node.js学习（七、express框架创建api接口）

根据官方文档，用如下方式构造请求：

app.get("/login/:username/:password",function (req, res) {
console.log(req);
res.send("get it");
});

在get的路径参数中填写请求路径，其中请求需要的参数用/：参数名表示。如上req代表请求数据，res代表服务器返回给浏览器的数据。那么服务器如何获取请求的参数呢，不妨打印一下req对象。上传代码至服务器，node app.js运行。浏览器请求http://goodboy.ren:3000/login/name/123，返回get it代表请求成功。此时查看服务器，打印如下一段：

IncomingMessage {
_readableState:
ReadableState {
objectMode: false,
highWaterMark: 16384,
buffer: [],
length: 0,
pipes: null,
pipesCount: 0,
flowing: null,
ended: false,
endEmitted: false,
reading: false,
sync: true,
needReadable: false,
emittedReadable: false,
readableListening: false,
resumeScheduled: false,
defaultEncoding: 'utf8',
ranOut: false,
awaitDrain: 0,
readingMore: false,
decoder: null,
encoding: null },
readable: true,
domain: null,
_events: {},
_eventsCount: 0,
_maxListeners: undefined,
socket:
Socket {
_connecting: false,
_hadError: false,
_handle:
TCP {
_externalStream: {},
fd: 12,
reading: true,
owner: [Circular],
onread: [Function: onread],
onconnection: null,
writeQueueSize: 0 },
_parent: null,
_host: null,
_readableState:
ReadableState {
objectMode: false,
highWaterMark: 16384,

4000
buffer: [],
length: 0,
pipes: null,
pipesCount: 0,
flowing: true,
ended: false,
endEmitted: false,
reading: true,
sync: false,
needReadable: true,
emittedReadable: false,
readableListening: false,
resumeScheduled: false,
defaultEncoding: 'utf8',
ranOut: false,
awaitDrain: 0,
readingMore: false,
decoder: null,
encoding: null },
readable: true,
domain: null,
_events:
{ end: [Object],
finish: [Function: onSocketFinish],
_socketEnd: [Function: onSocketEnd],
drain: [Object],
timeout: [Function],
error: [Function: socketOnError],
close: [Object],
data: [Function: socketOnData],
resume: [Function: onSocketResume],
pause: [Function: onSocketPause] },
_eventsCount: 10,
_maxListeners: undefined,
_writableState:
WritableState {
objectMode: false,
highWaterMark: 16384,
needDrain: false,
ending: false,
ended: false,
finished: false,
decodeStrings: false,
defaultEncoding: 'utf8',
length: 0,
writing: false,
corked: 0,
sync: true,
bufferProcessing: false,
onwrite: [Function],
writecb: null,
writelen: 0,
bufferedRequest: null,
lastBufferedRequest: null,
pendingcb: 0,
prefinished: false,
errorEmitted: false,
bufferedRequestCount: 0,
corkedRequestsFree: [Object] },
writable: true,
allowHalfOpen: true,
destroyed: false,
bytesRead: 0,
_bytesDispatched: 0,
_sockname: null,
_pendingData: null,
_pendingEncoding: '',
server:
Server {
domain: null,
_events: [Object],
_eventsCount: 3,
_maxListeners: undefined,
_connections: 1,
_handle: [Object],
_usingSlaves: false,
_slaves: [],
_unref: false,
allowHalfOpen: true,
pauseOnConnect: false,
httpAllowHalfOpen: false,
timeout: 120000,
_pendingResponseData: 0,
_connectionKey: '4:0.0.0.0:3000' },
_server:
Server {
domain: null,
_events: [Object],
_eventsCount: 3,
_maxListeners: undefined,
_connections: 1,
_handle: [Object],
_usingSlaves: false,
_slaves: [],
_unref: false,
allowHalfOpen: true,
pauseOnConnect: false,
httpAllowHalfOpen: false,
timeout: 120000,
_pendingResponseData: 0,
_connectionKey: '4:0.0.0.0:3000' },
_idleTimeout: 120000,
_idleNext: { _idleNext: [Circular], _idlePrev: [Circular] },
_idlePrev: { _idleNext: [Circular], _idlePrev: [Circular] },
_idleStart: 7105,
parser:
HTTPParser {
'0': [Function: parserOnHeaders],
'1': [Function: parserOnHeadersComplete],
'2': [Function: parserOnBody],
'3': [Function: parserOnMessageComplete],
'4': [Function: onParserExecute],
_headers: [],
_url: '',
_consumed: true,
socket: [Circular],
incoming: [Circular],
outgoing: null,
maxHeaderPairs: 2000,
onIncoming: [Function: parserOnIncoming] },
on: [Function: socketOnWrap],
_paused: false,
read: [Function],
_consuming: true,
_httpMessage:
ServerResponse {
domain: null,
_events: [Object],
_eventsCount: 1,
_maxListeners: undefined,
output: [],
outputEncodings: [],
outputCallbacks: [],
outputSize: 0,
writable: true,
_last: false,
chunkedEncoding: false,
shouldKeepAlive: true,
useChunkedEncodingByDefault: true,
sendDate: true,
_removedHeader: {},
_contentLength: null,
_hasBody: true,
_trailer: '',
finished: false,
_headerSent: false,
socket: [Circular],
connection: [Circular],
_header: null,
_headers: [Object],
_headerNames: [Object],
_onPendingData: [Function: updateOutgoingData],
req: [Circular],
locals: {} } },
connection:
Socket {
_connecting: false,
_hadError: false,
_handle:
TCP {
_externalStream: {},
fd: 12,
reading: true,
owner: [Circular],
onread: [Function: onread],
onconnection: null,
writeQueueSize: 0 },
_parent: null,
_host: null,
_readableState:
ReadableState {
objectMode: false,
highWaterMark: 16384,
buffer: [],
length: 0,
pipes: null,
pipesCount: 0,
flowing: true,
ended: false,
endEmitted: false,
reading: true,
sync: false,
needReadable: true,
emittedReadable: false,
readableListening: false,
resumeScheduled: false,
defaultEncoding: 'utf8',
ranOut: false,
awaitDrain: 0,
readingMore: false,
decoder: null,
encoding: null },
readable: true,
domain: null,
_events:
{ end: [Object],
finish: [Function: onSocketFinish],
_socketEnd: [Function: onSocketEnd],
drain: [Object],
timeout: [Function],
error: [Function: socketOnError],
close: [Object],
data: [Function: socketOnData],
resume: [Function: onSocketResume],
pause: [Function: onSocketPause] },
_eventsCount: 10,
_maxListeners: undefined,
_writableState:
WritableState {
objectMode: false,
highWaterMark: 16384,
needDrain: false,
ending: false,
ended: false,
finished: false,
decodeStrings: false,
defaultEncoding: 'utf8',
length: 0,
writing: false,
corked: 0,
sync: true,
bufferProcessing: false,
onwrite: [Function],
writecb: null,
writelen: 0,
bufferedRequest: null,
lastBufferedRequest: null,
pendingcb: 0,
prefinished: false,
errorEmitted: false,
bufferedRequestCount: 0,
corkedRequestsFree: [Object] },
writable: true,
allowHalfOpen: true,
destroyed: false,
bytesRead: 0,
_bytesDispatched: 0,
_sockname: null,
_pendingData: null,
_pendingEncoding: '',
server:
Server {
domain: null,
_events: [Object],
_eventsCount: 3,
_maxListeners: undefined,
_connections: 1,
_handle: [Object],
_usingSlaves: false,
_slaves: [],
_unref: false,
allowHalfOpen: true,
pauseOnConnect: false,
httpAllowHalfOpen: false,
timeout: 120000,
_pendingResponseData: 0,
_connectionKey: '4:0.0.0.0:3000' },
_server:
Server {
domain: null,
_events: [Object],
_eventsCount: 3,
_maxListeners: undefined,
_connections: 1,
_handle: [Object],
_usingSlaves: false,
_slaves: [],
_unref: false,
allowHalfOpen: true,
pauseOnConnect: false,
httpAllowHalfOpen: false,
timeout: 120000,
_pendingResponseData: 0,
_connectionKey: '4:0.0.0.0:3000' },
_idleTimeout: 120000,
_idleNext: { _idleNext: [Circular], _idlePrev: [Circular] },
_idlePrev: { _idleNext: [Circular], _idlePrev: [Circular] },
_idleStart: 7105,
parser:
HTTPParser {
'0': [Function: parserOnHeaders],
'1': [Function: parserOnHeadersComplete],
'2': [Function: parserOnBody],
'3': [Function: parserOnMessageComplete],
'4': [Function: onParserExecute],
_headers: [],
_url: '',
_consumed: true,

f459
socket: [Circular],
incoming: [Circular],
outgoing: null,
maxHeaderPairs: 2000,
onIncoming: [Function: parserOnIncoming] },
on: [Function: socketOnWrap],
_paused: false,
read: [Function],
_consuming: true,
_httpMessage:
ServerResponse {
domain: null,
_events: [Object],
_eventsCount: 1,
_maxListeners: undefined,
output: [],
outputEncodings: [],
outputCallbacks: [],
outputSize: 0,
writable: true,
_last: false,
chunkedEncoding: false,
shouldKeepAlive: true,
useChunkedEncodingByDefault: true,
sendDate: true,
_removedHeader: {},
_contentLength: null,
_hasBody: true,
_trailer: '',
finished: false,
_headerSent: false,
socket: [Circular],
connection: [Circular],
_header: null,
_headers: [Object],
_headerNames: [Object],
_onPendingData: [Function: updateOutgoingData],
req: [Circular],
locals: {} } },
httpVersionMajor: 1,
httpVersionMinor: 1,
httpVersion: '1.1',
complete: false,
headers:
{ host: 'goodboy.ren:3000',
connection: 'keep-alive',
'cache-control': 'max-age=0',
accept: 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
'upgrade-insecure-requests': '1',
'user-agent': 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.101 Safari/537.36',
'accept-encoding': 'gzip, deflate, sdch',
'accept-language': 'zh-CN,zh;q=0.8' },
rawHeaders:
[ 'Host',
'goodboy.ren:3000',
'Connection',
'keep-alive',
'Cache-Control',
'max-age=0',
'Accept',
'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
'Upgrade-Insecure-Requests',
'1',
'User-Agent',
'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.101 Safari/537.36',
'Accept-Encoding',
'gzip, deflate, sdch',
'Accept-Language',
'zh-CN,zh;q=0.8' ],
trailers: {},
rawTrailers: [],
upgrade: false,
url: '/login/name/123',
method: 'GET',
statusCode: null,
statusMessage: null,
client:
Socket {
_connecting: false,
_hadError: false,
_handle:
TCP {
_externalStream: {},
fd: 12,
reading: true,
owner: [Circular],
onread: [Function: onread],
onconnection: null,
writeQueueSize: 0 },
_parent: null,
_host: null,
_readableState:
ReadableState {
objectMode: false,
highWaterMark: 16384,
buffer: [],
length: 0,
pipes: null,
pipesCount: 0,
flowing: true,
ended: false,
endEmitted: false,
reading: true,
sync: false,
needReadable: true,
emittedReadable: false,
readableListening: false,
resumeScheduled: false,
defaultEncoding: 'utf8',
ranOut: false,
awaitDrain: 0,
readingMore: false,
decoder: null,
encoding: null },
readable: true,
domain: null,
_events:
{ end: [Object],
finish: [Function: onSocketFinish],
_socketEnd: [Function: onSocketEnd],
drain: [Object],
timeout: [Function],
error: [Function: socketOnError],
close: [Object],
data: [Function: socketOnData],
resume: [Function: onSocketResume],
pause: [Function: onSocketPause] },
_eventsCount: 10,
_maxListeners: undefined,
_writableState:
WritableState {
objectMode: false,
highWaterMark: 16384,
needDrain: false,
ending: false,
ended: false,
finished: false,
decodeStrings: false,
defaultEncoding: 'utf8',
length: 0,
writing: false,
corked: 0,
sync: true,
bufferProcessing: false,
onwrite: [Function],
writecb: null,
writelen: 0,
bufferedRequest: null,
lastBufferedRequest: null,
pendingcb: 0,
prefinished: false,
errorEmitted: false,
bufferedRequestCount: 0,
corkedRequestsFree: [Object] },
writable: true,
allowHalfOpen: true,
destroyed: false,
bytesRead: 0,
_bytesDispatched: 0,
_sockname: null,
_pendingData: null,
_pendingEncoding: '',
server:
Server {
domain: null,
_events: [Object],
_eventsCount: 3,
_maxListeners: undefined,
_connections: 1,
_handle: [Object],
_usingSlaves: false,
_slaves: [],
_unref: false,
allowHalfOpen: true,
pauseOnConnect: false,
httpAllowHalfOpen: false,
timeout: 120000,
_pendingResponseData: 0,
_connectionKey: '4:0.0.0.0:3000' },
_server:
Server {
domain: null,
_events: [Object],
_eventsCount: 3,
_maxListeners: undefined,
_connections: 1,
_handle: [Object],
_usingSlaves: false,
_slaves: [],
_unref: false,
allowHalfOpen: true,
pauseOnConnect: false,
httpAllowHalfOpen: false,
timeout: 120000,
_pendingResponseData: 0,
_connectionKey: '4:0.0.0.0:3000' },
_idleTimeout: 120000,
_idleNext: { _idleNext: [Circular], _idlePrev: [Circular] },
_idlePrev: { _idleNext: [Circular], _idlePrev: [Circular] },
_idleStart: 7105,
parser:
HTTPParser {
'0': [Function: parserOnHeaders],
'1': [Function: parserOnHeadersComplete],
'2': [Function: parserOnBody],
'3': [Function: parserOnMessageComplete],
'4': [Function: onParserExecute],
_headers: [],
_url: '',
_consumed: true,
socket: [Circular],
incoming: [Circular],
outgoing: null,
maxHeaderPairs: 2000,
onIncoming: [Function: parserOnIncoming] },
on: [Function: socketOnWrap],
_paused: false,
read: [Function],
_consuming: true,
_httpMessage:
ServerResponse {
domain: null,
_events: [Object],
_eventsCount: 1,
_maxListeners: undefined,
output: [],
outputEncodings: [],
outputCallbacks: [],
outputSize: 0,
writable: true,
_last: false,
chunkedEncoding: false,
shouldKeepAlive: true,
useChunkedEncodingByDefault: true,
sendDate: true,
_removedHeader: {},
_contentLength: null,
_hasBody: true,
_trailer: '',
finished: false,
_headerSent: false,
socket: [Circular],
connection: [Circular],
_header: null,
_headers: [Object],
_headerNames: [Object],
_onPendingData: [Function: updateOutgoingData],
req: [Circular],
locals: {} } },
_consuming: false,
_dumped: false,
next: [Function: next],
baseUrl: '',
originalUrl: '/login/name/123',
_parsedUrl:
Url {
protocol: null,
slashes: null,
auth: null,
host: null,
port: null,
hostname: null,
hash: null,
search: null,
query: null,
pathname: '/login/name/123',
path: '/login/name/123',
href: '/login/name/123',
_raw: '/login/name/123' },
params: { username: 'name', password: '123' },
query: {},
res:
ServerResponse {
domain: null,
_events: { finish: [Function: resOnFinish] },
_eventsCount: 1,
_maxListeners: undefined,
output: [],
outputEncodings: [],
outputCallbacks: [],
outputSize: 0,
writable: true,
_last: false,
chunkedEncoding: false,
shouldKeepAlive: true,
useChunkedEncodingByDefault: true,
sendDate: true,
_removedHeader: {},
_contentLength: null,
_hasBody: true,
_trailer: '',
finished: false,
_headerSent: false,
socket:
Socket {
_connecting: false,
_hadError: false,
_handle: [Object],
_parent: null,
_host: null,
_readableState: [Object],
readable: true,
domain: null,
_events: [Object],
_eventsCount: 10,
_maxListeners: undefined,
_writableState: [Object],
writable: true,
allowHalfOpen: true,
destroyed: false,
bytesRead: 0,
_bytesDispatched: 0,
_sockname: null,
_pendingData: null,
_pendingEncoding: '',
server: [Object],
_server: [Object],
_idleTimeout: 120000,
_idleNext: [Object],
_idlePrev: [Object],
_idleStart: 7105,
parser: [Object],
on: [Function: socketOnWrap],
_paused: false,
read: [Function],
_consuming: true,
_httpMessage: [Circular] },
connection:
Socket {
_connecting: false,
_hadError: false,
_handle: [Object],
_parent: null,
_host: null,
_readableState: [Object],
readable: true,
domain: null,
_events: [Object],
_eventsCount: 10,
_maxListeners: undefined,
_writableState: [Object],
writable: true,
allowHalfOpen: true,
destroyed: false,
bytesRead: 0,
_bytesDispatched: 0,
_sockname: null,
_pendingData: null,
_pendingEncoding: '',
server: [Object],
_server: [Object],
_idleTimeout: 120000,
_idleNext: [Object],
_idlePrev: [Object],
_idleStart: 7105,
parser: [Object],
on: [Function: socketOnWrap],
_paused: false,
read: [Function],
_consuming: true,
_httpMessage: [Circular] },
_header: null,
_headers: { 'x-powered-by': 'Express' },
_headerNames: { 'x-powered-by': 'X-Powered-By' },
_onPendingData: [Function: updateOutgoingData],
req: [Circular],
locals: {} },
route:
Route {
path: '/login/:username/:password',
stack: [ [Object] ],
methods: { get: true } } }

这里即为请求大全部信息，仔细查找发现一行

params: { username: ‘name’, password: ‘123’ }

这就是我们要或取的值，由此可知get请求的参数是放在params属性中，通过req.params即可获取参数对象。

通过以下代码测试一下：

app.get("/login/:username/:password",function (req, res) {
var user=req.params;
var ret="get userinfo username="+user.username+",password="+user.password;
res.send(ret);
});

执行代码再次请求，返回get userinfo username=name,password=123。说明获取到了所以的请求参数。实际开发过程中，还须对相应的参数进行处理再返回需要的数据。后续章节会进行讲述。

以上为get请求方式获取数据。当我们需要发送大量数据时，不得不使用post方式提交数据。那么post方法如何获得请求参数，复制开始的代码，修改一下，如下：

app.get("/login/:username/:password",function (req, res) {
var user=req.params;
var ret="get userinfo username="+user.username+",password="+user.password;
res.send(ret);
});

app.post("/login",function (req, res) {
console.log(req);
res.send("post success");
});

执行以上代码，用浏览器打开http://www.atool.org/httptest.php



按上图填写后点击发生请求按钮,返回post success。

通过打印日志发现，请求参数没有在打印的日志中。

这时我们需要借助第三方模块body-parser，git地址为https://github.com/expressjs/body-parser

里面有详细的使用说明，按照说明中的例子修改后完整代码如下：

var express=require('express');
var app=express();

var bodyParser = require('body-parser')

// parse application/x-www-form-urlencoded
app.use(bodyParser.urlencoded({ extended: false }))

// parse application/json
app.use(bodyParser.json())

app.get("/sayhello",function (req, res) {
res.send('Hello World!');
});

app.get("/login/:username/:password",function (req, res) {
var user=req.params;
var ret="get userinfo username="+user.username+",password="+user.password;
res.send(ret);
});

app.post("/login",function (req, res) {
var user=req.body;
console.log(user);
var ret="get userinfo username="+user.username+",password="+user.password;
res.send(ret);
});

var server = app.listen(3000);

执行后报错

Error: Cannot find module ‘body-parser’

at Function.Module._resolveFilename (module.js:325:15)

at Function.Module._load (module.js:276:25)

at Module.require (module.js:353:17)

at require (internal/module.js:12:17)

at Object. (/data/nodeweb/app.js:4:18)

at Module._compile (module.js:409:26)

at Object.Module._extensions..js (module.js:416:10)

at Module.load (module.js:343:32)

at Function.Module._load (module.js:300:12)

at Function.Module.runMain (module.js:441:10)

以上错误代表没有下载安装body-parser包，使用npm install -g body-parser 命令安装。安装完成后，执行node app.js。再次通过浏览器请求,获得返回结果。



大功告成。下篇记录如何使用mysql记录请求数据或者查询数据。