关于上篇book.java中使用类型不一样导致的报错

是在bookdao.java中解决

bookservlet.java

package servlet;
import java.io.IOException;
import beans.Book;
import dao.BookDao;
import java.util.ArrayList;
import javax.servlet.ServletException;
import javax.servlet.ServletContext;
import javax.servlet.RequestDispatcher;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class BookServlet extends HttpServlet
{
	public void service(HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException
	{
		String id =request.getParameter("id");
		BookDao dao=new BookDao();
		ArrayList books=dao.queryBookById( id);
		request.setAttribute("books", books);
		ServletContext application =this.getServletContext();
		RequestDispatcher rd=application.getRequestDispatcher("/showBook.jsp");
		rd.forward(request, response);	
	}
}

新建表books

bookdao.java

package dao;
import java.io.IOException;
import beans.Book;
import java.sql.*;
import java.util.ArrayList;
public class BookDao {
public ArrayList queryBookById(String id) {
		Connection conn=null;
		ArrayList books=new ArrayList();
		try {
			try {
				Class.forName("com.mysql.jdbc.Driver");
			      } 
catch (ClassNotFoundException e)
       {
				e.printStackTrace();
			      }

			String url="jdbc:mysql://localhost:3306/book?useUnicode=true&charaterEncoding=UTF-8";
			conn=DriverManager.getConnection(url,"root","123456");
			String sql="select * from books where id=?";
			PreparedStatement ps=conn.prepareStatement(sql);
			ps.setString(1, id);
			ResultSet rs=ps.executeQuery();
			while(rs.next()){
				Book book=new Book();
				book.setId(rs.getInt(1));
				book.setName(rs.getString(2));
				book.setPrice(rs.getDouble(3));
				books.add(book);
				}
			rs.close();
			ps.close();
			} 
catch (SQLException e) {
				e.printStackTrace();
			}
finally {
				try{
				        if(conn!=null){
					conn.close();
					conn=null;
					}
			}
catch(Exception e){}
			}
			return books;
		}
}

同时把class文件删去，重启启动tomcat6.0

成功访问

使用的是tomcat6.0+jdk1.6+mysql8.0+myeclipse10

注意

创建servlet，先建包

继续更改

tomcat6.0重启，测试结果

附上做好的项目下载链接，可直接导入

https://www.123pan.com/s/9QRqVv-WCuY.html