SSM框架整合

Java框架

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2019-3-20

AD:资源代下载服务

环境

  • Windows10
  • JDK1.8
  • MySql5.5

工具

  • Maven3.5
  • IDEA2017
  • Navicat(数据库连接工具)

准备工作

步骤

1、新建Maven webapp项目



建好基本目录,按住 Ctrl+Alt+Shift+s配置目录,如下图

新建几个包,如下图:

包名 名称 作用
dao 数据访问层(接口 与数据操作有关的都放在这里
entity 实体类 一般与数据库的表相对应,封装dao层取出来的数据为一个对象,也就是我们常说的pojo,一般只在dao层与service层之间传输
dto 数据传输层 用于service层与web层之间传输,相当于vo
service 业务逻辑(接口) 写我们的业务逻辑,在设计业务接口时候应该站在“使用者”的角度。
serviceImpl 业务逻辑(实现) 实现我们业务接口,一般事务控制是写在这里,没什么好说的。
controller 控制器 springmvc就是在这里发挥作用的

2、配置文件

配置完成的目录如下:

  1. pom.xml

    <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 http://maven.apache.org/maven-v4_0_0.xsd">
      <modelVersion>4.0.0</modelVersion>
      <groupId>com.messchx</groupId>
      <artifactId>ssmdemo</artifactId>
      <packaging>war</packaging>
      <version>1.0-SNAPSHOT</version>
      <name>ssmdemo Maven Webapp</name>
      <url>http://maven.apache.org</url>
    
      <build>
        <finalName>ssmdemo</finalName>
    
        <plugins>
          <plugin>
            <groupId>org.mortbay.jetty</groupId>
            <artifactId>maven-jetty-plugin</artifactId>
            <version>6.1.7</version>
            <configuration>
              <connectors>
                <connector implementation="org.mortbay.jetty.nio.SelectChannelConnector">
                  <port>8888</port>
                  <maxIdleTime>30000</maxIdleTime>
                </connector>
              </connectors>
              <webAppSourceDirectory>${project.build.directory}/${pom.artifactId}-${pom.version}
              </webAppSourceDirectory>
              <contextPath>/</contextPath>
            </configuration>
          </plugin>
    
          <!--mybatis逆向工程插件-->
          <plugin>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-maven-plugin</artifactId>
            <version>1.3.2</version>
          </plugin>
    
          <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
              <!-- 设置JDK版本 -->
              <source>1.8</source>
              <target>1.8</target>
            </configuration>
          </plugin>
        </plugins>
        <!--若不配置,可能会发送打包不全-->
        <resources>
          <resource>
            <!--需要打包的目录-->
            <directory>src/main/java</directory>
            <!--目录中的文件类型-->
            <includes>
              <include>**/*.xml</include>
              <include>**/*.properties</include>
            </includes>
          </resource>
          <resource>
            <!--需要打包的目录-->
            <directory>src/main/resources</directory>
            <!--目录中的文件类型-->
            <includes>
              <include>**/*.xml</include>
              <include>**/*.properties</include>
            </includes>
          </resource>
    
        </resources>
      </build>
    
      <properties>
        <!-- 设置项目编码编码 -->
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <!-- spring版本号 -->
        <spring.version>4.3.5.RELEASE</spring.version>
        <!-- mybatis版本号 -->
        <mybatis.version>3.4.1</mybatis.version>
      </properties>
      <dependencies>
        <!-- java ee -->
        <dependency>
          <groupId>javax</groupId>
          <artifactId>javaee-api</artifactId>
          <version>7.0</version>
        </dependency>
    
        <!-- 单元测试 -->
        <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>4.12</version>
        </dependency>
    
        <!-- 实现slf4j接口并整合 -->
        <dependency>
          <groupId>ch.qos.logback</groupId>
          <artifactId>logback-classic</artifactId>
          <version>1.2.2</version>
        </dependency>
    
        <!-- JSON -->
        <dependency>
          <groupId>com.fasterxml.jackson.core</groupId>
          <artifactId>jackson-databind</artifactId>
          <version>2.8.7</version>
        </dependency>
    
    
        <!-- 数据库 -->
        <dependency>
          <groupId>mysql</groupId>
          <artifactId>mysql-connector-java</artifactId>
          <version>5.1.41</version>
          <scope>runtime</scope>
        </dependency>
    
        <!-- 数据库连接池 -->
        <dependency>
          <groupId>com.mchange</groupId>
          <artifactId>c3p0</artifactId>
          <version>0.9.5.2</version>
        </dependency>
    
        <!-- MyBatis -->
        <dependency>
          <groupId>org.mybatis</groupId>
          <artifactId>mybatis</artifactId>
          <version>${mybatis.version}</version>
        </dependency>
    
        <!-- mybatis/spring整合包 -->
        <dependency>
          <groupId>org.mybatis</groupId>
          <artifactId>mybatis-spring</artifactId>
          <version>1.3.1</version>
        </dependency>
    
        <!-- Spring -->
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-core</artifactId>
          <version>${spring.version}</version>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-beans</artifactId>
          <version>${spring.version}</version>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-context</artifactId>
          <version>${spring.version}</version>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-jdbc</artifactId>
          <version>${spring.version}</version>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-tx</artifactId>
          <version>${spring.version}</version>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-web</artifactId>
          <version>${spring.version}</version>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-webmvc</artifactId>
          <version>${spring.version}</version>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-test</artifactId>
          <version>${spring.version}</version>
        </dependency>
      </dependencies>
    </project>
    
  2. spring配置文件,主要是dao、service、controller

    1. 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
          http://www.springframework.org/schema/context/spring-context.xsd">
          <!-- 配置整合mybatis过程 -->
          <!-- 1.配置数据库相关参数properties的属性:${url} -->
          <context:property-placeholder location="classpath:jdbc.properties" />
      
          <!-- 2.数据库连接池 -->
          <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
              <!-- 配置连接池属性 -->
              <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" />
              <!-- 当获取连接失败重试次数 -->
              <property name="acquireRetryAttempts" value="2" />
          </bean>
      
          <!-- 3.配置SqlSessionFactory对象 -->
          <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
              <!-- 注入数据库连接池 -->
              <property name="dataSource" ref="dataSource" />
              <!-- 配置MyBaties全局配置文件:mybatis-config.xml -->
              <property name="configLocation" value="classpath:mybatis-config.xml" />
              <!-- 扫描entity包 使用别名 -->
              <property name="typeAliasesPackage" value="com.soecode.lyf.entity" />
              <!-- 扫描sql配置文件:mapper需要的xml文件 -->
              <property name="mapperLocations" value="classpath:mapper/*.xml" />
          </bean>
      
          <!-- 4.配置扫描Dao接口包,动态实现Dao接口,注入到spring容器中 -->
          <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
              <!-- 注入sqlSessionFactory -->
              <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
              <!-- 给出需要扫描Dao接口包 -->
              <property name="basePackage" value="com.soecode.lyf.dao" />
          </bean>
      </beans>    

      jdbc.properties

      jdbc.driver=com.mysql.jdbc.Driver
      jdbc.url=jdbc:mysql://localhost:3306/ssm?useUnicode=true&characterEncoding=utf8
      jdbc.username=root
      jdbc.password=root    

      提示:配置文件中的jdbc.username,如果写成username,可能会与系统环境中的username变量冲突,所以到时候真正连接数据库的时候,用户名就被替换成系统中的用户名(有得可能是administrator),那肯定是连接不成功的

      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>
          <!-- 配置全局属性 -->
          <settings>
              <!-- 使用jdbc的getGeneratedKeys获取数据库自增主键值 -->
              <setting name="useGeneratedKeys" value="true" />
      
              <!-- 使用列别名替换列名 默认:true -->
              <setting name="useColumnLabel" value="true" />
      
              <!-- 开启驼峰命名转换:Table{create_time} -> Entity{createTime} -->
              <setting name="mapUnderscoreToCamelCase" value="true" />
          </settings>
      </configuration>
    2. 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"
             xmlns:tx="http://www.springframework.org/schema/tx"
             xsi:schemaLocation="http://www.springframework.org/schema/beans
          http://www.springframework.org/schema/beans/spring-beans.xsd
          http://www.springframework.org/schema/context
          http://www.springframework.org/schema/context/spring-context.xsd
          http://www.springframework.org/schema/tx
          http://www.springframework.org/schema/tx/spring-tx.xsd">
          <!-- 扫描service包下所有使用注解的类型 -->
          <context:component-scan base-package="com.messchx.ssm.service" />
      
          <!-- 配置事务管理器 -->
          <bean id="transactionManager"
                class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
              <!-- 注入数据库连接池 -->
              <property name="dataSource" ref="dataSource" />
          </bean>
      
          <!-- 配置基于注解的声明式事务 -->
          <tx:annotation-driven transaction-manager="transactionManager" />
      </beans>
    3. spring-controller.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"
             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
          http://www.springframework.org/schema/context/spring-context.xsd
          http://www.springframework.org/schema/mvc
          http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
          <!-- 配置SpringMVC -->
          <!-- 1.开启SpringMVC注解模式 -->
          <!-- 简化配置:
              (1)自动注册DefaultAnootationHandlerMapping,AnotationMethodHandlerAdapter
              (2)提供一些列:数据绑定,数字和日期的format @NumberFormat, @DateTimeFormat, xml,json默认读写支持
          -->
          <mvc:annotation-driven />
      
          <!-- 2.静态资源默认servlet配置
              (1)加入对静态资源的处理:js,gif,png
              (2)允许使用"/"做整体映射
           -->
          <mvc:default-servlet-handler/>
      
          <!-- 3.配置jsp 显示ViewResolver -->
          <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
              <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
              <property name="prefix" value="/WEB-INF/jsp/" />
              <property name="suffix" value=".jsp" />
          </bean>
      
          <!-- 4.扫描web相关的bean -->
          <context:component-scan base-package="com.messchx.ssm.controller" />
      </beans>
  3. web.xml

    <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_3_1.xsd"
             version="3.1" metadata-complete="true">
      <!-- 如果是用mvn命令生成的xml,需要修改servlet版本为3.1 -->
      <!-- 配置DispatcherServlet -->
      <servlet>
        <servlet-name>dispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!-- 配置springMVC需要加载的配置文件
            spring-dao.xml,spring-service.xml,spring-web.xml
            Mybatis - > spring -> springmvc
         -->
        <init-param>
          <param-name>contextConfigLocation</param-name>
          <param-value>classpath:spring/spring-*.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
      </servlet>
      <servlet-mapping>
        <servlet-name>dispatcherServlet</servlet-name>
        <!-- 默认匹配所有的请求 -->
        <url-pattern>/</url-pattern>
      </servlet-mapping>  
    </web-app>
  4. logback.xml(日志)

    <?xml version="1.0" encoding="UTF-8"?>
    <configuration debug="true">
        <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
            <!-- encoders are by default assigned the type ch.qos.logback.classic.encoder.PatternLayoutEncoder -->
            <encoder>
                <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
            </encoder>
        </appender>
    
        <root level="debug">
            <appender-ref ref="STDOUT" />
        </root>
    </configuration>
  5. generatorConfig.xml,mybatis逆向工程,生成dao(即mapper)和model(即po),这里先不用

    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE generatorConfiguration
            PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
            "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
    
    <generatorConfiguration>
        <!--导入属性配置-->
        <properties resource="jdbc.properties"></properties>
    
        <!--指定特定数据库的jdbc驱动jar包的位置-->
        <classPathEntry location="${jdbc.driverLocation}"/>
    
        <context id="default" targetRuntime="MyBatis3">
    
            <!-- optional,旨在创建class时,对注释进行控制 -->
            <commentGenerator>
                <property name="suppressDate" value="true"/>
                <property name="suppressAllComments" value="true"/>
            </commentGenerator>
    
            <!--jdbc的数据库连接 -->
            <jdbcConnection
                    driverClass="${jdbc.driverClasss}"
                    connectionURL="${jdbc.url}"
                    userId="${jdbc.username}"
                    password="${jdbc.password}">
            </jdbcConnection>
    
    
            <!-- 非必需,类型处理器,在数据库类型和java类型之间的转换控制-->
            <javaTypeResolver>
                <property name="forceBigDecimals" value="false"/>
            </javaTypeResolver>
    
    
            <!-- 实体类
            targetPackage 指定生成的model生成所在的包名
            targetProject 指定在该项目下所在的路径
            -->
            <javaModelGenerator targetPackage="com.messchx.ssm.entity"
                                targetProject="src/main/java">
    
                <!-- 是否允许子包,即targetPackage.schemaName.tableName -->
                <property name="enableSubPackages" value="false"/>
                <!-- 是否对model添加 构造函数 -->
                <property name="constructorBased" value="true"/>
                <!-- 是否对类CHAR类型的列的数据进行trim操作 -->
                <property name="trimStrings" value="true"/>
                <!-- 建立的Model对象是否 不可改变 即生成的Model对象不会有 setter方法,只有构造方法 -->
                <property name="immutable" value="false"/>
            </javaModelGenerator>
    
            <!--Mapper映射文件生成所在的目录 为每一个数据库的表生成对应的SqlMap文件 -->
            <sqlMapGenerator targetPackage="com.messchx.ssm.mapper"
                             targetProject="src/main/java">
                <property name="enableSubPackages" value="false"/>
            </sqlMapGenerator>
    
            <!-- 客户端代码,生成易于使用的针对Model对象和XML配置文件 的代码
            type="ANNOTATEDMAPPER",生成Java Model 和基于注解的Mapper对象
            type="MIXEDMAPPER",生成基于注解的Java Model 和相应的Mapper对象
            type="XMLMAPPER",生成SQLMap XML文件和独立的Mapper接口
            -->
            <javaClientGenerator targetPackage="com.messchx.ssm.dao"
                                 targetProject="src/main/java" type="XMLMAPPER">
                <property name="enableSubPackages" value="true"/>
            </javaClientGenerator>
    
            <!--数据库中的表-->
            <table tableName="user"></table>
        </context>
    </generatorConfiguration>
    

    到这里基本的配置都完了,剩下的就是写代码。

3、代码,应用实例(图书管理系统)

mysql数据文件:

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for appointment
-- ----------------------------
DROP TABLE IF EXISTS `appointment`;
CREATE TABLE `appointment` (
  `book_id` bigint(20) NOT NULL COMMENT '图书ID',
  `student_id` bigint(20) NOT NULL COMMENT '学号',
  `appoint_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '预约时间',
  PRIMARY KEY (`book_id`,`student_id`),
  KEY `idx_appoint_time` (`appoint_time`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='预约图书表';

-- ----------------------------
-- Records of appointment
-- ----------------------------
INSERT INTO `appointment` VALUES ('1000', '12345678910', '2018-01-16 15:44:36');
INSERT INTO `appointment` VALUES ('1001', '12345678910', '2018-01-16 15:58:02');

-- ----------------------------
-- Table structure for book
-- ----------------------------
DROP TABLE IF EXISTS `book`;
CREATE TABLE `book` (
  `book_id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '图书ID',
  `name` varchar(100) NOT NULL COMMENT '图书名称',
  `number` int(11) NOT NULL COMMENT '馆藏数量',
  PRIMARY KEY (`book_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1004 DEFAULT CHARSET=utf8 COMMENT='图书表';

-- ----------------------------
-- Records of book
-- ----------------------------
INSERT INTO `book` VALUES ('1000', 'Java程序设计', '9');
INSERT INTO `book` VALUES ('1001', '数据结构', '9');
INSERT INTO `book` VALUES ('1002', '设计模式', '10');
INSERT INTO `book` VALUES ('1003', '编译原理', '10');

3.1 dao层

在entity包中添加图书实体Book.java和预约图书实体Appointment.java
Book.java

public class Book {

    private long bookId;// 图书ID

    private String name;// 图书名称

    private int number;// 馆藏数量

    // 省略构造方法,getter和setter方法,toString方法

}

Appointment.java

   /**预约图书实体*/
public class Appointment {

    private long bookId;// 图书ID

    private long studentId;// 学号

    private Date appointTime;// 预约时间

    // 多对一的复合属性
    private Book book;// 图书实体
    
    // 省略构造方法,getter和setter方法,toString方法

}

在dao包新建接口BookDao.java和Appointment.java
BookDao.java

public interface BookDao {

    /**
     * 通过ID查询单本图书
     *
     * @param id
     * @return
     */
    Book queryById(long id);

    /**
     * 查询所有图书
     *
     * @param offset 查询起始位置
     * @param limit 查询条数
     * @return
     */
    List<Book> queryAll(@Param("offset") int offset, @Param("limit") int limit);

    /**
     * 减少馆藏数量
     *
     * @param bookId
     * @return 如果影响行数等于>1,表示更新的记录行数
     */
    int reduceNumber(long bookId);
}

AppointmentDao.java

public interface AppointmentDao {

    /**
     * 插入预约图书记录
     *
     * @param bookId
     * @param studentId
     * @return 插入的行数
     */
    int insertAppointment(@Param("bookId") long bookId, @Param("studentId") long studentId);

    /**
     * 通过主键查询预约图书记录,并且携带图书实体
     *
     * @param bookId
     * @param studentId
     * @return
     */
    Appointment queryByKeyWithBook(@Param("bookId") long bookId, @Param("studentId") long studentId);

}

提示:这里为什么要给方法的参数添加@Param注解呢?是因为该方法有两个或以上的参数,一定要加,不然mybatis识别不了。上面的BookDao接口的queryById方法和reduceNumber方法只有一个参数book_id,所以可以不用加 @Param注解,当然加了也无所谓~
我们不需要实现dao接口, mybatis会动态实现,但是我们需要编写相应的mapper。在mapper目录里新建两个文件BookDao.xml和ppointmentDao.xml,分别对应上面两个dao接口。

BookDao.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.messchx.ssm.dao.BookDao">
    <!-- 目的:为dao接口方法提供sql语句配置 -->
    <select id="queryById" resultType="Book" parameterType="long">
        <!-- 具体的sql -->
        SELECT
        book_id,
        name,
        number
        FROM
        book
        WHERE
        book_id = #{bookId}
    </select>

    <select id="queryAll" resultType="Book">
        SELECT
        book_id,
        name,
        number
        FROM
        book
        ORDER BY
        book_id
        LIMIT #{offset}, #{limit}
    </select>

    <update id="reduceNumber">
        UPDATE book
        SET number = number - 1
        WHERE
        book_id = #{bookId}
        AND number > 0
    </update>
</mapper>

AppointmentDao.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.messchx.ssm.dao.AppointmentDao">
    <insert id="insertAppointment">
        <!-- ignore 主键冲突,报错 -->
        INSERT ignore INTO appointment (book_id, student_id)
        VALUES (#{bookId}, #{studentId})
    </insert>

    <select id="queryByKeyWithBook" resultType="Appointment">
        <!-- 如何告诉MyBatis把结果映射到Appointment同时映射book属性 -->
        <!-- 可以自由控制SQL -->
        SELECT
        a.book_id,
        a.student_id,
        a.appoint_time,
        b.book_id "book.book_id",
        b.`name` "book.name",
        b.number "book.number"
        FROM
        appointment a
        INNER JOIN book b ON a.book_id = b.book_id
        WHERE
        a.book_id = #{bookId}
        AND a.student_id = #{studentId}
    </select>
</mapper>

mapper总结:namespace是该xml对应的接口全名,select和update中的id对应方法名,resultType是返回值类型,parameterType是参数类型(这个其实可选),最后#{…}中填写的是方法的参数,还有一个小技巧要交给大家,就是在返回Appointment对象包含了一个属性名为book的Book对象,那么可以使用”book.属性名”的方式来取值,看上面queryByKeyWithBook方法的sql。

测试:在测试分支建立相应的包,测试前需要让程序读入spring-dao和mybatis等配置文件,所以我这里就抽离出来一个BaseTest类,只要是测试方法就继承它即可。
BaseTest.java

/**
* 配置spring和junit整合,junit启动时加载springIOC容器 spring-test,junit
*/
@RunWith(SpringJUnit4ClassRunner.class)
// 告诉junit spring配置文件
@ContextConfiguration({ "classpath:spring/spring-dao.xml", "classpath:spring/spring-service.xml" })
public class BaseTest {

}

新建BookDaoTest.java和AppointmentDaoTest.java两个dao测试文件
BookDaoTest.java

public class BookDaoTest extends BaseTest {
    @Autowired
    private BookDao bookDao;

    @Test
    public void testQueryById() throws Exception {
        long bookId = 1000;
        Book book = bookDao.queryById(bookId);
        System.out.println(book);
    }

    @Test
    public void testQueryAll() throws Exception {
        List<Book> books = bookDao.queryAll(0, 4);
        for (Book book : books) {
            System.out.println(book);
        }
    }

    @Test
    public void testReduceNumber() throws Exception {
        long bookId = 1000;
        int update = bookDao.reduceNumber(bookId);
        System.out.println("update=" + update);
    }

}

BookDaoTest测试结果,testQueryById

testQueryAll

testReduceNumber

AppointmentDaoTest.java

public class AppointmentDaoTest extends BaseTest{
    @Autowired
    private AppointmentDao appointmentDao;

    @Test
    public void testInsertAppointment() throws Exception {
        long bookId = 1000;
        long studentId = 12345678910L;
        int insert = appointmentDao.insertAppointment(bookId, studentId);
        System.out.println("insert=" + insert);
    }

    @Test
    public void testQueryByKeyWithBook() throws Exception {
        long bookId = 1000;
        long studentId = 12345678910L;
        Appointment appointment = appointmentDao.queryByKeyWithBook(bookId, studentId);
        System.out.println(appointment);
        System.out.println(appointment.getBook());
    }

}

AppointmentDaoTest测试结果,testInsertAppointment

testQueryByKeyWithBook

3.2 servic层

我们先定义几个预约图书操作返回码的数据字典,也就是我们要返回给客户端的信息。我们这类使用枚举类

返回码 说明
1 预约成功
0 库存不足
-1 重复预约
-2 系统异常

AppointStateEnum.java

package com.messchx.ssm.enums;

/**
 * 使用枚举表述常量数据字典
 */
public enum AppointStateEnum {
    SUCCESS(1, "预约成功"), NO_NUMBER(0, "库存不足"), REPEAT_APPOINT(-1, "重复预约"), INNER_ERROR(-2, "系统异常");

    private int state;

    private String stateInfo;

    private AppointStateEnum(int state, String stateInfo) {
        this.state = state;
        this.stateInfo = stateInfo;
    }

    public int getState() {
        return state;
    }

    public String getStateInfo() {
        return stateInfo;
    }

    public static AppointStateEnum stateOf(int index) {
        for (AppointStateEnum state : values()) {
            if (state.getState() == index) {
                return state;
            }
        }
        return null;
    }

}

在dto包下新建AppointExecution.java用来存储我们执行预约操作的返回结果。
AppointExecution.java

/**
* 封装预约执行后结果
*/
public class AppointExecution {

    // 图书ID
    private long bookId;

    // 秒杀预约结果状态
    private int state;

    // 状态标识
    private String stateInfo;

    // 预约成功对象
    private Appointment appointment;

    public AppointExecution() {
    }

    // 预约失败的构造器
    public AppointExecution(long bookId, AppointStateEnum stateEnum) {
        this.bookId = bookId;
        this.state = stateEnum.getState();
        this.stateInfo = stateEnum.getStateInfo();
    }

    // 预约成功的构造器
    public AppointExecution(long bookId, AppointStateEnum stateEnum, Appointment appointment) {
        this.bookId = bookId;
        this.state = stateEnum.getState();
        this.stateInfo = stateEnum.getStateInfo();
        this.appointment = appointment;
    }
    
    // 省略getter和setter方法,toString方法

}

在exception包下新建三个文件NoNumberException.java RepeatAppointException.java AppointException.java预约业务异常类(都需要继承RuntimeException),分别是无库存异常、重复预约异常、预约未知错误异常,用于业务层非成功情况下的返回(即成功返回结果,失败抛出异常)。
NoNumberException.java

/**
* 库存不足异常
*/
public class NoNumberException extends RuntimeException {

    public NoNumberException(String message) {
        super(message);
    }

    public NoNumberException(String message, Throwable cause) {
        super(message, cause);
    }

}

RepeatAppointException.java

/**
* 重复预约异常
*/
public class RepeatAppointException extends RuntimeException {

    public RepeatAppointException(String message) {
        super(message);
    }

    public RepeatAppointException(String message, Throwable cause) {
        super(message, cause);
    }

}

AppointException.java

/**
* 预约业务异常
*/
public class AppointException extends RuntimeException {

    public AppointException(String message) {
        super(message);
    }

    public AppointException(String message, Throwable cause) {
        super(message, cause);
    }

}

在service包下新建BookService.java图书业务接口
BookService.java

/**
* 业务接口:站在"使用者"角度设计接口 三个方面:方法定义粒度,参数,返回类型(return 类型/异常)
*/
public interface BookService {

    /**
     * 查询一本图书
     *
     * @param bookId
     * @return
     */
    Book getById(long bookId);

    /**
     * 查询所有图书
     *
     * @return
     */
    List<Book> getList();

    /**
     * 预约图书
     *
     * @param bookId
     * @param studentId
     * @return
     */
    AppointExecution appoint(long bookId, long studentId);

}

在service.impl包下新建BookServiceImpl.java使用BookService接口,并实现里面的方法。
BookServiceImpl

@Service
public class BookServiceImpl implements BookService {

    private Logger logger = LoggerFactory.getLogger(this.getClass());

    // 注入Service依赖
    @Autowired
    private BookDao bookDao;

    @Autowired
    private AppointmentDao appointmentDao;


    @Override
    public Book getById(long bookId) {
        return bookDao.queryById(bookId);
    }

    @Override
    public List<Book> getList() {
        return bookDao.queryAll(0, 1000);
    }

    @Override
    @Transactional
    /**
     * 使用注解控制事务方法的优点: 1.开发团队达成一致约定,明确标注事务方法的编程风格
     * 2.保证事务方法的执行时间尽可能短,不要穿插其他网络操作,RPC/HTTP请求或者剥离到事务方法外部
     * 3.不是所有的方法都需要事务,如只有一条修改操作,只读操作不需要事务控制
     */
    public AppointExecution appoint(long bookId, long studentId) {
        try {
            // 减库存
            int update = bookDao.reduceNumber(bookId);
            if (update <= 0) {// 库存不足
                //return new AppointExecution(bookId, AppointStateEnum.NO_NUMBER);//错误写法                
                throw new NoNumberException("no number");
            } else {
                // 执行预约操作
                int insert = appointmentDao.insertAppointment(bookId, studentId);
                if (insert <= 0) {// 重复预约
                    //return new AppointExecution(bookId, AppointStateEnum.REPEAT_APPOINT);//错误写法
                    throw new RepeatAppointException("repeat appoint");
                } else {// 预约成功
                    Appointment appointment = appointmentDao.queryByKeyWithBook(bookId, studentId);
                    return new AppointExecution(bookId, AppointStateEnum.SUCCESS, appointment);
                }
            }
        // 要先于catch Exception异常前先catch住再抛出,不然自定义的异常也会被转换为AppointException,导致控制层无法具体识别是哪个异常
        } catch (NoNumberException e1) {
            throw e1;
        } catch (RepeatAppointException e2) {
            throw e2;
        } catch (Exception e) {
            logger.error(e.getMessage(), e);
            // 所有编译期异常转换为运行期异常
            //return new AppointExecution(bookId, AppointStateEnum.INNER_ERROR);//错误写法
            throw new AppointException("appoint inner error:" + e.getMessage());
        }
    }

}

测试一下业务代码
BookServiceImplTest.java

public class BookServiceImplTest extends BaseTest {

    @Autowired
    private BookService bookService;

    @Test
    public void testAppoint() throws Exception {
        long bookId = 1001;
        long studentId = 12345678910L;
        AppointExecution execution = bookService.appoint(bookId, studentId);
        System.out.println(execution);
    }

}

BookServiceImplTest测试结果

首次执行是“预约成功”,如果再次执行的话,应该会出现“重复预约”

在dto包里新建一个封装json返回结果的类Result.java,设计成泛型
Result.java

/**
* 封装json对象,所有返回结果都使用它
*/
public class Result<T> {

    private boolean success;// 是否成功标志

    private T data;// 成功时返回的数据

    private String error;// 错误信息

    public Result() {
    }

    // 成功时的构造器
    public Result(boolean success, T data) {
        this.success = success;
        this.data = data;
    }

    // 错误时的构造器
    public Result(boolean success, String error) {
        this.success = success;
        this.error = error;
    }

    // 省略getter和setter方法
}

3.3 controller层

BookController.java

@Controller
@RequestMapping("/book") // url:/模块/资源/{id}/细分 /seckill/list
public class BookController {

    private Logger logger = LoggerFactory.getLogger(this.getClass());

    @Autowired
    private BookService bookService;

    @RequestMapping(value = "/list", method = RequestMethod.GET)
    private String list(Model model) {
        List<Book> list = bookService.getList();
        model.addAttribute("list", list);
        // list.jsp + model = ModelAndView
        return "list";// WEB-INF/jsp/"list".jsp
    }

    @RequestMapping(value = "/{bookId}/detail", method = RequestMethod.GET)
    private String detail(@PathVariable("bookId") Long bookId, Model model) {
        if (bookId == null) {
            return "redirect:/book/list";
        }
        Book book = bookService.getById(bookId);
        if (book == null) {
            return "forward:/book/list";
        }
        model.addAttribute("book", book);
        return "detail";
    }

    //ajax json
    @RequestMapping(value = "/{bookId}/appoint", method = RequestMethod.POST, produces = {
            "application/json; charset=utf-8" })
    @ResponseBody
    private Result<AppointExecution> appoint(@PathVariable("bookId") Long bookId, @RequestParam("studentId") Long studentId) {
        if (studentId == null || studentId.equals("")) {
            return new Result<>(false, "学号不能为空");
        }
        //AppointExecution execution = bookService.appoint(bookId, studentId);//错误写法,不能统一返回,要处理异常(失败)情况
        AppointExecution execution = null;
        try {
            execution = bookService.appoint(bookId, studentId);
        } catch (NoNumberException e1) {
            execution = new AppointExecution(bookId, AppointStateEnum.NO_NUMBER);
        } catch (RepeatAppointException e2) {
            execution = new AppointExecution(bookId, AppointStateEnum.REPEAT_APPOINT);
        } catch (Exception e) {
            execution = new AppointExecution(bookId, AppointStateEnum.INNER_ERROR);
        }
        return new Result<AppointExecution>(true, execution);
    }

}