Java连接数据库的几句话--Java学习网

时间:2016-12-14 8:07:05

  核心提示:第一种:最普通的方式,利用java原生jdbc连接数据库package utils;import java.sql.Connection;importjava.sql.DriverManager;im...

第一种:最普通的方式,利用java原生jdbc连接数据库

package utils;

 

import java.sql.Connection;

importjava.sql.DriverManager;

importjava.sql.PreparedStatement;

import java.sql.ResultSet;

importjava.sql.SQLException;

public class JDBCUtilsDemo1{      

       static{

              /**

               *1. 加载驱动

               */

              try {

                     Class.forName("com.mysql.jdbc.Driver");    //利用反射加载驱动

              } catch (ClassNotFoundException e) {

                e.printStackTrace();     

              }

       }

       /**

        * 2.建立连接

        */

       public static Connection getConnection() {  

              try {

                     returnDriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test?characterEncoding=utf-8","root", "root");

              } catch (SQLException e) {

                      throw newRuntimeException(e);

              }

       }

       /**

        * 关闭连接

        * @param conn

        * @param prep

        * @param rs

        */

       public static void close(Connection conn,PreparedStatementprep,ResultSet rs){

        if(rs != null){

            try {

                rs.close();

            } catch (SQLException e) {

                e.printStackTrace();

            } finally{

                rs = null;

            }

        }

        if(prep != null){

            try {

                prep.close();

            } catch (SQLException e) {

                e.printStackTrace();

            } finally{

                prep = null;

            }

        }

        if(conn != null){

            try {

                conn.close();

            } catch (SQLException e) {

                e.printStackTrace();

            } finally{

                conn = null;

            }

        }

    }

       /**

        * 测试数据库连通性

        */

       public static void main(String[] args) {

       Connection conn=JDBCUtilsDemo1.getConnection();

              System.out.println(conn);

              JDBCUtilsDemo1.close(conn,null, null);

       }

}

第二种:利用properties.properties配置文件形式,利用java原生jdbc连接数据库

 

1.     配置文件:properties.properties

 

driver=com.mysql.jdbc.Driver

url=jdbc:mysql://127.0.0.1:3306/test?characterEncoding=utf-8

username=root

password=root

2.     源代码:

package utils;

 

import java.sql.Connection;

importjava.sql.DriverManager;

importjava.sql.PreparedStatement;

import java.sql.ResultSet;

importjava.sql.SQLException;

import java.util.Properties;

 

public class JDBCUtilsDemo2{      

       private static Properties prop;

       static {

             

              prop = new Properties();

              try {

                     prop.load(JDBCUtilsDemo2.class.getClassLoader().getResourceAsStream(

                                   "db.properties"));

                     Class.forName(prop.getProperty("driver"));

               

              } catch (Exception e) {

                     throw new RuntimeException(e);

              }

 

       }

 

       public static Connection getConnection(Connection conn) {

              if (conn==null) {

                     try {

                            conn=DriverManager.getConnection(prop.getProperty("url"),

                                          prop.getProperty("username"),prop.getProperty("password"));

                     } catch (SQLException e) {

                            throw new RuntimeException(e);

                     }

        

              }

                return conn;   

       }

       public static void close(Connection conn,PreparedStatementprep,ResultSet rs){

        if(rs != null){

            try {

                rs.close();

            } catch (SQLException e) {

                e.printStackTrace();

            } finally{

                rs = null;

            }

        }

        if(prep != null){

            try {

                prep.close();

            } catch (SQLException e) {

                e.printStackTrace();

            } finally{

                prep = null;

            }

        }

        if(conn != null){

            try {

    ,             conn.close();

            } catch (SQLException e) {

                e.printStackTrace();

            } finally{

                conn = null;

            }

        }

 

    }

public static voidmain(String[] args) {

       Connection conn = null;

       conn=JDBCUtilsDemo2.getConnection(conn);

       System.out.println(conn);

       JDBCUtilsDemo2.close(conn,null, null);

}     

}

第三种:利用c3p0-congig.xml配置文件形式,利用c3p0连接数据库

 

1配置文件:c3p0-congig.xml

<c3p0-config>

       <default-config>

              <property name="jdbcUrl">jdbc:mysql://127.0.0.1:3306/test</property>

              <propertyname="driverClass">com.mysql.jdbc.Driver</property>

              <propertyname="user">root</property>

              <propertyname="password">root</property>

              <propertyname="initialPoolSize">3</property>

              <propertyname="maxPoolSize">6</property>

              <propertyname="maxIdleTime">1000</property>

       </default-config>

</c3p0-config>

2.源代码:

package utils;

 

import java.sql.Connection;

importjava.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

 

import javax.sql.DataSource;

 

importcom.mchange.v2.c3p0.ComboPooledDataSource;

public class JDBCUtilsDemo3{

       /**

        * 获得一个数据源

        */

        private staticDataSource dataSource=new ComboPooledDataSource();

        public staticDataSource getDataSources() {

              return dataSource;

       }

        /**

         * 获取连接

         */

        public staticConnection getConnection(){

                try {

                     return dataSource.getConnection();

              } catch (SQLException e) {

                     throw new RuntimeException(e);

              }

        }

        /**

               * 关闭连接

               * @param conn

               * @param prep

               * @param rs

               */

              public static void close(Connectionconn,PreparedStatement prep,ResultSet rs){

               if(rs != null){

                   try {

                      rs.close();

                   } catch(SQLException e) {

                      e.printStackTrace();

                   } finally{

                       rs =null;

                   }

               }

               if(prep !=null){

                   try {

                      prep.close();

                   } catch(SQLException e) {

                      e.printStackTrace();

                   } finally{

                       prep =null;

                   }

               }

               if(conn !=null){

                   try {

                      conn.close();

                   } catch(SQLException e) {

                      e.printStackTrace();

                   } finally{

                       conn =null;

                   }

               }

           }

              /**

               * 测试数据库连通性

               */

              public static void main(String[] args) {

                     Connection conn = null;

                  conn=JDBCUtilsDemo3.getConnection();

                     System.out.println(conn);

                     JDBCUtilsDemo1.close(conn,null, null);

              }

}     

第四种:利用dbcp.properties配置文件形式,利用dbcp连接数据库

 

1配置文件:dbcp.properties

########DBCP配置文件##########

#驱动名

driverClassName=com.mysql.jdbc.Driver

#url

url=jdbc:mysql://127.0.0.1:3306/test

#用户名

username=root

#密码

password=root

#初试连接数

initialSize=30

#最大活跃数

maxTotal=30

#最大idle数

maxIdle=10

#最小idle数

minIdle=5

#最长等待时间(毫秒)

maxWaitMillis=1000

#程序中的连接不使用后是否被连接池回收(该版本要使用removeAbandonedOnMaintenance和removeAbandonedOnBorrow)

#removeAbandoned=true

removeAbandonedOnMaintenance=true

removeAbandonedOnBorrow=true

#连接在所指定的秒数内未使用才会被删除(秒)(为配合测试程序才配置为1秒)

removeAbandonedTimeout=1

2.源代码:

package utils;

 

import java.io.IOException;

import java.sql.Connection;

importjava.sql.PreparedStatement;

import java.sql.ResultSet;

importjava.sql.SQLException;

import java.util.Properties;

 

import javax.sql.DataSource;

 

importorg.apache.commons.dbcp.BasicDataSourceFactory;

 

public class JDBCUtilsDemo4{

       private static Properties props = new Properties();

       static {

              // 加载配置文件

              try {

                     props.load(JDBCUtilsDemo4.class.getClassLoader()

                                   .getResourceAsStream("dbcp.properties"));

              } catch (IOException e) {

                     throw new RuntimeException("配置文件加载失败");

              }

 

       }

 

       /**

        * 获得数据源

        *

        * @return

        */

       public static DataSource getDataSource() {

              try {

                     returnBasicDataSourceFactory.createDataSource(props);

              } catch (Exception e) {

                     throw new RuntimeException("获得数据源失败");

              }

       }

 

       /**

        * 获取连接

        *

        * @return

        */

       public static Connection getConnection() {

              try {

                     return getDataSource().getConnection();

              } catch (SQLException e) {

                     throw new RuntimeException("连接数据库失败");

              }

 

       }

 

       /**

        * 关闭连接

        *

        * @param conn

        * @param prep

        * @param rs

        */

       public static void close(Connection conn, PreparedStatementprep,

                     ResultSet rs) {

              if (rs != null) {

                     try {

                            rs.close();

                     } catch (SQLException e) {

                            e.printStackTrace();

                     } finally {

                            rs = null;

                     }

              }

              if (prep != null) {

                     try {

                            prep.close();

                     } catch (SQLException e) {

                            e.printStackTrace();

                     } finally {

                            prep= null;

                     }

              }

              if (conn != null) {

                     try {

                            conn.close();

                     } catch (SQLException e) {

                            e.printStackTrace();

                     } finally {

                            conn = null;

                     }

              }

       }

       /**

        * 测试数据库连通性

        */

       public static void main(String[] args) {

              Connection conn = null;

              conn = JDBCUtilsDemo4.getConnection();

              System.out.println(conn);

              JDBCUtilsDemo4.close(conn, null, null);

       }

 

}

第五种:利用mybatis-config.xml配置文件形式,利用MyBatis连接数据库

 

1配置文件:mybatis-config.xml

<?xmlversion="1.0" encoding="UTF-8" ?> 

<!DOCTYPEconfiguration 

  PUBLIC "-//mybatis.org//DTD Config3.0//EN" 

 "http://mybatis.org/dtd/mybatis-3-config.dtd"> 

<configuration>   

    <environmentsdefault="environment"> 

        <environmentid="environment"> 

            <transactionManager type="JDBC"/> 

            <dataSourcetype="POOLED"> 

                <propertyname="driver" value="com.mysql.jdbc.Driver" /> 

                <propertyname="url"value="jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&amp;characterEncoding=utf8"/> 

               <property name="username" value="root" /> 

                <propertyname="password" value="root" /> 

            </dataSource> 

        </environment> 

    </environments> 

     <!-- 加载SQL定义文件 -->

    <!-- <mappers> 

        <mapper resource=""/> 

    </mappers>     -->

</configuration>

2.源代码:

package utils;

importorg.apache.ibatis.session.SqlSession;

importorg.apache.ibatis.session.SqlSessionFactoryBuilder;

 

public class JDBCUtilsDemo5{

        private staticSqlSession session=null;

       public static SqlSession getSession(){

              try {

                     session= newSqlSessionFactoryBuilder().build(JDBCUtilsDemo5.class.getClassLoader().getResourceAsStream("mybatis-config.xml")).openSession();

              } catch (Exception e) {

                     throw new RuntimeException(e);

              }

              return session;

       }

    public static void close() {

          if(session!=null) {

                 session.close();

              }

       }

    public static void main(String[] args) {

          SqlSessionsession=null;

               session=JDBCUtilsDemo5.getSession();

               System.out.println(session);

               JDBCUtilsDemo5.close();

       }

}

第六种:利用hibernate.cfg.xml配置文件形式,利用hibernate连接数据库

 

1配置文件hibernate.cfg..xml

<?xml version='1.0'encoding='utf-8'?>

<!DOCTYPEhibernate-configuration PUBLIC

        "-//Hibernate/HibernateConfiguration DTD 3.0//EN"

       "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <!-- 数据库连接信息 -->         

     <propertyname="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>

     <propertyname="hibernate.connection.url">jdbc:mysql://127.0.0.1:3306/test</property>

     <propertyname="hibernate.connection.username">root</property>  

     <propertyname="connection.password">root</property>

     <!-- hibernate配置信息 -->

        <!-- SQL dialect 方言,用于配置生成针对哪个数据库的-->

        <propertyname="dialect">

        <!-- 方言类,Hibernate提供的,用于封装某种特定的 -->

               org.hibernate.dialect.MySQL5Dialect

        </property>

        <!-- 生成的sql是否打印到控制台 -->

        <propertyname="show_sql">true</property> 

        <!-- 打印的sql是否进行格式化 -->    

        <propertyname="format_sql">true</property>

        <!-- 在配置文件中关联映射文件 -->

        <!-- <mappingresource=""/> -->

    </session-factory>

</hibernate-configuration>

2.源代码:

package utils;

 

import org.hibernate.Session;

importorg.hibernate.SessionFactory;

importorg.hibernate.cfg.Configuration;

 

@SuppressWarnings("deprecation")

public class JDBCUtilsDemo6{

       private static Configuration config;

       private static SessionFactory sessionFactory;

       private static Session session;

       static {

              // 1.加载hibernate.cfg.xml配置文件

              config = new Configuration().configure();

              // 2.获取SessionFactory

              sessionFactory = config.buildSessionFactory();

       }

 

       // 3.得到session

       public static Session getSession() {

              session = sessionFactory.openSession();

              return session;

       }

 

       // 4.关闭session

       public static void close() {

              if (session != null) {

                     session.close();

              }

       }

 

       public static void main(String[] args) {

              Session session = JDBCUtilsDemo6.getSession();

              System.out.println(session);

              JDBCUtilsDemo6.close();

 

       }

}

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