Personal imitation SSM framework

Personal imitation SSM frame

1、Pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>


    <groupId>com.wnx.mall.tiny</groupId>
    <artifactId>web-my-ssm</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <name>web-my-ssm</name>

    <description> Personal imitation SSM frame </description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <!--servlet-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
            <scope>test</scope>
        </dependency>
        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.27</version>
        </dependency>
        <!--thymeleaf-->
        <dependency>
            <groupId>org.thymeleaf</groupId>
            <artifactId>thymeleaf</artifactId>
            <version>3.0.14.RELEASE</version>
        </dependency>
        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.22</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>


    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>8</source>
                    <target>8</target>
                    <!-- Reflection can get the real method name -->
                    <compilerArgs>
                        <arg>-parameters</arg>
                    </compilerArgs>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

2、Spring The configuration file

Put in resources\applicationContext.xml

<?xml version="1.0" encoding="utf-8"?>
<beans>
    <bean id="pmsBrandMapper" class="com.wnx.mall.tiny.mapper.impl.PmsBrandMapperImpl"/>
    <bean id="PmsBrandService" class="com.wnx.mall.tiny.service.impl.PmsBrandServiceImpl">
        <property name="pmsBrandMapper" ref="pmsBrandMapper"/>
    </bean>
    <bean id="brand" class="com.wnx.mall.tiny.controller.PmsBrandController">
        <property name="fruitService" ref="fruitService"/>
    </bean>
</beans>

3、Web.xml To configure

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0">
    <!--  Configure context parameters  -->
    <context-param>
        <param-name>view-prefix</param-name>
        <param-value>/</param-value>
    </context-param>d
    <context-param>
        <param-name>view-suffix</param-name>
        <param-value>.html</param-value>
    </context-param>
    <!--Spring The location of the configuration file -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>applicationContext.xml</param-value>
    </context-param>
</web-app>

4、 Context load listener ContextLoaderListener

be responsible for Create... When the context starts IOC Containers , Then save it to application Scope

package com.wnx.myssm.mylistner;



import com.wnx.myssm.myioc.BeanFactory;
import com.wnx.myssm.myioc.ClassPathXmlApplicationContext;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;



/** *  Context load listener  */
@WebListener
public class ContextLoaderListener implements ServletContextListener {
    
    @Override
    public void contextInitialized(ServletContextEvent sce) {
    

        //1. Create... When the context starts IOC Containers , Then save it to application Scope 
        ServletContext application = sce.getServletContext();
        String path = application.getInitParameter("contextConfigLocation");
        BeanFactory beanFactory = new ClassPathXmlApplicationContext(path);
        application.setAttribute("beanFactory",beanFactory);

    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
    

    }
}

5、 Front controller DispatcherServlet

package com.wnx.myssm.mysrpingmvc;




import com.wnx.myssm.myioc.BeanFactory;
import com.wnx.myssm.utils.StringUtil;
import lombok.SneakyThrows;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.Method;
import java.lang.reflect.Parameter;

/** *  all *.do Your request will enter the Servlet!!! */
@WebServlet("*.do")
public class DispatcherServlet extends ViewBaseServlet {
    

    private BeanFactory beanFactory ;

    public DispatcherServlet(){
    
    }

    public void init() throws ServletException {
    
        //1.Servlet At the bottom of the build, you will call Init() Method , Integrate ViewBaseServlet, Going to call ViewBaseServlet Of Init()
        super.init();
        //2. from application Scope to get IOC Containers 
        ServletContext application = getServletContext();
        Object beanFactoryObj = application.getAttribute("beanFactory");
        if(beanFactoryObj!=null){
    
            beanFactory = (BeanFactory)beanFactoryObj ;
        }else{
    
            throw new RuntimeException("IOC Container acquisition failed ！");
        }
    }

    @SneakyThrows
    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
        //1. obtain Bean ID
        String servletPath = request.getServletPath();
        servletPath = servletPath.substring(1);
        int lastDotIndex = servletPath.lastIndexOf(".do") ;
        servletPath = servletPath.substring(0,lastDotIndex);

        //2. according to ID Take out of the container Bean
        Object controllerBeanObj = beanFactory.getBean(servletPath);

        //3. Get method name 
        String operate = request.getParameter("operate");
        if(StringUtil.isEmpty(operate)){
     operate = "index" ; }

            Method[] methods = controllerBeanObj.getClass().getDeclaredMethods();
            for (Method method : methods) {
    
                //4. obtain Handler Method object 
                if (operate.equals(method.getName())) {
    
                    Parameter[] parameters = method.getParameters();
                    Object[] parameterValues = new Object[parameters.length];


                    //5. complete Controller Method parameter binding 
                    for (int i = 0; i < parameters.length; i++) {
    
                        Parameter parameter = parameters[i];
                        String parameterName = parameter.getName();

                        if ("request".equals(parameterName)) {
    
                            parameterValues[i] = request;
                        } else if ("response".equals(parameterName)) {
    
                            parameterValues[i] = response;
                        } else if ("session".equals(parameterName)) {
    
                            parameterValues[i] = request.getSession();
                        } else {
    
                            String parameterValue = request.getParameter(parameterName);
                            String typeName = parameter.getType().getName();
                            Object parameterObj = parameterValue;

                            if (parameterObj != null) {
    
                                if ("java.lang.Integer".equals(typeName)) {
    
                                    parameterObj = Integer.parseInt(parameterValue);
                                }
                            }

                            if (parameterObj != null) {
    
                                if ("java.lang.Long".equals(typeName)) {
    
                                    parameterObj = Long.parseLong(parameterValue);
                                }
                            }
                            parameterValues[i] = parameterObj;
                        }
                    }
                    //6. Reflection execution method 
                    method.setAccessible(true);
                    Object returnObj = method.invoke(controllerBeanObj, parameterValues);


                    //7. The view 
                    String methodReturnStr = (String) returnObj;
                    if (methodReturnStr.startsWith("redirect:")) {
    
                        String redirectStr = methodReturnStr.substring("redirect:".length());
                        response.sendRedirect(redirectStr);
                    } else {
    
                        super.processTemplate(methodReturnStr, request, response);
                    }
                }


            }


    }
}

6、 view resolver ViewBaseServlet

package com.wnx.myssm.mysrpingmvc;

import org.thymeleaf.TemplateEngine;
import org.thymeleaf.context.WebContext;
import org.thymeleaf.templatemode.TemplateMode;
import org.thymeleaf.templateresolver.ServletContextTemplateResolver;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class ViewBaseServlet extends HttpServlet {
    

    private TemplateEngine templateEngine;

    @Override
    public void init() throws ServletException {
    

        // 1. obtain ServletContext object 
        ServletContext servletContext = this.getServletContext();

        // 2. establish Thymeleaf Parser object 
        ServletContextTemplateResolver templateResolver = new ServletContextTemplateResolver(servletContext);

        // 3. Set parameters to the parser object 
        templateResolver.setTemplateMode(TemplateMode.HTML);
        templateResolver.setPrefix(servletContext.getInitParameter("view-prefix"));
        templateResolver.setSuffix(servletContext.getInitParameter("view-suffix"));
        templateResolver.setCacheTTLMs(60000L);
        templateResolver.setCacheable(true);
        templateResolver.setCharacterEncoding("utf-8");

        // 4. Create template engine object 
        templateEngine = new TemplateEngine();

        // 5. Set the template parser for the template engine object 
        templateEngine.setTemplateResolver(templateResolver);

    }

    protected void processTemplate(String templateName, HttpServletRequest req, HttpServletResponse resp) throws IOException {
    
        // 1. Set the content type and character set of the response body 
        resp.setContentType("text/html;charset=UTF-8");

        // 2. establish WebContext object 
        WebContext webContext = new WebContext(req, resp, getServletContext());

        // 3. Process template data 
        templateEngine.process(templateName, webContext, resp.getWriter());
    }
}

7、IOC Container context ClassPathXmlApplicationContext

• abstract Bean factory

package com.wnx.myssm.myioc;

/** * Bean Build factory  */
public interface BeanFactory {
    
    Object getBean(String id);
}

• Realization ：ClassPathXmlApplicationContext

package com.wnx.myssm.myioc;


import com.wnx.myssm.utils.StringUtil;
import lombok.SneakyThrows;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;

public class ClassPathXmlApplicationContext implements BeanFactory {
    

    private Map<String,Object> beanMap = new HashMap<>();


    @SneakyThrows
    public ClassPathXmlApplicationContext(){
    
        this("applicationContext.xml");
    }
    @SneakyThrows
    public ClassPathXmlApplicationContext(String path){
    
            if(StringUtil.isEmpty(path)){
     throw new RuntimeException("IOC The container's configuration file does not specify ..."); }

            //1. according to Resource Under the table of contents applicationContext.xml, Construct document objects 
            InputStream inputStream = getClass().getClassLoader().getResourceAsStream(path);
            DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder() ;
            Document document = documentBuilder.parse(inputStream);

            //2. Scan all Bean label 
            NodeList beanNodeList = document.getElementsByTagName("bean");
            for(int i = 0 ; i<beanNodeList.getLength() ; i++){
    
                Node beanNode = beanNodeList.item(i);
                if(beanNode.getNodeType() == Node.ELEMENT_NODE){
    
                    //1. according to Bean label , Construct objects from reflections 
                    Element beanElement = (Element)beanNode ;
                    String beanId =  beanElement.getAttribute("id");
                    String className = beanElement.getAttribute("class");
                    Class beanClass = Class.forName(className);
                    Object beanObj = beanClass.newInstance() ;

                    //2. Deposit in Map Containers 
                    beanMap.put(beanId , beanObj) ;

                }
            }
            //3. assemble bean Dependencies between 
            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();
                    for (int j = 0; j < beanChildNodeList.getLength() ; j++) {
    

                        //4. Take the dependent from the container Bean  Inject into the dependent Bean in 
                        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");
                            Object refObj = beanMap.get(propertyRef);
                            Object beanObj = beanMap.get(beanId);
                            Class beanClazz = beanObj.getClass();
                            Field propertyField = beanClazz.getDeclaredField(propertyName);
                            propertyField.setAccessible(true);
                            propertyField.set(beanObj,refObj);
                        }
                    }
                }
            }

    }

    /** *  according to ID obtain Bean * @param id ID * @return Bean */
    @Override
    public Object getBean(String id) {
    
        return beanMap.get(id);
    }
}

8、 Configure character encoding filter

package com.wnx.myssm.myfilter;




import com.wnx.myssm.utils.StringUtil;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

/** *  Character encoding filter   Filter  *.do  Request  */
@WebFilter(urlPatterns = {
    "*.do"},initParams = {
    @WebInitParam(name = "encoding",value = "UTF-8")})
public class CharacterEncodingFilter implements Filter {
    

    private String encoding = "UTF-8";

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    
        String encodingStr = filterConfig.getInitParameter("encoding");
        if(StringUtil.isNotEmpty(encodingStr)){
    
            encoding = encodingStr ;
        }
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
    
        ((HttpServletRequest)servletRequest).setCharacterEncoding(encoding);
        filterChain.doFilter(servletRequest,servletResponse);

    }

    @Override
    public void destroy() {
    

    }
}

9、 Persistence layer frame BaseMapper

package com.wnx.mall.tiny.mapper;

import com.wnx.myssm.mymapper.ConnUtil;

import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public abstract class BaseMapper<T> {
    
    private final String DRIVER = "com.mysql.cj.jdbc.Driver";
    private final String URL = "jdbc:mysql://localhost:3306/mall?useUnicode=true&characterEncoding=utf-8&useSSL=false";
    private final String USER = "root";
    private final String PWD = "root" ;


    private Connection conn ;
    private PreparedStatement psmt ;
    private ResultSet rs ;
    private Class entityClass ;

    public BaseMapper(){
    
        //1. Get program runtime ,T The type of actual reference .
        Type genericType = getClass().getGenericSuperclass();
        Type[] actualTypeArguments = ((ParameterizedType) genericType).getActualTypeArguments();
        Type actualType = actualTypeArguments[0];

        // 2. Construct the T Class object of 
        try {
    
            entityClass = Class.forName(actualType.getTypeName());
        } catch (ClassNotFoundException e) {
    
            e.printStackTrace();
        }
    }

    /** *  Get database connection  * @return  A database connection  */
    private Connection getConn(){
    
        return ConnUtil.getConn();
    }


    /** *  Release database related resources  * @param rs  Result set object  * @param psmt  Precompiled statement object  * @param conn  Database connection  */
    private void close(ResultSet rs, PreparedStatement psmt, Connection conn){
    
        try {
    
            if (rs != null) {
    
                rs.close();
            }
            if(psmt!=null){
    
                psmt.close();
            }
            if(conn!=null && !conn.isClosed()){
    
                conn.close();
            }
        } catch (SQLException e) {
    
            e.printStackTrace();
        }
    }

    /*** *  Placeholders for preprocessing statement objects ? Set parameters  * @param psmt  Preprocess the statement object  * @param params  Parameters  * @throws SQLException SQL abnormal  */
    private void setParams(PreparedStatement psmt , Object... params) throws SQLException {
    
        if(params!=null && params.length>0){
    
            for (int i = 0; i < params.length; i++) {
    
                psmt.setObject(i+1,params[i]);
            }
        }
    }

    /*** *  Perform database update operation  * @param sql  Database operation SQL * @param params  Update parameters  * @return  Rows affected  */
    protected int executeUpdate(String sql , Object... params){
    
        boolean insertFlag = false ;

        try {
    
            conn = getConn();
            psmt = conn.prepareStatement(sql,Statement.RETURN_GENERATED_KEYS);
            setParams(psmt,params);
            int count = psmt.executeUpdate() ;
            rs = psmt.getGeneratedKeys();

            if(rs.next()){
    
                return ((Long)rs.getLong(1)).intValue();
            }
            return count ;
        } catch (SQLException e) {
    
            e.printStackTrace();
        }finally {
    
            close(rs,psmt,conn);
        }
        return 0;
    }

    /** *  Give... By reflection technology obj Object's property Attribute propertyValue value  * @param obj  object model * @param property model Field  * @param propertyValue model value  */
    private void setValue(Object obj ,  String property , Object propertyValue){
    
        //1. Get the class of the object 
        Class clazz = obj.getClass();
        try {
    
            //2. Get the member variable according to the member variable name 
            Field field = clazz.getDeclaredField(property);

            //3. Reflection assignment 
            if(field!=null){
    
                field.setAccessible(true);
                field.set(obj,propertyValue);
            }
        } catch (Exception e) {
    
            e.printStackTrace();
        }
    }

    /** *  Execute complex queries , Returns, for example, statistical results  * @param sql  Database operation SQL * @param params  Update parameters  * @return  An array of objects  */
    protected Object[] executeComplexQuery(String sql , Object... params){
    
        try {
    
            //1. Execute the query 
            conn = getConn() ;
            psmt = conn.prepareStatement(sql);
            setParams(psmt,params);
            rs = psmt.executeQuery();

            //2. Construct column containers 
            ResultSetMetaData rsmd = rs.getMetaData();
            int columnCount = rsmd.getColumnCount();
            Object[] columnValueArr = new Object[columnCount];

            //3. The query results are put into the column container 
            if(rs.next()){
    
                for(int i = 0 ; i<columnCount;i++){
    
                    Object columnValue = rs.getObject(i+1);
                    columnValueArr[i]=columnValue;
                }
                //4. Return column container 
                return columnValueArr ;
            }
        } catch (SQLException e) {
    
            e.printStackTrace();
        } finally {
    
            close(rs,psmt,conn);
        }
        return null ;
    }

    /** *  Execute the query , Returns a single entity object  * @param sql  Database operation SQL * @param params  Query parameters  * @return  Entity Model */
    protected T load(String sql , Object... params){
    
        try {
    
            //1. Query operation 
            conn = getConn() ;
            psmt = conn.prepareStatement(sql);
            setParams(psmt,params);
            rs = psmt.executeQuery();

            //2. Object Assignment 
            ResultSetMetaData rsmd = rs.getMetaData();
            int columnCount = rsmd.getColumnCount();
            if(rs.next()){
    
                T entity = (T)entityClass.newInstance();

                for(int i = 0 ; i<columnCount;i++){
    
                    String columnName = rsmd.getColumnName(i+1);

                    //3. The transformation of hump naming 
                    while (columnName.contains("_")) {
    
                        int index = columnName.indexOf("_");
                        String target = columnName.substring(index + 1, index + 2);
                        columnName = columnName.replace(("_" + target), target.toUpperCase());
                    }

                    Object columnValue = rs.getObject(i+1);
                    setValue(entity,columnName,columnValue);
                }
                //3. Returns the object 
                return entity ;
            }
        } catch (Exception e) {
    
            e.printStackTrace();
        } finally {
    
            close(rs,psmt,conn);
        }
        return null ;
    }


    /*** *  Execute the query , return List * @param sql  Database operation SQL * @param params  Query parameters  * @return  Set of entities List */
    protected List<T> executeQuery(String sql , Object... params){
    
        List<T> list = new ArrayList<>();
        try {
    
            //1. Execute the query 
            conn = getConn() ;
            psmt = conn.prepareStatement(sql);
            setParams(psmt,params);
            rs = psmt.executeQuery();

            //2. Object Assignment 
            ResultSetMetaData rsmd = rs.getMetaData();
            int columnCount = rsmd.getColumnCount();
            while(rs.next()){
    
                T entity = (T)entityClass.newInstance();
                for(int i = 0 ; i<columnCount;i++){
    

                    String columnName = rsmd.getColumnName(i+1);

                    //3. The transformation of hump naming 
                    while (columnName.contains("_")) {
    
                        int index = columnName.indexOf("_");
                        String target = columnName.substring(index + 1, index + 2);
                        columnName = columnName.replace(("_" + target), target.toUpperCase());
                    }

                    Object columnValue = rs.getObject(i+1);
                    setValue(entity,columnName,columnValue);
                }

                //4. Add to collection 
                list.add(entity);
            }
        } catch (Exception e) {
    
            e.printStackTrace();
        } finally {
    
            close(rs,psmt,conn);
        }
        //5. Back to the assembly 
        return list ;
    }


}

10、 Transaction control TransactionManager

	package com.wnx.myssm.mytransaction;



import com.wnx.myssm.mymapper.ConnUtil;

import java.sql.Connection;
import java.sql.SQLException;

public class TransactionManager {
    

    // Open transaction 
    public static void beginTrans() throws SQLException {
    
        ConnUtil.getConn().setAutoCommit(false);
    }

    // Commit transaction 
    public static void commit() throws SQLException {
    
        Connection conn = ConnUtil.getConn();
        conn.commit();
        ConnUtil.closeConn();
    }

    // Roll back the transaction 
    public static void rollback() throws SQLException {
    
        Connection conn = ConnUtil.getConn();
        conn.rollback();
        ConnUtil.closeConn();
    }
}

11、 Thread knowledge

Use a connection Connection To say things , One request corresponds to one thread . Rewrite the get database connection class

• ConnUtil

package com.wnx.myssm.mymapper;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class ConnUtil {
    
    private static ThreadLocal<Connection> threadLocal = new ThreadLocal<>();

    private static final String DRIVER = "com.mysql.cj.jdbc.Driver";
    private static final String URL = "jdbc:mysql://localhost:3306/javaweb?useUnicode=true&characterEncoding=utf-8&useSSL=false&allowPublicKeyRetrieval=true";
    private static final String USER = "root";
    private static final String PWD = "root";

    /** *  Create database connection  * @return  Back to database connection  */
    private static Connection createConn() {
    
        try {
    
            Class.forName(DRIVER);
            return DriverManager.getConnection(URL, USER, PWD);
        } catch (ClassNotFoundException | SQLException e) {
    
            e.printStackTrace();
        }
        return null;
    }

    /** *  Get database connection  * @return  Database connection  */
    public static Connection getConn() {
    
        //1. If there is a connection with a local thread , Create a .
        Connection conn = threadLocal.get();
        if (conn == null) {
    
            conn = createConn();
            threadLocal.set(conn);
        }
        return threadLocal.get();

    }


    /** *  Close database connection  * @throws SQLException SQL abnormal  */
    public static void closeConn() throws SQLException {
    
        Connection conn = threadLocal.get();
        if(conn==null){
    
            return ;
        }
        if(!conn.isClosed()){
    
            conn.close();
            threadLocal.set(null);
        }
    }

}

Once something goes wrong , Let the current database connection rollback immediately .

• OpenSessionInViewFilter

package com.wnx.myssm.myfilter;



import com.wnx.myssm.mytransaction.TransactionManager;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
import java.sql.SQLException;

@WebFilter("*.do")
public class OpenSessionInViewFilter implements Filter {
    
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
    
        try{
    
            TransactionManager.beginTrans();
            System.out.println(" Open transaction ....");
            filterChain.doFilter(servletRequest, servletResponse);
            TransactionManager.commit();
            System.out.println(" Commit transaction ...");
        }catch (Exception e){
    
            e.printStackTrace();
            try {
    
                TransactionManager.rollback();
                System.out.println(" Roll back the transaction ....");
            } catch (SQLException ex) {
    
                ex.printStackTrace();
            }
        }
    }

    @Override
    public void destroy() {
    

    }
}

​