写一段完整的JQuery和Java程序，实现：在JQuery函数func1中将一段程序绑定到（使用bind函数）按钮（id是bt）上，点击按钮将文本框（id是tx）中的字符串用ajax（使用JSON格式）提交到后台Java函数func2，字符串反向后返回给前台的JQuery函数func3并弹出。

henry0 2019-05-19 原文

一、使用servlet实现

index.jsp:

<script type="text/javascript" src="js/jquery-1.9.1.js"></script>
  <script type="text/javascript">
        $(function(){
            $("#bt").bind("click",fun1);
        })
           function fun1(){     
              str = $("#tx").val();
              $.post("fun2",{str1:str},function(data){
                  alert(data);
              },"json");
          }
  </script>
  </head>
  <body>
    <input type="text" id="tx">
    <input type="button" id="bt" value="按钮">
  </body>

servlet:

@WebServlet("/fun2")
public class UserServlet extends HttpServlet {
    
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        String str = req.getParameter("str1");
        //System.out.println(str);
        String overString = overString(str);
        //System.out.println(overString);
        Gson gao = new Gson();
        String json = gao.toJson(overString);
        resp.getWriter().write(json);
    }
    
    /**
     * 字符串反转
     */
    public String overString(String str){
        if(str==null||str.length()<=0){
            return null;
        }
        StringBuilder strb = new StringBuilder("");
        char[] ch = str.toCharArray();
        for (int i = ch.length-1; i >=0; i--) {
            strb.append(ch[i]);    
        }
        return strb.toString();
    }

二、基于注解（SpringBoot）实现

index.jsp

<script type="text/javascript" src="https://code.jquery.com/jquery-1.9.1.min.js"></script>
<script type="text/javascript">
    function fun1(){     
        str = $("#tx").val();
        $.post("fun2",{str:str},function(data){
            alert(data.msg);
        },"json");
    }
     
    $(function(){
        $("#bt").bind("click",fun1);
    })
</script>
</head>
<body>
     <input type="text" id="tx">
    <input type="button" id="bt" value="按钮">
</body>

controller

@Controller
public class FuncController {
    @RequestMapping("/fun2")
    @ResponseBody
    public Map<String, String> getString(String str){
        String overString = this.overString(str);
        Map<String, String> map = new HashMap<>();
        map.put("msg", overString);
        System.out.println(overString);
        return map;
    }
    
    /**
     * 字符串反转
     */
    public String overString(String str){
        if(str==null||str.length()<=0){
            return null;
        }
        StringBuilder strb = new StringBuilder("");
        char[] ch = str.toCharArray();
        for (int i = ch.length-1; i >=0; i--) {
            strb.append(ch[i]);    
        }
        return strb.toString();
    }