- 对代码中的DAO层、service层、controller层及其相互之间的关系进行配置
- 【applicationContent.xml】
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- 【BeanFactory.java】—— Bean工厂类
package com.javaweb.qqzone.myssm.ioc;
public interface BeanFactory {
Object getBean(String id);
}
- 对applicationContent.xml文件中的参数进行读取，并组装各层之间的依赖关系
- 【ClassPathXmlApplicationContext.java】
package com.javaweb.qqzone.myssm.ioc;
import com.javaweb.qqzone.myssm.util.StringUtil;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;
public class ClassPathXmlApplicationContext implements BeanFactory{
private Map beanMap = new HashMap<>();
private String path = "applicationContext.xml";
public ClassPathXmlApplicationContext(){
this("applicationContext.xml");
}
public ClassPathXmlApplicationContext(String path) {
if (StringUtil.isEmpty(path)) {
throw new RuntimeException("IOC容器的配置文件没有指定....");
}
try {
InputStream inputStream = getClass().getClassLoader().getResourceAsStream(path);
//1.创建DocumentBuilderFactory对象
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
//2.创建DocumentBuilder对象
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
//3.创建Document对象
Document document = documentBuilder.parse(inputStream);
//4.获取所有的bean节点
NodeList beanNodeList = document.getElementsByTagName("bean");
for (int i = 0; i < beanNodeList.getLength(); i++) {
Node beanNode = beanNodeList.item(i);
if (beanNode.getNodeType() == Node.ELEMENT_NODE) {
Element beanElement = (Element) beanNode;
String beanId = beanElement.getAttribute("id");
String className = beanElement.getAttribute("class");
Class beanClass = Class.forName(className);
//创建bean实例
Object beanObj = beanClass.newInstance();
//将bean实例对象保存到map容器中
beanMap.put(beanId, beanObj);
//到目前为止，此处需要注意的是：bean和bean之间的依赖关系还没有设置
}
}
//5.组装bean之间的依赖关系
for (int i = 0; i < beanNodeList.getLength(); i++) {
Node beanNode = beanNodeList.item(i);
if (beanNode.getNodeType() == Node.ELEMENT_NODE) {
Element beanElement = (Element) beanNode;
String beanId = beanElement.getAttribute("id");
NodeList beanChildNodeList = beanElement.getChildNodes();
//System.out.println("length:"+beanChildNodeList.getLength());
for (int j = 0; j < beanChildNodeList.getLength(); j++) {
Node beanChildNode = beanChildNodeList.item(j);
if (beanChildNode.getNodeType() == Node.ELEMENT_NODE && "property".equals(beanChildNode.getNodeName())){
Element propertyElement = (Element) beanChildNode;
String propertyName = propertyElement.getAttribute("name");
String propertyRef = propertyElement.getAttribute("ref");
//1）找到property对应的实例
Object refObj = beanMap.get(propertyRef);
//2）将refObj设置到当前bean对应的实例的property属性上去
Object beanObj = beanMap.get(beanId);
Class beanClazz = beanObj.getClass();
Field propertyField = beanClazz.getDeclaredField(propertyName);
propertyField.setAccessible(true);
propertyField.set(beanObj, refObj);
}
}
}
}
} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (NoSuchFieldException e) {
e.printStackTrace();
}
}
@Override
public Object getBean(String id) {
return beanMap.get(id);
}
}
2.业务处理
主要负责业务的开启，提交，回滚阶段
- 【TransactionManager.java】
package com.javaweb.qqzone.myssm.transaction;
import com.javaweb.qqzone.myssm.util.ConnectionUtil;
import java.sql.Connection;
import java.sql.SQLException;
public class TransactionManager {
//开启事务
public static void beginTrans() throws SQLException {
ConnectionUtil.getConnection().setAutoCommit(false);
}
//提交事务
public static void commit() throws SQLException {
Connection conn = ConnectionUtil.getConnection();
conn.commit();
ConnectionUtil.closeConnection();
}
//回滚事务
public static void rollback() throws SQLException {
Connection conn = ConnectionUtil.getConnection();
conn.rollback();
ConnectionUtil.closeConnection();
}
}
3.监听器——监听上下文启动
监听上下文启动，在上下文启动时去创建IOC容器，然后将其保存到application作用域
后面中央控制器再从application作用域中去获取IOC容器
- 【ContextLoaderListener.java】
package com.javaweb.qqzone.myssm.listeners;
import com.javaweb.qqzone.myssm.ioc.BeanFactory;
import com.javaweb.qqzone.myssm.ioc.ClassPathXmlApplicationContext;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
//监听上下文启动，在上下文启动时去创建IOC容器，然后将其保存到application作用域
//后面中央控制器再从application作用域中去获取IOC容器
@WebListener
public class ContextLoaderListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent servletContextEvent) {
//1.获取ServletContext对象
ServletContext application = servletContextEvent.getServletContext();
//2.获取上下文的初始化参数
String path = application.getInitParameter("contextConfigLocation");
//3.创建IOC容器
BeanFactory beanFactory = new ClassPathXmlApplicationContext(path);
//4.将IOC容器保存到application作用域中
application.setAttribute("beanFactory", beanFactory);
}
@Override
public void contextDestroyed(ServletContextEvent servletContextEvent) {
}
}
4.字符串工具类
- 【StringUtil.java】
package com.javaweb.qqzone.myssm.util;
public class StringUtil {
//判断字符串是否为空或者null
public static boolean isEmpty(String str) {
return str==null || "".equals(str);
}
public static boolean isNotEmpty(String str) {
return !isEmpty(str);
}
}
