4.3---Spring框架之Spring中bean的注入方式---（深入版本）

Posted 2023-04-05 奔赴在自己的热爱中

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Spring基于xml注入bean的几种方式：

set()方法注入；
2.构造器注入：①通过index设置参数的位置；②通过type设置参数类型；
静态工厂注入；
实例工厂；

Spring IOC注入方式用得最多的是(1)(2)种；
注意：通过Spring创建的对象默认是单例的，如果需要创建多实例对象可以在标签后面添加一个属性：

<bean name="..." class="..." scope="prototype">

1、Set()注入：

假设有一个SpringAction，类中需要实例化一个SpringDao对象，那么就可以定义一个private的SpringDao成员变量，然后创建SpringDao的set方法（这是ioc的注入入口）：

package com.bless.springdemo.action; 
public class SpringAction  
    //注入对象springDao 
    private SpringDao springDao; 
    //一定要写被注入对象的set方法 
    public void setSpringDao(SpringDao springDao)  
    this.springDao = springDao; 
 
 
public void ok() 
    springDao.ok();

随后编写spring的xml文件中，name属性是class属性的一个别名，class属性指类的全名，因为在SpringAction中有一个公共属性Springdao，所以要在标签中创建一个标签指定SpringDao。标签中的name就是SpringAction类中的SpringDao属性名，ref指下面，这样其实是spring将SpringDaoImpl对象实例化并且调用SpringAction的setSpringDao方法将SpringDao注入：

<!--配置bean,配置后该类由spring管理--> 
<bean name="springAction" class="com.bless.springdemo.action.SpringAction"> 
<!--(1)依赖注入,配置当前类中相应的属性--> 
<property name="springDao" ref="springDao"></property> 
</bean> 
<bean name="springDao" class="com.bless.springdemo.dao.impl.SpringDaoImpl"></bean>

2、构造器注入：

这种方式的注入是指带有参数的构造函数注入，创建了两个成员变量SpringDao和User，注入方式是在SpringAction的构造函数中注入，也就是说在创建SpringAction对象时要将SpringDao和User两个参数值传进来：

public class SpringAction  
    //注入对象springDao 
    private SpringDao springDao; 
    private User user; 
 
    public SpringAction(SpringDao springDao,User user) 
    this.springDao = springDao; 
    this.user = user; 
    System.out.println("构造方法调用springDao和user"); 
 
 
public void save() 
    user.setName("哈哈"); 
    springDao.save(user);

在XML文件中使用标签，ref属性同样指向其它标签的name属性：

<!--配置bean,配置后该类由spring管理--> 
<bean name="springAction" class="com.bless.springdemo.action.SpringAction"> 
<!--(2)创建构造器注入,如果主类有带参的构造方法则需添加此配置--> 
<constructor-arg ref="springDao"></constructor-arg> 
<constructor-arg ref="user"></constructor-arg> 
</bean> 
<bean name="springDao" class="com.bless.springdemo.dao.impl.SpringDaoImpl"></bean> 
<bean name="user" class="com.bless.springdemo.vo.User"></bean>

解决构造方法参数的不确定性：
1.下面是设置index，就是参数位置：

<bean name="springAction" class="com.bless.springdemo.action.SpringAction"> 
<constructor-arg index="0" ref="springDao"></constructor-arg> 
<constructor-arg index="1" ref="user"></constructor-arg> 
</bean>

2.另一种是设置参数类型：

<constructor-arg type="java.lang.String" ref=""/>

spring框架事务注解配置方式

user=LF
password=LF
jdbcUrl=jdbc:oracle:thin:@localhost:1521:orcl
driverClass=oracle.jdbc.driver.OracleDriver

initialPoolSize=15
maxPoolSize=30
minPoolSize=5

<?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" 
    xmlns:tx="http://www.springframework.org/schema/tx"
    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
    http://www.springframework.org/schema/tx 
    http://www.springframework.org/schema/tx/spring-tx.xsd
    http://www.springframework.org/schema/aop 
    http://www.springframework.org/schema/aop/spring-aop.xsd"> 
    
    <!-- 配置自动扫描的包 -->
    <context:component-scan base-package="com.zr.trasaction"></context:component-scan>
    
    <!-- 引用外部文件 -->
    <context:property-placeholder location="classpath:db.properties"/>
    
    <!-- 配置dataSource -->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="user" value="${user}"></property>
        <property name="password" value="${password}"></property>
        <property name="jdbcUrl" value="${jdbcUrl}"></property>
        <property name="driverClass" value="${driverClass}"></property>
        
        <property name="initialPoolSize" value="${initialPoolSize}"></property>
        <property name="maxPoolSize" value="${maxPoolSize}"></property>
        <property name="minPoolSize" value="${minPoolSize}"></property>
    </bean>
    <!-- 配置jdbcTemplate -->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"></property>
    </bean>
    
    <!-- 配置事务管理器 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"></property>
    </bean>
    <!-- 配置事务声明方式 -->
    <tx:annotation-driven transaction-manager="transactionManager"/>
    
</beans>

package com.zr.trasaction.entity;



public class Amount {
    
    private String user;//用户名
    private double money;//金额
    public String getUser() {
        return user;
    }
    public void setUser(String user) {
        this.user = user;
    }
    public double getMoney() {
        return money;
    }
    public void setMoney(double money) {
        this.money = money;
    }
    public Amount() {
        super();
    }
    public Amount(String user, double money) {
        super();
        this.user = user;
        this.money = money;
    }
    @Override
    public String toString() {
        return "Amount [user=" + user + ", money=" + money + "]";
    }
    
    
    

}

package com.zr.trasaction.entity;

public class BalanceException extends RuntimeException {

    private static final long serialVersionUID = 1L;


    public BalanceException() {
        super();
    }

    public BalanceException(String message) {
        super(message);
    }

    public BalanceException(String message, Throwable cause) {
        super(message, cause);
    }

    
    public BalanceException(Throwable cause) {
        super(cause);
    }

   
    protected BalanceException(String message, Throwable cause,
                               boolean enableSuppression,
                               boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
    }
}

package com.zr.trasaction.dao;

public interface AmountDao {

    /**
     * 转出钱
     * @return
     */
    public boolean decreaseMoney(String username,double money) ;
    
    /**
     * 转入钱
     * @return
     */
    public boolean increaseMoney(String username,double money);
    
}

package com.zr.trasaction.daoImpl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

import com.zr.trasaction.dao.AmountDao;

@Repository
public class AmountDaoImpl implements AmountDao {
    @Autowired(required=true)
    private JdbcTemplate jdbcTemplate;
    
    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

    @Override
    public boolean decreaseMoney(String username, double money) {
        
        String sql = "UPDATE TEST SET MONEY=MONEY-? WHERE USERNAME=?";
        int i = -1;
        i = jdbcTemplate.update(sql,money, username);
        if(i>0){
            return true;
        }
        return false;
    }

    @Override
    public boolean increaseMoney(String username, double money) {
        String sql = "UPDATE TEST SET MONEY=MONEY+? WHERE USERNAME=?";
        int i = -1;
        i = jdbcTemplate.update(sql,money, username);
        if(i>0){
            return true;
        }
        return false;
    }

}

package com.zr.trasaction.Service;

import com.zr.trasaction.entity.Amount;

public interface AmountService {

    /**
     * 转账业务
     * @param desAmount 扣钱的账户
     * @param incAmount    增加的账户
     * @param money 转账的金额
     * @return
     */
    public boolean transferMoneyService(Amount desAmount,Amount incAmount,double money);
    
}

package com.zr.trasaction.ServiceImpl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Isolation;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

import com.zr.trasaction.Service.AmountService;
import com.zr.trasaction.daoImpl.AmountDaoImpl;
import com.zr.trasaction.entity.Amount;
import com.zr.trasaction.entity.BalanceException;

@Service("amountServiceImpl")
public class AmountServiceImpl implements AmountService {
    @Autowired(required=true)
    private AmountDaoImpl amountDaoImpl;
    @Autowired(required=true)
    private JdbcTemplate jdbcTemplate;

    public void setAmountDaoImpl(AmountDaoImpl amountDaoImpl) {
        this.amountDaoImpl = amountDaoImpl;
    }

    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }
    /**
     *    REQUIRED（默认值）:在有transaction状态下执行;如当前没有transaction，则创建新的transaction
     * 只读事务属性readOnly=true: 表示这个事务只读取数据但不更新数据, 这样可以帮助数据库引擎优化事务
     * 超时事务属性timeout=3: 事务在强制回滚之前可以保持多久. 这样可以防止长期运行的事务占用资源.单位为秒,一般不设置，使用默认的
     * noRollbackForClassName={"BalanceException"} 发生BalanceException异常不回滚
     */
    @Transactional(propagation=Propagation.REQUIRED,isolation=Isolation.READ_COMMITTED,readOnly=true,timeout=3/*,noRollbackForClassName={"BalanceException"}*/)
    @Override
    public boolean transferMoneyService(Amount desAmount, Amount incAmount,
            double money) {
        String sql = "SELECT MONEY FROM TEST WHERE USERNAME=?";
        double balance = jdbcTemplate.queryForObject(sql, Double.class, desAmount.getUser());

        boolean success1 = amountDaoImpl.decreaseMoney(desAmount.getUser(), money);
        boolean success2 = amountDaoImpl.increaseMoney(incAmount.getUser(), money);
        
        if(balance < money){
            throw new BalanceException("余额不足");
        }
        return success1 && success2;
    }

}

package com.zr.trasaction.test;

import javax.sql.DataSource;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jdbc.core.JdbcTemplate;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import com.zr.trasaction.Service.AmountService;
import com.zr.trasaction.ServiceImpl.AmountServiceImpl;
import com.zr.trasaction.daoImpl.AmountDaoImpl;
import com.zr.trasaction.entity.Amount;

public class TestA {

    public static void main(String[] args) {
        
        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
        
        
        Amount desAmount = new Amount("lf", 0);
        Amount incAmount = new Amount("tl", 0);
        AmountService impl = (AmountService) ac.getBean("amountServiceImpl");
        boolean isSuccess = impl.transferMoneyService(desAmount, incAmount, 10);
                 
        
    }
    
    
}

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