整个代码如下:
package database;
import java.sql.*;public class databasebean
{
private Connection connection=null;
private Statement statement=null;
private ResultSet resultset=null;
public databasebean()
{
Class.forName("com.mysql.jdbc.Driver").newInstance();
connection=DriverManager.getConnection("jdbc:mysql://127.0.0.1.3306/cdj","root","");
statement=connection.createStatement();
}
public boolean loginuser(String username,String userpassword)
{
boolean userExist=false;
try
{
String strSql="select*from user where uID='"+username+"' and uPS='"+userpassword+"'";
resultset=statement.executeQuery(strSql);
if(resultset.next())
{
userExist=true;
connection.close();
}
return userExist;
}catch(SQLException e){
e.printStack(); //有错
connection.close();
return false;
}
}
} //有错
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub }} 为什么会错呀
package database;
import java.sql.*;public class databasebean
{
private Connection connection=null;
private Statement statement=null;
private ResultSet resultset=null;
public databasebean()
{
Class.forName("com.mysql.jdbc.Driver").newInstance();
connection=DriverManager.getConnection("jdbc:mysql://127.0.0.1.3306/cdj","root","");
statement=connection.createStatement();
}
public boolean loginuser(String username,String userpassword)
{
boolean userExist=false;
try
{
String strSql="select*from user where uID='"+username+"' and uPS='"+userpassword+"'";
resultset=statement.executeQuery(strSql);
if(resultset.next())
{
userExist=true;
connection.close();
}
return userExist;
}catch(SQLException e){
e.printStack(); //有错
connection.close();
return false;
}
}
} //有错
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub }} 为什么会错呀
root cause java.lang.Error: Unresolved compilation problems:
The method printStack() is undefined for the type SQLException
Syntax error on token "}", delete this token database.databasebean.<init>(databasebean.java:32)
check.doPost(check.java:79)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
->
e.printStackTrace();
方法printStack() 没有定义要学会自己看错误提示。
你自己都标明了错误!
connection=DriverManager.getConnection("jdbc:mysql://127.0.0.1.3306/cdj","root","");
statement=connection.createStatement();connection.close();这四行都有错误提示错误原因:
message description The server encountered an internal error () that prevented it from fulfilling this request.exception javax.servlet.ServletException: Servlet execution threw an exception
root cause java.lang.Error: Unresolved compilation problems:
Unhandled exception type ClassNotFoundException
Unhandled exception type InstantiationException
Unhandled exception type IllegalAccessException
Unhandled exception type SQLException
Unhandled exception type SQLException
Unhandled exception type SQLException database.databasebean.<init>(databasebean.java:12)
check.doPost(check.java:79)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
import java.io.PrintWriter;
import database.databasebean;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class check extends HttpServlet { /**
* Constructor of the object.
*/
public check() {
super();
} /**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
} /**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out
.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print(" This is ");
out.print(this.getClass());
out.println(", using the GET method");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
} /**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { response.setContentType("text/html,");
response.setCharacterEncoding("utf-8");
PrintWriter out = response.getWriter();
out
.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
databasebean database=new databasebean();
String username=request.getParameter("name");
String userps=request.getParameter("password");
try{
if(database.loginuser(username, userps)){
out.write(username+",你已登陆成功!");
}
}catch(Exception e){
out.println("输入的用户名或密码有误!");
}
out.print(" This is ");
out.print(this.getClass());
out.println(", using the POST method");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
} /**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}}
劳烦大虾们帮忙啊, 刚开始学jsp,一些基本错误还不太会解决
{
Class.forName("com.mysql.jdbc.Driver").newInstance();
connection=DriverManager.getConnection("jdbc:mysql://127.0.0.1.3306/cdj","root","");
statement=connection.createStatement();
}
->
public databasebean()
{
try{
//以下语句有异常必须catch,看你的报错就知道了
Class.forName("com.mysql.jdbc.Driver").newInstance();
connection=DriverManager.getConnection("jdbc:mysql://127.0.0.1.3306/cdj","root","");
statement=connection.createStatement();
}catch(Exception e){
e.printStackTrace();
}
}
+--------------------+
| Database |
+--------------------+
| information_schema |
| cdj |
| mysql |
| student1 |
| test |
| testdb |
+--------------------+
6 rows in set (0.01 sec)mysql> use cdj;
Database changedmysql> select* from user;
+------+------+
| uID | uPS |
+------+------+
| qqq | 123 |
+------+------+这个是MYSQL中 的数据 应该没有错误吧