三个实体类

Location.java

publicclassLocation{privateIntegerlocation_id;privateStringcity;//...}

Department.java

publicclassDepartment{privateIntegerdepartment_id;privateStringdepartmentName;privateIntegerlocation_id;//...}

Employee.java

publicclassEmployee{privateIntegeremployeeId;privateStringlastName;privateStringemail;privatedoublesalary;privateIntegerdepartment_id;//...}

WebContent下的emplooyes.jsp中只有一行代码，跳转到servlet

<%response.sendRedirect("EmployeeServlet?method=listLocations");%>

EmployeeServlet.java

publicclassEmployeeServletextendsHttpServlet{privatestaticfinallongserialVersionUID=1L;protectedvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{StringmethodName=request.getParameter("method");try{Methodmethod=getClass().getDeclaredMethod(methodName,HttpServletRequest.class,HttpServletResponse.class);method.invoke(this,request,response);}catch(Exceptione){e.printStackTrace();}}protectedvoidlistLocations(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{Connectionconnection=DBManager.getConnection();Stringsql="select*fromlocation";List<Location>locations=newArrayList<Location>();Statementstatement=null;ResultSetresultSet=null;Locationlocation=null;try{statement=connection.createStatement();resultSet=statement.executeQuery(sql);while(resultSet.next()){location=newLocation();location.setCity(resultSet.getString("city"));location.setLocation_id(resultSet.getInt("location_id"));locations.add(location);}}catch(SQLExceptione){e.printStackTrace();}finally{DBManager.close(resultSet,statement,connection);}request.setAttribute("locations",locations);request.getRequestDispatcher("/WEB-INF/pages/employees.jsp").forward(request,response);}protectedvoidlistDepartments(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{intlocationId=Integer.parseInt(request.getParameter("locationId"));Stringsql="select*fromdepartmentwherelocation_id="+locationId;Connectionconnection=DBManager.getConnection();List<Department>departments=newArrayList<Department>();Departmentdepartment=null;ResultSetresultSet=null;Statementstatement=null;try{statement=connection.createStatement();resultSet=statement.executeQuery(sql);while(resultSet.next()){department=newDepartment();department.setDepartmentName(resultSet.getString("departmentName"));department.setDepartment_id(resultSet.getInt("department_id"));department.setLocation_id(resultSet.getInt("location_id"));departments.add(department);}}catch(SQLExceptione){e.printStackTrace();}finally{DBManager.close(resultSet,statement,connection);}ObjectMappermapper=newObjectMapper();Stringresult=mapper.writeValueAsString(departments);System.out.println(result);response.setContentType("text/javascript");response.setCharacterEncoding("UTF-8");response.getWriter().print(result);}protectedvoidlistEmployees(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{intdepartment_id=Integer.parseInt(request.getParameter("department_id"));Stringsql="select*fromemployeewheredepartment_id="+department_id;Connectionconnection=DBManager.getConnection();Statementstatement=null;ResultSetresultSet=null;List<Employee>employees=newArrayList<Employee>();Employeeemployee=null;try{statement=connection.createStatement();resultSet=statement.executeQuery(sql);while(resultSet.next()){employee=newEmployee();employee.setDepartment_id(resultSet.getInt("department_id"));employee.setEmail(resultSet.getString("email"));employee.setEmployeeId(resultSet.getInt("employee_id"));employee.setLastName(resultSet.getString("last_name"));employee.setSalary(resultSet.getDouble("salary"));employees.add(employee);}}catch(SQLExceptione){//TODOAuto-generatedcatchblocke.printStackTrace();}finally{DBManager.close(resultSet,statement,connection);}ObjectMappermapper=newObjectMapper();Stringresult=mapper.writeValueAsString(employees);System.out.println(result);response.setContentType("text/javascript");response.setCharacterEncoding("UTF-8");response.getWriter().print(result);}protectedvoidlistEmployeeInfo(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{intemployeeId=Integer.parseInt(request.getParameter("employeeId"));Stringsql="select*fromemployeewhereemployee_id="+employeeId;System.err.println(sql);Connectionconnection=DBManager.getConnection();Statementstatement=null;ResultSetresultSet=null;Employeeemployee=null;try{statement=connection.createStatement();resultSet=statement.executeQuery(sql);if(resultSet.next()){employee=newEmployee();employee.setDepartment_id(resultSet.getInt("department_id"));employee.setEmail(resultSet.getString("email"));employee.setEmployeeId(resultSet.getInt("employee_id"));employee.setLastName(resultSet.getString("last_name"));employee.setSalary(resultSet.getDouble("salary"));}}catch(Exceptione){e.printStackTrace();}finally{DBManager.close(resultSet,statement,connection);}ObjectMappermapper=newObjectMapper();Stringresult=mapper.writeValueAsString(employee);System.out.println(result);response.setContentType("text/javascript");response.setCharacterEncoding("UTF-8");response.getWriter().print(result);}publicstaticvoidmain(String[]args){System.out.println(DBManager.getConnection());}}

/WEB-INF/pages/employees.jsp浏览器不可达，只能通过servlet跳转到该页面

<%@pagelanguage="java"contentType="text/html;charset=UTF-8"pageEncoding="UTF-8"%><%@taglibprefix="c"uri="http://java.sun.com/jsp/jstl/core"%><!DOCTYPEhtmlPUBLIC"-//W3C//DTDHTML4.01Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"><html><head><metahttp-equiv="Content-Type"content="text/html;charset=UTF-8"><title>Inserttitlehere</title><scripttype="text/javascript"src="${pageContext.request.contextPath}/js/jquery-1.11.1.min.js"></script><scripttype="text/javascript"src="${pageContext.request.contextPath}/js/jquery.blockUI.js"></script><scripttype="text/javascript">$(function(){$(document).ajaxStart(function(){//使用blockUI。ajax请求发出时执行$.blockUI({message:$('#loading'),css:{top:($(window).height()-400)/2+'px',left:($(window).width()-400)/2+'px',width:'400px'},overlayCSS:{backgroundColor:'#00f'}})}).ajaxStop($.unblockUI);$("#city").change(function(){$("#departmentoption:not(:first)").remove();varlocation_id=$(this).val();if(location_id!=""){varurl="EmployeeServlet?method=listDepartments";varargs={"locationId":location_id,"time":newDate()};$.getJSON(url,args,function(data){if(data.length==0){alert("当前城市没有部门");}else{for(vari=0;i<data.length;i++){vardeptName=data[i].departmentName;vardeptId=data[i].department_id;//alert(deptName);$("#department").append("<optionvalue='"+deptId+"'>"+deptName+"</option>");}}});}});$("#department").change(function(){$("#employeeoption:not(:first)").remove();vardepartment_id=$(this).val();if(department_id!=""){varurl="EmployeeServlet?method=listEmployees";varargs={"department_id":department_id,"time":newDate()};$.getJSON(url,args,function(data){if(data.length==0){alert("当前部门没有员工");}else{for(vari=0;i<data.length;i++){varlastName=data[i].lastName;varemail=data[i].email;varsalary=data[i].salary;varemployeeId=data[i].employeeId;$("#employee").append("<optionvalue='"+employeeId+"'>"+lastName+"</option>");}}});}});$("#employee").change(function(){varemployeeId=$(this).val();if(employeeId!=""){varurl="EmployeeServlet?method=listEmployeeInfo";varargs={"employeeId":employeeId,"time":newDate()};$.getJSON(url,args,function(data){if(data.length==0){alert("数据丢失");}else{$("#employee_id").text(data.employeeId);$("#last_name").text(data.lastName);$("#email").text(data.email);$("#salary").text(data.salary);}});}//}});})</script></head><body><imgalt=""id="loading"src="${pageContext.request.contextPath}/p_w_picpaths/loading.gif">City:<selectid="city"><optionvalue="">请选择...</option><c:forEachitems="${locations}"var="location"><optionvalue="${location.location_id}">${location.city}</option></c:forEach></select>Department:<selectid="department"><optionvalue="">请选择...</option></select>Employee:<selectid="employee"><optionvalue="">请选择...</option></select><br/>员工编号:<spanid="employee_id"></span><br/>姓名：<spanid="last_name"></span><br/>email：<spanid="email"></span><br/>薪水：<spanid="salary"></span><br/></body></html>

源码http://yunpan.cn/cgephkTV2Tcmh （提取码：2492）