java访问数据库的代码

java访问数据库的方式有很多种，这里我只说两种，一种是普通的访问方式，一种是用context的方式。下面分别就是这两种的代码片段：

普通的访问方式：

public class AccessDatabase {
  private static  Connection getConnection()throws SQLException, ClassNotFoundException{
   Class.forName("com.mysql.jdbc.Driver");
      Connection conn=null;
      conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/mysql","root","root");
      return conn;
  }
    
 public static boolean queryUser(String name){
  boolean returnValue=false;
      String sql="select * from user where userName='"+name+"'";
      Connection conn=null;
      Statement st=null;
      ResultSet rs=null;
      try{
       conn=getConnection();
       st=conn.createStatement();
       System.out.println("SQL:"+sql);
       rs=st.executeQuery(sql);
       while(rs.next()){
         returnValue=true;
       }
       if(rs!=null){
        rs.close();
       }
       if(st!=null){
        st.close();
       }
       if(conn!=null){
        conn.close();
       }
      }
      catch(Exception e)
      {
        e.printStackTrace();
      }
      System.out.println("返回值:"+returnValue);
     return returnValue;
   }   
     public static void main(String[] args) {    
       System.out.println("DataBase Operation Demo");
        boolean b=queryUser("xiaoming");
        System.out.println("is have:"+b);
     }
}

context的访问方式：

 

package com.lina.tools;

 

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

 

import javax.naming.Context;

import javax.naming.InitialContext;

import javax.naming.NamingException;

import javax.sql.DataSource;

import org.apache.commons.dbutils.QueryRunner;

import org.apache.commons.dbutils.ResultSetHandler;

import org.apache.commons.dbutils.handlers.BeanListHandler;

 

/**

 * 数据源的连接

 *

 * @author admin

 *

 */

public class dbaccess {

       private Context ct = null;

       private Connection conn = null;

       private DataSource ds = null;

       private Statement state = null;

       private ResultSet result = null;

 

       public Connection getCon() {

              try {

                     ct = new InitialContext();

                     ds = (DataSource) ct.lookup("java:comp/env/mysource");

                     conn = ds.getConnection();

              } catch (NamingException e) {

                     e.printStackTrace();

              } catch (SQLException e) {

                     e.printStackTrace();

              }

              return conn;

       }

 

       /**

        * 查询

        *

        * @param sql

        * @param paras

        * @param rsh

        * @return Object对象，查询的是实体的对象，就返回实体bean的对象.

        */

       public Object query(String sql, Object paras[], ResultSetHandler rsh) {

              this.getCon(); // 获取连接

              QueryRunner qr = new QueryRunner(ds);

              Object result = null;

              try {

                     // 自动让参数与sql语句 中的？号匹配，再查询结果

                     result = qr.query(sql, paras, rsh);

              } catch (Exception e) {

                     e.printStackTrace();

              }

              return result;

 

       }

 

       /**

        * 增删改的方法

        *

        * @param sql

        * @param paras

        * @return 整型的，更改的条数

        */

       public int update(String sql, Object paras[]) {

              this.getCon();

              QueryRunner qr = new QueryRunner(ds);

              int result = -1;

              try {

                     result = qr.update(sql, paras);

              } catch (SQLException e) {

                     e.printStackTrace();

              }

              return result;

       }

      /**

       * 查询的一般方法

       * @param sql

       * @param param

       * @return

       */

       public ResultSet query(String sql, Object param[]) {

              conn = this.getCon();

              try {

                     PreparedStatement prp = conn.prepareStatement(sql);

                     for (int i=0; i<param.length; i++) {

                            prp.setObject(i+1, param[i]);

                     }

                     result = prp.executeQuery();

 

              } catch (SQLException e) {

                     e.printStackTrace();

              }

              return result;

       }

}

 

 

 

META-INF下的context.xml

<Context>

    <Resource name="mysource" type="javax.sql.DataSource"

       auth="Container"

       driverClassName="oracle.jdbc.driver.OracleDriver"

       url="jdbc:oracle:thin:@127.0.0.1:1521:orcl"

       username="system" password="triger" maxActive="200" maxIdle="20" maxWait="6000" />

</Context>