Convert PHP code to java code

<?php 

function bter_query($path, array $req = array()) { 
// API settings, add your Key and Secret at here 
$key = &#39;&#39;; 
$secret = &#39;&#39;; 

// generate a nonce to avoid problems with 32bits systems 
$mt = explode(&#39; &#39;, microtime()); 
$req[&#39;nonce&#39;] = $mt[1].substr($mt[0], 2, 6); 

// generate the POST data string 
$post_data = http_build_query($req, &#39;&#39;, &#39;&&#39;); 
$sign = hash_hmac(&#39;sha512&#39;, $post_data, $secret); 

// generate the extra headers 
$headers = array( 
&#39;KEY: &#39;.$key, 
&#39;SIGN: &#39;.$sign, 
); 

//!!! please set Content-Type to application/x-www-form-urlencoded if it&#39;s not the default value 

// curl handle (initialize if required) 
static $ch = null; 
if (is_null($ch)) { 
$ch = curl_init(); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
curl_setopt($ch, CURLOPT_USERAGENT, 
&#39;Mozilla/4.0 (compatible; Bter PHP bot; &#39;.php_uname(&#39;a&#39;).&#39;; PHP/&#39;.phpversion().&#39;)&#39; 
); 
} 
curl_setopt($ch, CURLOPT_URL, &#39;https://bter.com/api/&#39;.$path); 
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data); 
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers); 
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE); 

// run the query 
$res = curl_exec($ch); 

if ($res === false) throw new Exception(&#39;Curl error: &#39;.curl_error($ch)); 
//echo $res; 
$dec = json_decode($res, true); 
if (!$dec) throw new Exception(&#39;Invalid data: &#39;.$res); 
return $dec; 
} 

function get_top_rate($pair, $type=&#39;BUY&#39;) { 
$rate = 0; 

// our curl handle (initialize if required) 
static $ch = null; 
if (is_null($ch)) { 
$ch = curl_init(); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
curl_setopt($ch, CURLOPT_USERAGENT, 
&#39;Mozilla/4.0 (compatible; Bter PHP bot; &#39;.php_uname(&#39;a&#39;).&#39;; PHP/&#39;.phpversion().&#39;)&#39; 
); 
} 
curl_setopt($ch, CURLOPT_URL, &#39;https://bter.com/api/1/depth/&#39;.$pair); 
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE); 

// run the query 
$res = curl_exec($ch); 
if ($res === false) throw new Exception(&#39;Could not get reply: &#39;.curl_error($ch)); 
//echo $res; 
$dec = json_decode($res, true); 
if (!$dec) throw new Exception(&#39;Invalid data: &#39;.$res); 

if (strtoupper($type) == &#39;BUY&#39;) { 
$r =  $dec[&#39;bids&#39;][0]; 
$rate = $r[0]; 
} else  { 
$r = end($dec[&#39;asks&#39;]); 
$rate = $r[0]; 
} 

return $rate; 
} 


try { 
// example 1: get funds 
var_dump(bter_query(&#39;1/private/getfunds&#39;)); 

// example 2: place a buy order 
$pair = &#39;ltc_btc&#39;; 
$type = &#39;buy&#39;; 
$rate = get_top_rate($pair, $type) * 1.01; 
var_dump(bter_query(&#39;1/private/placeorder&#39;, 
array( 
&#39;pair&#39; => "$pair", 
&#39;type&#39; => "$type", 
&#39;rate&#39; => "$rate", 
&#39;amount&#39; => &#39;0.01&#39;, 
) 
  ) 
); 

// example 3: cancel an order 
var_dump(bter_query(&#39;1/private/cancelorder&#39;, array(&#39;order_id&#39; => 125811))); 

// example 4: get order status 
var_dump(bter_query(&#39;1/private/getorder&#39;, array(&#39;order_id&#39; => 15088))); 

//example 5: list all open orders 
var_dump(bter_query(&#39;1/private/orderlist&#39;)); 

} catch (Exception $e) { 
echo "Error:".$e->getMessage(); 

} 
?>