java c3p0连接数据库实例（mysql）完整实例

忘是亡心i 2021-07-25 01:09 399阅读 0赞

**目录**

1.下载包c3p0的jar包，因我之前就有所以就用这个c3p0-0.9.2.1.jar，并引入到你的项目中。

2.在src下放入xml配置：c3p0-config.xml

3.编写工具类：

4.编写测试类：

5.执行结果：

--------------------

### 1.下载包c3p0的jar包，因我之前就有所以就用这个c3p0-0.9.2.1.jar，并引入到你的项目中。 ###

### 2.在src下放入xml配置：c3p0-config.xml ###

<?xml version="1.0" encoding="UTF-8"?>
     <c3p0-config>
         
         <default-config>
             <property name="driverClass">com.mysql.jdbc.Driver</property>
             <property name="jdbcUrl">jdbc:mysql://localhost:3306/test</property>
             <property name="user">root</property>
             <property name="password">root</property>
             
             <property name="acquireIncrement">5</property>
             <property name="initialPoolSize">10</property>
             <property name="minPoolSize">5</property>
             <property name="maxPoolSize">20</property>
         </default-config>
     
         
         <named-config name="MySQL">
             <property name="driverClass">com.mysql.jdbc.Driver</property>
             <property name="jdbcUrl">jdbc:mysql://localhost:3306/test</property>
             <property name="user">root</property>
             <property name="password">root</property>
             
             <property name="acquireIncrement">5</property>
             <property name="initialPoolSize">10</property>
             <property name="minPoolSize">5</property>
             <property name="maxPoolSize">20</property>
         </named-config>
     
     </c3p0-config>

### 3.编写工具类： ###

package com.yszd;
     import java.sql.Connection;
     import java.sql.ResultSet;
     import java.sql.SQLException;
     import java.sql.Statement;
     import com.mchange.v2.c3p0.ComboPooledDataSource;
     
     public class C3P0_Utils {
         
         private static ComboPooledDataSource dataSource = null;
         //在静态代码块中创建数据库连接池
         static{
             try{
            	 dataSource = new ComboPooledDataSource("MySQL");//使用C3P0的命名配置来创建数据源
                 
             }catch (Exception e) {
                 throw new ExceptionInInitializerError(e);
             }
         }
         
         public static Connection getConnection() throws SQLException{
             //从数据源中获取数据库连接
             return dataSource.getConnection();
         }
         
         // 释放资源
         public static void release(Connection conn,Statement st,ResultSet rs){
             if(rs!=null){
                 try{
                     //关闭存储查询结果的ResultSet对象
                     rs.close();
                 }catch (Exception e) {
                     e.printStackTrace();
                 }
                 rs = null;
             }
             if(st!=null){
                 try{
                     //关闭负责执行SQL命令的Statement对象
                     st.close();
                 }catch (Exception e) {
                     e.printStackTrace();
                 }
             }
             
             if(conn!=null){
                 try{
                     //将Connection连接对象还给数据库连接池
                     conn.close();
                 }catch (Exception e) {
                     e.printStackTrace();
                 }
             }
         }
     }

### 4.编写测试类： ###

package com.yszd;
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    
    public class DataSourceTest {
    
        public void c3p0DataSourceTest() {
            Connection conn = null;
            PreparedStatement st = null;
            ResultSet rs = null;
            try{
                //获取数据库连接
                conn = C3P0_Utils.getConnection();
                //插入语句
                String sql = "insert into test(id,name) values(?,?)";
                st = conn.prepareStatement(sql);
                st.setInt(1, 1);
                st.setString(2, "test");
                st.executeUpdate();
            }catch (Exception e) {
                e.printStackTrace();
            }finally{
                //释放资源
            	C3P0_Utils.release(conn, st, rs);
            }
        }
        
        public static void main(String[] args) {
        	new DataSourceTest().c3p0DataSourceTest();
    	}
    }

### 5.执行结果： ###

![2020121817481022.png][]

[2020121817481022.png]: /images/20210724/e45a4637b5af4adda886a0fc022e1992.png