标签:String c3p0 dbcp connection static sql public 连接池
数据库连接池,DBUtil的模板,Druid使用(重点)
一、DBUtil模板
public class DBUtilTest {
public static Connection connection;
public static final String URL = "jdbc:mysql:///demo";
public static final String USERNAME = "";
public static final String PASSWORD = "";
static {
try {
Class.forName("com.mysql.cj.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
public static void testQuery() throws SQLException {
connection = DriverManager.getConnection(URL,USERNAME,PASSWORD);
String sql = "select * from emp where id = ?";
QueryRunner runner = new QueryRunner();
Emp query = runner.query(connection, sql, new BeanHandler<Emp>(Emp.class), 1);
System.out.println(query);
}
public static void testQuery2() throws SQLException {
connection = DriverManager.getConnection(URL,USERNAME,PASSWORD);
String sql = "select * from emp";
QueryRunner runner = new QueryRunner();
List<Emp> query = runner.query(connection, sql, new BeanListHandler<Emp>(Emp.class));
query.forEach((x)->{
System.out.println(x);
});
}
public static void insert() throws SQLException {
connection = DriverManager.getConnection(URL,USERNAME,PASSWORD);
String sql = "insert emp values(null,?,?)";
QueryRunner runner = new QueryRunner();
runner.update(connection,sql,1,2);
}
public static void main(String[] args) throws SQLException {
testQuery2();
}
}
二、数据库连接池
数据库连接池是为了减少频繁开关连接的时间,分析应该具备几个属性
1.初始大小
2.每次扩容大小
3.连接池最大个数
4.空闲连接死亡时间
各种数据库连接池
- DBCP
- C3P0
- Druid
- hikariCP
2.1.DBCP模板
public static void main(String[] args) throws SQLException {
// 数据库连接池资源
BasicDataSource basicDataSource = new BasicDataSource();
basicDataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
basicDataSource.setUrl("jdbc:mysql:///demo");
basicDataSource.setUsername("");
basicDataSource.setPassword("");
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet rs = null;
connection = basicDataSource.getConnection();
String sql = "select * from emp";
preparedStatement = connection.prepareStatement(sql);
rs = preparedStatement.executeQuery();
while (rs.next()){
System.out.println(rs.getInt(1)+
rs.getString(2)+
rs.getString(3));
}
connection.close();
}
2.2.C3P0
public static void main(String[] args) throws PropertyVetoException, SQLException {
ComboPooledDataSource cpds = new ComboPooledDataSource();
cpds.setDriverClass( "com.mysql.cj.jdbc.Driver" ); //loads the jdbc driver
cpds.setJdbcUrl( "jdbc:mysql://120.78.206.78:3306/demo" );
cpds.setUser("root");
cpds.setPassword("Root123..");
cpds.setMaxStatements( 180 );
Connection conn = cpds.getConnection();
System.out.println(conn);
conn.close();
}
第二种参照官网,进行xml配置
2.3.druid
druid是性能最好的数据库连接池
dbcp和c3p0区别,c3p0会自动回收不使用的连接
标签:String,c3p0,dbcp,connection,static,sql,public,连接池 来源: https://www.cnblogs.com/littlepage/p/11876764.html
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