@Autowired注入为null问题原因分析

<?xml version= "1.0" encoding= "utf-8" ?>

<beans xmlns= "http://www.springframework.org/schema/beans"

   xmlns:xsi= "http://www.w3.org/2001/xmlschema-instance"

   xmlns:context= "http://www.springframework.org/schema/context"

   xsi:schemalocation="

     http: //www.springframework.org/schema/beans

     http: //www.springframework.org/schema/beans/spring-beans.xsd

     http: //www.springframework.org/schema/context

     http: //www.springframework.org/schema/context/spring-context.xsd">

   <!-- spring注解扫描 -->

   <context:component-scan base- package = "com.*" />

   <!-- 1 . 数据源对象: c3p0连接池 -->

   <bean id= "datasource"

     class = "com.mchange.v2.c3p0.combopooleddatasource" >

     <property name= "driverclass" value= "org.h2.driver" ></property>

     <property name= "jdbcurl"

       value= "jdbc:h2:tcp://192.168.190.1/~/test" ></property>

     <property name= "user" value= "sa" ></property>

     <property name= "password" value= "123" ></property>

   </bean>

   <!-- 2 . jdbctemplate工具类实例 -->

   <bean id= "jdbctemplate"

     class = "org.springframework.jdbc.core.jdbctemplate" >

     <property name= "datasource" ref= "datasource" ></property>

   </bean>

   <!-- 3 .配置事务 -->

   <bean id= "datasourcetransactionmanager"

     class = "org.springframework.jdbc.datasource.datasourcetransactionmanager" >

     <property name= "datasource" ref= "datasource" ></property>

   </bean>

</beans>

public class test {

   public static void main(string[] args) {

     classpathxmlapplicationcontext classpathxmlapplicationcontext = new classpathxmlapplicationcontext(

         "spring.xml" );

     serviceif service = (serviceif) classpathxmlapplicationcontext.getbean( "serviceimpl" );

     service.add( "小王" , 23 );

   }

}

@component ( "transactionutil" )

public class transactionutil {

   /**

    * 初始化数据源

    */

   @autowired

   private datasourcetransactionmanager datasourcetransactionmanager;

   /**

    * 开启事务

    *

    * @return

    */

   public transactionstatus begin() {

     transactionstatus transaction = datasourcetransactionmanager.gettransaction( new defaulttransactiondefinition());

     system.out.println( " 开启事务成功 " );

     return transaction;

   }

   /**

    * 提交事物

    *

    * @param transaction

    */

   public void commit(transactionstatus transaction) {

     datasourcetransactionmanager.commit(transaction);

     system.out.println( " 事物提交成功 " );

   }

   /**

    * 回滚事务

    *

    * @param transaction

    */

   public void rollback(transactionstatus transaction) {

     datasourcetransactionmanager.rollback(transaction);

     system.err.println( " 事物进行回滚 " );

   }

}

@service ( "serviceimpl" )

public class serviceimpl implements serviceif {

   @autowired

   transactionutil transactionutil;

   private transactionstatus transactionstatus = null ;

   @override

   public void add(string name, integer age) {

     transactionstatus = transactionutil.begin();

     try {

       new daoimpl().add(name, age);

       transactionutil.commit(transactionstatus);

     } catch (exception e) {

       system.err.println( "error >>> 执行出现异常 即将进行回滚操作" );

       transactionutil.rollback(transactionstatus);

     }

   }

}

public class daoimpl implements daoif{

   /**

    * 注入jdbc模板类

    */

   @autowired

   private jdbctemplate jdbctemplate;

   /**

    * 第一条插入语句

    */

   private final string sql_insert_01 = "insert into user values (?,?)" ;

   /**

    * 添加sql执行

    *

    * @param name

    * @param age

    */

   public void add(string name, integer age) {

     jdbctemplate.update(sql_insert_01, name, age);

   }

}