create database `ssmbuild`;
use `ssmbuild`;
drop table if exists `books`;
create table `books`
(
`bookID` int(10) not null auto_increment comment ‘书id‘,
`bookName` varchar(100) not null comment ‘书名‘,
`bookCounts` int(10) not null comment ‘数量‘,
`detail` varchar(200) not null comment ‘描述‘,
key `bookID` (`bookID`)
) engine = INNODB
default charset = utf8;
insert into books (bookID, bookName, bookCounts, detail)
values (1, ‘java‘, 1, ‘从入门到放弃‘),
(2, ‘MySQL‘, 10, ‘从删库到跑路‘),
(3, ‘Linux‘, 5, ‘从进门到坐牢‘);
导入依赖
<!--依赖: junit,数据库驱动,连接池,servlet,jsp,mybatis,mybatis-spring,spring-->
<dependencies>
<!--junit-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<!--数据库驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
<!--数据库连接池-->
<dependency>
<groupId>com.mchange</groupId>
<artifactId>c3p0</artifactId>
<version>0.9.5.2</version>
</dependency>
<!--Servlet,JSP-->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.2</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<!--Mybatis-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.2</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>2.0.5</version>
</dependency>
<!--Spring-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.2.0.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>5.2.0.RELEASE</version>
</dependency>
<!--Lombok:可以不导,只是为了偷懒-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.12</version>
</dependency>
</dependencies>
静态资源导出
<!--静态资源导出问题-->
<build>
<resources>
<resource>
<directory>src/man/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
<resource>
<directory>src/man/resources</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
</build>
mybatis-config.xml初始化 :
<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
</configuration>
applicationContext.xml初始化 :
<?xml version="1.0" encoding="utf-8" ?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
</beans>
在resources包下添加一个数据库配置文件database.properties :
# 如果使用MySQL 8.0+ ,增加一个时区的配置
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssmbuild?useSSL=true&useUnicode=true&characterEncoding=utf8
jdbc.username=root
jdbc.password=123456
pojo包 Books类 :
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Books {
private int bookID;
private String bookName;
private int bookCounts;
private String detail;
}
mybatis-config.xml中添加别名 :
<typeAliases>
<package name="com.tan.pojo"/>
</typeAliases>
接口BookMapper :
public interface BookMapper {
//增加一本书
int addBook(Books books);
//删除一本书
int deleteBookById(@Param("bookId") int id);
//更新一本书
int updateBook(Books books);
//查询一本书
Books queryBookById(@Param("bookId") int id);
//查询全部书
List<Books> queryAllBook();
}
BookMapper.xml :
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.tan.dao.BookMapper">
<insert id="addBook" parameterType="Books">
insert into ssmbuild.books(bookName, bookCounts, detail)
values (#{bookName}, #{bookCounts}, #{detail});
</insert>
<delete id="deleteBookById" parameterType="int">
delete from ssmbuild.books where bookID=#{bookId}
</delete>
<update id="updateBook" parameterType="Books">
update ssmbuild.books
set bookName = #{bookName},bookCounts=#{bookCounts},detail=#{detail}
where bookID=#{bookId};
</update>
<select id="queryBookById" resultType="Books">
select * from ssmbuild.books where bookID=#{bookId}
</select>
<select id="queryAllBook" resultType="Books">
select * from ssmbuild.books
</select>
</mapper>
mybatis配置文件中添加mapper :
<mappers>
<mapper class="com.tan.dao.BookMapper"/>
</mappers>
BookService接口 :
public interface BookService {
//增加一本书
int addBook(Books books);
//删除一本书
int deleteBookById(int id);
//更新一本书
int updateBook(Books books);
//查询一本书
Books queryBookById(int id);
//查询全部书
List<Books> queryAllBook();
}
接口实现类BookServiceImpl :
public class BookServiceImpl implements BookService{
//service调dao层:组合Dao
private BookMapper bookMapper;
public void setBookMapper(BookMapper bookMapper) {
this.bookMapper = bookMapper;
}
public int addBook(Books books) {
return bookMapper.addBook(books);
}
public int deleteBookById(int id) {
return bookMapper.deleteBookById(id);
}
public int updateBook(Books books) {
return bookMapper.updateBook(books);
}
public Books queryBookById(int id) {
return bookMapper.queryBookById(id);
}
public List<Books> queryAllBook() {
return bookMapper.queryAllBook();
}
}
Dao层的配置原本在mybatis配置文件中,现在都可以整合到spring-dao.xml中.
spring-dao.xml :
<?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"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
<!--1.关联数据库文件-->
<context:property-placeholder location="classpath:database.properties"/>
<!--2.连接池, 可随意配置,此处选择c3p0
dbcp: 半自动化操作,不能自动连接
c3p0: 自动化操作(自动化加载配置文件,并且可以自动设置到对象中!)
druid: 阿里巴巴出品
hikari: SpringBoot 2.x 内置默认数据库连接池
-->
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="driverClass" value="${jdbc.driver}"/>
<property name="jdbcUrl" value="${jdbc.url}"/>
<property name="user" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
<!--c3p0连接池的私有属性-->
<property name="maxPoolSize" value="30"/>
<property name="minPoolSize" value="10"/>
<!--关闭连接后不自动commit-->
<property name="autoCommitOnClose" value="false"/>
<!--获取连接超时时间-->
<property name="checkoutTimeout" value="10000"/>
<!--获取连接失败重试次数-->
<property name="acquireRetryAttempts" value="2"/>
</bean>
<!--3.sqlSessionFactory-->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<!--绑定Mybatis的配置文件-->
<property name="configLocation" value="classpath:mybatis-config.xml"/>
</bean>
<!--4.配置dao接口扫描包,动态地实现了Dao接口可以注入到Spring容器中!-->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<!--注入sqlSessionFactory-->
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
<!--扫描dao包-->
<property name="basePackage" value="com.tan.dao"/>
</bean>
</beans>
但是mybatis-config.xml中还是留了一点,只是为了表示一下这里还有mybatis .
mybatis-config.xml :
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!--配置数据源,交给Spring去做-->
<typeAliases>
<package name="com.tan.pojo"/>
</typeAliases>
<mappers>
<mapper class="com.tan.dao.BookMapper"/>
</mappers>
</configuration>
spring-service.xml :
<?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"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
<!--1.扫描service下的包-->
<context:component-scan base-package="com.tan.service"/>
<!--2.将我们所有业务类注入到Spring中,可以通过配置,或者注解实现-->
<bean id="bookServiceImpl" class="com.tan.service.BookServiceImpl">
<property name="bookMapper" ref="bookMapper"/>
</bean>
<!--3.声明式事务配置-->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<!--注入数据源-->
<property name="dataSource" ref="dataSource"/>
</bean>
<!--4.aop事务支持(需要时再加)-->
</beans>
<?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">
<!--DispatcherServlet-->
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:applicationContext.xml</param-value>
</init-param>
<!--启动级别1,和tomcat一起启动-->
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<!-- /不包括.jsp , /*包括.jsp -->
<url-pattern>/</url-pattern>
</servlet-mapping>
<!--乱码过滤-->
<filter>
<filter-name>encodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>utf-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encodingFilter</filter-name>
<!-- /*过滤所有页面包括.jsp -->
<url-pattern>/*</url-pattern>
</filter-mapping>
<!--Session-->
<session-config>
<session-timeout>15</session-timeout>
</session-config>
</web-app>
<?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:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!--1.注解驱动-->
<mvc:annotation-driven/>
<!--2.静态资源过滤-->
<mvc:default-servlet-handler/>
<!--3.扫描包:controller-->
<context:component-scan base-package="com.tan.controller"/>
<!--4.视图解析器-->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/jsp/"/>
<property name="suffix" value=".jsp"/>
</bean>
</beans>
不知道为什么打包的时候没有自动生成,很奇怪应该是个bug,每次添加了新的jar包之后都要在这里手动添加一下
在controller包下新建BookController类
BookController.java :
@Controller
@RequestMapping("/book")
public class BookController {
//controller调service层
@Autowired
@Qualifier("bookServiceImpl")
private BookService bookService;
//查询全部的书籍,并返回到一个书籍的展示页面
@RequestMapping("/allBook")
public String list(Model model) {
List<Books> list = bookService.queryAllBook();
model.addAttribute("list",list);
return "allBook";
}
}
由视图解析器拼接字符串后跳转的路径为\WEB-INF\jsp\allBook.jsp
index.jsp :
<html>
<head>
<title>书籍页面</title>
</head>
<body>
<h3>
<a href="${pageContext.request.contextPath}/book/allBook">进入书籍页面</a>
</h3>
</body>
</html>
allBook.jsp :
<html>
<head>
<title>书籍展示</title>
</head>
<body>
<h1>书籍展示</h1>
</body>
</html>
点击后 :
当然真实情况没这么顺利
错误信息给的很少,大概意思就是没有jar包,且没办法部署项目.
直接搜错误信息结果范围太大, 找不到问题.
解决方法 : 没有jar包就在Project Structure中手动添加lib包和jar包依赖
这个比较好找,错误信息中给出了具体位置,就是spring相关的配置文件的头文件出错了
绑定异常,开始以为是mapper绑定出问题,检查之后没有任何问题.
于是检查输出文件
缺少BookMapper.xml八成是maven出问题
1.检查pom.xml静态资源过滤 OK
2.clean一下,在打包一下
? 结果打包出错,简单检查一下后发现项目名出错, 之前是sssmbuild
? 
由于之前项目名出错,中途改了回来, 但是maven配置中的artifactId没有改, 结果打包出错
由于我在视频中一眼看到就顺手改了一下, 所以自己没有遇到.??
错误信息 :
UnsatisfiedDependencyException:Error creating bean with name ‘bookController‘: Unsatisfied dependency expressed through field ‘bookService‘; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type ‘com.tan.service.BookService‘ available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value="bookServiceImpl")}
NoSuchBeanDefinitionException: No qualifying bean of type ‘com.tan.service.BookService‘ available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value="bookServiceImpl")}
大概意思就是bean不存在 ;
问题: bean不存在
步骤:
查看这个bean注入是否成功! ok
点击之后跳转到bean注入位置, bean注入没有问题
Junit单元测试,看我们的的代码是否能查询出来结果! ok
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);
}
}
}
查询成功,说明代码没有问题
问题一定不在我们底层,是spring出了问题!
bean注入成功,底层代码没有问题,说明只剩下spring调用有问题
springMVC整合的时候没有调用到我们service层的bean
可能情况:
applicationContext.xml 没有注入bean
applicationContext.xml只负责整合,没有出问题
web.xml中, 我们也绑定过配置文件! , 发现问题,
我们配置的是Spring-MVC.xml,这里确实没有service bean
,所以报空指针.
之前是classpath:spring-mvc.xml, 没办法调到spring-service.xml, 所以出现空指针异常
问题: bean不存在
步骤:
1. 查看这个bean注入是否成功! ok
2. Junit单元测试,看我们的的代码是否能查询出来结果! ok
3. 问题一定不在我们底层,是spring出了问题!
4. springMVC整合的时候没有调用到我们service层的bean
1.applicationContext.xml 没有注入bean
2.web.xml中, 我们也绑定过配置文件! , 发现问题,
我们配置的是Spring-MVC.xml,这里确实没有service bean,
所以报空指针.
原文：https://www.cnblogs.com/tanshishi/p/13274413.html