02-使用C3P0连接池连接MySql并且使用QueryRunner简化数据库操作

来源：互联网发布：mac中如何复制粘贴编辑：程序博客网时间：2024/06/18 02:42

1.导入相应的JARs

mysql驱动jar包：mysql-connector-java-5.1.28-bin.jar

C3P0需要的jar包：c3p0-0.9.2-pre1.jar和mchange-commons-0.2.jar

2.在src下添加C3P0配置文件：c3p0-config.xml

<?xml version="1.0" encoding="UTF-8"?><c3p0-config><default-config> <property name="jdbcUrl">jdbc:mysql://localhost:3306/grain</property><property name="driverClass">com.mysql.jdbc.Driver</property><property name="user">root</property><property name="password">123</property><property name="acquireIncrement">3</property><property name="initialPoolSize">10</property><property name="minPoolSize">2</property><property name="maxPoolSize">10</property></default-config></c3p0-config>

3.封装为JdbcUtils，用来获取Connection对象，以及开启和关闭事务。有以下接口：

Connection getConnection()：从c3p0连接池获取Connection对象，所以需要提供c3p0-config.xml配置文件；
beginTransaction()：为当前线程开启事务；
commitTransaction()：提交当前线程的事务；
rollbackTransaction()：回滚当前线程的事务；
releaseConnection(Connection)：如果参数连接对象不是当前事务的连接对象，那么关闭它，否则什么都不做；

4.测试JdbcUtils

@Testpublic void testJdbcUtils() throws SQLException {Connection con = JdbcUtils.getConnection();System.out.println(con);JdbcUtils.releaseConnection(con);System.out.println(con.isClosed());}

5.封装TxQueryRunner，使用JdbcUtils连接数据库，使用QueryRunner简化数据库操作

引入jar包：commons-dbutils-1.4.jar，有以下接口：

int[] batch(String sql, Object[][] params)：执行批处理，参数sql是SQL语句模板，params为参数；
T query(String sql, ResultSetHandler<T> rh)：执行查询，执行查询，参数sql为要执行的查询语句模板，rh是结果集处理，用来把结果集映射成你想要的结果；
T query(String sql, ResultSetHandler<T> rh, Object… params)：执行查询，参数sql为要执行的查询语句模板，rh是结果集处理，用来把结果集映射成你想要的结果，params是sql语句的参数；
int update(String sql)：执行增、删、改语句，参数sql是要执行的SQL语句；
int update(Stringsql, Object param)：执行增、删、改语句，参数sql是要执行的SQL语句，参数param是参数（一个参数）；
int update(String sql, Object… params)：执行增、删、改语句，参数sql是要执行的SQL语句，参数params是参数（多个参数）；

6.测试TxQueryRunner

@Testpublic void testUpdate() throws SQLException {String sql = "insert into user_info(uid,uname,phonenumber,region,address,postcode) values(?,?,?,?,?,?)";Object[] params = {"0001","xiaoming","12345678912","China","Beijing","123456"};QueryRunner q = new TxQueryRunner();q.update(sql,params);}@Testpublic void testUpdate2() throws SQLException {try{JdbcUtils.beginTransaction();String sql = "insert into user_info(uid,uname,phonenumber,region,address,postcode) values(?,?,?,?,?,?)";Object[] params1 = {"0002","xiaoming","12345678912","China","Beijing","123456"};Object[] params2 = {"0003","xiaoming","12345678912","China","Beijing","123456"};QueryRunner q = new TxQueryRunner();q.update(sql,params1);q.update(sql,params2);JdbcUtils.commitTransaction();}catch(Exception e){try{JdbcUtils.rollbackTransaction();}catch(SQLException ee){}}}//单行结果集，BeanHandler@Testpublic void testQuery() throws SQLException{String sql = "select * from user_info where uid = ?";QueryRunner q = new TxQueryRunner();User u = q.query(sql, new BeanHandler<User>(User.class),"0001");System.out.println(u);}//多行结果集，BeanListHandler@Testpublic void testQuery2() throws SQLException{String sql = "select * from user_info";QueryRunner q = new TxQueryRunner();List<User> list_u = q.query(sql, new BeanListHandler<User>(User.class));System.out.println(list_u);}//单行结果集，map@Testpublic void testQuery3() throws SQLException{String sql = "select * from user_info where uid = ?";QueryRunner q = new TxQueryRunner();Map<String,Object> map_u = q.query(sql, new MapHandler(),"0001");System.out.println(map_u);}//多行结果集，List<map>@Testpublic void testQuery4() throws SQLException{String sql = "select * from user_info";QueryRunner q = new TxQueryRunner();List<Map<String,Object>> list_map_u = q.query(sql, new MapListHandler());System.out.println(list_map_u);}//单行单列，ScalarHandler@Testpublic void testQuery5() throws SQLException{String sql = "select count(*) from user_info";QueryRunner q = new TxQueryRunner();Object obj = q.query(sql, new ScalarHandler());//select count(*)的结果强转成NumberNumber n = (Number)obj;System.out.println(n.longValue());}

0 0