向指定 URL 发送POST方法的请求(状态码200和其他有区别)

public static String sendPost(String url, String param) {
OutputStreamWriter out = null;
BufferedReader in = null;
String result = "";
try {
URL realUrl = new URL(url);
// 打开和URL之间的连接
HttpURLConnection  conn = (HttpURLConnection) 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());
out = new OutputStreamWriter(conn.getOutputStream(), "utf-8"); // 8859_1
out.write(param); // post的关键所在
// 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
int code = conn.getResponseCode(); 
if(code == 200) {
in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
}else{
in = new BufferedReader(new InputStreamReader(conn.getErrorStream()));
}
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;
}