invalid = false;
        if(err || data === undefined)
        {
            invalid = true;
        }
        if(!invalid) readData = data;
        console.log(readData); // logs data from a file
    });

    return readData;
}

var serverHandler = (request, response) =>
{   
        let responseData = readFileContent(request.url);

        if(responseData != undefined)
        {
            response.writeHead(200, {'Content-Type':'text/html'});
            response.write(''+ responseData.toString()); // there is a problem: writes data only when I pass some exact string (e.g. 'LOREM')
        }
        else{
            response.writeHead(404);
            response.write('Error occured');
        }
        response.end(responseData.toString());
    }


http.createServer(serverHandler).listen(+ port);


console.log('Server is lisntening on port ' + port);

对于“ C：/ folderpath / node server.js 8080” cmd，有一些控制台输出：

Server is lisntening on port 8080

lorem

lorem

lorem

'poems / lorem'文件的内容=='lorem'

Answer 1

我认为您的问题与异步性有关。

为文件读取功能提供回调，该回调返回文件内容。

赞：

var readFileContent = (filePath, callback) => 
{

    fs.readFile(path.normalize(process.cwd() + filePath), 'utf-8', (err, data) => 
    {
        let invalid = false;
        if(err || data === undefined)
        {
            invalid = true;
        }
        if(!invalid) readData = data;
        callback(readData)
    });

}

然后在服务器处理程序函数中执行以下操作：

var serverHandler = (request, response) =>
{   
   readFileContent(request.url, (responseData) => {
      if(responseData != undefined) {
           response.writeHead(200, {'Content-Type':'text/html'});
           response.write(''+ responseData.toString()); 
        }
       else {
          response.writeHead(404);
          response.write('Error occured');
       }
       response.end(responseData.toString());
    }); 
 }

Response.write不显示变量字符串

1 个答案: