手写SpringIOC注解实现版本

刺骨的言语ヽ痛彻心扉 2022-03-20 15:44 249阅读 0赞

### 1.Maven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/xsd/maven-4.0.0.xsd">
    	<modelVersion>4.0.0</modelVersion>
    
    	<groupId>com.weichai</groupId>
    	<artifactId>SpringIocByAnnotation</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<packaging>jar</packaging>
    
    	<name>SpringIocByAnnotation</name>
    	<url>http://maven.apache.org</url>
    
    	<properties>
    		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    	</properties>
    
    	<dependencies>
    		
    		<dependency>
    			<groupId>org.springframework</groupId>
    			<artifactId>spring-core</artifactId>
    			<version>4.2.0.RELEASE</version>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework</groupId>
    			<artifactId>spring-context</artifactId>
    			<version>4.2.0.RELEASE</version>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework</groupId>
    			<artifactId>spring-aop</artifactId>
    			<version>4.2.0.RELEASE</version>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework</groupId>
    			<artifactId>spring-orm</artifactId>
    			<version>4.2.0.RELEASE</version>
    		</dependency>
    		
    		<dependency>
    			<groupId>org.springframework</groupId>
    			<artifactId>spring-jdbc</artifactId>
    			<version>4.2.0.RELEASE</version>
    		</dependency>
    		<dependency>
    			<groupId>org.aspectj</groupId>
    			<artifactId>aspectjrt</artifactId>
    			<version>1.8.0</version>
    		</dependency>
    		<dependency>
    			<groupId>org.aspectj</groupId>
    			<artifactId>aspectjweaver</artifactId>
    			<version>1.8.0</version>
    		</dependency>
    		<dependency>
    			<groupId>cglib</groupId>
    			<artifactId>cglib</artifactId>
    			<version>3.2.0</version>
    		</dependency>
    		
    		<dependency>
    			<groupId>com.mchange</groupId>
    			<artifactId>c3p0</artifactId>
    			<version>0.9.5.2</version>
    		</dependency>
    		
    		<dependency>
    			<groupId>mysql</groupId>
    			<artifactId>mysql-connector-java</artifactId>
    			<version>5.1.45</version>
    		</dependency>
    		
    		<dependency>
    			<groupId>org.apache.commons</groupId>
    			<artifactId>commons-dbcp2</artifactId>
    			<version>2.5.0</version>
    		</dependency>
    		
    		<dependency>
    			<groupId>dom4j</groupId>
    			<artifactId>dom4j</artifactId>
    			<version>1.6.1</version>
    		</dependency>
    		
    		<dependency>
    			<groupId>commons-lang</groupId>
    			<artifactId>commons-lang</artifactId>
    			<version>2.6</version>
    		</dependency>
    		<dependency>
    			<groupId>junit</groupId>
    			<artifactId>junit</artifactId>
    			<version>3.8.1</version>
    			<scope>test</scope>
    		</dependency>
    	</dependencies>
    </project>

### 2.数据库连接配置文件 ###

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:context="http://www.springframework.org/schema/context"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           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">
     
        
        <bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource">
            <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://localhost:3306/test" />
            <property name="username" value="root"/>
            <property name="password" value="123456"/>
        </bean>
     
        
        <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
            <constructor-arg name="dataSource" ref="dataSource" />
        </bean>
    </beans>

### 3.SpringIOC核心实现方式 ###

3.1 注解

package com.weichai.annotation;
    
    import java.lang.annotation.ElementType;
    import java.lang.annotation.Retention;
    import java.lang.annotation.RetentionPolicy;
    import java.lang.annotation.Target;
    
    /**
       *   自定义注解 注入到Spring容器
     * @author linhaiy
     * @date 2019.01.25
     */
    @Target({ ElementType.TYPE })
    @Retention(RetentionPolicy.RUNTIME)
    public @interface ExtService {
    
    }

package com.weichai.annotation;
    
    import java.lang.annotation.ElementType;
    import java.lang.annotation.Retention;
    import java.lang.annotation.RetentionPolicy;
    import java.lang.annotation.Target;
    
    /**
        *    自定义注解 从Spring容器获取bean
     * @author linhaiy
     * @date 2019.01.25
     */
    @Target({ ElementType.FIELD })
    @Retention(RetentionPolicy.RUNTIME)
    public @interface ExtResource {
    
    }

3.2 常用反射工具类

package com.weichai.util;
    
    import java.io.File;
    import java.io.FileFilter;
    import java.io.IOException;
    import java.net.JarURLConnection;
    import java.net.URL;
    import java.net.URLDecoder;
    import java.util.ArrayList;
    import java.util.Enumeration;
    import java.util.List;
    import java.util.jar.JarEntry;
    import java.util.jar.JarFile;
    
    /**
        *    常用反射工具类
     * @author linhaiy
     * @date 2019.01.25
     */
    public class ClassUtil {
    
    	/**
    	 * 从包package中获取所有的Class
    	 * 
    	 * @param packageName
    	 * @return
    	 */
    	public static List<Class<?>> getClasses(String packageName) {
    		List<Class<?>> classes = new ArrayList<Class<?>>(); // 第一个class类的集合
    		boolean recursive = true; // 是否循环迭代
    		String packageDirName = packageName.replace('.', '/'); // 获取包的名字 并进行替换
    		// 定义一个枚举的集合 并进行循环来处理这个目录下的things
    		Enumeration<URL> dirs;
    		try {
    			dirs = Thread.currentThread().getContextClassLoader().getResources(packageDirName);
    			// 循环迭代下去
    			while (dirs.hasMoreElements()) {
    				// 获取下一个元素
    				URL url = dirs.nextElement();
    				// 得到协议的名称
    				String protocol = url.getProtocol();
    				// 如果是以文件的形式保存在服务器上
    				if ("file".equals(protocol)) {
    					// 获取包的物理路径
    					String filePath = URLDecoder.decode(url.getFile(), "UTF-8");
    					// 以文件的方式扫描整个包下的文件 并添加到集合中
    					findAndAddClassesInPackageByFile(packageName, filePath, recursive, classes);
    				} else if ("jar".equals(protocol)) {
    					// 如果是jar包文件
    					// 定义一个JarFile
    					JarFile jar;
    					try {
    						// 获取jar
    						jar = ((JarURLConnection) url.openConnection()).getJarFile();
    						// 从此jar包 得到一个枚举类
    						Enumeration<JarEntry> entries = jar.entries();
    						// 同样的进行循环迭代
    						while (entries.hasMoreElements()) {
    							// 获取jar里的一个实体 可以是目录 和一些jar包里的其他文件 如META-INF等文件
    							JarEntry entry = entries.nextElement();
    							String name = entry.getName();
    							// 如果是以/开头的
    							if (name.charAt(0) == '/') {
    								// 获取后面的字符串
    								name = name.substring(1);
    							}
    							// 如果前半部分和定义的包名相同
    							if (name.startsWith(packageDirName)) {
    								int idx = name.lastIndexOf('/');
    								// 如果以"/"结尾 是一个包
    								if (idx != -1) {
    									// 获取包名 把"/"替换成"."
    									packageName = name.substring(0, idx).replace('/', '.');
    								}
    								// 如果可以迭代下去 并且是一个包
    								if ((idx != -1) || recursive) {
    									// 如果是一个.class文件 而且不是目录
    									if (name.endsWith(".class") && !entry.isDirectory()) {
    										// 去掉后面的".class" 获取真正的类名
    										String className = name.substring(packageName.length() + 1, name.length() - 6);
    										try {
    											// 添加到classes
    											classes.add(Class.forName(packageName + '.' + className));
    										} catch (ClassNotFoundException e) {
    											e.printStackTrace();
    										}
    									}
    								}
    							}
    						}
    					} catch (IOException e) {
    						e.printStackTrace();
    					}
    				}
    			}
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    		return classes;
    	}
    
    	/**
    	    * 以文件的形式来获取包下的所有Class
    	 * @param packageName
    	 * @param filePath
    	 * @param recursive
    	 * @param classes
    	 */
    	private static void findAndAddClassesInPackageByFile(String packageName, String packagePath,
    			final boolean recursive, List<Class<?>> classes) {
    		// TODO Auto-generated method stub
    		// 获取此包的目录 建立一个File
    		File dir = new File(packagePath);
    		// 如果不存在或者 也不是目录就直接返回
    		if (!dir.exists() || !dir.isDirectory()) {
    			return;
    		}
    		// 如果存在 就获取包下的所有文件 包括目录
    		File[] dirfiles = dir.listFiles(new FileFilter() {
    			// 自定义过滤规则 如果可以循环(包含子目录) 或则是以.class结尾的文件(编译好的java类文件)
    			public boolean accept(File file) {
    				return (recursive && file.isDirectory()) || (file.getName().endsWith(".class"));
    			}
    		});
    		// 循环所有文件
    		for (File file : dirfiles) {
    			// 如果是目录 则继续扫描
    			if (file.isDirectory()) {
    				findAndAddClassesInPackageByFile(packageName + "." + file.getName(), file.getAbsolutePath(), recursive,
    						classes);
    			} else {
    				// 如果是java类文件 去掉后面的.class 只留下类名
    				String className = file.getName().substring(0, file.getName().length() - 6);
    				try {
    					// 添加到集合中去
    					classes.add(Class.forName(packageName + '.' + className));
    				} catch (ClassNotFoundException e) {
    					e.printStackTrace();
    				}
    			}
    		}
    	}
    	
    	/**
    	    *    取得某一类所在包的所有类名 不含迭代
    	 * @param classLocation
    	 * @param packageName
    	 * @return
    	 */
    	public static String[] getPackageAllClassName(String classLocation, String packageName) {
    		// 将packageName分解
    		String[] packagePathSplit = packageName.split("[.]");
    		String realClassLocation = classLocation;
    		int packageLength = packagePathSplit.length;
    		for (int i = 0; i < packageLength; i++) {
    			realClassLocation = realClassLocation + File.separator + packagePathSplit[i];
    		}
    		File packeageDir = new File(realClassLocation);
    		if (packeageDir.isDirectory()) {
    			String[] allClassName = packeageDir.list();
    			return allClassName;
    		}
    		return null;
    	}
    	
    	/**
    	    * 取得某个接口下所有实现这个接口的类
    	 * @param c
    	 * @return
    	 */
    	public static List<Class> getAllClassByInterface(Class c) {
    		List<Class> returnClassList = null;
    
    		if (c.isInterface()) {
    			// 获取当前的包名
    			String packageName = c.getPackage().getName();
    			// 获取当前包下以及子包下所以的类
    			List<Class<?>> allClass = getClasses(packageName);
    			if (allClass != null) {
    				returnClassList = new ArrayList<Class>();
    				for (Class classes : allClass) {
    					// 判断是否是同一个接口
    					if (c.isAssignableFrom(classes)) {
    						// 本身不加入进去
    						if (!c.equals(classes)) {
    							returnClassList.add(classes);
    						}
    					}
    				}
    			}
    		}
    
    		return returnClassList;
    	}
    }

3.3 手写Spring专题 注解版本注入bean核心类

package com.weichai.springimpl;
    
    import java.lang.reflect.Field;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.concurrent.ConcurrentHashMap;
    
    import org.apache.commons.lang.StringUtils;
    
    import com.weichai.annotation.ExtService;
    import com.weichai.util.ClassUtil;
    
    /**
       * 手写Spring专题 注解版本注入bean
     * @author linhaiy
     * @date 2019.01.25
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public class ClassPathXmlApplicationContext {
    
    	private String packageName;        //扫包范围
    	ConcurrentHashMap<String, Object> initBean = null;
    	
    	public ClassPathXmlApplicationContext(String packageName) {
    		super();
    		this.packageName = packageName;
    	}
    	
    	/**
    	    *    使用beanID查找对象(SringIOC注解实现主类 )
    	 * @param beanId
    	 * @return
    	 * @throws Exception
    	 */
    	public Object getBean(String beanId) throws Exception {
    		List<Class> listClassAnnotation = findClassByExisService();         // 1.使用反射机制获取该包下所有的类已经存在bean的注解类
    		if(listClassAnnotation == null || listClassAnnotation.isEmpty()) {
    			throw new Exception("没有需要初始化的bean");
    		}
    		initBean = initBean(listClassAnnotation);                    // 2.使用Java反射机制初始化对象
    		if (initBean == null || initBean.isEmpty()) {
    			throw new Exception("初始化bean为空!");
    		}
    		Object object = initBean.get(beanId);                        // 3.使用beanID查找查找对应bean对象
    		attriAssign(object);                                         // 4.使用反射读取类的属性,赋值信息
    		return object; 
    	}
    
    	/**
    	    *   使用反射读取类的属性,赋值信息
    	 * @param object
    	 */
    	private void attriAssign(Object object) throws IllegalArgumentException, IllegalAccessException {
    		// TODO Auto-generated method stub
    		Class<? extends Object> classInfo = object.getClass();        // 1.获取类的属性是否存在 获取bean注解
    		Field[] declaredFields = classInfo.getDeclaredFields();
    		for(Field field : declaredFields) {
    			String name = field.getName();               // 属性名称
    			Object bean = initBean.get(name);            // 2.使用属性名称查找bean容器赋值
    			if(bean !=null) {
    				field.setAccessible(true);               // 私有访问允许访问
    				field.set(object, bean);                 // 给属性赋值
    				continue;
    			}
    		}
    	}
    
    	/**
    	   *    初始化bean对象,ConcurrentHashMap保存
    	 * @param listClassAnnotation
    	 * @return
    	 * @throws InstantiationException
    	 * @throws IllegalAccessException
    	 */
    	private ConcurrentHashMap<String, Object> initBean(List<Class> listClassAnnotation) throws InstantiationException, IllegalAccessException {
    		// TODO Auto-generated method stub
    		ConcurrentHashMap concurrentHashMap = new ConcurrentHashMap<String, Object>();
    		for(Class classInfo : listClassAnnotation) {
    			Object newInstance = classInfo.newInstance();        // 初始化对象
    			String beanId = toLowerCaseFirstOne(classInfo.getSimpleName());     // 获取父类名称
    			concurrentHashMap.put(beanId, newInstance);
    		}
    		return concurrentHashMap;
    	}
    
    	/**
    	   *    首字母转小写
    	 * @param simpleName
    	 * @return
    	 */
    	private String toLowerCaseFirstOne(String s) {
    		// TODO Auto-generated method stub
    		if (Character.isLowerCase(s.charAt(0)))
    			return s;
    		else
    			return (new StringBuilder()).append(Character.toLowerCase(s.charAt(0))).append(s.substring(1)).toString();
    	}
    
    	/**
    	   *    使用反射机制获取该包下所有的类已经存在bean的注解类
    	 * @return
    	 * @throws Exception 
    	 */
    	private List<Class> findClassByExisService() throws Exception {
    		// TODO Auto-generated method stub
    		if(StringUtils.isEmpty(packageName)) {          // 1.使用反射机制获取该包下所有的类
    			throw new Exception("扫包地址不能为空!");
    		}
    		List<Class<?>> classByPackageName = ClassUtil.getClasses(packageName);     // 2.使用反射技术获取当前包下所有的类
    		List<Class> exisClassesAnnotation = new ArrayList<Class>();                // 3.存放类上有bean注入注解
    		
    		// 4.判断该类上属否存在注解
    		for(Class classInfo : classByPackageName) {
    			ExtService extService = (ExtService) classInfo.getDeclaredAnnotation(ExtService.class);
    			if(extService !=null) {
    				exisClassesAnnotation.add(classInfo);
    				continue;
    			}
    		}
    		return exisClassesAnnotation;
    	}
    }

### 4.测试类 ###

4.1 一般测试方式相关代码

package com.weichai.service;
    
    public interface OrderService {
    
    	public void addOrder();
    }

package com.weichai.service;
    
    import com.weichai.annotation.ExtService;
    
    @ExtService
    public class OrderServiceImpl implements OrderService {
    
    	public void addOrder() {
    		// TODO Auto-generated method stub
            System.out.println("欢迎进入addOrder方法!");
    	}
    
    }

package com.weichai.service;
    
    public interface UserService {
    
    	public void add();
    }

package com.weichai.service;
    
    import com.weichai.annotation.ExtResource;
    import com.weichai.annotation.ExtService;
    
    @ExtService
    public class UserServiceImpl implements UserService {
    
    	@ExtResource
    	private OrderService orderServiceImpl;
    	
    	public void add() {
    		// TODO Auto-generated method stub
    		orderServiceImpl.addOrder();
    		System.out.println("我是使用反射机制调用order的执行方法！");
    	}
    
    }

package com.weichai.SpringIocByAnnotation;
    
    import com.weichai.service.UserService;
    import com.weichai.springimpl.ClassPathXmlApplicationContext;
    
    /**
     * SpringIOC注解实现测试
     * @author linhaiy
     * @date 2019.01.25
     */
    public class SpringIocTest {
    
    	public static void main(String[] args) throws Exception {
    		// TODO Auto-generated method stub
    		ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("com.weichai.service");
    		UserService userService = (UserService) app.getBean("userServiceImpl");
    		userService.add();
    	}
    
    }

4.2 数据库操作依赖注入测试

package com.weichai.entity;
    
    import java.io.Serializable;
    
    /**
        *    用户实体类
     * @author linhaiy
     * @date 2019.01.25
     */
    public class User implements Serializable {
    
    	private Integer id;
    	private String userName;
    	private String userPwd;
    	private Integer age;
    	private String address;
    	public Integer getId() {
    		return id;
    	}
    	public void setId(Integer id) {
    		this.id = id;
    	}
    	public String getUserName() {
    		return userName;
    	}
    	public void setUserName(String userName) {
    		this.userName = userName;
    	}
    	public String getUserPwd() {
    		return userPwd;
    	}
    	public void setUserPwd(String userPwd) {
    		this.userPwd = userPwd;
    	}
    	public Integer getAge() {
    		return age;
    	}
    	public void setAge(Integer age) {
    		this.age = age;
    	}
    	public String getAddress() {
    		return address;
    	}
    	public void setAddress(String address) {
    		this.address = address;
    	}
    	@Override
    	public String toString() {
    		return "User [id=" + id + ", userName=" + userName + ", userPwd=" + userPwd + ", age=" + age + ", address="
    				+ address + "]";
    	}
    	
    }

package com.weichai.dao;
    
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.List;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    import org.springframework.jdbc.core.JdbcTemplate;
    import org.springframework.jdbc.core.RowMapper;
    
    import com.weichai.annotation.ExtService;
    import com.weichai.entity.User;
    
    /**
        * 数据持久层接口接入
     * @author linhaiy
     * @date 2019.01.25
     */
    @ExtService
    public class UserDao {
    
    	public String SQL = "SELECT * FROM USER";
    	
    	public List<User> findAll(){
    		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("ApplicationContext.xml");
            JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate", JdbcTemplate.class);
    		System.out.println("底层查询。。。。。。");
    		List<User> list = jdbcTemplate.query(SQL, new RowMapper<User>() {
    			public User mapRow(ResultSet rs, int rowNum) throws SQLException {
    				User user = new User();
    				user.setId(rs.getInt("id"));
    				user.setUserName(rs.getString("userName"));
    				user.setUserPwd(rs.getString("userPwd"));
    				user.setAge(rs.getInt("age"));
    				user.setAddress(rs.getString("address"));
    				return user;
    			}
    		});
    		return list;
    	}
    }

package com.weichai.dao;
    
    import java.util.List;
    
    import com.weichai.annotation.ExtResource;
    import com.weichai.annotation.ExtService;
    import com.weichai.entity.User;
    
    @ExtService
    public class UserService {
    
    	@ExtResource
    	private UserDao userDao;
    	
    	public List<User> findAll(){
    		System.out.println("进入查询。。。。。。");
    		return userDao.findAll();
    	}
    }

package com.weichai.SpringIocByAnnotation;
    
    import java.util.List;
    import com.weichai.dao.UserService;
    import com.weichai.entity.User;
    import com.weichai.springimpl.ClassPathXmlApplicationContext;
    
    public class UserTest {
    
    	public static void main(String[] args) throws Exception {
    		// TODO Auto-generated method stub
    		ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("com.weichai.dao");    //输入要扫描的包
    		UserService userService = (UserService) app.getBean("userService");
    		List<User> list = userService.findAll();
    		System.out.println(list);
    	}
    
    }