手写spring+springmvc+mybatis框架篇【开篇】

>>最全面的Java面试大纲及答案解析(建议收藏)  

我们平日开发时所用的SSM框架,可是你真的了解它吗?技术革新,换代应接不暇,只有理解了源码才能保证在技术快速更迭的时代中真正站稳脚跟。本系列文章抽丝剥茧,源码分析百度有很多,在这里只列举几个我收录的优秀的博客推荐给大家,本文不过多的分析源码,更注重将代码理解后的实现。 话不多说,开启正题。(由于本人是小白,理解的不深所以写出来的东西比较浅显易懂。如果有错误还望各位大佬指出来,帮助我提高)

项目介绍:此项目是在手写SSM框架的基础上开发了一个简单的登录功能。

首先是spring框架的实现,spring的依赖注入特性是集成其他所有框架的基础。在spring2.5版本之前,只支持配置文件注入。在2.5之后加入了@Autowired注解,实现了注解注入。我们的这个spring框架当然是都支持啦。首先是xml版本注入。目前支持的是构造器注入和set属性注入。

实现思路:

1.用dom4j解析xml文件。获取各个节点的属性和内容。

2.用枚举定义IOC的bean的规则,用BeanFacory的getBean方法读取配置信息,如果xml读取到的属性和IOCRULES的枚举内容匹配的话,用BeanDefinitionMap对象保存,然后用反射实例化一个对象。

3.读取在xml文件中读取到的扫包路径,扫描此路径下的有注解的类按照自下而上的顺序存储在componentList中。

4.将componentList对象按照顺序实例化出对象。

一些高大上的名词,其实就是一些对象或者数据结构。比如我们常说的spring容器其实就指的是一个map对象集合,在spring源码其实就是DefaultListableBeanFactory类中如下对象

1
private final Map<String, BeanDefinition> beanDefinitionMap = new ConcurrentHashMap<String, BeanDefinition>(256);

将这些对象实例化之后就是我们说的注入。再比如springmvc中的handlerMapping,其实就是map集合,key是方法名,value是@RequestMapping的路径。再比如...还有很多,

在实战之前我先提出几个我自己想到的问题,希望大家看的时候带着问题提来看。

1.spring有xml配置,也有注解配置,那么先实例化的是哪种版本呢?

2. 构造器注入,属性注入如何实现的?

3. 在指定包的路径下有那么多要注入的bean,service层调用dao,所以dao层一定要在service之前注入,然后在service层属性注入的时候才能将dao层注入,那么如何保证实例化的顺序呢?这也是难点。

4.我们使用的时候只需要用@Autowired标记接口,即可使用。但是我们知道接口并不能实例化对象,那么spring是如何做到的呢?而且有的接口有实现类,在mybatis中连实现类都没有,如何实现的呢?

效果图

 

下面开始实战:

项目必须用jdk1.8,不然会报错.里面一些方法只有1.8才有。

2 用到了lombok这个jar包,主要是简化了代码量,一个注解就可以省略getset方法。

3 解析xml用的dom4j,在小型xml文件的解析和操作中dom4j是最佳选择

4 在最后的demo中,RegisterServiceImpl,UserServiceImpl,RegisterService,UserService等文件没有真正的使用。只是考虑多层注入的时候,为了测试注入的顺序是否是对的。在dao层真正用的是UserMapper这个接口。

    先介绍一下工具类吧。省的代码中出现的时候大家看不懂

1
2
3
4
5
6
7
8
9
10
11
package spring.Utils;
 
/**
 * Created by Xiao Liang on 2018/6/27.
 * 注解工具类:判断注解是否为空
 */
public class  AnnotationUtils {
    public  static <T>  boolean isEmpty(T t){
        return  t == null ? true : false;
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
package spring.Utils;
 
/**
 * @ClassName ConvertUtis
 * @Description 根据传入的属性和类名,将属性名强转为类名的属性
 * @Data 2018/7/4
 * @Author xiao liang
 */
public class ConvertUtis {
 
    public static Object  convert(String className,String parameter){
        if (className.equals("String")){
            return parameter;
        }
        else if (className.equals("Integer")){
            return Integer.valueOf(parameter);
        }
        else if (className.equals("int")){
            return Integer.valueOf(parameter);
        }
        else if (className.equals("Float")){
            return Float.valueOf(parameter);
        }
        else if (className.equals("Double")){
            return Integer.valueOf(parameter);
        }
        else if (className.equals("Long")){
            return Long.valueOf(parameter);
        }
        else if (className.equals("Short")){
            return Short.valueOf(parameter);
        }
        else if (className.equals("Byte")){
            return Byte.valueOf(parameter);
        }
        else if (className.equals("Boolean")){
            return Boolean.valueOf(parameter);
        }
        return null;
 
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
package spring.Utils;
 
/**
 * @ClassName GetMethodName
 * @Description 根据属性名拼接set方法
 * @Data 2018/7/4
 * @Author xiao liang
 */
public class GetMethodName {
    public   static  String getSetMethodNameByField(String propertyName) {
        String methodName = "set" + propertyName.substring(0, 1).toUpperCase() + propertyName.substring(1);
        return methodName;
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
package spring.Utils;
 
/**
 * @ClassName isBasicType
 * @Description 判断是不是基本数据类型
 * @Data 2018/7/4
 * @Author xiao liang
 */
public class isBasicTypeUtils {
    public static boolean  isBasicType(String typeName){
        if (typeName.equals("String")){
            return true;
        }
        else if(typeName.equals("Integer")){
            return true;
        }
        else if(typeName.equals("int")){
            return true;
        }
        else if(typeName.equals("Long")){
            return true;
        }
        else if(typeName.equals("Short")){
            return true;
        }
        else if(typeName.equals("Float")){
            return true;
        }
        else if(typeName.equals("Double")){
            return true;
        }
        else if(typeName.equals("Byte")){
            return true;
        }
        return false;
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
package spring.Utils;
 
import java.util.HashSet;
import java.util.List;
import java.util.Set;
 
/**
 *  @Author xiao liang
 *  @Desprition 在链表中添加数据,添加时保证只有一个相同的实例
 */
public class ListAddUtils {
    public static <T> void add(List<T> list ,T t) {
        Set<T> set1 = new HashSet<>(list);
        if (set1.add(t)){
            list.add(t);
        }
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
package spring.Utils;
/**
 *  @Author xiao liang
 *  判断字符串是否为空
 */
public class StringUtils {
    public static boolean isEmpty(String string) {
        if ((string == null) || "".equals(string)) {
            return true;
        }
        return false;
    }
}

还有一个常量类。

1
2
3
4
5
6
7
8
9
10
11
12
13
package spring.constants;
 
import spring.xml.FileSystemXmlApplicationContext;
/**
 * Created by Xiao Liang on 2018/6/27.
 * @Description :保存的是各个配置文件的路径
 */
public interface Constants {
    String PATH = FileSystemXmlApplicationContext.class.getResource("/").getPath();
    String contextConfigLocation = "application.xml";
    String springmvcConfigLocation = "spring-mvc.xml";
    String mybatisConfigLocation = "MyUserMapper.xml";
}

还有三个xml文件。application.xml

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
<?xml version="1.0" encoding="UTF-8"?>
<beans>
    <bean id="hostess" class="spring.Person">
        <property name ="userName" value = "admin"></property>
        <property name ="passWord" value = "admin"></property>
    </bean>
    <bean class="spring.mybatis.JDBCUtils" id="dataSource">
        <property name="user" value="root"></property>
        <property name="password" value="qinliang"></property>
        <property name="driver" value="com.mysql.jdbc.Driver"></property>
        <property name="url" value="jdbc:mysql://localhost:3306/test"></property>
    </bean>
 
    <component-scan base-package="spring.demo" >
    </component-scan>
 
</beans>

springmvc.xml

1
2
3
4
5
6
7
<?xml version="1.0" encoding="UTF-8"?>
<beans>
    <bean id="viewResolver" class="spring.springmvc.ViewResolver">
        <property name="prefix" value="/WEB-INF/views/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>
</beans>

MyUserMapper.xml

1
2
3
4
5
6
7
8
<?xml version="1.0" encoding="UTF-8"?>
<mapper namespace="spring.demo.repository.UserMapper">
 
    <select id="queryUser" resultType="spring.dataObject.User">
        select * from login_user where username = #{username} AND password = #{password}
    </select>
 
</mapper>

这是一个maven项目,pom.xml文件内容如下

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
<?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>com.myspring</groupId>
    <artifactId>start</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>
    <name>start Maven Webapp</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>
 
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
 
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
 
        <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.0</version>
            <scope>provided</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-api -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.25</version>
        </dependency>
 
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>1.7.25</version>
        </dependency>
 
 
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
        </dependency>
 
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.1.3-b06</version>
        </dependency>
 
        <dependency>
            <groupId>dom4j</groupId>
            <artifactId>dom4j</artifactId>
            <version>1.6.1</version>
        </dependency>
 
        <!-- https://mvnrepository.com/artifact/jstl/jstl -->
        <dependency>
            <groupId>jstl</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <!--数据库连接池和数据库连接-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.8</version>
        </dependency>
 
 
    </dependencies>
 
    <build>
        <finalName>start</finalName>
        <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
            <plugins>
                <plugin>
                    <artifactId>maven-clean-plugin</artifactId>
                    <version>3.0.0</version>
                </plugin>
                <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
                <plugin>
                    <artifactId>maven-resources-plugin</artifactId>
                    <version>3.0.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.7.0</version>
                </plugin>
                <plugin>
                    <artifactId>maven-surefire-plugin</artifactId>
                    <version>2.20.1</version>
                </plugin>
                <plugin>
                    <artifactId>maven-war-plugin</artifactId>
                    <version>3.2.0</version>
                </plugin>
                <plugin>
                    <artifactId>maven-install-plugin</artifactId>
                    <version>2.5.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-deploy-plugin</artifactId>
                    <version>2.8.2</version>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

下面是项目的业务逻辑代码,可以过一下,就是最简单的三层架构。业务逻辑代码中中有一些为了测试用,并没有实际的意义

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
package spring.demo.controller;
 
import spring.annotation.MyAutowired;
import spring.annotation.MyController;
import spring.annotation.MyModelAttribute;
import spring.annotation.MyRequestMapping;
import spring.dataObject.User;
import spring.demo.service.UserService;
import spring.springmvc.MyModelAndView;
import spring.springmvc.MyModelMap;
import spring.xmlRules.RequestMethod;
/**
 * Created by Xiao Liang on 2018/6/27.
 */
@MyController
public class LoginController {
 
    @MyAutowired
    private UserService userService;
    //测试用的@MyRequstParam(value = "userName") String userName,  @MyRequstParam(value = "passWord") Integer passWord
    //返回值只支持MyModelAndView,数据模型和视图模型相结合
    @MyRequestMapping(value = "/hello", method = RequestMethod.POST)
    public MyModelAndView login(@MyModelAttribute("User") User user) {
        MyModelAndView myModelAndView = new MyModelAndView("success");
        MyModelMap myModel = new MyModelMap();
        User user1 = userService.queryUser("admin", "admin");
        myModel.addAttribute("test", user1.getUserName());
        myModelAndView.setModelMap(myModel);
        return myModelAndView;
    }
    @MyRequestMapping("/hello22")
    public String test() {
        return "success";
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
package spring.demo.controller;
 
import spring.annotation.MyAutowired;
import spring.annotation.MyController;
import spring.annotation.MyRequestMapping;
import spring.demo.service.RegisterService;
import spring.demo.service.UserService;
/**
 * Created by Xiao Liang on 2018/6/27.
 */
@MyController
public class RegisterController {
    @MyAutowired
    private UserService userService;
    @MyAutowired
    private RegisterService registerService;
    @MyRequestMapping("/register")
    public void regeister(){
        userService.queryUser("","");
        registerService.register();
    }
}
1
2
3
4
5
6
7
8
9
package spring.demo.service;
 
import spring.dataObject.User;
/**
 * Created by Xiao Liang on 2018/6/27.
 */
public interface UserService {
     User queryUser(String userName, String passWord);
}
1
2
3
4
5
6
7
8
package spring.demo.service;
 
/**
 * Created by Xiao Liang on 2018/6/27.
 */
public interface RegisterService {
    void register();
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
package spring.demo.service.impl;
 
import spring.annotation.MyAutowired;
import spring.annotation.MyService;
import spring.dataObject.User;
import spring.demo.repository.RegisterDao;
import spring.demo.repository.UserDao;
import spring.demo.repository.UserMapper;
import spring.demo.service.UserService;
/**
 * Created by Xiao Liang on 2018/6/27.
 */
@MyService
public class UserServiceImpl implements UserService {
    @MyAutowired
    private UserDao userDao;
    @MyAutowired
    private RegisterDao registerDao;
    @MyAutowired
    private UserMapper userMapper;
    @Override
    public User queryUser(String userName, String passWord) {
        return userMapper.queryUser(userName,passWord);
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
package spring.demo.service.impl;
 
import spring.annotation.MyAutowired;
import spring.annotation.MyService;
import spring.demo.repository.RegisterDao;
import spring.demo.service.RegisterService;
/**
 * Created by Xiao Liang on 2018/6/27.
 */
@MyService
public class RegisterServiceImpl implements RegisterService{
    @MyAutowired
    private RegisterDao registerDao;
    @Override
    public void register() {
        registerDao.register();
    }
}
1
2
3
4
5
6
7
8
package spring.demo.repository;
 
/**
 * Created by Xiao Liang on 2018/6/27.
 */
public interface UserDao {
      void test();
}
1
2
3
4
5
6
7
8
package spring.demo.repository;
 
/**
 * Created by Xiao Liang on 2018/6/27.
 */
public interface RegisterDao {
     void register();
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
package spring.demo.repository.impl;
 
import spring.annotation.MyRepository;
import spring.demo.repository.UserDao;
/**
 * Created by Xiao Liang on 2018/6/27.
 */
@MyRepository
public class UserDaoImpl implements UserDao {
    @Override
    public void test() {
        System.out.println("我是UserDao");
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
package spring.demo.repository.impl;
 
import spring.annotation.MyRepository;
import spring.demo.repository.RegisterDao;
/**
 * Created by Xiao Liang on 2018/6/27.
 */
@MyRepository
public class RegisterDaoImpl implements RegisterDao{
    @Override
    public void register() {
        System.out.println("我是RegisterDao");
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
package spring.demo.repository;
 
import spring.dataObject.User;
/**
 * @ClassName UserMapper
 * @Description
 * @Data 2018/7/7
 * @Author xiao liang
 */
public interface UserMapper {
    User queryUser(String userName,String passWord);
}

我将此项目上传到了github,需要的童鞋可以自行下载。

https://github.com/836219171/MySSM