java發送get、post http請求

直接上代碼

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

import javax.servlet.http.HttpServletRequest;

import org.jdom.CDATA;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.output.XMLOutputter;

public class OperationDao {

	public static String sendRequest(OperationBeanBase opBean)
			throws JDOMException, Exception {
		if (opBean.getRequestType().equals("post"))
			return sendPostRequest(opBean);
		else if (opBean.getRequestType().equals("get"))
			return sendGetRequest(opBean);
		return "";
	}

	public static String sendPostRequest(OperationBeanBase opBean)
			throws JDOMException, Exception {
		URL url = new URL(opBean.getUrlString());
		URLConnection con = url.openConnection();
		con.setUseCaches(false);
		con.setDoOutput(true);//開啓輸入輸出
  		con.setDoInput(true);

		BufferedWriter out = new BufferedWriter(new OutputStreamWriter(
				con.getOutputStream(),"UTF-8"));
		out.write(opBean.getXMLString());
		out.flush();
		out.close();

		StringBuffer sendBack = new StringBuffer();
		try {
			InputStream is = con.getInputStream();
			InputStreamReader isr = new InputStreamReader(is,"UTF-8");
			BufferedReader br = new BufferedReader(isr);
			String s = "";
			while ((s = br.readLine()) != null) {
				sendBack.append(s);
			}
		} catch (Exception e) {
			System.out.println(e.toString());
		}

		return sendBack.toString();
	}

	public static String sendGetRequest(OperationBeanBase opBean)
			throws JDOMException, Exception {
		URL url = new URL(opBean.getUrlString());
		URLConnection con = url.openConnection();
		con.connect();
		StringBuffer sendBack = new StringBuffer();		
		try {
			InputStream is = con.getInputStream();
			InputStreamReader isr = new InputStreamReader(is,"UTF-8");
			BufferedReader br = new BufferedReader(isr);
			String s = "";
			while ((s = br.readLine()) != null) {
				sendBack.append(s);
			}
		} catch (Exception e) {
			System.out.println(e.toString());
		}
		
		// System.out.println(sendBack);
		return sendBack.toString();
	}

}

網上還有一個版本是模擬ajax的異步請求。有異步需求的朋友可以參考那篇文章。

今天又找打基於HttpURLConnection的實現

參考地址：http://code.google.com/intl/zh-TW/appengine/docs/java/urlfetch/usingjavanet.html

import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.OutputStreamWriter;

// ...
        String message = URLEncoder.encode("my message", "UTF-8");

        try {
            URL url = new URL("http://www.example.com/comment");
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setDoOutput(true);
            connection.setRequestMethod("POST");

            OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream());
            writer.write("message=" + message);
            writer.close();
    
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                // OK
            } else {
                // Server returned HTTP error code.
            }
        } catch (MalformedURLException e) {
            // ...
        } catch (IOException e) {
            // ...
        }

好處是可以得到http狀態，進行判斷。

若要在外寄要求中設定 HTTP 標頭，調用 HttpURLConnection 的 setRequestProperty() 方法

 connection.setRequestProperty("X-MyApp-Version", "2.7.3");

根據預設，HttpURLConnection 將隨着 HTTP 重新導向。URL 拾取服務最多將進行 5 次重新導向。
若要停用下列重新導向，調用 HttpURLConnection 的 setFollowRedirects() 方法：

connection.setFollowRedirects(false);