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/shared/HelperBaseCh4.java /shared/HelperBaseCh4.java

package shared;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.beans.BeanUtils;

public abstract class HelperBaseCh4 {

protected enum SessionData {

READ, IGNORE
    };
    private Method methodDefault = null;
    protected HttpServlet servlet;
    protected HttpServletRequest request;
    protected HttpServletResponse response;
    protected Logger logger;

public HelperBaseCh4(
            HttpServlet servlet,
            HttpServletRequest request,
            HttpServletResponse response) {
        this.servlet = servlet;
        this.request = request;
        this.response = response;
        initLogger();
    }

protected void initLogger() {
        String logName = "bytesizebook.webdev";
        String initName = servlet.getInitParameter("logName");
        if (initName != null) logName = initName;

Level logLevel = Level.DEBUG;
        String strLevel = servlet.getInitParameter("logLevel");
        if (strLevel != null) {
            logLevel = Level.toLevel(strLevel);
        }
        
        logger = LogManager.getLogger(logName);
        logger.atLevel(logLevel);
    }

protected void doGet()
            throws ServletException, IOException {
        response.getWriter().print("The doGet method must be overridden"
                + " in the class that extends HelperBase.");
    }

protected void doPost()
            throws ServletException, IOException {
        response.getWriter().print("The doPost method must be overridden"
                + " in the class that extends HelperBase.");
    }

protected abstract void copyFromSession(Object helper);

public void addHelperToSession(String name,
            SessionData state) {
        if (SessionData.READ == state) {
            Object sessionObj =
                    request.getSession().getAttribute(name);
            if (sessionObj != null) {
                copyFromSession(sessionObj);
            }
        }
        request.getSession().setAttribute(name, this);
    }

public void addHelperToSession(String name,
            boolean checkSession) {
        if (checkSession) {
            Object sessionObj =
                    request.getSession().getAttribute(name);
            if (sessionObj != null) {
                copyFromSession(sessionObj);
            }
        }
        request.getSession().setAttribute(name, this);
    }

protected String executeButtonMethod()
            throws ServletException, IOException {
        String result = "";
        methodDefault = null;
        Class clazz = this.getClass();
        Class enclosingClass = clazz.getEnclosingClass();
        while (enclosingClass != null) {
            clazz = this.getClass();
            enclosingClass = clazz.getEnclosingClass();
        }

try {
            result = executeButtonMethod(clazz, true);
        } catch (Exception ex) {
            writeError(request, response,
                    "Button Method Error", ex);
            return "";
        }

return result;
    }

protected String executeButtonMethod(Class clazz,
            boolean searchForDefault)
            throws IllegalAccessException, InvocationTargetException {
        String result = "";
        Method[] methods = clazz.getDeclaredMethods();
        for (Method method : methods) {
            ButtonMethod annotation =
                    method.getAnnotation(ButtonMethod.class);
            if (annotation != null) {
                if (searchForDefault && annotation.isDefault()) {
                    methodDefault = method;
                }
                if (request.getParameter(annotation.buttonName())
                        != null) {
                    result = invokeButtonMethod(method);
                    break;
                }
            }
        }
        if (result.equals("")) {
            Class superClass = clazz.getSuperclass();
            if (superClass != null) {
                result =
                        executeButtonMethod(superClass,
                        methodDefault == null);
            }
            if (result.equals("")) {
                if (methodDefault != null) {
                    result = invokeButtonMethod(methodDefault);
                } else {
                    logger.error(
                            "(executeButtonMethod) No default method "
                            + "was specified, but one was needed.");
                    result = "No default method was specified,.";
                }
            }
        }
        return result;
    }

protected String invokeButtonMethod(Method buttonMethod)
            throws IllegalAccessException, InvocationTargetException {
        String resultInvoke = "Could not invoke method";
        try {
            resultInvoke =
                    (String) buttonMethod.invoke(this,
                    (Object[]) null);
        } catch (IllegalAccessException iae) {
            logger.error("(invoke) Button method is not public.",
                    iae);
            throw iae;
        } catch (InvocationTargetException ite) {
            logger.error("(invoke) Button method exception",
                    ite);
            throw ite;
        }
        return resultInvoke;
    }

public void fillBeanFromRequest(Object data) {
        BeanUtils.copyProperties(request.getParameterMap(), data);
    }

public void populateThrow(Object data) {
        BeanUtils.copyProperties(request.getParameterMap(), data);
    }

static public void writeError(
            javax.servlet.http.HttpServletRequest request,
            javax.servlet.http.HttpServletResponse response,
            String title,
            Exception ex)
            throws IOException, ServletException {
        java.io.PrintWriter out = response.getWriter();
        response.setContentType("text/html");
        out.println("<html>");
        out.println("  <head>");
        out.println("    <title>" + title + "</title>");
        out.println("  </head>");
        out.println("  <body>");
        out.println("<h2>" + title + "</h2>");
        if (ex.getMessage() != null) {
            out.println("    <h3>" + ex.getMessage() + "</h3>");
        }
        if (ex.getCause() != null) {
            out.println("    <h4>" + ex.getCause() + "</h4>");
        }
        StackTraceElement[] trace = ex.getStackTrace();
        if (trace != null && trace.length > 0) {
            out.print("<pre>");
        }
        ex.printStackTrace(out);
        out.println("</pre>");
        out.println("  </body>");
        out.println("</html>");
        out.close();
    }
}

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