java如何利用java.net.URLConnection发送HTTP请求
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运用原生Java Api发送简单的Get请求、Post请求步骤
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
发送请求与接收响应流类 HttpRequestor
package me.http;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.InetSocketAddress;
import java.net.Proxy;
import java.net.URL;
import java.net.URLConnection;
import java.util.Iterator;
import java.util.Map;
public class HttpRequestor {
private String charset = "utf-8";
private Integer connectTimeout = null;
private Integer socketTimeout = null;
private String proxyHost = null;
private Integer proxyPort = null;
/**
* Do GET request
* @param url
* @return
* @throws Exception
* @throws IOException
*/
public String doGet(String url) throws Exception {URL localURL = new URL(url);
URLConnection connection = this.openConnection(localURL);HttpURLConnection httpURLConnection = (HttpURLConnection)connection;httpURLConnection.setRequestProperty("Accept-Charset", charset);httpURLConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");InputStream inputStream = null;
InputStreamReader inputStreamReader = null;BufferedReader reader = null;
StringBuffer resultBuffer = new StringBuffer();String tempLine = null;
//响应失败
if (httpURLConnection.getResponseCode() >= 300) {throw new Exception("HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());}
try {
inputStream = httpURLConnection.getInputStream();inputStreamReader = new InputStreamReader(inputStream);reader = new BufferedReader(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();
}
}
return resultBuffer.toString();
}
/**
* Do POST request
* @param url
* @param parameterMap
* @return
* @throws Exception
*/
public String doPost(String url, Map parameterMap) throws Exception {/* Translate parameter map to parameter date string */StringBuffer parameterBuffer = new StringBuffer();if (parameterMap != null) {
Iterator iterator = parameterMap.keySet().iterator();String key = null;
String value = 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("POST parameter : " + parameterBuffer.toString());URL localURL = new URL(url);
URLConnection connection = this.openConnection(localURL);HttpURLConnection httpURLConnection = (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()));OutputStream outputStream = null;
OutputStreamWriter outputStreamWriter = null;InputStream inputStream = null;
InputStreamReader inputStreamReader = null;BufferedReader reader = null;
StringBuffer resultBuffer = new StringBuffer();String tempLine = null;
try {
outputStream = httpURLConnection.getOutputStream();outputStreamWriter = new OutputStreamWriter(outputStream);outputStreamWriter.write(parameterBuffer.toString());outputStreamWriter.flush();
//响应失败
if (httpURLConnection.getResponseCode() >= 300) {throw new Exception("HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());}
//接收响应流
inputStream = httpURLConnection.getInputStream();inputStreamReader = new InputStreamReader(inputStream);reader = new BufferedReader(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();
}
}
return resultBuffer.toString();
}
private URLConnection openConnection(URL localURL) throws IOException {URLConnection connection;
if (proxyHost != null && proxyPort != null) {Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress(proxyHost, proxyPort));connection = localURL.openConnection(proxy);} else {
connection = localURL.openConnection();
}
return connection;
}
/**
* Render request according setting
* @param request
*/
private void renderRequest(URLConnection connection) {if (connectTimeout != null) {
connection.setConnectTimeout(connectTimeout);}
if (socketTimeout != null) {
connection.setReadTimeout(socketTimeout);}
}
/*
* Getter & Setter
*/
public Integer getConnectTimeout() {
return connectTimeout;
}
public void setConnectTimeout(Integer connectTimeout) {this.connectTimeout = connectTimeout;
}
public Integer getSocketTimeout() {
return socketTimeout;
}
public void setSocketTimeout(Integer socketTimeout) {this.socketTimeout = socketTimeout;
}
public String getProxyHost() {
return proxyHost;
}
public void setProxyHost(String proxyHost) {this.proxyHost = proxyHost;
}
public Integer getProxyPort() {
return proxyPort;
}
public void setProxyPort(Integer proxyPort) {this.proxyPort = proxyPort;
}
public String getCharset() {
return charset;
}
public void setCharset(String charset) {
this.charset = charset;
}
}
为测试方便,新建一个项目,并新建一个Servlet,接收post请求并对HttpRequestor请求响应,发出响应流:此处使用了
注解: @WebServlet("/LoginServlet") ,也可以在web.xml配置Servletpackage me.loginServlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/**
* Servlet implementation class LoginServlet*/
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {private static final long serialVersionUID = 1L;/**
* @see HttpServlet#HttpServlet()
*/
public LoginServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stub
System.out.println("111");
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stub
String username = request.getParameter("username");String blog = request.getParameter("blog");System.out.println(username);
System.out.println(blog);
response.setContentType("text/plain; charset=UTF-8");response.setCharacterEncoding("UTF-8");
//响应流
response.getWriter().write("It is ok!");
}
}
测试类Test.java
package me.http;
import java.util.HashMap;
import java.util.Map;
public class Test {
public static void main(String[] args) {
/* Post Request */
Map dataMap = new HashMap();
dataMap.put("username", "Nick Huang");
dataMap.put("blog", "IT");
try {
System.out.println(new HttpRequestor().doPost("http://localhost:8081/TestProgect2/LoginServlet", dataMap));//System.out.println(new HttpRequestor().doGet("http://localhost:8081/TestProgect2/LoginServlet"));} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
/* Get Request */
}
}
1.接收post请求类LoginServlet,控制台测试结果2.HttpRequestor接收LoginServlet返回的流
OK,完成
对于接收TestProgect2项目中LoginServlet.java类返回的流,在真实环境中可能是异步接收返回的流的,当一台机器A向另外一台机器B发送请求,B接收到A的信息,将信息处理后,需要将处理结果返回即响应返回给A,A会接收到B返回的信息可以另外建一个Servlet类HttpListenerServlet.java来专门异步接收返回的信息package me.http;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/**
* Servlet implementation class HttpListenerServlet*/
@WebServlet("/HttpListenerServlet")
public class HttpListenerServlet extends HttpServlet {private static final long serialVersionUID = 1L;/**
* @see HttpServlet#HttpServlet()
*/
public HttpListenerServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stub
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stub
InputStream inputStream = null;
inputStream = request.getInputStream();
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);BufferedReader reader = new BufferedReader(inputStreamReader);String tempLine = null;
StringBuffer resultBuffer=new StringBuffer();while ((tempLine = reader.readLine()) != null) {resultBuffer.append(tempLine);
}
System.out.println(resultBuffer.toString());}
}
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