【Java开源代码栏目提醒】:网学会员,鉴于大家对Java开源代码十分关注,论文会员在此为大家搜集整理了“UsersDAO.java”一文,供大家参考学习!
package struts2.dataAccess;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
public class UsersDAO {
//判断参数传入的用户名是否已经存在,存在返回true,否则返回false
public boolean isExist (String username){
boolean flag = false;
Connection conn = Connections.getConnection();
try{
String sql = "select * from users where username=?";
PreparedStatement stm = conn.prepareStatement(sql);
stm.setString(1,username);
ResultSet rs= stm.executeQuery();
if(rs.next()) {
flag = true;
}
conn.close();
}
catch(Exception e)
{
e.printStackTrace();
}
return flag;
}
//保存用户至数据库
public void saveUser(String username, String password)
{
Connection conn = Connections.getConnection();
try{
String
sql = "insert into users values(?,?,?)";
PreparedStatement stm = conn.prepareStatement(sql);
int id = generateID();
if(id==-1){
return;
}
stm.setInt(1, id);
stm.setString(2,username);
stm.setString(3,password);
stm.execute();
conn.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
//生成下一个用户的ID。下一个用户ID值=数据库中已有的最大ID值+1
public int generateID(){
int id=-1;
Connection conn = Connections.getConnection();
try{
String sql = "select max(ID) from users";
Statement stm = conn.createStatement();
ResultSet rs = stm.executeQuery(sql);
if(rs.next()){
id = rs.getInt(1);
id++;
}
conn.close();
}
catch(Exception e)
{
e.printStackTrace();
}
return id;
}
public boolean validate(String username, String pass
word)
{
boolean flag = false;
Connection conn = Connections.getConnection();
try{
String sql = "select * from users where username=? and password=?";
PreparedStatement stm = conn.prepareStatement(sql);
stm.setString(1,username);
stm.setString(2,password);
ResultSet rs= stm.executeQuery();
if(rs.next())
{
// System.out.println(rs.getString("username"));
flag=true;
}
conn.close();
}
catch(Exception e)
{
e.printStackTrace();
}
return flag;
}
public static void main(String[] args){
UsersDAO usersDAO = new UsersDAO();
if(usersDAO.validate("admin", "admin"))
{
System.out.println("true");
}
}
}