Java 使用 URLConnection 模拟 Http Get和Post 提交。

1、URLConnectionHelper

package com.hcm.rulconnetion.utils;import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;public class URLConnectionHelper {/*** 向指定URL发送GET方法的请求* * @param url*            发送请求的URL* @param params*            请求参数，请求参数应该是name1=value1&name2=value2的形式。* @return URL所代表远程资源的响应*/public static String sendGet(String url, String params) {String result = "";BufferedReader in = null;try {String urlName = url + "?" + params;URL realUrl = new URL(urlName);// 打开和URL之间的连接URLConnection conn = realUrl.openConnection();// 设置通用的请求属性conn.setRequestProperty("accept", "*/*");conn.setRequestProperty("connection", "Keep-Alive");conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");// 建立实际的连接conn.connect();// 获取所有响应头字段Map<String, List<String>> map = conn.getHeaderFields();// 遍历所有的响应头字段for (String key : map.keySet()) {System.out.println(key + "--->" + map.get(key));}// 定义BufferedReader输入流来读取URL的响应in = new BufferedReader(new InputStreamReader(conn.getInputStream()));String line;while ((line = in.readLine()) != null) {result += "\n" + line;}} catch (Exception e) {System.out.println("发送GET请求出现异常！" + e);e.printStackTrace();}// 使用finally块来关闭输入流finally {try {if (in != null) {in.close();}} catch (IOException ex) {ex.printStackTrace();}}return result;}/*** 向指定URL发送POST方法的请求* * @param url*            发送请求的URL* @param params*            请求参数，请求参数应该是name1=value1&name2=value2的形式。* @return URL所代表远程资源的响应*/public static String sendPost(String url, String params) {PrintWriter out = null;BufferedReader in = null;String result = "";try {URL realUrl = new URL(url);// 打开和URL之间的连接URLConnection conn = realUrl.openConnection();// 设置通用的请求属性conn.setRequestProperty("accept", "*/*");conn.setRequestProperty("connection", "Keep-Alive");conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");// 发送POST请求必须设置如下两行conn.setDoOutput(true);conn.setDoInput(true);// 获取URLConnection对象对应的输出流out = new PrintWriter(conn.getOutputStream());// 发送请求参数out.print(params);// flush输出流的缓冲out.flush();// 定义BufferedReader输入流来读取URL的响应in = new BufferedReader(new InputStreamReader(conn.getInputStream()));String line;while ((line = in.readLine()) != null) {result += "\n" + line;}} catch (Exception e) {System.out.println("发送POST请求出现异常！" + e);e.printStackTrace();}// 使用finally块来关闭输出流、输入流finally {try {if (out != null) {out.close();}if (in != null) {in.close();}} catch (IOException ex) {ex.printStackTrace();}}return result;}
}

2、测试sendGet方法

@Test
public void testSendGet() {String url = "http://127.0.0.1:8086/web_test/a.jsp";String str = URLConnectionHelper.sendGet(url, null);System.out.println(str);
}

3、测试sendPost方法

@Test
public void testSendPost() {String url = "http://127.0.0.1:8086/web_test/UserLoginServlet";String params = "username=admin&password=123456";String str = URLConnectionHelper.sendPost(url, params);System.out.println(str);
}