URLConnection发送HTTP请求的方法_动力节点Java学院整理

2024-01-27 12:40:03 53

如何通过Java发送HTTP请求，通俗点讲，如何通过Java（模拟浏览器）发送HTTP请求。

Java有原生的API可用于发送HTTP请求，即java.net.URL、java.net.URLConnection，这些API很好用、很常用，但不够简便；
所以，也流行有许多JavaHTTP请求的framework，如，Apache的HttpClient。

目前项目主要用到Java原生的方式，所以，这里主要介绍此方式。

运用原生JavaApi发送简单的Get请求、Post请求

HTTP请求粗分为两种，一种是GET请求，一种是POST请求。使用Java发送这两种请求的代码大同小异，只是一些参数设置的不同。步骤如下：

1.通过统一资源定位器（java.net.URL）获取连接器（java.net.URLConnection）

2.设置请求的参数

3.发送请求

4.以输入流的形式获取返回内容

5.关闭输入流

简单的Get请求示例如下：

packagecom.bjpowernode.httprequestdemo;

importjava.io.BufferedReader;
importjava.io.InputStream;
importjava.io.InputStreamReader;
importjava.net.HttpURLConnection;
importjava.net.URL;
importjava.net.URLConnection;

publicclassHttpGetRequest{

/**
*Main
*@paramargs
*@throwsException
*/
publicstaticvoidmain(String[]args)throwsException{
System.out.println(doGet());
}

/**
*GetRequest
*@return
*@throwsException
*/
publicstaticStringdoGet()throwsException{
URLlocalURL=newURL("http://localhost:8080/OneHttpServer/");
URLConnectionconnection=localURL.openConnection();
HttpURLConnectionhttpURLConnection=(HttpURLConnection)connection;

httpURLConnection.setRequestProperty("Accept-Charset","utf-8");
httpURLConnection.setRequestProperty("Content-Type","application/x-www-form-urlencoded");

InputStreaminputStream=null;
InputStreamReaderinputStreamReader=null;
BufferedReaderreader=null;
StringBufferresultBuffer=newStringBuffer();
StringtempLine=null;

if(httpURLConnection.getResponseCode()>=300){
thrownewException("HTTPRequestisnotsuccess,Responsecodeis"+httpURLConnection.getResponseCode());
}

try{
inputStream=httpURLConnection.getInputStream();
inputStreamReader=newInputStreamReader(inputStream);
reader=newBufferedReader(inputStreamReader);

while((tempLine=reader.readLine())!=null){
resultBuffer.append(tempLine);
}

}finally{

if(reader!=null){
reader.close();
}

if(inputStreamReader!=null){
inputStreamReader.close();
}

if(inputStream!=null){
inputStream.close();
}

}

returnresultBuffer.toString();
}

}

简单的Post请求示例如下：

packagecom.bjpowernode.httprequestdemo;

importjava.io.BufferedReader;
importjava.io.InputStream;
importjava.io.InputStreamReader;
importjava.io.OutputStream;
importjava.io.OutputStreamWriter;
importjava.net.HttpURLConnection;
importjava.net.URL;
importjava.net.URLConnection;

publicclassHttpPostRequest{

/**
*Main
*@paramargs
*@throwsException
*/
publicstaticvoidmain(String[]args)throwsException{
System.out.println(doPost());
}

/**
*PostRequest
*@return
*@throwsException
*/
publicstaticStringdoPost()throwsException{
StringparameterData="username=nickhuang&blog=http://www.cnblogs.com/nick-huang/";

URLlocalURL=newURL("http://localhost:8080/OneHttpServer/");
URLConnectionconnection=localURL.openConnection();
HttpURLConnectionhttpURLConnection=(HttpURLConnection)connection;

httpURLConnection.setDoOutput(true);
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setRequestProperty("Accept-Charset","utf-8");
httpURLConnection.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
httpURLConnection.setRequestProperty("Content-Length",String.valueOf(parameterData.length()));

OutputStreamoutputStream=null;
OutputStreamWriteroutputStreamWriter=null;
InputStreaminputStream=null;
InputStreamReaderinputStreamReader=null;
BufferedReaderreader=null;
StringBufferresultBuffer=newStringBuffer();
StringtempLine=null;

try{
outputStream=httpURLConnection.getOutputStream();
outputStreamWriter=newOutputStreamWriter(outputStream);

outputStreamWriter.write(parameterData.toString());
outputStreamWriter.flush();

if(httpURLConnection.getResponseCode()>=300){
thrownewException("HTTPRequestisnotsuccess,Responsecodeis"+httpURLConnection.getResponseCode());
}

inputStream=httpURLConnection.getInputStream();
inputStreamReader=newInputStreamReader(inputStream);
reader=newBufferedReader(inputStreamReader);

while((tempLine=reader.readLine())!=null){
resultBuffer.append(tempLine);
}

}finally{

if(outputStreamWriter!=null){
outputStreamWriter.close();
}

if(outputStream!=null){
outputStream.close();
}

if(reader!=null){
reader.close();
}

if(inputStreamReader!=null){
inputStreamReader.close();
}

if(inputStream!=null){
inputStream.close();
}

}

returnresultBuffer.toString();
}

}

简单封装

如果项目中有多处地方使用HTTP请求，我们适当对其进行封装，

可以大大减少代码量（不需每次都写一大段原生的请求Sourcecode）
也可以使配置更灵活、方便（全局设置一些项目特有的配置，比如已商榷的timeout时间、已确定的ProxyServer，避免以后改动繁琐）

以下简单封装成HttpRequestor，以便使用：

packagecom.bjpowernode.util.httprequestor;

importjava.io.BufferedReader;
importjava.io.IOException;
importjava.io.InputStream;
importjava.io.InputStreamReader;
importjava.io.OutputStream;
importjava.io.OutputStreamWriter;
importjava.net.HttpURLConnection;
importjava.net.InetSocketAddress;
importjava.net.Proxy;
importjava.net.URL;
importjava.net.URLConnection;
importjava.util.Iterator;
importjava.util.Map;


publicclassHttpRequestor{

privateStringcharset="utf-8";
privateIntegerconnectTimeout=null;
privateIntegersocketTimeout=null;
privateStringproxyHost=null;
privateIntegerproxyPort=null;

/**
*DoGETrequest
*@paramurl
*@return
*@throwsException
*@throwsIOException
*/
publicStringdoGet(Stringurl)throwsException{

URLlocalURL=newURL(url);

URLConnectionconnection=openConnection(localURL);
HttpURLConnectionhttpURLConnection=(HttpURLConnection)connection;

httpURLConnection.setRequestProperty("Accept-Charset",charset);
httpURLConnection.setRequestProperty("Content-Type","application/x-www-form-urlencoded");

InputStreaminputStream=null;
InputStreamReaderinputStreamReader=null;
BufferedReaderreader=null;
StringBufferresultBuffer=newStringBuffer();
StringtempLine=null;

if(httpURLConnection.getResponseCode()>=300){
thrownewException("HTTPRequestisnotsuccess,Responsecodeis"+httpURLConnection.getResponseCode());
}

try{
inputStream=httpURLConnection.getInputStream();
inputStreamReader=newInputStreamReader(inputStream);
reader=newBufferedReader(inputStreamReader);

while((tempLine=reader.readLine())!=null){
resultBuffer.append(tempLine);
}

}finally{

if(reader!=null){
reader.close();
}

if(inputStreamReader!=null){
inputStreamReader.close();
}

if(inputStream!=null){
inputStream.close();
}

}

returnresultBuffer.toString();
}

/**
*DoPOSTrequest
*@paramurl
*@paramparameterMap
*@return
*@throwsException
*/
publicStringdoPost(Stringurl,MapparameterMap)throwsException{

/*Translateparametermaptoparameterdatestring*/
StringBufferparameterBuffer=newStringBuffer();
if(parameterMap!=null){
Iteratoriterator=parameterMap.keySet().iterator();
Stringkey=null;
Stringvalue=null;
while(iterator.hasNext()){
key=(String)iterator.next();
if(parameterMap.get(key)!=null){
value=(String)parameterMap.get(key);
}else{
value="";
}

parameterBuffer.append(key).append("=").append(value);
if(iterator.hasNext()){
parameterBuffer.append("&");
}
}
}

System.out.println("POSTparameter:"+parameterBuffer.toString());

URLlocalURL=newURL(url);

URLConnectionconnection=openConnection(localURL);
HttpURLConnectionhttpURLConnection=(HttpURLConnection)connection;

httpURLConnection.setDoOutput(true);
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setRequestProperty("Accept-Charset",charset);
httpURLConnection.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
httpURLConnection.setRequestProperty("Content-Length",String.valueOf(parameterBuffer.length()));

OutputStreamoutputStream=null;
OutputStreamWriteroutputStreamWriter=null;
InputStreaminputStream=null;
InputStreamReaderinputStreamReader=null;
BufferedReaderreader=null;
StringBufferresultBuffer=newStringBuffer();
StringtempLine=null;

try{
outputStream=httpURLConnection.getOutputStream();
outputStreamWriter=newOutputStreamWriter(outputStream);

outputStreamWriter.write(parameterBuffer.toString());
outputStreamWriter.flush();

if(httpURLConnection.getResponseCode()>=300){
thrownewException("HTTPRequestisnotsuccess,Responsecodeis"+httpURLConnection.getResponseCode());
}

inputStream=httpURLConnection.getInputStream();
inputStreamReader=newInputStreamReader(inputStream);
reader=newBufferedReader(inputStreamReader);

while((tempLine=reader.readLine())!=null){
resultBuffer.append(tempLine);
}

}finally{

if(outputStreamWriter!=null){
outputStreamWriter.close();
}

if(outputStream!=null){
outputStream.close();
}

if(reader!=null){
reader.close();
}

if(inputStreamReader!=null){
inputStreamReader.close();
}

if(inputStream!=null){
inputStream.close();
}

}

returnresultBuffer.toString();
}

privateURLConnectionopenConnection(URLlocalURL)throwsIOException{
URLConnectionconnection;
if(proxyHost!=null&&proxyPort!=null){
Proxyproxy=newProxy(Proxy.Type.HTTP,newInetSocketAddress(proxyHost,proxyPort));
connection=localURL.openConnection(proxy);
}else{
connection=localURL.openConnection();
}
returnconnection;
}

/**
*Renderrequestaccordingsetting
*@paramrequest
*/
privatevoidrenderRequest(URLConnectionconnection){

if(connectTimeout!=null){
connection.setConnectTimeout(connectTimeout);
}

if(socketTimeout!=null){
connection.setReadTimeout(socketTimeout);
}

}

/*
*Getter&Setter
*/
publicIntegergetConnectTimeout(){
returnconnectTimeout;
}

publicvoidsetConnectTimeout(IntegerconnectTimeout){
this.connectTimeout=connectTimeout;
}

publicIntegergetSocketTimeout(){
returnsocketTimeout;
}

publicvoidsetSocketTimeout(IntegersocketTimeout){
this.socketTimeout=socketTimeout;
}

publicStringgetProxyHost(){
returnproxyHost;
}

publicvoidsetProxyHost(StringproxyHost){
this.proxyHost=proxyHost;
}

publicIntegergetProxyPort(){
returnproxyPort;
}

publicvoidsetProxyPort(IntegerproxyPort){
this.proxyPort=proxyPort;
}

publicStringgetCharset(){
returncharset;
}

publicvoidsetCharset(Stringcharset){
this.charset=charset;
}

}

写一个调用的测试类：

packagecom.bjpowernode.util.httprequestor;

importjava.util.HashMap;
importjava.util.Map;

publicclassCall{

publicstaticvoidmain(String[]args)throwsException{

/*PostRequest*/
MapdataMap=newHashMap();
dataMap.put("username","NickHuang");
dataMap.put("blog","IT");
System.out.println(newHttpRequestor().doPost("http://localhost:8080/OneHttpServer/",dataMap));

/*GetRequest*/
System.out.println(newHttpRequestor().doGet("http://localhost:8080/OneHttpServer/"));
}

}

OK，完成！！

简单测试

以上的请求地址都是http://localhost:8080/OneHttpServer/

这是自己的一个用于测试的WebApplication，就一个简单的Servlet和web.xml。毕竟需要测试请求参数是否能正常接收，处理超时的情况。

LoginServlet

importjava.io.IOException;
importjavax.servlet.ServletException;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;

publicclassLoginServletextendsHttpServlet{
privatestaticfinallongserialVersionUID=1L;

publicLoginServlet(){
super();
}

protectedvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
this.doPost(request,response);
}

protectedvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
Stringusername=request.getParameter("username");
Stringblog=request.getParameter("blog");

System.out.println(username);
System.out.println(blog);

response.setContentType("text/plain;charset=UTF-8");
response.setCharacterEncoding("UTF-8");
response.getWriter().write("Itisok!");
}

}

web.xml



OneHttpServer

LoginServlet




LoginServlet
LoginServlet
LoginServlet


LoginServlet
/LoginServlet

URLConnection发送HTTP请求的方法_动力节点Java学院整理

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