HttpUtil

1、发送doPost请求，在web那边使用request.setCharacterEncoding("UTF-8");保证中文不乱码，不需要第三方jar包

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)");
    conn.setRequestProperty("charset", "utf-8");
    // 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(new OutputStreamWriter(conn.getOutputStream(), "utf-8"));
    // 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;
}

 2、拼装URL参数信息

public static String buildQueryStr(Map<String, Object> params) {
    if (CheckNull.isNull(params)) {
        return "";
    }
    StringBuffer sb = new StringBuffer();
    for (String k : params.keySet()) {
        sb.append(k);
        sb.append("=");
        sb.append(params.get(k).toString());
        sb.append("&");
    }
    return sb.toString().substring(0, sb.length() - 1);
}