SSM框架整合

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：

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>

spring配置文件，主要是dao、service、controller

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>

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>

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>

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>

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>

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);
    }

}

SSM框架整合

环境

工具

准备工作

步骤

1、新建Maven webapp项目

2、配置文件

3、代码，应用实例（图书管理系统）

3.1 dao层

3.2 servic层

3.3 controller层

messchx

引用和评论

ActiveMQ入门及与SpringBoot整合

如何实现一个楼中楼的评论系统

在Java程序中监听mysql的binlog

Jerry和您聊聊Chrome开发者工具

Bitmap 和布隆过滤器傻傻分不清？你这不应该啊

Spring和idea为什么不推荐使用@Autowired注入

Just for fun——迅速写完快速排序

SSM框架整合

环境

工具

准备工作

步骤

1、新建Maven webapp项目

2、配置文件

3、代码，应用实例（图书管理系统）

3.1 dao层

3.2 servic层

3.3 controller层

messchx

引用和评论

ActiveMQ入门及与SpringBoot整合

如何实现一个楼中楼的评论系统

在Java程序中监听mysql的binlog

Jerry和您聊聊Chrome开发者工具

Bitmap 和 布隆过滤器傻傻分不清？你这不应该啊

Spring和idea为什么不推荐使用@Autowired注入

Just for fun——迅速写完快速排序

Bitmap 和布隆过滤器傻傻分不清？你这不应该啊