（三）JDBC连接池&DBUtils—C3P0的使用

（三）JDBC连接池&DBUtils—C3P0的使用

C3P0开源免费的连接池！目前使用他的开源项目有：Spring、Hibernate等。使用第三方工具需要导入jar包，C3P0使用时还需要添加配置文件c3p0-config.xml

通过这个配置来加载驱动和获取连接

C3P0配置文件

需要从官网下载平常可以自己收藏一份来使用

<?xml version="1.0" encoding="UTF-8"?> <c3p0-config>   <default-config> <property name="driverClass">com.mysql.jdbc.Driver</property> <property name="jdbcUrl">jdbc:mysql:///web08</property> <property name="user">root</property> <property name="password">123456</property> <property name="initialPoolSize">5</property> <property name="maxPoolSize">20</property> </default-config>   <named-config name="itheima"> <property name="driverClass">com.mysql.jdbc.Driver</property> <property name="jdbcUrl">jdbc:mysql:///web08</property> <property name="user">root</property> <property name="password">123456</property> </named-config> </c3p0-config>

这是比较常用的配置

具体参数有：

 

常见配置项：

 

 

C3P0提供核心工具类：

ComboPooledDataSource，如果要使用连接池，必须创建该类的实例对象。

public class C3P0Utils { private static ComboPooledDataSource dataSource=new ComboPooledDataSource("itheima"); public static DataSource getDataSource(){ return dataSource; } public static Connection getConnection(){ try { return dataSource.getConnection(); } catch (SQLException e) { // TODO Auto-generated catch block throw new RuntimeException(e); } } }

public class C3P0Utils {
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te static ComboPooledDataSource dataSource=new ComboPooledDataSource("itheima");
public static DataSource getDataSource(){
return dataSource;
}
public static Connection getConnection(){
try {
return dataSource.getConnection();
} catch (SQLException e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);
}
}

}

public class TestC3P0 {
@Test
public void testAddUser1() {
Connection conn = null;
PreparedStatement pstmt = null;

try {
// 2.从池子中获取连接
conn = C3P0Utils.getConnection();
String sql = "insert into tbl_user values(null,?,?)";
pstmt = conn.prepareStatement(sql);
pstmt.setString(1, "德玛");
pstmt.setString(2, "西亚");
int rows = pstmt.executeUpdate();
if (rows > 0) {
System.out.println("添加成功!");
} else {
System.out.println("添加失败!");
}
} catch (Exception e) {
throw new RuntimeException(e);
} finally {
JDBCUtils_V3.release(conn, pstmt, null);
}
}

@Test
public void testAddUser() {
Connection conn = null;
PreparedStatement pstmt = null;
// 1.创建C3P0连接池对象
//在ComboPooledDataSource()方法中参数部分是C3P0配置文件里面的 名字
//加载默认的配置
ComboPooledDataSource dataSource=new ComboPooledDataSource();

//加载有名称的配置
//ComboPooledDataSource dataSource1=new ComboPooledDataSource("itheima");

try {
// 2.从池子中获取连接
conn = dataSource.getConnection();
String sql = "insert into tbl_user values(null,?,?)";
pstmt = conn.prepareStatement(sql);
pstmt.setString(1, "赵信");
pstmt.setString(2, "德邦");
int rows = pstmt.executeUpdate();
if (rows > 0) {
System.out.println("添加成功!");
} else {
System.out.println("添加失败!");
}
} catch (Exception e) {
throw new RuntimeException(e);
} finally {
JDBCUtils_V3.release(conn, pstmt, null);
}
}
}