addbook.java

书店实现用struts实现的一个系统 采用mysql数据库

/**
 * 该Servlet接受来自addBook.jsp的请求
 * 用于添加图书
 */
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import bean.BookInf;
import bean.DBClass;
import bean.StrClass;

public class AddBook extends HttpServlet{
	public void doGet(HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException {
		HttpSession session=request.getSession();
		String toJsp="/bookManage.jsp";	//toJsp用于储存本Servlet将要转到的JSP地址
		BookInf errInf=new BookInf();	//errInf用于储存错误提示信息
		
		request.setCharacterEncoding("gb2312");
		String id=request.getParameter("id").trim();
		String name=request.getParameter("name").trim();
		String author=request.getParameter("author").trim();
		String publisher=request.getParameter("publisher").trim();
		String type=request.getParameter("type");
		String price=request.getParameter("price").trim();
		String ifNew=request.getParameter("ifNew").trim();
        DBClass db=new DBClass();
		
		/* 检查表单信息的合法性 */
		if(id.equals("")){
			errInf.setId("*本项必须填写!");
			toJsp="/addBook.jsp";
		}else if (isExist(id)){
			errInf.setId("*与其它图书的ID冲突！");
			toJsp="/addBook.jsp";
		}
		
		if(name.equals("")){
			errInf.setName("*本项必须填写!");
			toJsp="/addBook.jsp";
		} 
		

		if(author.equals("")){
			errInf.setAuthor("*本项必须填写!");
			toJsp="/addBook.jsp";
		}
		

		if(publisher.equals("")){
			errInf.setPublisher("*本项必须填写!");
			toJsp="/addBook.jsp";
		}

		if(type.equals("0")){
			errInf.setType("*本项必须填写!");
			toJsp="/addBook.jsp";
		}

		if(price.equals("")){
			errInf.setPrice("*本项必须填写!");
			toJsp="/addBook.jsp";
		}
		
		/* 添加图书 */
		if(toJsp.equals("/bookManage.jsp")){
			String command="INSERT INTO book VALUES("
			              + "\'"+ id + "\'"+ ","
			              + "\'"+ name + "\'"+ "," 
			              + "\'"+ author + "\'"+ ","
			              + "\'"+ publisher + "\'"+ ","
			              + "\'"+ type + "\'"+ ","
			              + "\'"+ ifNew + "\'"+ ","
			              + "\'"+ price + "\'"+ ")";
	        db.connect();
	        db.executeUpdate(command);
			db.closeConnection();
		}  
		request.setAttribute("errInf", errInf);
		RequestDispatcher dispatcher = 
		                  request.getRequestDispatcher(toJsp);		            
		dispatcher.forward(request, response);
		
	}
	
	public void doPost(HttpServletRequest request, HttpServletResponse response) 
	throws ServletException, IOException {
		doGet(request, response);
	}
	
	public boolean isExist(String id){
		boolean bool =false;
		String query="SELECT * FROM book WHERE id="+"\'"+ id +"\'";
		DBClass db=new DBClass();	
			db.connect();
			ResultSet resultset=db.executeQuery(query);
			try{
				if(resultset.next()){
					bool=true;
				} 
			}catch(SQLException sqle){
			    System.err.println("Erro with connection:"+sqle);
			}
			db.closeConnection();
			return bool;
	}
}