c3p0 | 易学教程

Hibernate学习基本配置

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hibernate是一个持久层框架，是一个ORM（object，relattional mapping）对象关系映射框架，对jdbc进行了轻量级对象框架。所谓的对象关系映射是指，一个java对象和关系型数据库里的表简历一种映射关系，从而操作对象就可以操作表。入门学习所需jar包创建实体类创建映射映射需要通过 XML 的配置文件来完成，这个配置文件可以任意命名。尽量统一命名规范（类名 .hbm.xml ） <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.gream">  <class name="com.gream.Cstomer" table ="cst_customer" >  <id name="cust_id" column="cust_id" >  <generator class="increment"

The use of c3p0.idle_test_period.

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问题 I'm new to c3op, and confused about the use of : c3p0.idle_test_period In this link : HowTo configure the C3P0 connection pool idleTestPeriod : Must be set in hibernate.cfg.xml (or hibernate.properties), Hibernate default: 0, If this is a number greater than 0, c3p0 will test all idle, pooled but unchecked-out connections, every this number of seconds. What is the purpose of this kind of test (idel, pooled connections), and the relationship between c3p0.idle_test_period and c3p0.timeout? 回答1:

c3p0 hangs in awaitAvailable with hibernate

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I have console application that hangs during execution. Here is my configuration: cfg.setProperty("hibernate.connection.driver_class", "com.mysql.jdbc.Driver"); cfg.setProperty("hibernate.connection.url", "jdbc:mysql://localhost:3306/db?user=db&password=db"); cfg.setProperty("hibernate.connection.username", "db"); cfg.setProperty("hibernate.connection.password", "db"); cfg.setProperty("hibernate.connection.pool_size", "5"); cfg.setProperty("hibernate.connection.autocommit", "false"); cfg.setProperty("hibernate.c3p0.min_size", "5"); cfg.setProperty("hibernate.c3p0.max_size", "20"); cfg

连接池

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连接池定义：连接池（dataSource），也可以叫做数据源：所谓的池，就是在内存中开辟的一片空间，可以看作是一个容器，连接池就是接收连接的一个容器。作用：减少连接数据库的创建和关闭，实现连接的复用来提高程序执行的效率。传统不使用连接池访问数据库的弊端需要访问数据库的时候才会创建连接，当访问数据库结束后又会将连接销毁；而创建连接和销毁连接是很耗内存的和很耗时间，而使用连接的时间却又很短；所以运行效率很低。使用连接池有说明好处当程序启动时，会创建一个连接池，里面会事先创建多个连接，当需要连接数据库的时候，就会直接到连接池中取出一个连接来使用，结束后将线程归坏给连接池（close方法），实现了连接的复用；这样就省略了’创建连接‘和’销毁连接‘的步骤；提高了运行效率连接池配置文件在src根目录下创建file类型文件，名称为c3p0.properties 格式为： c3p0 . DriverClass = ( 包名 + 类名 ) c3p0 . JdbcUrl = jdbc : mysql : / / localhost : 端口号 / 数据库 ? characterEncoding = 编码 c3p0 . User = ( 数据库用户名 ) c3p0 . Password = ( 数据库密码 ) 在src根目录下创建XML File类型文件，名称为c3p0-config

C3P0 apparent deadlock when the threads are all empty?

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I'm using C3P0 as a connection pool in Tomcat, and I'm seeing very worrying errors: 2010-09-16 13:25:00,160 [Timer-0] WARN com.mchange.v2.async.ThreadPoolAsynchronousRunner - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@43502400 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks! 2010-09-16 13:25:01,407 [Timer-0] WARN com.mchange.v2.async.ThreadPoolAsynchronousRunner - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@43502400 -- APPARENT DEADLOCK!!! Complete Status: Managed Threads: 10 Active Threads: 0 Active Tasks: Pending

Java Database connection pool (BoneCP vs DBPool vs c3p0)

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问题 For a Java app outside of a J2EE container, which connection pool library is the best? I heard c3p0 is getting outdated. Jakarta's common pool library is no longer under development Therefore I'm left with BoneCP and DBPool. From what I can tell both have limited activity. The main difference I can see is performance, which BoneCP seems to win out with. However the documentation is pretty weak. Which database pool library have you used in the real world and why? What was the good and bad? 回答1

JDBC Connection pooling using C3P0

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问题 Following is my helper class to get DB connection: I've used the C3P0 connection pooling as described here. public class DBConnection { private static DataSource dataSource; private static final String DRIVER_NAME; private static final String URL; private static final String UNAME; private static final String PWD; static { final ResourceBundle config = ResourceBundle .getBundle("props.database"); DRIVER_NAME = config.getString("driverName"); URL = config.getString("url"); UNAME = config

c3p0 连接池

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C3P0数据源　　C3P0是一个开源的JDBC连接池，它实现了数据源和JNDI绑定，支持JDBC3规范和JDBC2的标准扩展。目前使用它的开源项目有 Hibernate，Spring 等。C3P0数据源在项目开发中使用得比较多。　　c3p0与dbcp区别 dbcp没有自动回收空闲连接的功能 c3p0有自动回收空闲连接功能创建 c3p0-config.xml: <?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://localhost:3306/testsvnb?useSSL=false&serverTimezone=Hongkong&characterEncoding=utf-8

连接池c3p0

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连接池c3p0 C3P0:hibernate和spring使用，有自动回收空闲连接的功能. 使用步骤: 　　1.导入jar包(c3p0-0.9.1.2.jar) 　　2.使用api a.硬编码(不推荐) 　　new ComboPooledDataSource() 步骤：　　1.创建一个DataSourse项目　　2.新建一个包com.c3p0.hjh 　　3.编写一个类C3p0Test01.java 　　4.导包，lib下放入c3p0-0.9.2.1.jar和mchange-commons-java-0.2.3.4.jar;导完jar记得buildpath一下代码执行前数据库数据：代码执行后数据库数据： JDBCUtil.java工具类源码： package com.util.hjh; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class JDBCUtil { final static String driver = "com.mysql.jdbc

使用c3p0连接池

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首先我们需要知道为什么要使用连接池：因为jdbc没有保持连接的能力，一旦超过一定时间没有使用（大约几百毫秒），连接就会被自动释放掉，每次新建连接都需要140毫秒左右的时间而C3P0连接池会池化连接，随时取用，平均每次取用只需要10-20毫秒，所以如果是很多客户端并发随机访问数据库的话，使用连接池的效率会高。接下来我们看使用c3p0需要做那些准备：首先需要导入相对应的jar包：c3p0-0.9.1.2-jdk1.3.jar，然后就是链接数据库的配置文件：c3p0-config.xml,配置如下 1 <?xml version="1.0" encoding="UTF-8"?> 2 <c3p0-config> 3  4 <default-config> 5 <property name="initialPoolSize">10</property> 6 <property name="maxIdleTime">30</property> 7 <property name="maxPoolSize">100</property> 8 <property name="minPoolSize">10</property> 9 <property name="maxStatements">200</property> 10 <

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