URLConnection發(fā)送HTTP請求的方法_動力節(jié)點Java學院整理
更新時間：2017年07月18日 11:16:58 作者：nick-huang
這篇文章主要介紹了URLConnection發(fā)送HTTP請求的方法，主要介紹了如何通過Java（模擬瀏覽器）發(fā)送HTTP請求，有興趣的可以了解一下
如何通過Java發(fā)送HTTP請求，通俗點講，如何通過Java（模擬瀏覽器）發(fā)送HTTP請求。
Java有原生的API可用于發(fā)送HTTP請求，即java.net.URL、java.net.URLConnection，這些API很好用、很常用，但不夠簡便；
所以，也流行有許多Java HTTP請求的framework，如，Apache的HttpClient。
目前項目主要用到Java原生的方式，所以，這里主要介紹此方式。
運用原生Java Api發(fā)送簡單的Get請求、Post請求
HTTP請求粗分為兩種，一種是GET請求，一種是POST請求。使用Java發(fā)送這兩種請求的代碼大同小異，只是一些參數(shù)設(shè)置的不同。步驟如下：
1.通過統(tǒng)一資源定位器（java.net.URL）獲取連接器（java.net.URLConnection）
2.設(shè)置請求的參數(shù)
3.發(fā)送請求
4.以輸入流的形式獲取返回內(nèi)容
5.關(guān)閉輸入流
簡單的Get請求示例如下：
package com.bjpowernode.httprequestdemo;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
public class HttpGetRequest {
/**
* Main
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
System.out.println(doGet());
}
/**
* Get Request
* @return
* @throws Exception
*/
public static String doGet() throws Exception {
URL localURL = new URL("http://localhost:8080/OneHttpServer/");
URLConnection connection = localURL.openConnection();
HttpURLConnection httpURLConnection = (HttpURLConnection)connection;
httpURLConnection.setRequestProperty("Accept-Charset", "utf-8");
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;
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();
}
}
簡單的Post請求示例如下：
package com.bjpowernode.httprequestdemo;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
public class HttpPostRequest {
/**
* Main
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
System.out.println(doPost());
}
/**
* Post Request
* @return
* @throws Exception
*/
public static String doPost() throws Exception {
String parameterData = "username=nickhuang&blog=http://www.cnblogs.com/nick-huang/";
URL localURL = new URL("http://localhost:8080/OneHttpServer/");
URLConnection connection = localURL.openConnection();
HttpURLConnection httpURLConnection = (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()));
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(parameterData.toString());
outputStreamWriter.flush();
if (httpURLConnection.getResponseCode() >= 300) {
throw new Exception("HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());
}
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();
}
}
簡單封裝
如果項目中有多處地方使用HTTP請求，我們適當對其進行封裝，
- 可以大大減少代碼量（不需每次都寫一大段原生的請求Source code）
- 也可以使配置更靈活、方便（全局設(shè)置一些項目特有的配置，比如已商榷的time out時間、已確定的Proxy Server，避免以后改動繁瑣）
以下簡單封裝成HttpRequestor，以便使用：
package com.bjpowernode.util.httprequestor;
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 = 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;
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 = 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();
if (httpURLConnection.getResponseCode() >= 300) {
throw new Exception("HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());
}
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;
}
}
寫一個調(diào)用的測試類：
package com.bjpowernode.util.httprequestor;
import java.util.HashMap;
import java.util.Map;
public class Call {
public static void main(String[] args) throws Exception {
/* Post Request */
Map dataMap = new HashMap();
dataMap.put("username", "Nick Huang");
dataMap.put("blog", "IT");
System.out.println(new HttpRequestor().doPost("http://localhost:8080/OneHttpServer/", dataMap));
/* Get Request */
System.out.println(new HttpRequestor().doGet("http://localhost:8080/OneHttpServer/"));
}
}
OK，完成??！
簡單測試
以上的請求地址都是http://localhost:8080/OneHttpServer/
這是自己的一個用于測試的Web Application，就一個簡單的Servlet和web.xml。畢竟需要測試請求參數(shù)是否能正常接收，處理超時的情況。
LoginServlet
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public LoginServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
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");
response.getWriter().write("It is ok!");
}
}
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5"> <display-name>OneHttpServer</display-name> <welcome-file-list> <welcome-file>LoginServlet</welcome-file> </welcome-file-list> <servlet> <description></description> <display-name>LoginServlet</display-name> <servlet-name>LoginServlet</servlet-name> <servlet-class>LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/LoginServlet</url-pattern> </servlet-mapping> </web-app>
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