SSM整合

ssm整合原理

ssm框架是指Spring（业务层）、SpringMVC（web层）和Mybatis（持久层）将系统分成表现层、controller层、service层、dao层四层从而达到加速开发、简化开发的目的

添加依赖

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>SpringMVC_Case</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.10.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.2.10.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.2.10.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</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>5.1.47</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.16</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.0</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.1</version>
                <configuration>
                    <port>80</port>
                    <path>/</path>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

架构及文件分布

配置类

JdbcConfig.java：传递关于数据库的信息，包括地址名字密码等，另外还需要配置事务

package com.itheima.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;

import javax.sql.DataSource;

public 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;

    @Bean
    public DataSource dataSource(){
        DruidDataSource dds=new DruidDataSource();
        dds.setDriverClassName(driver);
        dds.setUrl(url);
        dds.setUsername(username);
        dds.setPassword(password);
        return dds;
    }

    @Bean
    public PlatformTransactionManager transactionManager(DataSource dataSource){
        DataSourceTransactionManager dataSourceTransactionManager=new DataSourceTransactionManager();
        dataSourceTransactionManager.setDataSource(dataSource);
        return dataSourceTransactionManager;
    }
}

Mybatis.java：用来放置Mybatis配置，包括类型包扫描、dao层包扫描

package com.itheima.config;

import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.springframework.context.annotation.Bean;

import javax.sql.DataSource;

public class MybatisConfig {
    @Bean
    public SqlSessionFactoryBean sqlSessionFactoryBean(DataSource dataSource){
        SqlSessionFactoryBean sfb=new SqlSessionFactoryBean();
        sfb.setDataSource(dataSource);
        sfb.setTypeAliasesPackage("com.itheima.domain");
        return sfb;
    }

    @Bean
    public MapperScannerConfigurer mapperScannerConfigurer(){
        MapperScannerConfigurer msc=new MapperScannerConfigurer();
        msc.setBasePackage("com.itheima.dao");
        return msc;
    }
}

ServletConfig.java：servlet的配置类，用来设置由上往下的加载Spring配置，加载SpringMvc和设置那些请求需要经过SpringMvc处理

package com.itheima.config;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class ServletConfig extends AbstractAnnotationConfigDispatcherServletInitializer {
    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{SpringConfig.class};
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class[]{SpringMvcConfig.class};
    }

    @Override
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }
}

SpringMvcConfig.java

package com.itheima.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

@Configuration
@ComponentScan({"com.itheima.controller","com.itheima.config"})
@EnableWebMvc
public class SpringMvcConfig {
}

SpringConfig.java

package com.itheima.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.PropertySource;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
@ComponentScan({"com.itheima"})
@PropertySource("classpath:jdbc.properties")
@Import({JdbcConfig.class,MybatisConfig.class})
@EnableTransactionManagement
public class SpringConfig {
}

创建pojo文件

Book.java

package com.learn.domain;


public class book {

  private long id;
  private String type;
  private String name;
  private String description;


  public long getId() {
    return id;
  }

  public void setId(long id) {
    this.id = id;
  }


  public String getType() {
    return type;
  }

  public void setType(String type) {
    this.type = type;
  }


  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }


  public String getDescription() {
    return description;
  }

  public void setDescription(String description) {
    this.description = description;
  }

}

Dao层（连接数据库）

创建接口BookDao：

其中查询全部返回结果需要一个大的列表所以返回值设为List<pojo类>

通过id号查找只需要返回一个记录，所以返回值设为一个pojo类即可

新增、删除、修改都不需要返回东西，只需要一个展示已经执行成功的信息这件事交给service来办就可以

package com.learn.dao;

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.awt.print.Book;

public interface BookDao {
    /*查询全部*/
    @Select("select * from tbl_book")
    Boolean select(Book book);

    /*通过id号查询*/
    @Select("select * from tbl_book where id=#{id}")
    Book getById(Integer id);

    /*新增*/
    @Insert("insert into tbl_book (type,name,description) values (#{type},#{name},#{description})")
    void save(Book book);

    /*删除*/
    @Delete("delete from tbl_book where id=#{id}")
    void delete(Integer id);

    /*修改*/
    @Update("update tbl_book set type=#{type},name=#{name},description=#{description} where id=#{id}")
    void update(Book book);
}

service层

BookService接口

package com.learn.service;

import com.learn.domain.book;
import com.sun.org.apache.xpath.internal.operations.Bool;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Transactional
public interface BookService {
    /*检索所有数据*/
    List<Book> select();

    /*通过id查找*/
    Book getById(Integer id);

    /*新增*/
    Boolean save(Book Book);

    /*删除*/
    Boolean delete(Integer id);

    /*修改*/
    Boolean update(Book Book);
}

BookService实现类：

package com.learn.service.impl;

import com.learn.dao.BookDao;
import com.learn.domain.book;
import com.learn.service.BookService;
import com.sun.org.apache.xpath.internal.operations.Bool;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
@Service
public class BookServiceImpl implements BookService {
    @Autowired
    public BookDao bookDao;
    
    @Override
    public List<Book> select() {
        return bookDao.select();
    }

    @Override
    public Book getById(Integer id) {
        return bookDao.getById(id);
    }

    @Override
    public Boolean save(Book Book) {
        bookDao.save(Book);
        return true;
    }

    @Override
    public Boolean delete(Integer id) {
        bookDao.delete(id);
        return true;
    }

    @Override
    public Boolean update(Book Book) {
        bookDao.update(Book);
        return true;
    }
}

前端接收设置

在前后端交换数据的过程中，前后端缺乏约定性的格式

对于这个前后端有个约定：

格式为：类似这种

{
    "data": [
        {
            "id": 1,
            "type": "计算机理论",
            "name": "Spring实战 第5版",
            "description": "Spring入门经典教程，深入理解Spring原理技术内幕"
        }
    ],
    "code": 20011,
    "msg": ""
}

我们后端需要做的就是：

1. 定义Code，用于设置返回值

   package com.learn.controller;
   
   public class Code {
       public static final Integer GET_OK=20011;
       public static final Integer SAVE_OK=20021;
       public static final Integer DELETE_OK=20031;
       public static final Integer UPDATE_OK=20041;
   
       public static final Integer GET_ERR=20010;
       public static final Integer SAVE_ERR=20020;
       public static final Integer DELETE_ERR=20030;
       public static final Integer UPDATE_ERR=20040;
   
   }

2. 定义Result，关于data、code、msg的pojo

   package com.learn.controller;
   
   public class result {
   
   
       private Object data;
       private Integer code;
       private String msg;
   
   
       public Object getData() {
           return data;
       }
   
       public void setData(Object data) {
           this.data = data;
       }
   
       public Integer getCode() {
           return code;
       }
   
       public void setCode(Integer code) {
           this.code = code;
       }
   
       public String getMsg() {
           return msg;
       }
   
       public void setMsg(String msg) {
           this.msg = msg;
       }
   
       public result(Object data, Integer code, String msg) {
           this.data = data;
           this.code = code;
           this.msg = msg;
       }
   
       public result(Object data, Integer code) {
           this.data = data;
           this.code = code;
       }
   
       public result() {
       }
   }

3. BookController，类似于servlet类用来前后端交互

package com.learn.controller;

import com.learn.domain.book;
import com.learn.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/books")
public class BookController {
    @Autowired
    private BookService bookService;

    @GetMapping
    public result select(){
        List<Book> list=bookService.select();
        Integer code=list!=null ? Code.GET_OK:Code.GET_ERR;
        String msg= list!=null ? "":"啥也没查到";
        return new result(list,code,msg);
    }

    @GetMapping("/{id}")
    public result getById(@PathVariable Integer id){
        Book book=bookService.getById(id);
        Integer code=book!=null ? Code.GET_OK:Code.GET_ERR;
        String msg= book!=null ? "":"啥也没查到";
        return new result(book,code,msg);
    }

    @PostMapping
    public result save(@RequestBody Book book){
        boolean flag= bookService.save(book);
        return new result(flag,flag ? Code.SAVE_OK:Code.SAVE_ERR);
    }

    @DeleteMapping("/{id}")
    public result delete(@PathVariable Integer id){
        boolean flag= bookService.delete(id);
        return new result(flag,flag?Code.DELETE_OK:Code.DELETE_ERR);
    }

    @PutMapping
    public result update(@RequestBody Book book){
        boolean flag= bookService.update(book);
        return new result(flag,flag?Code.UPDATE_OK:Code.UPDATE_ERR);
    }
}

三层架构的调用基本上是这样的

以删除操作为例：

常见出错

1. 使用maven架构，必须带webapp切记
2. 别忘记在JdbcConfig中设置事务和在service中添加事务
3. jdbc资源包属性和统一