servlet ，数据库 .

servlet部分

public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  //设置接收信息的字符集
     request.setCharacterEncoding("UTF-8");
      //接收浏览器端提交的信息
     String selectcont = request.getParameter("people");
     System.out.println("selected="+selectcont);
     String uname = request.getParameter("uname");
     String psw = request.getParameter("psw"); 
     System.out.println("username="+uname);
   //设置输出信息的格式及字符集       
        response.setContentType("text/xml; charset=UTF-8");
        response.setHeader("Cache-Control", "no-cache");
        //创建输出流对象
        PrintWriter out = response.getWriter();
        //依据验证结果输出不同的数据信息
        out.println("<response>"); 
       
        //数据库操作
        DB db = new DB();
        ResultSet rs;
        int insRes = 0;
        String strSql=null;
        //判断用户名是否重复
        strSql = "select * from classuser where username='"
        + uname + "'";
        rs = db.seletUser(strSql);
      
        boolean bnoRepeat = false;
        try {
         if ( !rs.next()) {
          bnoRepeat = true;
         }
     } catch (SQLException e) {
      e.printStackTrace();
     }
         //用户名不重复,插入记录
    if (bnoRepeat){
         strSql = "Insert Into classuser values('"+ uname + "','" + psw + "')";
         insRes = db.inserUser(strSql);
    }
    if(!bnoRepeat){
     out.println("<res>" + "注册失败!用户名已存在，重新输入用户名" + "</res>");
    }else if(insRes>0){
     out.println("<res>" + "注册成功！" + "</res>");
    }else{
     out.println("<res>" + "注册失败！" + "</res>");
    }
 
    out.println("</response>");
    out.close();
   }

数据库C3P0连接池获取数据库连接

import java.beans.PropertyVetoException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class ConnectionExa {
 private static ComboPooledDataSource datasource = null;
 private static String driverClass = null;
 private static String url = null;
 private static String psw = null;
 private static String username = null;
 
 public static Connection getConn(){
  Connection conn = null;
  Properties p = new Properties();
  System.out.println(ConnectionExa.class.getResource("").getPath());
  try {
   p.load(ConnectionExa.class.getResourceAsStream("/conf/aboutData.properties"));
   
  } catch (FileNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  driverClass = p.getProperty("driverClass");
  url = p.getProperty("url");
  username = p.getProperty("username");
  psw = p.getProperty("password");
        datasource = new ComboPooledDataSource();
  try {
   datasource.setDriverClass(driverClass);
    datasource.setJdbcUrl(url);
       datasource.setUser(username);
       datasource.setPassword(psw);
       datasource.setMaxPoolSize(30);
       datasource.setMinPoolSize(2);
       datasource.setMaxIdleTime(60);
       datasource.setInitialPoolSize(3);
      
    conn = datasource.getConnection();
    return conn;
  } catch (PropertyVetoException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (SQLException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  return null;
  
 }
 
 public static void main(String[]args){
  System.out.println(ConnectionExa.getConn());
  
  
 }
 
}

数据库操作

 

public class DB {

 /**
  * @param args
  */
 private Connection conn= null;
 public DB(){
  conn = ConnectionExa.getConn();
 }
 //插入数据
 public int inserUser(String sql0){
  
  int i = 0;
  String sql = sql0;
  try {
   Statement st = conn.createStatement();
   i = st.executeUpdate(sql);
  } catch (SQLException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  return i;
  
 }
 
 //查询数据
 public ResultSet seletUser(String sql0){
  String sql = sql0;
  PreparedStatement ps = null;
  try {
   ps = conn.prepareStatement(sql);
   ResultSet rs = ps.executeQuery();
   return rs;
  } catch (SQLException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  return null;
 }
 //关闭连接
 public void close(){
  
   try {
    if(conn != null){
     conn.close();
    }
   } catch (SQLException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  
 }
 //测试操作
 public static void main(String[] args) throws SQLException {
  // TODO Auto-generated method stub
  DB db = new DB();
//  User user = new User();
//  user.setPassword("111111");
//  user.setUsername("lsx2");
//  System.out.println(db.inserUser(user).getPassword());
  ResultSet rs = db.seletUser("lsx2");
//   System.out.println(db.seletUser("lsx"));
   while(rs.next()){
    try {
     System.out.println(rs.getString(1));
    } catch (SQLException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }
   }
  
 }

}