PHP使用cUrl将数组发布到javaservlet

我正试图将以下示例数组从php发布到javaservlet：

$tags = $tagger->tag($nlquery);
$js_string = json_encode($tags);    
echo $js_string

结果：

{"Example","NN"},{"1","NN"}

cUrl代码：

        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, "http://localhost:8080/first/SPARQL");
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");                                                                     
        curl_setopt($ch, CURLOPT_POSTFIELDS, $js_string);                                                                  
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);                                                                      
        curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json', 'Content-Length: ' . strlen($js_string)));
        curl_setopt($ch, CURLOPT_VERBOSE, 1);
        $response = curl_exec($ch);
        curl_close($ch);
        echo $response;

javaservlet代码：

protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
        // TODO Auto-generated method stub
        res.setContentType("text/html");
        res.addHeader("Access-Control-Allow-Origin", "*");
        PrintWriter out = res.getWriter();
        String jsonData[];
        jsonData= req.getParameterValues("js_string");
        for(int i = 0; i < jsonData.length; i++)
        {
        System.out.println(jsonData[i]);
        }

然而，这会在java端的jsonData.length行产生一个NullPointerException。我是不是从php端传递了$js_string错误？或者他们的java端代码有问题吗？

更新：
使用以下代码：

BufferedReader br = new BufferedReader(new InputStreamReader (req.getInputStream()));
        String str = br.readLine();
        String[] jsondata = new String[]{str}; 
        int i;
        for(i=0; i < jsondata.length;i++){
            System.out.println(jsondata[i]);
        }

返回正确的结果{"Example","NN"},{"1","NN"}，但是，现在我不能循环它，因为它不认为它是一个多维数组。这是我在使用servlet（静态，用于开发目的）之前使用的代码

String[][] phpsearch ={{"Example","NN"},{"1","NN"}};
for(int i=0; i<phpsearch.length; i++) {
                System.out.println("loop "+i);
                if(phpsearch[i][1]=="NN"){
                    result=searchLabel(phpsearch[i][0].toLowerCase());
                    System.out.println("array "+phpsearch[i][0] );
}
}

也许没有那么有效，但至少它有效：

BufferedReader br = new BufferedReader(new InputStreamReader (req.getInputStream()));
        String str = br.readLine();
        str = str.replace(",", "|");
        str = str.replace("}|{", ",");
        str = str.replace("}", "");
        str = str.replace("{", "");
        String[] rows = str.split(",");
        System.out.println("rows");
        for(int i=0; i<rows.length; i++) {
            System.out.println("loop "+i);
            System.out.println(rows[i]);
            //System.out.println(jsondata[i][1]);
        }
        String[][] jsondata = new String[rows.length][]; 
        int r = 0;
        for (String row : rows) {
            jsondata[r++] = row.split("''|");
        }
        System.out.println("jsondata");
        for(int i=0; i<jsondata.length; i++) {
            System.out.println("loop "+i);
            System.out.println(jsondata[i][0]);
            System.out.println(jsondata[i][1]);
            //System.out.println(jsondata[i][1]);
        }

结果是一个二维数组，就像上面的静态示例一样。