编程式事务 与 事务超时

这篇日志有三个目的

1.回顾编程式事务

2.回顾mybatis

3.测试事务的超时时间设置是否能起到作用

首先祭上pom.xml，里面所有的依赖都是必须的，所有用不到的依赖我都干掉了

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.wangx.demo</groupId>
    <artifactId>mybatis-transaction</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>mybatis-transaction</name>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <spring.version>4.3.9.RELEASE</spring.version>
    </properties>

    <dependencies>
        <!-- ojdbc -->
        <dependency>
            <groupId>com.oracle</groupId>
            <artifactId>ojdbc7</artifactId>
            <version>12.1.0.2</version>
        </dependency>
        
        <!-- 线程池 -->
        <dependency>
            <groupId>commons-dbcp</groupId>
            <artifactId>commons-dbcp</artifactId>
            <version>1.4</version>
        </dependency>
        
        <!-- logback需要的一套依赖 -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.3</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>1.1.2</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.1.2</version>
        </dependency>
        
        <!-- spring基本支持 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        
        <!-- spring-jdbc，对事务等东东提供了支持 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        
    </dependencies>
    
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.5</version>
                <configuration>
                    <!-- 指定source和target的版本 -->
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

 只需要一个类就搞定，显然我没有在事务里做任何操作，因为这个不是重点。重点是我sleep了50秒，而我TransactionTemplate 的超时时间明明设置的是5秒，为毛没有超时呢

package com.demo.transaction.program;

import java.util.concurrent.TimeUnit;

import org.apache.commons.dbcp.BasicDataSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.TransactionStatus;
import org.springframework.transaction.support.AbstractPlatformTransactionManager;
import org.springframework.transaction.support.TransactionCallback;
import org.springframework.transaction.support.TransactionTemplate;

public class Main {

    private static Logger logger = LoggerFactory.getLogger(Main.class);

    public static void main(String[] args) {
        new Main().writeSysparam();
    }

    public void writeSysparam() {
        logger.debug("进入writeSysparam()方法");
        TransactionTemplate template = new TransactionTemplate();
        template.setTransactionManager(getTrasationManager());
        template.setTimeout(5);
        template.execute(new TransactionCallback<Object>() {
            @Override
            public Object doInTransaction(TransactionStatus status) {
                try {
                    TimeUnit.SECONDS.sleep(50);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                return null;
            }
        });
    }

    public AbstractPlatformTransactionManager getTrasationManager() {
        BasicDataSource dataSource = new BasicDataSource();
        dataSource.setDriverClassName("oracle.jdbc.OracleDriver");
        dataSource.setUrl("jdbc:oracle:thin:@localhost:1521/OPENBANKCOREDB");
        dataSource.setUsername("coredb");
        dataSource.setPassword("coredb");
        
        DataSourceTransactionManager transactionManager = new DataSourceTransactionManager();
        transactionManager.setDataSource(dataSource);
        return transactionManager;
    }
}

 关于对于事务超时时间的解释，有一片文章写得很好：http://jinnianshilongnian.iteye.com/blog/1986023

然后我们自己来梳理一下：

TransactionTemplate类继承自DefaultTransactionDefinition

template.setTimeout(5) 往里看是 this.timeout = 5;

那么这个timeout在哪里会用到呢，根据上面那篇博文的指引，是在

template.execute(...

---> this.transactionManager.getTransaction(this)   (TransactionTemplate类)

---> doBegin(transaction, definition); (抽象类AbstractPlatformTransactionManager或者说DataSourceTransactionManager类的实例)

在DataSourceTransactionManager中doBegin的实现中，有如下一段代码

　　　　　　　int timeout = determineTimeout(definition);
            if (timeout != TransactionDefinition.TIMEOUT_DEFAULT) {
                txObject.getConnectionHolder().setTimeoutInSeconds(timeout);
            }

其中determineTimeout(definition)就是从definition中取出timeout