java 测试post请求 在body里面传递参数怎么设置，怎么接收。报错

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public String post(String strURL,String params) {

    System.out.println(strURL); System.out.println(params); try { URL url = new URL(strURL);// 创建连接 HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setDoOutput(true); connection.setDoInput(true); connection.setUseCaches(false); connection.setInstanceFollowRedirects(true); connection.setRequestMethod("POST");// 设置请求方式   connection.setRequestProperty("Accept","application/json");// 设置接收数据的格式   connection.setRequestProperty("Content-Type","application/json");// 设置发送数据的格式   connection.connect(); OutputStreamWriter out = new OutputStreamWriter( connection.getOutputStream(),"UTF-8");// utf-8编码   out.append(params); out.flush(); out.close(); // 读取响应   int length = (int) connection.getContentLength();// 获取长度   InputStream is = connection.getInputStream(); if (length != -1){ byte[] data = new byte[length]; byte[] temp = new byte[512]; int readLen = 0; int destPos = 0; while ((readLen = is.read(temp)) > 0){ System.arraycopy(temp, 0, data, destPos, readLen); destPos += readLen; } String result = new String(data, "UTF-8"); System.out.println(result); return result; } } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } return "error";

}

@RequestMapping(value="/text", method = RequestMethod.POST)
@ResponseBody
public String text(HttpServletRequest request,HttpServletResponse response,@RequestBody   String t){
    System.out.println(t);
    
    
    return "DetailedRules";
}