JavaScript中如何调用Java方法

<table id="carttable">
  <thead>
    <tr>
      <th class="product_remove">
        <label>
          <input class="check-all check" type="checkbox"/>  全选
        </label>
        <a class="fl delete" id="deleteall" href="javascript:;" rel="external nofollow" ><i class="fa fa-trash-o"></i></a>
      </th>
      <th class="product_thumb">图片</th>
      <th class="product_name">名称</th>
      <th class="product-price">价格</th>
       <th class="product_quantity">款式</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td class="product_remove">
        <input class="check-one check" type="checkbox"/>
      </td>
      <td class="product_thumb">
        <a href="shopshoesdetails.jsp?shoes_id=<%=shoes.getshoes_id() %>" rel="external nofollow" rel="external nofollow" >
          <img src="${pagecontext.request.contextpath}/shopservlet?method=getshopsshoesimage&shoes_id=<%=shoes.getshoes_id() %>" alt="">
        </a>
      </td>
      <td class="product_name">
        <a href="shopshoesdetails.jsp?shoes_id=<%=shoes.getshoes_id() %>" rel="external nofollow" rel="external nofollow" ><%=shoes.getbrand() %>/<%=shoes.getseries() %>/<%=shoes.getname() %>
        </a>
      </td>
      <td class="product-price"><%=shoes.getprice() %></td>
      <td class="product_quantity"><%=shoes.getsex() %>/<%=shoes.getsize() %></td>
    </tr>
  </tbody>
</table>

public void deletefromcart(string shoes_id) {
    system.out.println("shopshoesdao.deletefromcart");
    string[] shoes_ids = shoes_id.split(",");
    
    connection connection = dbutil.getconnection();
    preparedstatement preparedstatement = null;
    
    try {
      for (string string : shoes_ids) {
        int id = integer.parseint(string);
        string sql = "delete from user_product_cart where shoes_id = ?";
        preparedstatement = connection.preparestatement(sql);
        preparedstatement.setint(1, id);
        preparedstatement.executeupdate();
      }
    } catch (sqlexception e) {
      // todo auto-generated catch block
      e.printstacktrace();
    }finally {
      dbutil.close(preparedstatement);
      dbutil.close(connection);
    }
  }

protected void service(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
    // todo auto-generated method stub
    system.out.println("service");
    request.setcharacterencoding("utf-8");
    string method=request.getparameter("method");
    system.out.println(method);
    if(method.equals("addproduct")) {
      addproduct(request,response);
    }else if(method.equals("getshopsshoesimage")) {
      try {
        getshopsshoesimage(request,response);
      } catch (sqlexception e) {
        // todo auto-generated catch block
        e.printstacktrace();
      }
    }else if(method.equals("addtocart")) {
      try {
        addtocart(request, response);
      } catch (sqlexception e) {
        // todo auto-generated catch block
        e.printstacktrace();
      }
    }else if(method.equals("deletefromcart")) {
      try {
        deletefromcart(request, response);
      } catch (sqlexception e) {
        // todo auto-generated catch block
        e.printstacktrace();
      }
    }else if(method.equals("payfromcart")) {
      try {
        payfromcart(request, response);
      } catch (sqlexception e) {
        // todo auto-generated catch block
        e.printstacktrace();
      }
    }
  }
private void deletefromcart(httpservletrequest request, httpservletresponse response) throws ioexception, sqlexception {
    // todo auto-generated method stub
    system.out.println("deletefromcart");
    request.setcharacterencoding("utf-8");
    int user_id= integer.parseint(request.getparameter("user_id"));
    system.out.println(user_id);
    string shoes_id = request.getparameter("shoes_id");
    system.out.println(shoes_id);
    shopshoesdao shopshoesdao = new shopshoesdao();
    shopshoesdao.deletefromcart(shoes_id);
    request.getsession().setattribute("shoes_id", shoes_id);
    response.sendredirect(request.getcontextpath()+"/cart.jsp");
  }

// 点击全部删除
  deleteall.onclick = function () {
    if (selectedtotal.innerhtml != 0) {
      var con = confirm('确定删除所选商品吗？'); //弹出确认框
      if (con) {
        var shoes_id = '';
        for (var i = 0; i < tr.length; i++) {
          // 如果被选中，就删除相应的行
          if (tr[i].getelementsbytagname('input')[0].checked) {
            shoes_id = shoes_id + tr[i].cells[0].innerhtml + ',';
            
            //tr[i].parentnode.removechild(tr[i]); // 删除相应节点
            //i--; //回退下标位置
          }
        }
        alert(shoes_id);
        window.location.href="shopservlet?method=deletefromcart&shoes_id=" rel="external nofollow" +shoes_id+"&user_id="+22;
        alert("删除成功！");
      }
    } else {
      alert('请选择商品！');
    }
    gettotal(); //更新总数
  }