创建一个BaseServlet来利用反射自动根据前台传来的method自动分发方法

创建模板Serclet,让实例都继承这个模板,来实现自动解析"method",并且再利用反射来调用方法.从而实现自动分发方法.

@WebServlet("/BaseServlet")
public class BaseServlet extends HttpServlet
{
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");//解决tomcat的post请求中文乱码问题
        resp.setContentType("text/html;charset=utf-8");//解决响应乱码问题

        //获取方法名
        String methodName = req.getParameter("method");

        //使用"反射"解决重复判断的问题

        try
        {
            Class clazz = this.getClass();
            Method method = clazz.getDeclaredMethod(methodName, HttpServletRequest.class, HttpServletResponse.class);
            method.setAccessible(true);
            method.invoke(this, req,resp);
        }
        catch (NoSuchMethodException e)
        {
            e.printStackTrace();
        }
        catch (IllegalAccessException e)
        {
            e.printStackTrace();
        }
        catch (InvocationTargetException e)
        {
            e.printStackTrace();
        }

    }
}

子类继承BaseServlet.

@WebServlet("/UserServlet")
public class UserServlet extends BaseServlet
{
    //用BeanFactory来反射创造service对象
    UserServiceImpl userservice = BeanFactory.createBean("userservice", UserServiceImpl.class);

    private void login(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    {
        //告诉Tomcat用utf-8来解码
        req.setCharacterEncoding("utf-8");
        //告诉Tomcat对于text/html 用utf-8来编码，并且告诉浏览器用utf-8来解码。
        resp.setContentType("text/html; charset = utf-8");


        //登录方法
        String username = req.getParameter("username");
        String password = req.getParameter("password");

        User user = userservice.login(username, password);

        //将user放入session域中.做到只登陆一次的功能.
        req.getSession().setAttribute("user",user);

        //将user变为json串,返回到登录页面中

        ObjectMapper objectMapper = new ObjectMapper();
        String json = objectMapper.writeValueAsString(user);
        resp.getWriter().write(json);

    }

}

子类继承BaseServlet

@WebServlet("/StudentServlet")
public class StudentServlet extends BaseServlet
{
    //创建studentService实现类
    StudentServiceImpl studentservice = BeanFactory.createBean("studentservice", StudentServiceImpl.class);

    //分页查询
    protected void selectByPage(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    {
        //告诉Tomcat用utf-8来解码
        req.setCharacterEncoding("utf-8");
        //告诉Tomcat对于text/html 用utf-8来编码，并且告诉浏览器用utf-8来解码。
        resp.setContentType("text/html; charset = utf-8");


        //获取当前页和总页数
        String currPage = req.getParameter("currPage");
        String pageSize = req.getParameter("pageSize");
        //调用service层的方法
        PageInfo<Student> studentList = studentservice.selectByPage(currPage, pageSize);

        //将返回值包装成json串 并且返回
        ObjectMapper objectMapper = new ObjectMapper();
        String json = objectMapper.writeValueAsString(studentList);

        resp.getWriter().write(json);
    }

    //添加学生
    protected void addStudent(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    {

        //获取学生信息
        Map<String, String[]> map = req.getParameterMap();
        Student addstudent = new Student();
        //封装之前注册日期转换
        ConvertUtils.register(new Converter()
        {
            public Object convert(Class type, Object value)
            {
                SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
                try
                {
                    return simpleDateFormat.parse(value.toString());
                }
                catch (ParseException e)
                {
                    e.printStackTrace();
                }
                return null;
            }
        }, Date.class);

        try
        {
            BeanUtils.populate(addstudent, map);
        }
        catch (IllegalAccessException e)
        {
            e.printStackTrace();
        }
        catch (InvocationTargetException e)
        {
            e.printStackTrace();
        }

        ObjectMapper objectMapper = new ObjectMapper();
        String json = objectMapper.writeValueAsString(studentservice.addStudent(addstudent));
        resp.getWriter().write(json);

    }

    //修改学生
    protected void updateStudent(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    {
        //获取学生信息
        Map<String, String[]> map = req.getParameterMap();
        Student updatestudent = new Student();
        //封装之前注册日期转换
        ConvertUtils.register(new Converter()
        {
            public Object convert(Class type, Object value)
            {
                SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
                try
                {
                    return simpleDateFormat.parse(value.toString());
                }
                catch (ParseException e)
                {
                    e.printStackTrace();
                }
                return null;
            }
        }, Date.class);

        try
        {
            BeanUtils.populate(updatestudent, map);
        }
        catch (IllegalAccessException e)
        {
            e.printStackTrace();
        }
        catch (InvocationTargetException e)
        {
            e.printStackTrace();
        }

        ObjectMapper objectMapper = new ObjectMapper();
        Integer res = studentservice.updateStudent(updatestudent);
        String json = objectMapper.writeValueAsString(res);
        resp.getWriter().write(json);
    }

    //删除学生的功能
    protected void deleteStudent(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    {
        //获取要删除学生的id
        String number = req.getParameter("number");

        Integer res = studentservice.deleteStudent(number);

        ObjectMapper objectMapper = new ObjectMapper();
        String json = objectMapper.writeValueAsString(res);
        resp.getWriter().write(json);
    }
}

标签：BaseServlet,utf,String,resp,req,json,自动,new,method
来源： https://blog.csdn.net/qq_46190347/article/details/110940389