如何使用jquery将json数组发布到java servlet

Question

我目前正在开发spring mvc应用程序，我需要发布JSON array 。

当我访问request.getParameter("paramValue")来获取param attibute时，它返回一个null值，

这是我的前端代码：

$.ajax(url, {
    async: true,
    type: 'post',
    contentType: 'application/json',
    data:  JSON.stringify({
        "test":"test value"
    })
}).done(function (response) {
    console.log(data);
}).fail(function (xhr) {
    console.log("request failed");
    console.log(xhr);
});

这是我的服务器端代码：

@RequestMapping(value = "/Products", method = RequestMethod.POST)
public void saveProducts(HttpServletRequest req, HttpServletResponse res) throws Exception {

    System.out.println(req.getContentType());
    System.out.println(req.getContentLength());
    System.out.println(req.getContextPath());
    System.out.println(req.getParameterValues("test"));
    System.out.println(req.getMethod());

    StringBuilder buffer = new StringBuilder();
    BufferedReader reader = req.getReader();
    String line;
    while ((line = reader.readLine()) != null) {
        buffer.append(line);
    }
    String data = buffer.toString();

    System.out.println(data);

    System.out.println(req.getParameter("test"));
}

输出是：

application/json
22

null
POST
{"test" : "Test DAta"}
null

我无法弄清楚发生了什么，请帮助我。

Answer 1

在你的ajax函数中删除这一行

contentType: 'application/json',

并替换此行

data:  JSON.stringify({
        "test":"test value"
    })

同

data: {
   "test":"test value"
}

而你也可以使用

req.getParameter("test")

代替

req.getParameterValues("test")

Answer 2

你可以使用这个：

var data ={id: 1, name :'test'}


       $.ajax(url, {
        async: true,
        type: 'post',
        contentType: 'application/json',
        data: data
    }).done(function (response) {
        console.log(data);
    }).fail(function (xhr) {
        console.log("request failed");
        console.log(xhr);
    });

并在服务器端创建一个pojo：

public class Product{
  private long id;
  private String name;
 // getters and setters

添加库杰克逊。

在您的控制器中添加此方法：

@RequestMapping(value = "/Products", method = RequestMethod.POST)
public RepsoneEntity<? >saveProducts(@requestBody Product pr){
     LOG.debug(pr.toString());
  return new reRepsoneEntity<Product>(pr,HttpStatus.ACCEPTED);
}

Answer 3

我最后修改了几个注释并更改了服务器端方法的返回类型，

@RequestMapping(value = "/Products", method = RequestMethod.POST, produces = "application/json;charset=UTF-8")

 public ResponseEntity<?> saveProducts(@RequestParam(value = "data") String brand) { return ResponseEntity.ok(brand); }</code> front end $.ajax(url, { async: true, type: "POST", data: {"data" : JSON.stringify({"Brand" : "Test Brand"})}   

public ResponseEntity<?> saveProducts(@RequestParam(value = "data") String brand) { return ResponseEntity.ok(brand); }</code> front end $.ajax(url, { async: true, type: "POST", data: {"data" : JSON.stringify({"Brand" : "Test Brand"})}

public ResponseEntity<?> saveProducts(@RequestParam(value = "data") String brand) { return ResponseEntity.ok(brand); }</code> front end $.ajax(url, { async: true, type: "POST", data: {"data" : JSON.stringify({"Brand" : "Test Brand"})}

public ResponseEntity<?> saveProducts(@RequestParam(value = "data") String brand) { return ResponseEntity.ok(brand); }</code> front end $.ajax(url, { async: true, type: "POST", data: {"data" : JSON.stringify({"Brand" : "Test Brand"})}

  }).done(function (response) { console.log(response); }).fail(function (xhr) { console.log("request failed"); console.log(xhr); }); 

我使用org.json来访问解析为文本的json对象，使用gson来处理POJO

现在它的工作原理:)