java day50【综合案例day02】

发布时间：2020-12-15 05:28:16 所属栏目：Java 来源：网络整理

导读：由 java day49【综合案例day01】步骤： 9. 优化Servlet 9.1 ?目的减少Servlet的数量，现在是一个功能一个Servlet，将其优化为一个模块一个Servlet，相当于在数据库中一张表对应一个Servlet，在Servlet中提供不同的方法，完成用户的请求。 Idea控制台中文乱

由 java day49【综合案例day01】步骤：

9. 优化Servlet

9.1 ?目的

减少Servlet的数量，现在是一个功能一个Servlet，将其优化为一个模块一个Servlet，

相当于在数据库中一张表对应一个Servlet，在Servlet中提供不同的方法，完成用户的请求。

Idea控制台中文乱码解决：-Dfile.encoding=gb2312

9.2 BaseServlet编写：

public class BaseServlet extends HttpServlet {



??? @Override

??? protected void service(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException {

??????? //System.out.println("baseServlet的service方法被执行了...");


??????? //完成方法分发

??????? //1.获取请求路径

??????? String uri = req.getRequestURI(); //?? /travel/user/add

??????? System.out.println("请求uri:"+uri);//? /travel/user/add

??????? //2.获取方法名称

??????? String methodName = uri.substring(uri.lastIndexOf(‘/‘) + 1);

??????? System.out.println("方法名称："+methodName);

??????? //3.获取方法对象Method

??????? //谁调用我？我代表谁

??????? System.out.println(this);//UserServlet的对象[email?protected]

??????? try {

???????? ???//获取方法

??????????? Method method = this.getClass().getMethod(methodName,HttpServletRequest.class,HttpServletResponse.class);

??????????? //4.执行方法

??????????? //暴力反射

??????????? //method.setAccessible(true);

??????????? method.invoke(this,req,resp);

? ??????} catch (NoSuchMethodException e) {

??????????? e.printStackTrace();

??????? } catch (IllegalAccessException e) {

??????????? e.printStackTrace();

??????? } catch (InvocationTargetException e) {

??????????? e.printStackTrace();

??????? }

??? }

}

9.3 UserServlet改写

将之前的Servlet实现的功能，抽取到UserServlet中的不同方法中实现，并且将UserService创建抽取到成员变量位置

@WebServlet("/user/*") // /user/add /user/find
public class UserServlet extends BaseServlet {

??? //声明UserService业务对象
??? private UserService service = new UserServiceImpl();

??? /**
???? * 注册功能
???? * @param request
???? * @param response
???? * @throws ServletException
???? * @throws IOException
???? */
??? public void regist(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {

??????? //验证校验
??????? String check = request.getParameter("check");
??????? //从sesion中获取验证码
??????? HttpSession session = request.getSession();
????? ??String checkcode_server = (String) session.getAttribute("CHECKCODE_SERVER");
??????? session.removeAttribute("CHECKCODE_SERVER");//为了保证验证码只能使用一次
??????? //比较
??????? if(checkcode_server == null || !checkcode_server.equalsIgnoreCase(check)){
??????????? //验证码错误
??????????? ResultInfo info = new ResultInfo();
??????????? //注册失败
??????????? info.setFlag(false);
??????????? info.setErrorMsg("验证码错误");
??????????? //将info对象序列化为json
??????????? ObjectMapper mapper = new ObjectMapper();
??????????? String json = mapper.writeValueAsString(info);
??????????? response.setContentType("application/json;charset=utf-8");
??????????? response.getWriter().write(json);

???? return;

??????? }


??????? //1.获取数据

??????? Map<String,String[]> map = request.getParameterMap();


??????? //2.封装对象

??????? User user = new User();

??????? try {

??????????? BeanUtils.populate(user,map);

??????? } catch (IllegalAccessException e) {

??????????? e.printStackTrace();

??????? } catch (InvocationTargetException e) {

??????????? e.printStackTrace();

??????? }


??????? //3.调用service完成注册

??????? //UserService service = new UserServiceImpl();

??????? boolean flag = service.regist(user);

??????? ResultInfo info = new ResultInfo();

??????? //4.响应结果

??????? if(flag){

??????????? //注册成功

??????????? info.setFlag(true);

??????? }else{

??????????? //注册失败

??????????? info.setFlag(false);

??????????? info.setErrorMsg("注册失败!");

??????? }


??????? //将info对象序列化为json

??????? ObjectMapper mapper = new ObjectMapper();

??????? String json = mapper.writeValueAsString(info);


??????? //将json数据写回客户端

??????? //设置content-type

??????? response.setContentType("application/json;charset=utf-8");

??????? response.getWriter().write(json);


??? }


??? /**

???? * 登录功能

???? * @param request
 ???? * @param response
 ???? * @throws ServletException

???? * @throws IOException

???? */

??? public void login(HttpServletRequest request,IOException {

??????? //1.获取用户名和密码数据

??????? Map<String,String[]> map = request.getParameterMap();

??????? //2.封装User对象

??????? User user = new User();

??????? try {

??????????? BeanUtils.populate(user,map);

??????? } catch (IllegalAccessException e) {

??????????? e.printStackTrace();

??????? } catch (InvocationTargetException e) {

??????????? e.printStackTrace();

??????? }


??????? //3.调用Service查询

?????? // UserService service = new UserServiceImpl();

??????? User u? = service.login(user);


??????? ResultInfo info = new ResultInfo();


??????? //4.判断用户对象是否为null

??????? if(u == null){

??????????? //用户名密码或错误

??????????? info.setFlag(false);

??????????? info.setErrorMsg("用户名密码或错误");

??????? }

??????? //5.判断用户是否激活

??????? if(u != null && !"Y".equals(u.getStatus())){

??????????? //用户尚未激活

??????????? info.setFlag(false);

??????????? info.setErrorMsg("您尚未激活，请激活");

??????? }

??????? //6.判断登录成功

??????? if(u != null && "Y".equals(u.getStatus())){

??????????? request.getSession().setAttribute("user",u);//登录成功标记


??????????? //登录成功

??????????? info.setFlag(true);

??????? }


??????? //响应数据

??????? ObjectMapper mapper = new ObjectMapper();


??????? response.setContentType("application/json;charset=utf-8");

??????? mapper.writeValue(response.getOutputStream(),info);

??? }


??? /**

???? * 查询单个对象

???? * @param request
 ???? * @param response
 ???? * @throws ServletException

???? * @throws IOException

???? */

??? public void findOne(HttpServletRequest request,IOException {

??????? //从session中获取登录用户

??????? Object user = request.getSession().getAttribute("user");

??????? //将user写回客户端


??????? ObjectMapper mapper = new ObjectMapper();

??????? response.setContentType("application/json;charset=utf-8");

??????? mapper.writeValue(response.getOutputStream(),user);

??? }


??? /**

???? * 退出功能

???? * @param request
 ???? * @param response
 ???? * @throws ServletException

???? * @throws IOException

???? */

??? public void exit(HttpServletRequest request,IOException {

??????? //1.销毁session

??????? request.getSession().invalidate();


??????? //2.跳转登录页面

??????? response.sendRedirect(request.getContextPath()+"/login.html");

??? }


??? /**

???? * 激活功能

???? * @param request
 ???? * @param response
 ???? * @throws ServletException

???? * @throws IOException

???? */

??? public void active(HttpServletRequest request,IOException {

??????? //1.获取激活码

??????? String code = request.getParameter("code");

??????? if(code != null){

??????????? //2.调用service完成激活

??????????? //UserService service = new UserServiceImpl();

???? ???????boolean flag = service.active(code);


??????????? //3.判断标记

??????????? String msg = null;

??????????? if(flag){

??????????????? //激活成功

??????????????? msg = "激活成功，请<a href=‘login.html‘>登录</a>";

??????????? }else{

??????????????? //激活失败

??????????????? msg = "激活失败，请联系管理员!";

??????????? }

??????????? response.setContentType("text/html;charset=utf-8");

??????????? response.getWriter().write(msg);

??????? }

??? }

}

9.4 ?页面路径改写

header.html

UserServiceImpl发送邮件

10. 分类数据展示

10.1 效果：

10.2 分析：

10.3 ?代码实现：

10.3.1? 后台代码

CategoryServlet

@WebServlet("/category/*")
public class CategoryServlet extends BaseServlet {


??? private CategoryService service = new CategoryServiceImpl();


??? /**

???? * 查询所有

???? * @param request
 ???? * @param response
 ???? * @throws ServletException

???? * @throws IOException

???? */

??? public void findAll(HttpServletRequest request,IOException {

??????? //1.调用service查询所有

??? ????List<Category> cs = service.findAll();

??????? //2.序列化json返回

?????? /* ObjectMapper mapper = new ObjectMapper();

??????? response.setContentType("application/json;charset=utf-8");

??????? mapper.writeValue(response.getOutputStream(),cs);*/

?????? writeValue(cs,response);


??? }


}

CategoryService

public class CategoryServiceImpl implements CategoryService {


??? private CategoryDao categoryDao = new CategoryDaoImpl();


??? @Override

??? public List<Category> findAll() {

??????? return categoryDao.findAll();

??? }

}

CategoryDao

public class CategoryDaoImpl implements CategoryDao {


??? private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());


??? @Override

??? public List<Category> findAll() {

??????? String sql = "select * from tab_category ";

??????? return template.query(sql,new BeanPropertyRowMapper<Category>(Category.class));

??? }

}

在BaseServlet中封装了序列化json的方法

/**

?* 直接将传入的对象序列化为json，并且写回客户端

?* @param obj
 ?*/
public void writeValue(Object obj,HttpServletResponse response) throws IOException {

??? ObjectMapper mapper = new ObjectMapper();

??? response.setContentType("application/json;charset=utf-8");

??? mapper.writeValue(response.getOutputStream(),obj);

}


/**

?* 将传入的对象序列化为json，返回

?* @param obj
 ?* @return

?*/
public String writeValueAsString(Object obj) throws JsonProcessingException {

??? ObjectMapper mapper = new ObjectMapper();

??? return mapper.writeValueAsString(obj);

}

10.3.2 ?前台代码

hader.html加载后，发送ajax请求，请求category/findAll

//查询分类数据

?$.get("category/findAll",{},function (data) {

???? //[{cid:1,cname:国内游},{}]

???? var lis = ‘<li class="nav-active"><a href="index.html">首页</a></li>‘;

???? //遍历数组,拼接字符串(<li>)

???? for (var i = 0; i < data.length; i++) {

???????? var li = ‘<li><a href="route_list.html">‘+data[i].cname+‘</a></li>‘;


???????? lis += li;

? ???????

???? }

???? //拼接收藏排行榜的li,<li><a href="favoriterank.html">收藏排行榜</a></li>

???? 

???? lis+= ‘<li><a href="favoriterank.html">收藏排行榜</a></li>‘;


???? //将lis字符串，设置到ul的html内容中

???? $("#category").html(lis);

?});

10.4 ?对分类数据进行缓存优化

分析发现，分类的数据在每一次页面加载后都会重新请求数据库来加载，对数据库的压力比较大，

而且分类的数据不会经常产生变化，所有可以使用redis来缓存这个数据。

分析：

10.5 优化代码实现

期望数据中存储的顺序就是将来展示的顺序，使用redis的sortedset

@Override
public List<Category> findAll() {

??? //1.从redis中查询

??? //1.1获取jedis客户端

??? Jedis jedis = JedisUtil.getJedis();

??? //1.2可使用sortedset排序查询

??? Set<String> categorys = jedis.zrange("category",-1);

??? List<Category> cs = null;

??? //2.判断查询的集合是否为空

??? if (categorys == null || categorys.size() == 0) {


??????? System.out.println("从数据库查询....");

??????? //3.如果为空,需要从数据库查询,在将数据存入redis

??????? //3.1 从数据库查询

??????? cs = categoryDao.findAll();

??????? //3.2 将集合数据存储到redis中的 category的key

??????? for (int i = 0; i < cs.size(); i++) {


??????????? jedis.zadd("category",cs.get(i).getCid(),cs.get(i).getCname());

??????? }

??? } else {

??????? System.out.println("从redis中查询.....");


??????? //4.如果不为空,将set的数据存入list

??????? cs = new ArrayList<Category>();

??????? for (String name : categorys) {

??????????? Category category = new Category();

??????????? category.setCname(name);

??????????? cs.add(category);


??????? }

??? }



??? return cs;

}

11. 旅游线路的分页展示

点击了不同的分类后，将来看到的旅游线路不一样的。

通过分析数据库表结构，发现，旅游线路表和分类表时一个多对一的关系

查询不同分类的旅游线路sql

Select * from tab_route where cid = ?;

11.1??? 类别id的传递

Redis中查询score（cid）

public class CategoryServiceImpl implements CategoryService {


??? private CategoryDao categoryDao = new CategoryDaoImpl();


??? @Override

??? public List<Category> findAll() {

??????? //1.从redis中查询

??????? //1.1获取jedis客户端

??????? Jedis jedis = JedisUtil.getJedis();

??????? //1.2可使用sortedset排序查询

??????? //Set<String> categorys = jedis.zrange("category",-1);

??????? //1.3查询sortedset中的分数(cid)和值(cname)

??????? Set<Tuple> categorys = jedis.zrangeWithScores("category",-1);


??????? List<Category> cs = null;

??????? //2.判断查询的集合是否为空

??????? if (categorys == null || categorys.size() == 0) {


??????????? System.out.println("从数据库查询....");

??????????? //3.如果为空,在将数据存入redis

??????????? //3.1 从数据库查询

??????????? cs = categoryDao.findAll();

??????????? //3.2 将集合数据存储到redis中的 category的key

??????????? for (int i = 0; i < cs.size(); i++) {


???? ???????????jedis.zadd("category",cs.get(i).getCname());

??????????? }

??????? } else {

??????????? System.out.println("从redis中查询.....");


??????????? //4.如果不为空,将set的数据存入list

??????????? cs = new ArrayList<Category>();

??????????? for (Tuple tuple : categorys) {

??????????????? Category category = new Category();

??????????????? category.setCname(tuple.getElement());

??????????????? category.setCid((int)tuple.getScore());

??????????????? cs.add(category);


??????????? }

??????? }



??????? return cs;

??? }

}

页面传递cid

header.html传递cid

var li = ‘<li><a href="route_list.html?cid=‘+data[i].cid+‘">‘+data[i].cname+‘</a></li>‘;

获取cid

$(function () {

?? var search = location.search;

?? //alert(search);//?id=5

??? // 切割字符串，拿到第二个值

??? var cid = search.split("=")[1];

});

11.2???根据id查询不同类别的旅游线路数据

分页展示旅游线路数据：

11.2.1? ?分析

11.2.2 ?编码

1.客户端代码编写

$(function () {

??? var search = location.search;

??? ????// 切割字符串，拿到第二个值

??? var cid = search.split("=")[1];


??? //当页码加载完成后，调用load方法，发送ajax请求加载数据

??? load(cid);

});

function load(cid,currentPage){

??? //发送ajax请求，请求route/pageQuery,传递cid

??? $.get("route/pageQuery",{cid:cid,currentPage:currentPage},function (pb) {

??????? //解析pagebean数据，展示到页面上


??????? //1.分页工具条数据展示

??????? //1.1 展示总页码和总记录数

??????? $("#totalPage").html(pb.totalPage);

??????? $("#totalCount").html(pb.totalCount);


??????? ????????var lis = "";


??????? var fristPage = ‘<li onclick="javascipt:load(‘+cid+‘)"><a href="javascript:void(0)">首页</a></li>‘;


??????? //计算上一页的页码

??????? var beforeNum =? pb.currentPage - 1;

??????? if(beforeNum <= 0){

??????????? beforeNum = 1;

??????? }


??????? var beforePage = ‘<li? onclick="javascipt:load(‘+cid+‘,‘+beforeNum+‘)" class="threeword"><a href="javascript:void(0)">上一页</a></li>‘;


??????? lis += fristPage;

??????? lis += beforePage;

??????? //1.2 展示分页页码

??????? /*

??????????? 1.一共展示10个页码，能够达到前5后4的效果

??????????? 2.如果前边不够5个，后边补齐10个

??????????? 3.如果后边不足4个，前边补齐10个

??????? */


??????? // 定义开始位置begin,结束位置 end

??????? var begin; // 开始位置

??????? var end ; //? 结束位置



??????? //1.要显示10个页码

??????? if(pb.totalPage < 10){

??????????? //总页码不够10页


??????????? begin = 1;

??????????? end = pb.totalPage;

??????? }else{

??????????? //总页码超过10页


??????????? begin = pb.currentPage - 5 ;

??????????? end = pb.currentPage + 4 ;


??????????? //2.如果前边不够5个，后边补齐10个

??????????? if(begin < 1){

??????????????? begin = 1;

??????????????? end = begin + 9;

??????????? }


??????????? //3.如果后边不足4个，前边补齐10个

??????????? if(end > pb.totalPage){

??????????????? end = pb.totalPage;

??????????????? begin = end - 9 ;

??????????? }

??????? }



??????? for (var i = begin; i <= end ; i++) {

??????????? var li;

??????????? //判断当前页码是否等于i

??????????? if(pb.currentPage == i){


??????????????? li = ‘<li class="curPage" onclick="javascipt:load(‘+cid+‘,‘+i+‘)"><a href="javascript:void(0)">‘+i+‘</a></li>‘;


??????????? }else{

??????????????? //创建页码的li

??????????????? li = ‘<li onclick="javascipt:load(‘+cid+‘,‘+i+‘)"><a href="javascript:void(0)">‘+i+‘</a></li>‘;

??????????? }

??????????? //拼接字符串

??????????? lis += li;

??????? }






???? ????????var lastPage = ‘<li class="threeword"><a href="javascript:;">末页</a></li>‘;

??????? var nextPage = ‘<li class="threeword"><a href="javascript:;">下一页</a></li>‘;


??????? lis += nextPage;

??????? lis += lastPage;



??????? //将lis内容设置到 ul

??????? $("#pageNum").html(lis);




??????? 

??????? //2.列表数据展示

??????? var route_lis = "";


??????? for (var i = 0; i < pb.list.length; i++) {

??????????? //获取{rid:1,rname:"xxx"}

??????????? var route = pb.list[i];


??????????? var li = ‘<li>n‘ +

??????????????? ‘??????????????????????? <div class="img"><img src="‘+route.rimage+‘" style="width: 299px;"></div>n‘ +

??????????????? ‘??????????????????????? <div class="text1">n‘ +

??????????????? ‘??????????????????????????? <p>‘+route.rname+‘</p>n‘ +

??????????????? ‘??????????????????????????? <br/>n‘ +

??????????????? ‘????????? ??????????????????<p>‘+route.routeIntroduce+‘</p>n‘ +

??????????????? ‘??????????????????????? </div>n‘ +

??????????????? ‘??????????????????????? <div class="price">n‘ +

??????????????? ‘??????????????????????????? <p class="price_num">n‘ +

????????? ??????‘??????????????????????????????? <span>&yen;</span>n‘ +

??????????????? ‘??????????????????????????????? <span>‘+route.price+‘</span>n‘ +

??????????????? ‘??????????????????????????????? <span>起</span>n‘ +

??????????????? ‘??????????????????????? ????</p>n‘ +

??????????????? ‘??????????????????????????? <p><a href="route_detail.html">查看详情</a></p>n‘ +

??????????????? ‘??????????????????????? </div>n‘ +

??????????????? ‘??????????????????? </li>‘;

??????????? route_lis += li;

??????? }

??????? $("#route").html(route_lis);


??????? //定位到页面顶部

??????? window.scrollTo(0,0);

??? });


}

2.服务器端代码编写

? ?a) ?创建PageBean对象

public class PageBean<T> {


??? private int totalCount;//总记录数

??? private int totalPage;//总页数

??? private int currentPage;//当前页码

??? private int pageSize;//每页显示的条数


??? private List<T> list;//每页显示的数据集合


??? public int getTotalCount() {

??????? return totalCount;

??? }


??? public void setTotalCount(int totalCount) {

??????? this.totalCount = totalCount;

??? }


??? public int getTotalPage() {

??????? return totalPage;

??? }


??? public void setTotalPage(int totalPage) {

??????? this.totalPage = totalPage;

??? }


??? public int getCurrentPage() {

??????? return currentPage;

??? }


??? public void setCurrentPage(int currentPage) {

??????? this.currentPage = currentPage;

??? }


??? public int getPageSize() {

??????? return pageSize;

??? }


??? public void setPageSize(int pageSize) {

??????? this.pageSize = pageSize;

??? }


??? public List<T> getList() {

??????? return list;

??? }


??? public void setList(List<T> list) {

??????? this.list = list;

??? }

}

b) RouteServlet

@WebServlet("/route/*")
public class RouteServlet extends BaseServlet {


??? private RouteService routeService = new RouteServiceImpl();


??? /**

???? * 分页查询

???? * @param request
 ???? * @param response
 ???? * @throws ServletException

???? * @throws IOException

???? */

??? public void pageQuery(HttpServletRequest request,IOException {

??????? //1.接受参数

??????? String currentPageStr = request.getParameter("currentPage");

??????? String pageSizeStr = request.getParameter("pageSize");

??????? String cidStr = request.getParameter("cid");


??????? int cid = 0;//类别id

??????? //2.处理参数

??????? if(cidStr != null && cidStr.length() > 0){

??????????? cid = Integer.parseInt(cidStr);

??????? }

??????? int currentPage = 0;//当前页码，如果不传递，则默认为第一页

??????? if(currentPageStr != null && currentPageStr.length() > 0){

??????????? currentPage = Integer.parseInt(currentPageStr);

??????? }else{

??????????? currentPage = 1;

??????? }


??????? int pageSize = 0;//每页显示条数，如果不传递，默认每页显示5条记录

??????? if(pageSizeStr != null && pageSizeStr.length() > 0){

??????????? pageSize = Integer.parseInt(pageSizeStr);

??????? }else{

???? ???????pageSize = 5;

??????? }


??????? //3. 调用service查询PageBean对象

??????? PageBean<Route> pb = routeService.pageQuery(cid,currentPage,pageSize);


??????? //4. 将pageBean对象序列化为json，返回

??????? writeValue(pb,response);


??? }


}

c) RouteService

public class RouteServiceImpl implements RouteService {

??? private RouteDao routeDao = new RouteDaoImpl();

??? @Override

??? public PageBean<Route> pageQuery(int cid,int currentPage,int pageSize) {

??????? //封装PageBean

??????? PageBean<Route> pb = new PageBean<Route>();

??????? //设置当前页码

??????? pb.setCurrentPage(currentPage);

??????? //设置每页显示条数

??????? pb.setPageSize(pageSize);

??????? 

??????? //设置总记录数

??????? int totalCount = routeDao.findTotalCount(cid);

??????? pb.setTotalCount(totalCount);

??????? //设置当前页显示的数据集合

??????? int start = (currentPage - 1) * pageSize;//开始的记录数

??????? List<Route> list = routeDao.findByPage(cid,start,pageSize);

??????? pb.setList(list);


??????? //设置总页数 = 总记录数/每页显示条数

??????? int totalPage = totalCount % pageSize == 0 ? totalCount / pageSize :(totalCount / pageSize) + 1 ;

??????? pb.setTotalPage(totalPage);



??????? return pb;

??? }

}

d) RouteDao

public class RouteDaoImpl implements RouteDao {

??? private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());


??? @Override

??? public int findTotalCount(int cid) {

??????? String sql = "select count(*) from tab_route where cid = ?";

??????? return template.queryForObject(sql,Integer.class,cid);

??? }


??? @Override

??? public List<Route> findByPage(int cid,int start,int pageSize) {

??????? String sql = "select * from tab_route where cid = ? limit ?,?";


??????? return template.query(sql,new BeanPropertyRowMapper<Route>(Route.class),cid,pageSize);
??? }
}

（编辑：李大同）

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