【JDBC】C3P0连接池的使用

c3p0连接池的c3p0-config.xml配置文件

<?xml version="1.0" encoding="utf-8"?>
<c3p0-config>
    <default-config>
        <property name="driverclass">com.mysql.cj.jdbc.driver</property>
        <property name="jdbcurl">jdbc:mysql:///jdbctest?servertimezone=hongkong</property>
        <property name="user">root</property>
        <property name="password">1234</property>
        <property name="initialpoolsize">5</property>
        <property name="maxpoolsize">20</property>
    </default-config>
</c3p0-config>

工具类

package jdbcutils;

import java.sql.connection;
import java.sql.resultset;
import java.sql.statement;

import com.mchange.v2.c3p0.combopooleddatasource;

public class jdbcutils {
    private static final combopooleddatasource cpds = new combopooleddatasource();
    
    public static connection getconection() throws exception {
        return cpds.getconnection();
    }
    
    public static void release(statement stmt, connection conn) {
        if(stmt != null) {
            try {
                stmt.close();
            }catch(exception e) {
                e.printstacktrace();
            }
            stmt = null;
        }
        
        if(conn != null) {
            try {
                conn.close();
            }catch(exception e) {
                e.printstacktrace();
            }
            conn = null;
        }       
    }
    
    public static void release(resultset rs, statement stmt, connection conn) {
        if(rs != null) {
            try {
                rs.close();
            }catch(exception e) {
                e.printstacktrace();
            }
            rs = null;
        }
        
        if(stmt != null) {
            try {
                stmt.close();
            }catch(exception e) {
                e.printstacktrace();
            }
            stmt = null;
        }
        
        if(conn != null) {
            try {
                conn.close();
            }catch(exception e) {
                e.printstacktrace();
            }
            conn = null;
        }       
    }
}

单元测试

package demo1;

import java.sql.connection;
import java.sql.preparedstatement;
import java.sql.resultset;

import org.junit.test;

import jdbcutils.jdbcutils;

public class jdbcdemo4 {
    
    @test
    public void demo4() {
        connection conn = null;
        preparedstatement pstmt = null;
        resultset rs = null;

        try {
            // 获得连接
            conn = jdbcutils.getconection();
            // 编写sql
            string sql = "select * from course";
            // 预编译sql
            pstmt = conn.preparestatement(sql);
            // 执行sql
            rs = pstmt.executequery();
            while (rs.next()) {
                system.out.println(rs.getint("id") + " " + rs.getstring("name") + " " + rs.getstring("category") + " "
                        + rs.getstring("desp") + " " + rs.gettimestamp("createtime"));
            }
        } catch (exception e) {
            e.printstacktrace();
        } finally {
            jdbcutils.release(rs, pstmt, conn);
        }
    }
}