struts2.3.24 + spring4.1.6 + hibernate4.3.11+ mysql5.5.25开发环境搭建及相关说明。
一、目标
1、搭建传统的ssh开发环境,并成功运行(插入、查询)
2、了解c3p0连接池相关配置
3、了解验证hibernate的二级缓存,并验证
4、了解spring事物配置,并验证
5、了解spring的IOC(依赖注入),将struts2的action对象(bean)交给spring管理,自定义bean等...并验证
6、了解spring aop(面向切面编程),并编写自定义切面函数,验证结果
二、前期准备
开发环境:eclipse for java ee;mysql5.5.25;jdk1.7.0_79;navicat10.1.7(可选);
创建数据库demo:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
|
/*
Navicat MySQL Data Transfer
Source Server : localhost_3306
Source Server Version : 50519
Source Host : localhost:3306
Source Database : demo
Target Server Type : MYSQL
Target Server Version : 50519
File Encoding : 65001
Date : 2016-01-09 23:36:02
*/
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for `user`
-- ----------------------------
DROP TABLE IF EXISTS ` user `;
CREATE TABLE ` user ` (
`id` bigint (20) NOT NULL AUTO_INCREMENT,
`account` varchar (200) NOT NULL ,
` name ` varchar (200) NOT NULL ,
`address` varchar (1000) NOT NULL ,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
|
新建web工程,目录结构如下:
jar包准备,放到WEB-INF的lib目录下(有兴趣的可以用maven管理过程,但是有时候下载jar包很慢...)
相关jar包都可以在下载下来的struts、spring、hibernate中找到,这里给个参考,有些是可以删除的,比如spring mvc部分的jar包:
三、配置web.xml
配置一个struts2的filter,映射所有*.action请求,由StrutsPrepareAndExecuteFilter对象来处理;
配置context-param参数,指定spring配置文件的路径,<context-param>中的参数可以用ServletContext.getInitParameter(“param-name”)来获取;
配置listener,主要是读取applicationContext.xml配置文件信息,创建bean等初始化工作;
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
|
<? xml version = "1.0" encoding = "UTF-8" ?>
< web-app xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" xmlns = "http://java.sun.com/xml/ns/javaee" xsi:schemaLocation = "http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id = "WebApp_ID" version = "3.0" >
< display-name >SSH</ display-name >
< filter >
< filter-name >struts2</ filter-name >
< filter-class >org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</ filter-class >
</ filter >
< filter-mapping >
< filter-name >struts2</ filter-name >
< url-pattern >*.action</ url-pattern >
</ filter-mapping >
< 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 >
< welcome-file-list >
< welcome-file >index.jsp</ welcome-file >
</ welcome-file-list >
</ web-app >
|
四、配置applicationContext.xml
配置自动扫描ssh包下的@Repostory,@Service等注解,并生成对应的bean;
配置数据源(jdbc连接池为c3p0,可以参考c3p0的详细配置),连接池主要作用是快速提供connection,重复利用,不需要每次销毁创建,需配置用户名、密码、最大连接数、最小连接数、初始连接数等相关参数;
配置sessionFactory(可以参考hibernate的详细配置,这里配置开启二级缓存),主要作用是提供session,执行sql语句;这里我们将会通过HibernateTemplate来对数据库进行操作,方便spring进行实物控制;ps,hibernate配置中还要配置类与数据库表的映射;
配置事务管理器bean为HibernateTransactionManager,并把成员属性sessionFactory初始化为之前配置的sessionFactory bean;
配置事务的传播特性,并配置一个切面引用它,对所有ssh.service包及子包下所有add、delete、update、save方法进行事务控制,还可以配置事务传播行为等参数;
最后是一个自定义aop相关配置,对ssh.aop.AopTest下所有test开头的方法应用自定义切面‘myAop'进行控制,后续会验证结果;
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
|
<? xml version = "1.0" encoding = "UTF-8" ?>
< beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:p = "http://www.springframework.org/schema/p"
xmlns:context = "http://www.springframework.org/schema/context"
xmlns:tx = "http://www.springframework.org/schema/tx"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop = "http://www.springframework.org/schema/aop"
xmlns:jdbc = "http://www.springframework.org/schema/jdbc"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-4.1.xsd
http://www.springframework.org/schema/jdbc
http://www.springframework.org/schema/jdbc/spring-jdbc-4.1.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.1.xsd">
<!-- scans the classpath for annotated components (including @Repostory
and @Service that will be auto-registered as Spring beans -->
< context:component-scan base-package = "ssh" />
<!--配数据源 -->
< bean name = "dataSource" class = "com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method = "close" >
< property name = "driverClass" value = "com.mysql.jdbc.Driver" />
< property name = "jdbcUrl" value = "jdbc:mysql://localhost:3306/demo" />
< property name = "user" value = "root" />
< property name = "password" value = "root" />
< property name = "acquireIncrement" value = "1" ></ property >
< property name = "initialPoolSize" value = "80" ></ property >
< property name = "maxIdleTime" value = "60" ></ property >
< property name = "maxPoolSize" value = "80" ></ property >
< property name = "minPoolSize" value = "30" ></ property >
< property name = "acquireRetryDelay" value = "1000" ></ property >
< property name = "acquireRetryAttempts" value = "60" ></ property >
< property name = "breakAfterAcquireFailure" value = "false" ></ property >
<!-- 如出现Too many connections, 注意修改mysql的配置文件my.ini,增大最多连接数配置项,(查看当前连接命令:show processlist) -->
</ bean >
< bean id = "sessionFactory" class = "org.springframework.orm.hibernate4.LocalSessionFactoryBean" >
< property name = "dataSource" ref = "dataSource" />
< property name = "hibernateProperties" >
< props >
< prop key = "hibernate.dialect" >org.hibernate.dialect.MySQLDialect</ prop >
< prop key = "hibernate.show_sql" >true</ prop >
< prop key = "hibernate.hbm2ddl.auto" >update</ prop >
< prop key = "current_session_context_class" >thread</ prop >
< prop key = "hibernate.cache.use_second_level_cache" >true</ prop >
< prop key = "hibernate.cache.region.factory_class" >org.hibernate.cache.ehcache.EhCacheRegionFactory</ prop >
< prop key = "hibernate.cache.use_query_cache" >true</ prop >
< prop key = "hibernate.cache.provider_configuration_file_resource_path" >ehcache.xml</ prop >
</ props >
</ property >
< property name = "mappingLocations" >
< list >
< value >classpath:ssh/model/User.hbm.xml</ value >
</ list >
</ property >
<!--
<property name="annotatedClasses">
<list>
<value>ssh.model.User</value>
</list>
</property>
-->
</ bean >
<!-- 配置事务管理器 -->
< bean id = "transactionManager"
class = "org.springframework.orm.hibernate4.HibernateTransactionManager" >
< property name = "sessionFactory" ref = "sessionFactory" />
</ bean >
<!-- 事务的传播特性 -->
< tx:advice id = "txadvice" transaction-manager = "transactionManager" >
< tx:attributes >
< tx:method name = "add*" propagation = "REQUIRED" read-only = "false" rollback-for = "java.lang.Exception" />
< tx:method name = "delete*" propagation = "REQUIRED" read-only = "false" rollback-for = "java.lang.Exception" />
< tx:method name = "update*" propagation = "REQUIRED" read-only = "false" rollback-for = "java.lang.Exception" />
< tx:method name = "save*" propagation = "REQUIRED" read-only = "false" rollback-for = "java.lang.Exception" />
</ tx:attributes >
</ tx:advice >
< aop:config >
< aop:pointcut id = "pcMethod" expression = "execution(* ssh.service..*.*(..))" />
< aop:advisor pointcut-ref = "pcMethod" advice-ref = "txadvice" />
</ aop:config >
<!-- 自定义aop处理 测试 -->
< bean id = "aopTest" class = "ssh.aop.AopTest" ></ bean >
< bean id = "myAop" class = "ssh.aop.MyAop" ></ bean >
< aop:config proxy-target-class = "true" >
< aop:aspect ref = "myAop" >
< aop:pointcut id = "pcMethodTest" expression = "execution(* ssh.aop.AopTest.test*(..))" />
< aop:before pointcut-ref = "pcMethodTest" method = "before" />
< aop:after pointcut-ref = "pcMethodTest" method = "after" />
</ aop:aspect >
</ aop:config >
</ beans >
|
五、配置struts.xml
配置struts.objectFactory常数为spring,表示action由通过spring的bean中获取;
配置result type为"json",也可以配置其它的,这里为了前后端数据交互简便,配置成json格式;
配置两个action,addUser和queryAllUser;
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
|
<? xml version = "1.0" encoding = "UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
"http://struts.apache.org/dtds/struts-2.3.dtd">
< struts >
< constant name = "struts.objectFactory" value = "spring" />
< constant name = "struts.enable.DynamicMethodInvocation" value = "false" />
< constant name = "struts.devMode" value = "false" />
< package name = "default" extends = "struts-default,json-default" >
< global-results >
< result type = "json" >
< param name = "root" >json</ param >
< param name = "contentType" >text/html</ param >
</ result >
</ global-results >
< action name = "addUser" class = "userAction" method = "addUser" >
< result >.</ result >
</ action >
< action name = "queryAllUser" class = "userAction" method = "queryAllUser" >
< result >.</ result >
</ action >
</ package >
<!-- Add packages here -->
</ struts >
|
六、编写相关代码
注意事项:
dao继承HibernateDaoSupport类,所有数据库相关操作用hibernateTemplate操作;
给dao层,service层,action添加相应注解,注册为spring的bean;
附代码如下:
UserAction.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
|
package ssh.action;
import java.io.PrintWriter;
import java.util.List;
import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.Logger;
import org.apache.struts2.ServletActionContext;
import org.springframework.stereotype.Controller;
import ssh.aop.AopTest;
import ssh.model.User;
import ssh.service.UserService;
import com.google.gson.Gson;
@Controller
public class UserAction {
Logger logger = Logger.getLogger(UserAction. class );
@Resource
private UserService userService;
@Resource
private AopTest aopTest;
public void addUser(){
PrintWriter out = null ;
try {
HttpServletRequest request = ServletActionContext.getRequest();
HttpServletResponse response = ServletActionContext.getResponse();
response.setContentType( "text/html;charset=UTF-8" );
String account = request.getParameter( "account" );
String name = request.getParameter( "name" );
String address = request.getParameter( "address" );
User user = new User();
user.setAccount(account);
user.setAddress(address);
user.setName(name);
userService.add(user);
out = response.getWriter();
out.write( new Gson().toJson( "success" ));
} catch (Exception e){
e.printStackTrace();
logger.error(e.getMessage());
if (out != null )
out.write( new Gson().toJson( "fail" ));
} finally {
out.flush();
out.close();
}
}
public void queryAllUser(){
PrintWriter out = null ;
aopTest.test1();
aopTest.test2();
//logger.error("i");
try {
HttpServletResponse response = ServletActionContext.getResponse();
response.setContentType( "text/html;charset=UTF-8" );
Gson gson = new Gson();
List<User> userList= userService.queryAllUser();
String gsonStr = gson.toJson(userList);
out = response.getWriter();
out.write(gsonStr);
} catch (Exception e) {
e.printStackTrace();
logger.error(e.getMessage());
if (out != null )
out.write( new Gson().toJson( "fail" ));
} finally {
out.flush();
out.close();
}
}
}
|
AopTest.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
|
package ssh.aop;
public class AopTest {
public void test1(){
System.out.println( "AopTest test1 method is running~" );
}
public void test2(){
System.out.println( "AopTest test2 method is running~" );
}
}
|
MyAop.java
1
2
3
4
5
6
7
8
9
10
11
12
13
|
package ssh.aop;
public class MyAop {
public void before(){
System.out.println( "befor~" );
}
public void after(){
System.out.println( "after~" );
}
}
|
BaseDao.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
|
package ssh.dao.base;
import javax.annotation.Resource;
import org.hibernate.SessionFactory;
import org.springframework.orm.hibernate4.support.HibernateDaoSupport;
public class BaseDao extends HibernateDaoSupport{
@Resource
public void setMySessionFactory(SessionFactory sessionFactory){
this .setSessionFactory(sessionFactory);
}
}
|
UserDao.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
|
package ssh.dao;
import java.util.ArrayList;
import java.util.List;
import org.springframework.orm.hibernate4.HibernateTemplate;
import org.springframework.stereotype.Repository;
import ssh.dao.base.BaseDao;
import ssh.model.User;
@Repository
public class UserDao extends BaseDao{
public void add(User user){
this .getHibernateTemplate().save(user);
}
@SuppressWarnings ( "unchecked" )
public List<User> queryAllUser(){
List<User> users = new ArrayList<User>();
HibernateTemplate hibernateTemplate = this .getHibernateTemplate();
hibernateTemplate.setCacheQueries( true );
users = (List<User>) hibernateTemplate.find( "from User" );
hibernateTemplate.setCacheQueries( false );
return users;
}
}
|
User.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
|
package ssh.model;
import java.io.Serializable;
public class User implements Serializable{
/**
*
*/
private static final long serialVersionUID = -6190571611246371934L;
private Long id;
private String account;
private String name;
private String address;
public String getAccount() {
return account;
}
public String getName() {
return name;
}
public String getAddress() {
return address;
}
public void setAccount(String account) {
this .account = account;
}
public void setName(String name) {
this .name = name;
}
public void setAddress(String address) {
this .address = address;
}
/**
* @return the id
*/
public Long getId() {
return id;
}
/**
* @param id the id to set
*/
public void setId(Long id) {
this .id = id;
}
}
|
User.hbm.xml
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
|
<? xml version = "1.0" ?>
<!--
~ Hibernate, Relational Persistence for Idiomatic Java
~
~ Copyright (c) 2010, Red Hat Inc. or third-party contributors as
~ indicated by the @author tags or express copyright attribution
~ statements applied by the authors. All third-party contributions are
~ distributed under license by Red Hat Inc.
~
~ This copyrighted material is made available to anyone wishing to use, modify,
~ copy, or redistribute it subject to the terms and conditions of the GNU
~ Lesser General Public License, as published by the Free Software Foundation.
~
~ This program is distributed in the hope that it will be useful,
~ but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
~ or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
~ for more details.
~
~ You should have received a copy of the GNU Lesser General Public License
~ along with this distribution; if not, write to:
~ Free Software Foundation, Inc.
~ 51 Franklin Street, Fifth Floor
~ Boston, MA 02110-1301 USA
-->
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
< hibernate-mapping package = "ssh.model" >
< class name = "User" table = "user" >
< cache usage = "read-write" />
< id name = "id" column = "id" >
< generator class = "increment" />
</ id >
< property name = "account" type = "java.lang.String" column = "account" />
< property name = "name" type = "java.lang.String" column = "name" />
< property name = "address" type = "java.lang.String" column = "address" />
</ class >
</ hibernate-mapping >
|
UserService.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
|
package ssh.service;
import java.util.List;
import javax.annotation.Resource;
import org.springframework.stereotype.Service;
import ssh.dao.UserDao;
import ssh.model.User;
@Service
public class UserService {
@Resource
private UserDao userDao = new UserDao();
public List<User> queryAllUser(){
return userDao.queryAllUser();
}
public void add(User user){
userDao.add(user);
}
}
|
index.jsp(记得添加jquery库)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
|
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
< html >
< head >
< meta http-equiv = "Content-Type" content = "text/html; charset=UTF-8" >
< title >Insert title here</ title >
< style >
.mt20{
margin-top: 20px;
}
</ style >
</ head >
< body >
< div style = "text-align: center;" >
< div class = "mt20" >< label >账号:</ label >< input id = "account" type = "text" /></ div >
< div class = "mt20" >< label >姓名:</ label >< input id = "name" type = "text" /></ div >
< div class = "mt20" >< label >地址:</ label >< input id = "address" type = "text" /></ div >
< div class = "mt20" >< button id = "addUser" >添加</ button ></ div >
</ div >
< h3 >用户列表:</ h3 >
< ul id = "userList" >
</ ul >
< script type = "text/javascript" src = "js/jquery-1.11.1.min.js" ></ script >
< script >
$(function() {
$.ajax({
url : 'queryAllUser.action',
type : 'post',
dataType : 'json',
success : function(data) {
try {
for(var i = 0; i < data.length ; i++){
$("#userList").append("<li>< span style = 'color:red' >id="+data[i].id+"</ span >,account="+data[i].account+",name="+data[i].name+",address="+data[i].address+"</ li >");
}
} catch (e) {};
}
,
error : function(e) {
alert("sys error");
}
});
$("#addUser").on("click", function() {
var account = $("#account").val();
var name = $("#name").val();
var address = $("#address").val();
$.ajax({
url : 'addUser.action',
type : 'post',
dataType : 'json',
data : {
account : account,
name : name,
address : address
},
success : function(data) {
try {
$("#userList").append("< li >account="+account+",name="+name+",address="+address+"</ li >");
alert("添加成功");
} catch (e) {
}
},
error : function(e) {
alert("sys error");
}
});
});
});
</ script >
</ body >
</ html >
|
七、验证结果
回到开头,开始熟悉了解相关技术,并验证结果
1、搭建传统的ssh开发环境,并成功运行(插入、查询)
如下图:查询及添加用户成功;
2、了解c3p0连接池相关配置
数据库连接是一种昂贵的资源,开启及关闭比较消耗性能,因此可以用连接池来管理,初始化若干个连接,重复使用,而不是重复创建关闭,有点类似线程池;
配置如下,要根据实际项目情况合理配置最小最大连接数,详细的各个参数含义可以参考链接
另外要验证连接数相关配置很简单,可以自己写个程序验证,比如当配置最大连接数为10的时候,可以写个程序验证,当打开10个connection后,第11个connection会一直处于等待状态,获取不到;所以要根据情况合理配置连接数,否则有可能会影响应用性能;
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
|
<!--配数据源 -->
<bean name= "dataSource" class = "com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method= "close" >
<property name= "driverClass" value= "com.mysql.jdbc.Driver" />
<property name= "jdbcUrl" value= "jdbc:mysql://localhost:3306/demo" />
<property name= "user" value= "root" />
<property name= "password" value= "root" />
<property name= "acquireIncrement" value= "1" ></property>
<property name= "initialPoolSize" value= "80" ></property>
<property name= "maxIdleTime" value= "60" ></property>
<property name= "maxPoolSize" value= "80" ></property>
<property name= "minPoolSize" value= "30" ></property>
<property name= "acquireRetryDelay" value= "1000" ></property>
<property name= "acquireRetryAttempts" value= "60" ></property>
<property name= "breakAfterAcquireFailure" value= "false" ></property>
<!-- 如出现Too many connections, 注意修改mysql的配置文件my.ini,增大最多连接数配置项,(查看当前连接命令:show processlist) -->
</bean>
|
3、了解验证hibernate的二级缓存,并验证
hibernate的一级缓存是指session范围的缓存,默认开启,二级缓存是sessionFactory范围缓存,在配置sessionFactory的时候,我们已经配置二级缓存为ehcache,接下来验证效果,查询user操作,发现第一次查询会操作数据库,打印sql语句,刷新页面后,发现查询成功且没打印sql语句,如下图,可见二级缓存工作OK;
4、了解spring事物配置,并验证
所谓事务控制,原理都一样,就是要保证原子性、一致性、隔离性、持久性,jdbc编程的时候,都是自己控制,通过set autocommit=false设置成不自动提交,然后开始写具体的数据库操作,发生异常的时候rollback,否则commit;其实spring对事物的控制原理也差不多,加了一些封装,配置等,更加方便而已,比如可以在service层不同方法进行控制等;
验证的话很简单,在service层某个方法(注意方法名要符合spring配置文件中配置的规则)内写两个插入user的操作,在中间抛出一个异常,然后执行,如果发现第一个user插入成功,说明事务控制失效,否则ok;
5、了解spring的IOC(依赖注入),将struts2的action对象(bean)交给spring管理,自定义bean等...并验证
仔细观察的话,在配置applicationContext.xml文件的过程中,主要工作都是在配置bean相关信息,这些bean都是事先创建好的,其实所谓的bean就是对象;
之所以把对象的创建交给spring容器,目的是为了解耦;
另外在用struts的时候,spring把action注册为bean,默认是单例的,访问的时候并不是每次都new出一个action,在并发访问的时候,会有风险;
不过,可以通过scope="prototype",把action配置成多例;ps:struts2中的action默认是多例;
注意:applicationContext.xml配置的bean和自定义注解的bean都是可以在程序运行的过程中直接获取的,通过@Resource等方式,这个很好验证,写个小程序即可;
6、了解spring aop(面向切面编程),并编写自定义切面函数,验证结果
切面编程这种形式很多地方都用了该思想,什么过滤器,拦截器,事务控制等等...
其原理还是java的反射和动态代理,在方法执行前后加以控制,加入自己要执行的代码;
小例子中加了个切面,在方法执行前后打印before和after字符串,如下图,工作正常,代码参考前面部分:
1
2
3
4
5
6
7
8
9
10
|
<!-- 自定义aop处理 测试 -->
<bean id= "aopTest" class = "ssh.aop.AopTest" ></bean>
<bean id= "myAop" class = "ssh.aop.MyAop" ></bean>
<aop:config proxy-target- class = "true" >
<aop:aspect ref= "myAop" >
<aop:pointcut id= "pcMethodTest" expression= "execution(* ssh.aop.AopTest.test*(..))" />
<aop:before pointcut-ref= "pcMethodTest" method= "before" />
<aop:after pointcut-ref= "pcMethodTest" method= "after" />
</aop:aspect>
</aop:config>
|
@author 风一样的码农
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:http://www.cnblogs.com/chenpi/p/5153593.html