ssm整合过程梳理

目录

一、ssm是什么？

1、基本概念

1.1、Spring

1.2、SpringMVC

1.3、MyBatis

二、步骤

1.创建maven项目并导入依赖

2.Mybatis层编写

一，配置

二，代码编写

3.spring层编写

4.SpringMVC层编写

至此，框架搭建基本结束！ 后面就是一些简单的功能实现需要的代码编写。

1.编写controller层

列如实现查询功能：

2.前端构造

总结

---

---

一、ssm是什么？

1、基本概念

SSM框架是Spring + Spring MVC + MyBatis的缩写，这个是继SSH之后，目前比较主流的Java EE企业级框架，适用于搭建各种大型的企业级应用系统。

1.1、Spring

        Spring是一个开源框架，Spring是于2003 年兴起的一个轻量级的Java 开发框架，由Rod Johnson 在其著作Expert One-On-One J2EE Development and Design中阐述的部分理念和原型衍生而来。它是为了解决企业应用开发的复杂性而创建的。Spring使用基本的JavaBean来完成以前只可能由EJB完成的事情。然而，Spring的用途不仅限于服务器端的开发。从简单性、可测试性和松耦合的角度而言，任何Java应用都可以从Spring中受益。 简单来说，Spring是一个轻量级的控制反转（IoC）和面向切面（AOP）的容器框架。

1.2、SpringMVC

        Spring MVC属于SpringFrameWork的后续产品，已经融合在Spring Web Flow里面。Spring MVC 分离了控制器、模型对象、分派器以及处理程序对象的角色，这种分离让它们更容易进行定制。

1.3、MyBatis

       MyBatis 本是apache的一个开源项目iBatis, 2010年这个项目由apache software foundation 迁移到了google code，并且改名为MyBatis 。MyBatis是一个基于Java的持久层框架。iBATIS提供的持久层框架包括SQL Maps和Data Access Objects（DAO）MyBatis 消除了几乎所有的JDBC代码和参数的手工设置以及结果集的检索。MyBatis 使用简单的 XML或注解用于配置和原始映射，将接口和 Java 的POJOs（Plain Old Java Objects，普通的 Java对象）映射成数据库中的记录

二、步骤

1.创建maven项目并导入依赖

所需要的依赖：

1，junit,数据库驱动,连接池,servlet,jsp,mybatis,mybatis-spring,spring

        
            junit
            junit
            4.13.2
        
        

        
        
            javax.servlet
            jstl
            1.2
        
        
            javax.servlet
            javax.servlet-api
            4.0.1
            provided
        
        
        
            javax.servlet.jsp
            javax.servlet.jsp-api
            2.3.3
            provided
        
        
        

        
            org.mybatis
            mybatis
            3.5.6
        
        
        

        
            org.mybatis
            mybatis-spring
            2.0.6
        
        
        

        
        
            com.mchange
            c3p0
            0.9.5.5
        

        
        
            mysql
            mysql-connector-java
            8.0.25
         
        
        
            org.springframework
            spring-webmvc
            5.3.9
        
        
            org.springframework
            spring-jdbc
            5.3.9
        

2.Maven资源过滤设置（解决静态资源导出问题）

        

            
                src/main/java
                
                    **/*.properties
                    **/*.xml
                
                false
            
        
    

2.Mybatis层编写

一，配置

1.数据库配置文件database.properties

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssmbuild?useSSL=false&useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
jdbc.username=root
jdbc.password=123456

2.IDEA关连数据库导入对应的数据库

3.编写Mybatis核心配置文件

二，代码编写

1.编写跟数据库对应字段的实体类；

2.在dao层编写对应操作的接口，以及~Mapper.xml配置文件去绑定每一个接口

    
    
        insert into ssmbuild.books(bookName, detail, bookCounts)
         values (#{bookName},#{detail},#{bookCounts});
    
    
    
        
        delete from ssmbuild.books
        where bookID=#{bookId}
    
    
    
        
        update ssmbuild.books
        set bookName=#{bookName},detail = #{detail},bookCounts = #{bookCounts}
        where bookId = #{bookId}
    
    
    
        select * from ssmbuild.books
        where bookID= #{bookId}
    
    
    
        select * from ssmbuild.books
    

3.编写业务层（调用dao层）以及实现类

package com.yy.service;

import com.yy.dao.BookMapper;
import com.yy.pojo.Books;

import java.util.List;

public class BookServiceImpl implements BookService {
    
    //service调用dao层：组合Dao
    
    private BookMapper bookMapper;
    //加一个set方法方便spring托管
    public void setBookMapper(BookMapper bookMapper) {
        this.bookMapper = bookMapper;
    }

    public int addBook(Books books) {
        return bookMapper.addBook(books);
    }

    public int deleteBookId(int id) {
        return bookMapper.deleteBookId(id);
    }

    public int updateBook(Books books) {
        return bookMapper.updateBook(books);
    }

    public Books queryBookById(int id) {
        return bookMapper.queryBookById(id);
    }

    public List queryAllBook() {
        return bookMapper.queryAllBook();
    }
}

3.spring层编写

1.spring整合dao层的主要配置文件编写

2.整合service层

---

4.SpringMVC层编写

1.添加web并进行配置web.xml

    
    
        springmvc
        org.springframework.web.servlet.DispatcherServlet
        
            contextConfigLocation
            classpath:applicationContext.xml
        
        1
    
    
        springmvc
        /
    
    

    
        encodingFilter
        org.springframework.web.filter.CharacterEncodingFilter
        
            encoding
            utf-8
        
    
    
        encodingFilter
        /*
    
    

    
        15
    

2.mvc层整合配置文件

至此，框架搭建基本结束！ 后面就是一些简单的功能实现需要的代码编写。

1.编写controller层

列如实现查询功能：

package com.yy.controller;

import com.yy.pojo.Books;
import com.yy.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

import java.util.List;

@Controller
@RequestMapping("/book")
public class BookController {
    //controller层调用service层
    @Autowired
    @Qualifier("BookServiceImpl")
    private BookService bookService ;
    
    //查询全部的书籍,并且返回到一个书籍展示页面
    @RequestMapping("/allBook")
    public String list(Model model){
        List books = bookService.queryAllBook();
        model.addAttribute("list",books);
        return "allBook";
    }
}

2.前端构造

编写jsp文件。。。优化啥的不计~

实现的查询结果界面如图所示：

总结

下面主要是说明一下在项目实现过程中出现的一些问题：

首先是数据库连接异常，或者数据库连接失败，大致如下：

Caused by: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: Connections could not be acquired from the underlying database!
。。。
。。。
。。。
。。。

代码太多不一一列举，主要是解决办法。首先我们要确认自己的mysql版本，如果是8.0以上的最好使用的数据库驱动的jar包与数据库版本相匹配，有时候很多情况都是因为版本不一致，导致读取底层数据库失败。列如小编的MySQL是8.0的，所以使用的驱动是8.0.25的，然后需要注意的是，如果使用的是Mysql8.0+，增加一个时区的配置：

url=jdbc:mysql://localhost:3306/ssmbuild?useSSL=false&useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai

例外，如多使用c3p0连接数据库连接不上时出现如下异常信息时：

一月 03, 2022 6:15:53 下午 com.mchange.v2.log.MLog 
信息: MLog clients using java 1.4+ standard logging.
一月 03, 2022 6:15:54 下午 com.mchange.v2.c3p0.C3P0Registry 
信息: Initializing c3p0-0.9.5.5 [built 11-December-2019 22:18:33 -0800; debug? true; trace: 10]
一月 03, 2022 6:15:55 下午 com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource 
信息: Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 3, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, contextClassLoaderSource -> caller, dataSourceName -> 1hgek8xam8q10no6e8599|524d6d96, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> com.mysql.cj.jdbc.Driver, extensions -> {}, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, forceSynchronousCheckins -> false, forceUseNamedDriverClass -> false, identityToken -> 1hgek8xam8q10no6e8599|524d6d96, idleConnectionTestPeriod -> 0, initialPoolSize -> 3, jdbcUrl -> jdbc:mysql://localhost:3306/ssmbuild?useSSL=false&useUnicode=true&characterEncoding=utf8&serverTimezone=Asia, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 0, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 15, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 3, numHelperThreads -> 3, preferredTestQuery -> null, privilegeSpawnedThreads -> false, properties -> {user=******, password=******}, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, userOverrides -> {}, usesTraditionalReflectiveProxies -> false ]
一月 03, 2022 6:16:25 下午 com.mchange.v2.resourcepool.BasicResourcePool 
警告: com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@1e34cc74 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 
java.sql.SQLException: Access denied for user 'young'@'localhost' (using password: YES)
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
	at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836)
	at com.mysql.cj.jdbc.ConnectionImpl.(ConnectionImpl.java:456)
	at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246)
	at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197)
	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1176)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1163)
	at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44)
	at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1908)
	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)
一月 03, 2022 6:21:34 下午 com.mchange.v2.log.MLog 
信息: MLog clients using java 1.4+ standard logging.
一月 03, 2022 6:21:35 下午 com.mchange.v2.c3p0.C3P0Registry 
信息: Initializing c3p0-0.9.5.5 [built 11-December-2019 22:18:33 -0800; debug? true; trace: 10]
一月 03, 2022 6:21:35 下午 com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource 
信息: Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 3, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, contextClassLoaderSource -> caller, dataSourceName -> 1hgek8xam8q8bf81o4hum0|524d6d96, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> com.mysql.cj.jdbc.Driver, extensions -> {}, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, forceSynchronousCheckins -> false, forceUseNamedDriverClass -> false, identityToken -> 1hgek8xam8q8bf81o4hum0|524d6d96, idleConnectionTestPeriod -> 0, initialPoolSize -> 3, jdbcUrl -> jdbc:mysql://localhost:3306/ssmbuild?useSSL=false&useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai, maxAdministrativeTaskTime -> 0, maxConnectionAge -。。。

需要在我们的数据库配置文件中，在每个数据名前加入jdbc，即可避免：

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssmbuild?useSSL=false&useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
jdbc.username=root
jdbc.password=123456

如果在项目使用tomcat运行过程中出现错误，我们可以通过多编写测试类来查找：

import com.yy.pojo.Books;
import com.yy.service.BookService;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MyTest {
    @Test
    public void test(){
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        BookService bookServiceImpl = (BookService) context.getBean("BookServiceImpl"); 
        for (Books books : bookServiceImpl.queryAllBook()) {
            System.out.println(books);
        }
    }
}

查看预期结果是否符合：

Books(bookID=1, bookName=Java, bookCounts=1, detail=从入门道放弃)
Books(bookID=2, bookName=MySQL, bookCounts=10, detail=从删库到跑路)
Books(bookID=3, bookName=Linux, bookCounts=3, detail=从进门到进牢)

额外补充一点，在maven工程中，idea一般不会自动把项目依赖包部署到web项目，需要我们手动导入。在WEB-INF目录中新建一个lib目录然后导入所有包，不然tomcat会启动报错，出现一个或多个筛选器失败。。！

 若有不足之处，欢迎业界大佬点评留言~