Android网络编程之一个Android下菜单系统模块的实现(服务器端—更新菜单)

更新菜单与更新桌号步骤完全一样，需要注意的是菜单名称含有中文，所以在servlet中将信息以xml形式发出时，应注意将其编码设定为gbk，如下：

<?xml version='1.0' encoding='gbk'?>

新建Menu数据实体类：

public class Menu {
    private int id;
    private int price;
    private int typeId;
    private String name;
    private String pic;
    private String remark;
    
    getters & setters .. 
}

在UpdateDao与UpdateDaoImpl中添加新方法getMenuList()获取菜单列表：

public interface UpdateDao {
    // 获得餐桌列表
    public List<Table> getTableList();
    // 获得菜单列表
    public List<Menu> getMenuList();
}

    @Override
    public List<Menu> getMenuList() {
        // jdbc连接数据库准备工作
        DBUtil util = new DBUtil();
        Connection conn = util.openConnection();
        
        // 读出所有菜品信息准备工作
        String sql = "select id, price, typeId, name, pic, remark from menutbl ";
        Statement statement = null;
        ResultSet rs = null;
        
        try {
            statement = conn.createStatement();
            rs = statement.executeQuery(sql);
            // 新建list容纳所有桌号实体类对象
            List<Menu> menulist = new ArrayList<Menu>(); 
            while (rs.next()) {
                Menu menu = new Menu();
                menu.setId(rs.getInt(1));
                menu.setPrice(rs.getInt(2));
                menu.setTypeId(rs.getInt(3));
                menu.setName(rs.getString(4));
                menu.setPic(rs.getString(5));
                menu.setRemark(rs.getString(6));
                menulist.add(menu);
            }
            // 别忘了返回list
            return menulist;
            
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (rs != null) {
                    rs.close();
                    rs = null;
                }
                if (statement != null) {
                    statement.close();
                    statement = null;
                }
                if (conn != null) {
                    conn.close();
                    conn = null;
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

然后是专门为更新菜单服务的UpdateMenuServlet：

public class UpdateMenuServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        resp.setContentType("text/html");
        PrintWriter pw = new PrintWriter(resp.getOutputStream());
        
        // 获取所有菜单信息列表
        UpdateDao updateDao = new UpdateDaoImpl();
        List<Menu> menuList = updateDao.getMenuList();
        
        // 将所有信息以xml格式输出, 此处设定编码为gbk, 否则中文乱码
        pw.println("<?xml version='1.0' encoding='gbk'?>");
        pw.println("<menulist>");
                
        for (int i = 0; i < menuList.size(); i++) {
            Menu menu = menuList.get(i);
            pw.println("<menu>");
            
                pw.print("<id>");
                    pw.print(menu.getId());
                pw.print("</id>");
                
                pw.print("<price>");
                    pw.print(menu.getPrice());
                pw.print("</price>");
                
                pw.print("<typeId>");
                    pw.print(menu.getTypeId());
                pw.print("</typeId>");
                
                pw.print("<name>");
                    pw.print(menu.getName());
                pw.print("</name>");
                
                pw.print("<pic>");
                    pw.print(menu.getPic());
                pw.print("</pic>");
                
                pw.print("<remark>");
                    pw.print(menu.getRemark());
                pw.print("</remark>");
            
            pw.println("</menu>");
        }
        
        pw.println("</menulist>");
        pw.flush();
        pw.close();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        doGet(req, resp);
    }

}

注册servlet：

<servlet>
    <servlet-name>UpdateMenuServlet</servlet-name>
    <servlet-class>com.moka.servlet.UpdateMenuServlet</servlet-class>
</servlet>
     
<servlet-mapping>
    <servlet-name>UpdateMenuServlet</servlet-name>
    <url-pattern>/servlet/UpdateMenuServlet</url-pattern>
</servlet-mapping>