Spring （五）Spring之数据访问与事务管理

梦里梦外; 2023-06-11 03:28 108阅读 0赞

## 个人博客网：[https://wushaopei.github.io/][https_wushaopei.github.io]    (你想要这里多有) ##

## 一、Spring之数据访问 ##

### 1、Spring数据访问工程环境搭建 ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70][]

**jdbc.properties配置文件：**

jdbc.user=root
    jdbc.password=root
    jdbc.driverClass=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql://localhost:3306/jdbctemplate

applicationContext.xml配置文件：

<context:property-placeholder location="classpath:jdbc.properties"/>
 	
 	<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"> 
 		<property name="user" value="${jdbc.user}" />
 		<property name="password" value="${jdbc.password}" />
 		<property name="driverClass" value="${jdbc.driverClass}" />
 		<property name="jdbcUrl" value="${jdbc.url}" />
 	</bean>
 	
 	
 	<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
 		<property name="dataSource" ref="dataSource"/>
 	</bean>

测试代码：

@Test
         public void testDataSource() throws Exception {
    	ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
    	DataSource dataSource = (DataSource) applicationContext.getBean("dataSource");
    	System.out.println( dataSource.getConnection() );
    	System.out.println(applicationContext.getBean("jdbcTemplate"));
        }

### **2、Spring之JdbcTemplate使用** ###

在Spring中提供了对jdbc的封装类叫JdbcTemplate。它可以很方便的帮我们执行sql语句，操作数据库。

先准备单表的数据库数据

drop database  if exists jdbctemplate;
    
    create database jdbctemplate;
    
    use jdbctemplate;
    
    CREATE TABLE `employee` (
      `id` int(11) primary key AUTO_INCREMENT,
      `name` varchar(100) DEFAULT NULL,
      `salary` decimal(11,2) DEFAULT NULL
    );
    
    insert  into `employee`(`id`,`name`,`salary`) 
    values (1,'李三',5000.23),(2,'李四',4234.77),(3,'王五',9034.51),
    (4,'赵六',8054.33),(5,'孔七',6039.11),(6,'曹八',7714.11);
    
    select * from employee;

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 1][]

**创建一个与数据库表对应的javaBean类**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 2][]

### 3、将id=5的记录的salary字段更新为1300.00 ###

@ContextConfiguration(locations="classpath:applicationContext.xml")
    @RunWith(SpringJUnit4ClassRunner.class)
    public class JdbcTempalteTest {
    	@Autowired
    	JdbcTemplate jdbcTemplate;
    	@Test
    	public void test2() throws Exception {
    		// 实验2：将id=5的记录的salary字段更新为1300.00
    		String sql = "update employee set salary = ? where id = ?";
    		System.out.println( jdbcTemplate.update(sql, new BigDecimal(1300),5) );
    	}
    }

### 4、批量插入 ###

@Test
 	public void test3() throws Exception {
 		String sql = "insert into employee(`name`,`salary`) values(?,?)";
 //		jdbcTemplate.update(sql, "尚硅谷94V587",new BigDecimal(100000)); //插入一条
 		
 		List<Object[]> batchArgs = new ArrayList<Object[]>();
 		batchArgs.add(new Object[] {"新来的1",new BigDecimal(30000)});
 		batchArgs.add(new Object[] {"新来的2",new BigDecimal(40000)});
 		batchArgs.add(new Object[] {"新来的3",new BigDecimal(50000)});
 		
 		jdbcTemplate.batchUpdate(sql, batchArgs);
 	}

分析图解：

![20191028231704713.png][]

数据库结果：

![20191028231724919.png][]

### 5、查询id=5的数据库记录，封装为一个Java对象返回 ###

@Test
 	public void test4() throws Exception {
 		String sql = "select id,name,salary from employee where id = ?";
 //		rowMapper是将查询到的ResultSet的每一行记录转换成为一个javaBean对象
 			
 		Employee employee = jdbcTemplate.queryForObject(sql, new BeanPropertyRowMapper<Employee>(Employee.class), 5);
 		System.out.println( employee );
 	}

![20191028231757823.png][]

### 6、查询salary>4000的数据库记录，封装为List集合返回 ###

public void test5() throws Exception {
 //	QueryRunner
 //		update()	====>>>>		insert、update、delete
 //		到底是查一条，还是查多条记录，由ResultSetHandler决定
 //	Jdbctempalte
 //		update()	====>>>>		insert、update、delete
 //	queryForObject		查一个对象
 //	query				查多个对象
 		
 	String sql = "select id,name,salary from employee where salary > ?";
 	List<Employee> employees = jdbcTemplate.query(sql,
 			new BeanPropertyRowMapper<Employee>(Employee.class), new BigDecimal(4000));
 	employees.forEach(System.out::println);
 	}

### 7、查询最大salary ###

@Test
    	public void test6() throws Exception {
    		String sql = "select max(salary) from employee";
    		BigDecimal maxSalary = jdbcTemplate.queryForObject(sql, BigDecimal.class);
    		System.out.println( maxSalary );
    	}

### 8、**使用带有具名参数的SQL语句插入一条员工记录，并以Map形式传入参数值** ###

配置*NamedParameterJdbcTemplate*

<bean id="namedParameterJdbcTemplate" 
 		class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">
 		<constructor-arg index="0" ref="dataSource" />
 	</bean>

**Test中添加以下注解，用于注入xml中解析执行具名参数所用**

![20191028232009488.png][]

@Test
 	public void test7() throws Exception {
 		/**
 		 * :name	就是占位符，参数。名是name。	一起，就是具名参数
 		 */
 		String sql = "insert into employee(`name`,`salary`) values(:name,:salary)";
 		
 		Map<String, Object>paramMap = new HashMap<>();
 		paramMap.put("name", "这是具名参数的name");
 		paramMap.put("salary", new BigDecimal(100000));
 		
 		namedParameterJdbcTemplate.update(sql, paramMap);
 	}

**Mysql 结果：**

![20191028232105788.png][]

### 9、**重复8，以SqlParameterSource形式传入参数值** ###

@Test
    	public void test8() throws Exception {
    		/**
    		 * :name	就是占位符，参数。名是name。		一起，就是具名参数
    		 */
    		String sql = "insert into employee(`name`,`salary`) values(:name,:salary)";
    		Employee employee = new Employee(null, "新插入的帅哥", new BigDecimal(3000));
    		namedParameterJdbcTemplate.update(sql, new BeanPropertySqlParameterSource(employee));
    	}

### 10、**创建Dao，自动装配JdbcTemplate对象** ###

@Repository
 public class EmployeeDao {
 
 	@Autowired
 	private JdbcTemplate jdbcTemplate;
 	
 	public Employee queryEmployeeById(Integer id) {
 		String sql = "select id,name,salary from employee where id = ?";
 		Employee employee = jdbcTemplate.queryForObject(sql,
 				new BeanPropertyRowMapper<Employee>(Employee.class), id);
 		return employee;
 	}
 	
 }

配置内容：

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

测试代码：

@ContextConfiguration(locations = "classpath:applicationContext.xml")
    @RunWith(SpringJUnit4ClassRunner.class)
    public class JdbcTempalteTest {
    
    	@Autowired
    	JdbcTemplate jdbcTemplate;
    	
    	@Autowired
    	NamedParameterJdbcTemplate namedParameterJdbcTemplate;
    	
    	@Autowired
    	EmployeeDao employeeDao;
    
    	@Test
    	public void test9() throws Exception {
    		System.out.println( employeeDao.queryEmployeeById(1) );
    	}
    }

### 11、通过继承JdbcDaoSupport创建JdbcTemplate的Dao ###

@Repository
 public class EmployeeDao extends JdbcDaoSupport {
 
 //	@Autowired
 //	private JdbcTemplate jdbcTemplate;
 	
 	public Employee queryEmployeeById(Integer id) {
 		String sql = "select id,name,salary from employee where id = ?";
 		Employee employee = getJdbcTemplate().queryForObject(sql,
 				new BeanPropertyRowMapper<Employee>(Employee.class), id);
 		return employee;
 	}
 	
 	@Autowired
 	public void setJdbcTemplate2(JdbcTemplate jdbcTemplate) {
 		setJdbcTemplate(jdbcTemplate);
 	}
 	
 }

**源码分析方法实现与调用过程：**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 3][]

## 二、声明式事务 ##

事务分为**声明式**和编程式两种:

> **声明式事务：**声明式事务是指通过注解（和xml配置）的形式对事务的各种特性进行控制和管理。
> 
> **编码式（编程式）事务：**指的是通过编码的方式实现事务的声明。

### 1、编码方式实现事务： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 4][]

### 2、**声明式事务环境搭建** ###

### **2.1、准备测试数据库** ###

##创建tx数据库
    drop database if exists `tx`;
    CREATE database `tx`;
    ##切换tx数据库
    USE `tx`;
    
    ##删除用户表
    DROP TABLE IF EXISTS `user`;
    ##创建用户表
    CREATE TABLE `user` (
      `id` int primary key auto_increment,	
      `username` varchar(50) NOT NULL,
      `money` int(11) DEFAULT NULL
    );
    ##插入数据
    insert  into `user`(`username`,`money`) values ('张三',1000),('李四',1000);
    
    ##删除图书表
    drop table if exists `book`;
    ##创建图书表
    create table `book`(
        `id` int primary key auto_increment,
        `name` varchar(500) not null,
        `stock` int
    );
    ##插入数据
    insert into book(`name`,`stock`) values('java编程思想',100),('C++编程思想',100);
    
    ##查看数据
    select * from book;
    select * from user;

### **   2.2、创建一个Java工程，导入Jar包** ###

![20191028232658171.png][]

@Repository
    public class UserDao {
    
    	@Autowired
    	JdbcTemplate jdbcTemplate;
    
    	public void updateUser() {
    		jdbcTemplate.update("update user set username = '用户表被修改了'");
    	}
    }
    
    @Repository
    public class BookDao {
    
    	@Autowired
    	JdbcTemplate jdbcTemplate;
    
    	public void updateBook() {
    		jdbcTemplate.update("update book set name = '图书表被修改了'");
    	}
    }

Service

@Service
    public class TransactionService {
    
    	@Autowired
    	private UserDao userDao;
    
    	@Autowired
    	private BookDao bookDao;
    
    	public void multiUpdate() {
    		userDao.updateUser();
    		int i = 12 / 0 ;
    		bookDao.updateBook();
    	}
    
    }

### **3、测试Service的默认事务** ###

【1】测试service服务层的默认事务

默认一个sql一个事务

@ContextConfiguration(locations="classpath:applicationContext.xml")
    @RunWith(SpringJUnit4ClassRunner.class)
    public class SpringTest {
    	
    	@Autowired
    	TransactionService transactionService;
    
    	@Test
    	public void testMultiUpdate() throws Exception {
    		transactionService.multiUpdate();
    	}
    	
    }

**异常的演示**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 5][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 6][]

### **Spring事务引入的分析------PlatformTransactionManager类简单介绍** ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 7][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 8][]

### 4、使用Spring的注解声明事务管制 ###

【1】测试Spring的声明式事务

TransactionService中的修改

/**
    	 * @Transactional表示当前方法有事务管理
    	 */
    	@Transactional
    	public void multiUpdate() {
    		userDao.updateUser();
    //		int i = 12 / 0 ;
    		bookDao.updateBook();
    	}

配置文件中的内容：

<bean id="transactionManager" 
 		class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
 		
 		<property name="dataSource" ref="dataSource" />	
 	</bean>
 	
 	
 	<tx:annotation-driven transaction-manager="transactionManager"/>

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 9][]

## **5、noRollbackFor和noRollbackForClassName测试不回滚的异常** ##

【1】noRollbackFor和noRollbackForClassName测试不回滚的异常

/**
 	 * @throws FileNotFoundException 
 	 * @Transactional表示当前方法有事务管理 
 	 * 	Spring底层默认是回滚运行时异常，以运行时子异常 
 	 * noRollbackFor设置哪些异常不回滚事务 
 	 * noRollbackForClassName设置哪些类型的异常不回滚事务 
 	 */
 	@Transactional(noRollbackForClassName="java.lang.ArithmeticException")
 	public void multiUpdate() throws FileNotFoundException {
 		userDao.updateUser();
 		int i = 12 / 0 ;
 		bookDao.updateBook();
 	}

运行时异常回滚

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 10][]

**编译异常：不回滚**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 11][]

### **6、自定义设置回滚异常** ###

【1】rollbackFor和rollbackForClassName回滚的异常

/**
 	 * @throws FileNotFoundException 
 	 * @Transactional表示当前方法有事务管理 
 	 * 	Spring底层默认是回滚运行时异常，以运行时子异常 
 	 * 	rollbackFor是设置哪个异常回滚事务 
 	 * rollbackForClassName是设置哪个异常类名也会回滚事务 
 	 */
 	@Transactional()
 	public void multiUpdate() throws FileNotFoundException {
 		userDao.updateUser();
 //		int i = 12 / 0 ;
 		int i = 12 ;
 		if (i == 12) {
 			throw new FileNotFoundException("asdf");
 		}
 		bookDao.updateBook();
 	}

### 7、事务的只读属性 ###

实验4：测试readOnly只读属性

/**
 	 * @throws FileNotFoundException 
 	 * @Transactional表示当前方法有事务管理 
 	 * 	Spring底层默认是回滚运行时异常，以运行时子异常 
 	 * readOnly 设置当前执行的sql语句是不是只是select查询
 	 * 	如果设置为false就允许执行insert，delete、update
 	 */
 	@Transactional(readOnly=true)
 	public void multiUpdate() throws FileNotFoundException {
 		userDao.updateUser();
 		bookDao.updateBook();
 	}

![2019102823350077.png][]

### **8、事务超时属性timeout(秒为单位)** ###

/**
 	 * @throws FileNotFoundException 
 	 * @throws InterruptedException 
 	 * @Transactional表示当前方法有事务管理 
 	 * 	Spring底层默认是回滚运行时异常，以运行时子异常 
 	 * timeout设置连接的超时属性。
 	 * timeout=3表示3秒后不允许再执行sql语句
 	 */
 	@Transactional(timeout=3)
 	public void multiUpdate() throws InterruptedException {
 		userDao.updateUser();
 		Thread.sleep(4000);
 		bookDao.updateBook();
 	}

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 12][]

### **10、事务的传播特性propagation** ###

> **什么是事务的传播行为：**
> 
> 当事务方法被另一个事务方法调用时，必须指定事务应该如何传播。例如：方法可能继续在现有事务中运行，也可能开启一个新事务，并在自己的事务中运行。

事务的传播行为可以由传播属性指定。Spring定义了7种类传播行为。

事务的传播特性，有以下几种类型：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 13][]

### **11、注解演示事物传播特性** ###

**UserService**

**BookService**

**TransactionService**

**实验1：大小事务传播特性都是*REQUIRED***

@Transactional(propagation = Propagation.REQUIRED)
    	public void multiTransaction() {
    	@Transactional(propagation = Propagation.REQUIRED)
    	public void updateBook() {
            @Transactional(propagation=Propagation.REQUIRED)
            public void updateUser() {

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 14][]

**实验2：大小事务传播特性都是*REQUIRES\_NEW***

@Transactional(propagation = Propagation.REQUIRES_NEW)
    	public void multiTransaction()
    	@Transactional(propagation = Propagation.REQUIRES_NEW)
    	public void updateBook()
    	@Transactional(propagation = Propagation.REQUIRES_NEW)
    	public void updateUser()

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 15][]

**实验3：大事务是*REQUIRED*，小事务都是*REQUIRES\_NEW***

@Transactional(propagation = Propagation.REQUIRED)
    	public void multiTransaction()
    	@Transactional(propagation = Propagation.REQUIRES_NEW)
    	public void updateBook()
    	@Transactional(propagation = Propagation.REQUIRES_NEW)
    	public void updateUser()

实验3跟实验2一样。

**实验4：大事务是*REQUIRED*，小1*REQUIRED*，小2*REQUIRES\_NEW***

@Transactional(propagation = Propagation.REQUIRED)
    	public void multiTransaction()
    	@Transactional(propagation = Propagation.REQUIRED)
    	public void updateBook()
    	@Transactional(propagation = Propagation.REQUIRES_NEW)
    	public void updateUser()

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 16][]

## 三、**xml配置式事务声明** ##

> 去掉。所有@Transactional的注解。

配置文件内容：

<?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"
 	xmlns:aop="http://www.springframework.org/schema/aop"
 	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/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
 		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
 
 	<context:component-scan base-package="com.webcode"></context:component-scan>
 
 		
 	<context:property-placeholder location="classpath:jdbc.properties"/>
 	
 	<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"> 
 		<property name="user" value="${jdbc.user}" />
 		<property name="password" value="${jdbc.password}" />
 		<property name="driverClass" value="${jdbc.driverClass}" />
 		<property name="jdbcUrl" value="${jdbc.url}" />
 	</bean>
 	
 	
 	<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
 		<property name="dataSource" ref="dataSource"/>
 	</bean>
 	
 	
 	<bean id="transactionManager" 
 		class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
 		<property name="dataSource" ref="dataSource" />	
 	</bean>
 	
 	
 	<tx:advice id="tx_advice" transaction-manager="transactionManager">
 		<tx:attributes>
 			
 			<tx:method name="save*" propagation="REQUIRED"/>
 			<tx:method name="update*" propagation="REQUIRED"/>
 			<tx:method name="delete*" propagation="REQUIRED"/>
 			
 			<tx:method name="multiTransaction" propagation="REQUIRED"/>
 			<tx:method name="updateUser" propagation="REQUIRES_NEW"/>
 			
 			<tx:method name="*" read-only="true"/>
 		</tx:attributes>
 	</tx:advice>
 	
 	
 	<aop:config>
 		
 		<aop:advisor advice-ref="tx_advice" 
 			pointcut="execution(public * com.webcode.service..*Service*.*(..))"/>
 	</aop:config>
 
 </beans>

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjQwNTY3MA_size_16_color_FFFFFF_t_70 17][]

## 四、**Spring整合Web** ##

### 1、在web工程中添加Spring的jar包 ###

Spring的核心包
        spring-beans-4.0.0.RELEASE.jar
        spring-context-4.0.0.RELEASE.jar
        spring-core-4.0.0.RELEASE.jar
        spring-expression-4.0.0.RELEASE.jar
    aop包
        spring-aop-4.0.0.RELEASE.jar
        spring-aspects-4.0.0.RELEASE.jar
        com.springsource.org.aopalliance-1.0.0.jar
        com.springsource.org.aspectj.weaver-1.6.8.RELEASE.jar
    JDBC-ORM包
        spring-jdbc-4.0.0.RELEASE.jar
        spring-orm-4.0.0.RELEASE.jar
        spring-tx-4.0.0.RELEASE.jar
    Spring的web整合包
        spring-web-4.0.0.RELEASE.jar
    测试包
        spring-test-4.0.0.RELEASE.jar

>  *  ServletContext在web工程启动的时候创建
>  *  在Web工程停止的时候销毁

整合Spring和Web容器分两个步骤：

> 1、导入spring-web-4.0.0.RELEASE.jar
> 
> 2、在web.xml配置文件中配置org.springframework.web.context.ContextLoaderListener监听器监听ServletContext的初始化
> 
> 3、在web.xml配置文件中配置contextConfigLocation上下文参数。配置Spring配置文件的位置，以用于初始化Spring容器

**在web.xml中配置**

<context-param>
 	<param-name>contextConfigLocation</param-name>
 	<param-value>classpath:applicationContext.xml</param-value>
 </context-param>
 <listener>
 	<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
 </listener>

**获取WebApplicationContext上下文对象的方法如下：**

**方法一（推荐）：**

WebApplicationContextUtils.*getWebApplicationContext*(getServletContext())

方法二（不推荐）：

getServletContext().getAttribute(WebApplicationContext.*ROOT\_WEB\_APPLICATION\_CONTEXT\_ATTRIBUTE*);

[https_wushaopei.github.io]: https://wushaopei.github.io/
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