java网络编程中向指定URL发送GET POST请求示例

import java.io.bufferedreader;
import java.io.ioexception;
import java.io.inputstreamreader;
import java.io.outputstream;
import java.io.printwriter;
import java.net.httpurlconnection;
import java.net.url;
import java.net.urlconnection;
import java.util.list;
import java.util.map;

public class httprequest {
    /**
     * 向指定url发送get方法的请求
     *
     * @param url
     *            发送请求的url
     * @param param
     *            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结果
     */
    public static string sendget(string url, string param) {
        string result = "";
        bufferedreader in = null;
        try {
            string urlnamestring = url + "?" + param;
            url realurl = new url(urlnamestring);
            // 打开和url之间的连接
            urlconnection connection = realurl.openconnection();
            // 设置通用的请求属性
            connection.setrequestproperty("accept", "*/*");
            connection.setrequestproperty("connection", "keep-alive");
            connection.setrequestproperty("user-agent",
                    "mozilla/4.0 (compatible; msie 6.0; windows nt 5.1;sv1)");
            // 建立实际的连接
            connection.connect();
            // 获取所有响应头字段
            /*
             * map<string, list<string>> map = connection.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(
                    connection.getinputstream()));
            string line;
            while ((line = in.readline()) != null) {
                result += 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 (exception e2) {
                e2.printstacktrace();
            }
        }
        return result;
    }

    /**
     * 向指定 url 发送post方法的请求
     *
     * @param url
     *            发送请求的 url
     * @param param
     *            请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
     * @return 所代表远程资源的响应结果
     */
    public static string sendpost(string url, string param) {
        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(param);
            // 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 += 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;
    }
}