Java 發送 Http請求工具類

HttpClient.java

package util;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;

public class HttpClient {
    /**
     * 向指定 URL 發送POST方法的請求
     * 
     * @param url 發送請求的 URL
     * @param param 請求參數，請求參數應該是 name1=value1&name2=value2 的形式。
     * @return 所代表遠程資源的響應結果
     */
    public static String sendPost(String url, String param) {
        PrintWriter out = null;
        BufferedReader in = null;
        StringBuffer result = new StringBuffer();
        try {
            URL realUrl = new URL(url);

            // 打開和URL之間的連接
            URLConnection conn = realUrl.openConnection();

            // 設置通用的請求屬性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");

            // 發送POST請求必須設置如下兩行
            conn.setDoOutput(true);
            conn.setDoInput(true);

            // 獲取URLConnection對象對應的輸出流
            out = new PrintWriter(conn.getOutputStream());

            // 發送請求參數
            out.print(param);

            // flush輸出流的緩沖
            out.flush();

            // 定義BufferedReader輸入流來讀取URL的響應
            in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            String line = null;
            while ((line = in.readLine()) != null) {
                result.append(line);
            }
        } catch (Exception e) {
            System.out.println("發送 POST 請求出現異常！" + e);
            e.printStackTrace();
        }
        // 使用finally塊來關閉輸出流、輸入流
        finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result.toString();
    }
}