向指定URL发送POST，GET请求

/**
* 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(),"UTF-8"));
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();
return result;
}
//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;
}

/**
* post方法 参数为json对象
* @param url
* @param jsonParam 封装为json对象的参数；
* @return
*/
public static String sendPost(String url,JSONObject jsonParam) {

try{
//创建连接
URL realUrl = new URL(url);
HttpURLConnection connection = (HttpURLConnection) realUrl.openConnection();
connection.setDoOutput(true);
connection.setDoInput(true);
connection.setRequestMethod("POST");
connection.setUseCaches(false);
connection.setInstanceFollowRedirects(true);

//connection.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
connection.setRequestProperty("Content-Type","application/json; charset=UTF-8");

connection.connect();

//               POST请求
DataOutputStream out = new DataOutputStream(connection.getOutputStream());
//out.writeBytes(obj.toString());//这个中文会乱码
out.write(jsonParam.toString().getBytes("UTF-8"));//这样可以处理中文乱码问题
out.flush();
out.close();
//读取响应
BufferedReader reader = new BufferedReader(new InputStreamReader(
connection.getInputStream()));
String lines;
StringBuffer sb = new StringBuffer("");
while ((lines = reader.readLine()) != null) {
lines = new String(lines.getBytes(), "utf-8");
sb.append(lines);
}
System.out.println(sb);
reader.close();
// 断开连接
connection.disconnect();
return sb.toString();
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return HttpUtils.Error_perfix+"url解析异常！";
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return HttpUtils.Error_perfix+"不支持的编码格式！";
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return HttpUtils.Error_perfix+"服务端异常！";
}
}