在JavaScript中想要调用Java的方法，我通过JavaScript访问servlet，再通过servlet调用Java某个类的方法。

HTML代码

<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>

ShopShoesDao.java

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);
    }
  }

ShopServlet.java

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");
  }

javascrip代码

// 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
  }