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1. 介绍

1.1 概念介绍

SSM项目是指基于Spring+SpringMVC+MyBatis框架搭建的Java Web项目。

• Spring是负责管理和组织项目的IOC容器和AOP功能
• SpringMVC是一个轻量级的MVC框架，用于处理Web请求和响应
• MyBatis是一种持久化框架，用于进行数据库操作的ORM框架。

学习笔记：
Spring：https://blog.csdn.net/meini32/article/details/132474555
SpringMVC：https://blog.csdn.net/meini32/article/details/132545058
Mybatis：https://blog.csdn.net/meini32/article/details/132068955
Mybatis商品增删改查案例：https://blog.csdn.net/meini32/article/details/132095237

2 SSM整合框架

关键内容

Spring

• SpringConfig

SpringMVC

• SpringMvcConfig
• ServletConfig

Mybatis

• MyBatisConfig
• JdbcConfig
• jdbc.properties

MyBatis
jdbc.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/db1
jdbc.username=root
jdbc.password=123456

package com.it.config;import javax.sql.DataSource;
import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;//jdbcConfigpublic class jdbcConfig {@Value("${jdbc.driver}")private String driver;@Value("${jdbc.url}")private String url;@Value("${jdbc.username}")private String username;@Value("${jdbc.password}")private String password;//数据源@Beanpublic DataSource dataSource(){DruidDataSource druidDataSource = new DruidDataSource();druidDataSource.setDriverClassName(driver);druidDataSource.setUrl(url);druidDataSource.setUsername(username);druidDataSource.setPassword(password);return druidDataSource;}
}
-----------------------------------------------------
package com.it.config;import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.springframework.context.annotation.Bean;
import javax.sql.DataSource;//MyBatisConfig
public class MybatisConfig {//创建和管理数据库会话@Beanpublic SqlSessionFactoryBean sqlSessionFactory(DataSource dataSource){SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();factoryBean.setDataSource(dataSource);factoryBean.setTypeAliasesPackage("com.it.domain");return factoryBean;}@Bean//创建并配置MapperScannerConfigurer对象public MapperScannerConfigurer mapperScannerConfigurer(){MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();mapperScannerConfigurer.setBasePackage("com.it.dao");return mapperScannerConfigurer;}
}

web容器配置类

SpringMVC

• SpringMvcConfig
• ServletConfig

//ServletConfig
@Configuration
public class ServletConfig extends AbstractAnnotationConfigDispatcherServletInitializer {@Overrideprotected Class<?>[] getRootConfigClasses() {return new Class[]{SpringConfig.class};}@Overrideprotected Class<?>[] getServletConfigClasses() {return new Class[]{SpringMvcConfig.class};}@Overrideprotected String[] getServletMappings() {return new String[]{"/"};}
}----------------------------------------------------------------------
//SpringMvcConfig
@Configuration
@ComponentScan("com.it.controller")
@EnableWebMvc
public class SpringMvcConfig {
}

Spring

• SpringConfig

//整合Spring应用程序，实现对组件和属性的管理和使用
@Configuration
@ComponentScan({"com.it.service"})
@PropertySource("jdbc.properties")
@Import({jdbcConfig.class, MybatisConfig.class})
public class SpringConfig {
}

3. SSM功能模块开发

内容

• 表与实体类；
• dao（接口+自动代理）
• service（接口+实现类）
• controller

添加相关依赖

<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>org.example</groupId><artifactId>spring-ssm</artifactId><packaging>war</packaging><version>1.0-SNAPSHOT</version><dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>5.2.9.RELEASE</version></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.9.0</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.5</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>1.3.0</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.32</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>5.3.13</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-test</artifactId><version>5.3.13</version></dependency><!--    数据库连接池依赖--><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.2.6</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.28</version></dependency><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version><scope>provided</scope></dependency></dependencies><build><plugins><plugin><groupId>org.apache.tomcat.maven</groupId><artifactId>tomcat7-maven-plugin</artifactId><version>2.2</version><configuration><port>81</port><path></path></configuration></plugin></plugins></build>
</project>

import lombok.Data;@Data
public class User {private int id;private String username;private String password;
}------------------------------------------------------------------------
package com.it.dao;import com.it.domain.User;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;import java.util.List;//用户增删改查接口
public interface UserDao {@Insert("INSERT INTO tb_user values (null,#{name},#{password}}})")public void save(User user);@Update("UPDATE tb_user set name=#{id},password=#{password} where id=#{id}}")public void update(User user);@Delete("DELETE from tb_user where id = #{id}}")public void delete(Integer id);@Select("SELECT * FROM tb_user")public List<User> selectAll();@Select("SELECT * FROM tb_user WHERE id=#{id}")public User selectById(Integer id);}----------------------------------------------------------------------
package com.it.service;import com.it.domain.User;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;import java.util.List;public interface UserService {/*** 保存* @param user* @return*/public boolean save(User user);/*** 修改* @param user* @return*/public boolean update(User user);/*** 删除* @param id* @return*/public boolean delete(Integer id);/*** 查全部* @return*/public List<User> selectAll();/*** 按id查找* @param id* @return*/public User selectById(Integer id);
}---------------------------------------------------------------------------
package com.it.service.impl;import com.it.dao.UserDao;
import com.it.domain.User;
import com.it.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.util.List;@Service
public class UserServiceImpl implements UserService {@Autowired //自动装配private UserDao userDao;public boolean save(User user) {userDao.save(user);return true;}public boolean update(User user) {userDao.update(user);return true;}public boolean delete(Integer id) {userDao.delete(id);return true;}public List<User> selectAll() {return userDao.selectAll();}public User selectById(Integer id) {return userDao.selectById(id);}
}------------------------------------------------------------------------
package com.it.controller;import com.it.domain.User;
import com.it.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;import java.util.List;@RestController
@RequestMapping("/user")
public class UserController {@Autowiredprivate UserService userService;@PostMappingpublic boolean save(@RequestBody User user) {return userService.save(user);}@PutMappingpublic boolean update(@RequestBody User user) {return userService.update(user);}@DeleteMapping("/{id}")public boolean delete(@PathVariable Integer id) {System.out.println(userService.delete(id));return userService.delete(id);}@GetMappingpublic List<User> selectAll() {System.out.println(userService.selectAll());return userService.selectAll();}@GetMapping("/{id}")public User selectById(@PathVariable Integer id) {return userService.selectById(id);}
}

4 测试

4.1 业务层接口测试

4.2 表现层接口测试

5.优化 -表现层数据封装

• 前端接受数据格式封装到code属性用于区分操作
• 将特殊消息封装到message（msg）属性中

public class Result{private Object data;private Integer code;private String msg;
}

package com.it.controller;public class Code {//成功public static final Integer SAVE_OK = 20011;public static final Integer DELETE_OK = 20021;public static final Integer UPDATE_OK = 20031;public static final Integer GET_OK = 20041;public static final Integer PUT_OK = 20051;//失败public static final Integer SAVE_ERR = 20010;public static final Integer DELETE_ERR = 20020;public static final Integer UPDATE_ERR = 20030;public static final Integer GET_ERR = 20040;public static final Integer PUT_ERR = 20050;
}
----------------------------------------------------------------------------
package com.it.controller;import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;@Datapublic class Result {private Object data;private Integer code;private String msg;public Result(Integer code, String msg) {this.code = code;this.msg = msg;}public Result(Object data, Integer code) {this.data = data;this.code = code;}public Result(Object data, Integer code, String msg) {this.data = data;this.code = code;this.msg = msg;}
}
---------------------------------------------------------------------------
import java.util.List;@RestController
@RequestMapping("/user")
public class UserController {@Autowiredprivate UserService userService;@PostMappingpublic Result save(@RequestBody User user) {boolean save = userService.save(user);return new Result(save,save?Code.SAVE_OK:Code.SAVE_ERR);}

6.异常处理

出现异常位置及原因

• 框架内部抛出异常：不合规使用
• 数据层抛出异常：外边服务器故障（超时访问）
• 业务层抛出异常：业务逻辑书写错误（遍历业务书写操作等）
• 表现层抛出异常：数据收集、校验等规则导致
• 工具类抛出异常：工具书写不严谨不健壮

项目异常分类

1. 业务异常
   • 原因：用户行为导致
   • 解决：发送相应的信息传递给用户，提醒规范操作。
2. 系统异常
   • 原因：项目运行时可预计但无法避免的异常
   • 解决：发送固定消息安抚用户；发送消息给处理人员；记录日志；
3. 其他异常
   • 原因：未预期的异常
   • 解决：同上

解决：集中统一处理项目中出现的异常（异常处理器）

@RestControllerAdvice
作用：为Rest风格开发的控制器类做增强
.
@ExceptionHandler
作用：位于方法上方，设置指定异常处理方案，出现异常后终止原始控制器，转入当前方法执行。

package com.it.controller;import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestController;@RestController
public class ProjectExceptionAdvice {@ExceptionHandler(Exception.class)public Result doException(Exception e){System.out.println("出现异常");return new Result(500,"出错");}
}

步骤

1. 自定义项目系统级异常
2. 自定义业务级异常；
3. 自定义异常编码；
4. 触发自定义异常（模拟异常操作）；
5. 拦截异常并处理异常；
6. 测试结果

package com.it.controller;import lombok.Data;//自定义项目级异常
@Data
public class SystemException extends RuntimeException{private Integer code;public SystemException(String message, Throwable cause, Integer code) {super(message);this.code = code;}}

package com.it.controller;import lombok.Data;//自定义项目业务级异常
@Data
public class BusinessException extends RuntimeException{private Integer code;public BusinessException(String message, Integer code) {super(message);this.code = code;}public BusinessException(String message, Throwable cause, Integer code) {super(message,cause);this.code = code;}
}

//异常编码public static final Integer SYSTEM_UNKNOW_ERROR = 50001;public static final Integer SYSTEM_TIMEOUT_ERROR = 50002;public static final Integer PROJECT_VALIDATE_ERROR = 60001;public static final Integer PROJECT_BUSINESS_ERROR = 60002;

package com.it.service.impl;import com.it.controller.BusinessException;
import com.it.controller.Code;
import com.it.dao.UserDao;
import com.it.domain.User;
import com.it.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.util.List;@Service
public class UserServiceImpl implements UserService {@Autowired //自动装配private UserDao userDao;//自定义异常public User selectById(Integer id) {if(id<0){throw new BusinessException("请输入正确的id",Code.PROJECT_BUSINESS_ERROR);}return userDao.selectById(id);}
}

package com.it.controller;import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.RestControllerAdvice;//拦截并处理异常
@RestControllerAdvice
public class ProjectExceptionAdvice {@ExceptionHandler(Exception.class)public Result doException(Exception e){System.out.println("出现异常");return new Result(500,"出错");}@ExceptionHandler(BusinessException.class)public Result doBussinessException(Exception e){System.out.println("出现业务异常");return new Result(501,null,"出错");}@ExceptionHandler(SystemException.class)public Result doSystemException(Exception e){System.out.println("出现系统异常");return new Result(500,"出错");}
}

测试结果