Dao层IEmployeeDao.javapackagecn.itcast.dao;importcn.itcast.entity.Employee;importcn.itcast.utils.PageBean;/***2.数据访问层，接口设计*@authorJie.Yuan**/publicinterfaceIEmployeeDao{/***分页查询数据*/publicvoidgetAll(PageBean
pb);/***查询总
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数*/publicintgetTotalCount();}EmployeeDao.javapackagecn.itcast.dao.impl;importjava.sql.SQLException;importjava.util.List;importorg.apache.commons.dbutils.QueryRunner;importorg.apache.commons.dbutils.handlers.BeanListHandler;importorg.apache.commons.dbutils.handlers.ScalarHandler;importcn.itcast.dao.IEmployeeDao;importcn.itcast.entity.Employee;importcn.itcast.utils.JdbcUtils;importcn.itcast.utils.PageBean;/***2.数据访问层实现*@authorJie.Yuan**/publicclassEmployeeDaoimplementsIEmployeeDao{@OverridepublicvoidgetAll(PageBeanpb){//2.查询总记录数; 设置到pb对象中inttotalCount=this.getTotalCount();pb.setTotalCount(totalCount);/**问题：jsp页面，如果当前页为首页，再点击上一页报错！* 如果当前页为末页，再点下一页显示有问题！*解决：* 1.如果当前页<=0; 当前页设置当前页为1;* 2.如果当前页>最大页数； 当前页设置为最大页数*///判断if(pb.getCurrentPage()<=0){pb.setCurrentPage(1); //把当前页设置为1}elseif(pb.getCurrentPage()>pb.getTotalPage()){pb.setCurrentPage(pb.getTotalPage()); //把当前页设置为最大页数}//1.获取当前页：计算查询的起始行、返回的行数intcurrentPage=pb.getCurrentPage();intindex=(currentPage-1)*pb.getPageCount(); //查询的起始行intcount=pb.getPageCount(); //查询返回的行数//3.分页查询数据; 把查询到的数据设置到pb对象中Stringsql="select*fromemployeelimit?,?";try{//得到Queryrunner对象QueryRunnerqr=JdbcUtils.getQueryRuner();//根据当前页，查询当前页数据(一页数据)ListpageData=qr.query(sql,newBeanListHandler(Employee.class),index,count);//设置到pb对象中pb.setPageData(pageData);}catch(Exceptione){thrownewRuntimeException(e);}}@OverridepublicintgetTotalCount(){Stringsql="selectcount(*)fromemployee";try{//创建QueryRunner对象QueryRunnerqr=JdbcUtils.getQueryRuner();//执行查询，返回结果的第一行的第一列Longcount=qr.query(sql,newScalarHandler());returncount.intValue();}catch(Exceptione){thrownewRuntimeException(e);}}}Entity层Employee.javapackagecn.itcast.entity;/***1.实体类设计(因为用了DbUtils组件，属性要与数据库中字段一致)*@authorJie.Yuan**/publicclassEmployee{privateintempId; //员工idprivateStringempName; //员工名称privateintdept_id; //部门idpublicintgetEmpId(){returnempId;}publicvoidsetEmpId(intempId){this.empId=empId;}publicStringgetEmpName(){returnempName;}publicvoidsetEmpName(StringempName){this.empName=empName;}publicintgetDept_id(){returndept_id;}publicvoidsetDept_id(intdeptId){dept_id=deptId;}}Service层IEmployeeService.javapackagecn.itcast.service;importcn.itcast.entity.Employee;importcn.itcast.utils.PageBean;/***3.业务逻辑层接口设计*@authorJie.Yuan**/publicinterfaceIEmployeeService{/***分页查询数据*/publicvoidgetAll(PageBeanpb);}EmployeeService.javapackagecn.itcast.service.impl;importcn.itcast.dao.IEmployeeDao;importcn.itcast.dao.impl.EmployeeDao;importcn.itcast.entity.Employee;importcn.itcast.service.IEmployeeService;importcn.itcast.utils.PageBean;/***3.业务逻辑层，实现*@authorJie.Yuan**/publicclassEmployeeServiceimplementsIEmployeeService{//创建Dao实例privateIEmployeeDaoemployeeDao=newEmployeeDao();@OverridepublicvoidgetAll(PageBeanpb){try{employeeDao.getAll(pb);}catch(Exceptione){thrownewRuntimeException(e);}}}Servlet层IndexServlet.javapackagecn.itcast.servlet;importjava.io.IOException;importjava.io.PrintWriter;importjavax.servlet.ServletException;importjavax.servlet.http.HttpServlet;importjavax.servlet.http.HttpServletRequest;importjavax.servlet.http.HttpServletResponse;importcn.itcast.entity.Employee;importcn.itcast.service.IEmployeeService;importcn.itcast.service.impl.EmployeeService;importcn.itcast.utils.PageBean;/***4.控制层开发*@authorJie.Yuan**/publicclassIndexServletextendsHttpServlet{//创建Service实例privateIEmployeeServiceemployeeService=newEmployeeService();//跳转资源privateStringuri;publicvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{try{//1.获取“当前页”参数； (第一次访问当前页为null)StringcurrPage=request.getParameter("currentPage");//判断if(currPage==null||"".equals(currPage.trim())){currPage="1"; //第一次访问，设置当前页为1;}//转换intcurrentPage=Integer.parseInt(currPage);//2.创建PageBean对象，设置当前页参数；传入service方法参数PageBeanpageBean=newPageBean();pageBean.setCurrentPage(currentPage);//3.调用service employeeService.getAll(pageBean); //【pageBean已经被dao填充了数据】//4.保存pageBean对象，到request域中request.setAttribute("pageBean",pageBean);//5.跳转uri="/WEB-INF/list.jsp";}catch(Exceptione){e.printStackTrace(); //测试使用//出现错误，跳转到错误页面；给用户友好提示uri="/error/error.jsp";}request.getRequestDispatcher(uri).forward(request,response);}publicvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{this.doGet(request,response);}}Utils层JdbcUtils.javapackagecn.itcast.utils;importjavax.sql.DataSource;importorg.apache.commons.dbutils.QueryRunner;importcom.mchange.v2.c3p0.ComboPooledDataSource;/***工具类*1.初始化C3P0连接池*2.创建DbUtils核心工具类对象*@authorJie.Yuan**/publicclassJdbcUtils{/*** 1.初始化C3P0连接池*/privatestatic DataSourcedataSource;static{dataSource=newComboPooledDataSource();}/***2.创建DbUtils核心工具类对象*/publicstaticQueryRunnergetQueryRuner(){//创建QueryRunner对象，传入连接池对象//在创建QueryRunner对象的时候，如果传入了数据源对象；//那么在使用QueryRunner对象方法的时候，就不需要传入连接对象；//会自动从数据源中获取连接(不用关闭连接)returnnewQueryRunner(dataSource);}}PageBean.javapackagecn.itcast.utils;importjava.util.List;importcn.itcast.entity.Employee;/***封装分页的参数**@authorJie.Yuan**/publicclassPageBean{privateintcurrentPage=1;//当前页,默认显示第一页privateintpageCount=4; //每页显示的行数(查询返回的行数),默认每页显示4行privateinttotalCount; //总记录数privateinttotalPage; //总页数=总记录数/每页显示的行数 (1)privateListpageData; //分页查询到的数据//返回总页数publicintgetTotalPage(){if(totalCount%pageCount==0){totalPage=totalCount/pageCount;}else{totalPage=totalCount/pageCount1;}returntotalPage;}publicvoidsetTotalPage(inttotalPage){this.totalPage=totalPage;}publicintgetCurrentPage(){returncurrentPage;}publicvoidsetCurrentPage(intcurrentPage){this.currentPage=currentPage;}publicintgetPageCount(){returnpageCount;}publicvoidsetPageCount(intpageCount){this.pageCount=pageCount;}publicintgetTotalCount(){returntotalCount;}publicvoidsetTotalCount(inttotalCount){this.totalCount=totalCount;}publicListgetPageData(){returnpageData;}publicvoidsetPageData(ListpageData){this.pageData=pageData;}}
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