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三个实体类
Location.java
public class Location {
private Integer location_id;
private String city;
//...
}Department.java
public class Department {
private Integer department_id;
private String departmentName;
private Integer location_id;
//...
}Employee.java
public class Employee {
private Integer employeeId;
private String lastName;
private String email;
private double salary;
private Integer department_id;
//...
}WebContent下的emplooyes.jsp中只有一行代码，跳转到servlet
<%
response.sendRedirect("EmployeeServlet?method=listLocations");
%>EmployeeServlet.java
public class EmployeeServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String methodName = request.getParameter("method");
try {
Method method = getClass().getDeclaredMethod(methodName, HttpServletRequest.class, HttpServletResponse.class);
method.invoke(this, request, response);
} catch (Exception e) {
e.printStackTrace();
}
}
protected void listLocations(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Connection connection = DBManager.getConnection();
String sql = "select * from location";
Listlocations = new ArrayList();
Statement statement = null;
ResultSet resultSet = null;
Location location = null;
try {
statement = connection.createStatement();
resultSet = statement.executeQuery(sql);
while(resultSet.next()){
location = new Location();
location.setCity(resultSet.getString("city"));
location.setLocation_id(resultSet.getInt("location_id"));
locations.add(location);
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
DBManager.close(resultSet, statement, connection);
}
request.setAttribute("locations", locations);
request.getRequestDispatcher("/WEB-INF/pages/employees.jsp").forward(request, response);
}
protected void listDepartments(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
int locationId = Integer.parseInt(request.getParameter("locationId"));
String sql = "select * from department where location_id = " + locationId;
Connection connection = DBManager.getConnection();
Listdepartments = new ArrayList();
Department department = null;
ResultSet resultSet = null;
Statement statement = null;
try {
statement = connection.createStatement();
resultSet = statement.executeQuery(sql);
while(resultSet.next()){
department = new Department();
department.setDepartmentName(resultSet.getString("departmentName"));
department.setDepartment_id(resultSet.getInt("department_id"));
department.setLocation_id(resultSet.getInt("location_id"));
departments.add(department);
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
DBManager.close(resultSet, statement, connection);
}
ObjectMapper mapper = new ObjectMapper();
String result = mapper.writeValueAsString(departments);
System.out.println(result);
response.setContentType("text/javascript");
response.setCharacterEncoding("UTF-8");
response.getWriter().print(result);
}
protected void listEmployees(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
int department_id = Integer.parseInt(request.getParameter("department_id"));
String sql = "select * from employee where department_id = " + department_id;
Connection connection = DBManager.getConnection();
Statement statement = null;
ResultSet resultSet = null;
Listemployees = new ArrayList();
Employee employee = null;
try {
statement = connection.createStatement();
resultSet = statement.executeQuery(sql);
while(resultSet.next()){
employee = new Employee();
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 (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
DBManager.close(resultSet, statement, connection);
}
ObjectMapper mapper = new ObjectMapper();
String result = mapper.writeValueAsString(employees);
System.out.println(result);
response.setContentType("text/javascript");
response.setCharacterEncoding("UTF-8");
response.getWriter().print(result);
}
protected void listEmployeeInfo(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
int employeeId = Integer.parseInt(request.getParameter("employeeId"));
String sql = "select * from employee where employee_id = " + employeeId;
System.err.println(sql);
Connection connection = DBManager.getConnection();
Statement statement = null;
ResultSet resultSet = null;
Employee employee = null;
try {
statement = connection.createStatement();
resultSet = statement.executeQuery(sql);
if (resultSet.next()) {
employee = new Employee();
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(Exception e){
e.printStackTrace();
}finally{
DBManager.close(resultSet, statement, connection);
}
ObjectMapper mapper = new ObjectMapper();
String result = mapper.writeValueAsString(employee);
System.out.println(result);
response.setContentType("text/javascript");
response.setCharacterEncoding("UTF-8");
response.getWriter().print(result);
}
public static void main(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