Spring 中毒太深！离开 Spring 我居然连最基本的接口都不会写了。。。 - ToB企服应用市场:ToB评测及商务社交产业平台

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.4.0</version>
<relativePath/>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>

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package com.lonely.wolf.note.springboot.demo;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/hello")
public class HelloController {
@GetMapping("/demo")
public String helloWorld(String name){
return "Hello：" + name;
}
}

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package com.lonely.wolf.note.springboot;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication(scanBasePackages = "com.lonely.wolf.note.springboot")
class MySpringBootApplication {
public static void main(String[] args) {
SpringApplication.run(MySpringBootApplication.class, args);
}
}

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<packaging>war</packaging>
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.4</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.7</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.72</version>
</dependency>
</dependencies>

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<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:javaee="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
version="2.4">
<display-name>Lonely Wolf Web Application</display-name>
<servlet>
<servlet-name>helloServlet</servlet-name>
<servlet-class>com.lonely.wolf.mini.spring.servlet.HelloServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>helloServlet</servlet-name>
<url-pattern>/hello/*</url-pattern>
</servlet-mapping>
</web-app>

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package com.lonely.wolf.mini.spring.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* 原始Servlet接口编写，一般需要实现GET和POST方法，其他方法可以视具体情况选择性继承
*/
public class HelloServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
response.getWriter().write("Hello：" + request.getParameter("name"));
}
}

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<servlet>
<servlet-name>myDispatcherServlet</servlet-name>
<servlet-class>com.lonely.wolf.mini.spring.v1.MyDispatcherServlet</servlet-class>
<init-param>
<param-name>defaultConfig</param-name>
<param-value>application.properties</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>myDispatcherServlet</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>

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basePackages=com.lonely.wolf.mini.spring

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package com.lonely.wolf.mini.spring.annotation;
import java.lang.annotation.*;
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface WolfAutowired {
String value() default "";
}
package com.lonely.wolf.mini.spring.annotation;
import java.lang.annotation.*;
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface WolfController {
String value() default "";
}
package com.lonely.wolf.mini.spring.annotation;
import java.lang.annotation.*;
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface WolfGetMapping {
String value() default "";
}
package com.lonely.wolf.mini.spring.annotation;
import java.lang.annotation.*;
@Target({ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface WolfRequestParam {
String value() default "";
}
package com.lonely.wolf.mini.spring.annotation;
import java.lang.annotation.*;
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface WolfService {
String value() default "";
}

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package com.lonely.wolf.mini.spring.v1;
import com.lonely.wolf.mini.spring.annotation.*;
import com.lonely.wolf.mini.spring.v1.config.MyConfig;
import org.apache.commons.lang3.StringUtils;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.URL;
import java.util.*;
public class MyDispatcherServlet extends HttpServlet {
private MyConfig myConfig = new MyConfig();
private List<String> classNameList = new ArrayList<String>();
private Map<String,Object> iocContainerMap = new HashMap<>();
private Map<String,HandlerMapping> handlerMappingMap = new HashMap<>();
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
this.doDispatch(request, response);
} catch (Exception e) {
e.printStackTrace();
}
}
private void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception{
String requestUrl = this.formatUrl(request.getRequestURI());
HandlerMapping handlerMapping = handlerMappingMap.get(requestUrl);
if (null == handlerMapping){
response.getWriter().write("404 Not Found");
return;
}
//获取方法中的参数类型
Class<?>[] paramTypeArr = handlerMapping.getMethod().getParameterTypes();
Object[] paramArr = new Object[paramTypeArr.length];
for (int i=0;i<paramTypeArr.length;i++){
Class<?> clazz = paramTypeArr[i];
//参数只考虑三种类型，其他不考虑
if (clazz == HttpServletRequest.class){
paramArr[i] = request;
}else if (clazz == HttpServletResponse.class){
paramArr[i] = response;
} else if (clazz == String.class){
Map<Integer,String> methodParam = handlerMapping.getMethodParams();
paramArr[i] = request.getParameter(methodParam.get(i));
}else{
System.out.println("暂不支持的参数类型");
}
}
//反射调用controller方法
handlerMapping.getMethod().invoke(handlerMapping.getTarget(), paramArr);
}
private String formatUrl(String requestUrl) {
requestUrl = requestUrl.replaceAll("/+","/");
if (requestUrl.lastIndexOf("/") == requestUrl.length() -1){
requestUrl = requestUrl.substring(0,requestUrl.length() -1);
}
return requestUrl;
}
@Override
public void init(ServletConfig config) throws ServletException {
//1.加载配置文件
try {
doLoadConfig(config.getInitParameter("defaultConfig"));
} catch (Exception e) {
System.out.println("加载配置文件失败");
return;
}
//2.根据获取到的扫描路径进行扫描
doScanPacakge(myConfig.getBasePackages());
//3.将扫描到的类进行初始化，并存放到IOC容器
doInitializedClass();
//4.依赖注入
doDependencyInjection();
System.out.println("DispatchServlet Init End..." );
}
private void doDependencyInjection() {
if (iocContainerMap.size() == 0){
return;
}
//循环IOC容器中的类
Iterator<Map.Entry<String,Object>> iterator = iocContainerMap.entrySet().iterator();
while (iterator.hasNext()){
Map.Entry<String,Object> entry = iterator.next();
Class<?> clazz = entry.getValue().getClass();
Field[] fields = clazz.getDeclaredFields();
//属性注入
for (Field field : fields){
//如果属性有WolfAutowired注解则注入值（暂时不考虑其他注解）
if (field.isAnnotationPresent(WolfAutowired.class)){
String value = toLowerFirstLetterCase(field.getType().getSimpleName());//默认bean的value为类名首字母小写
if (field.getType().isAnnotationPresent(WolfService.class)){
WolfService wolfService = field.getType().getAnnotation(WolfService.class);
value = wolfService.value();
}
field.setAccessible(true);
try {
Object target = iocContainerMap.get(beanName);
if (null == target){
System.out.println(clazz.getName() + "required bean:" + beanName + ",but we not found it");
}
field.set(entry.getValue(),iocContainerMap.get(beanName));//初始化对象，后面注入
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
}
//初始化HanderMapping
String requestUrl = "";
//获取Controller类上的请求路径
if (clazz.isAnnotationPresent(WolfController.class)){
requestUrl = clazz.getAnnotation(WolfController.class).value();
}
//循环类中的方法，获取方法上的路径
Method[] methods = clazz.getMethods();
for (Method method : methods){
//假设只有WolfGetMapping这一种注解
if(!method.isAnnotationPresent(WolfGetMapping.class)){
continue;
}
WolfGetMapping wolfGetMapping = method.getDeclaredAnnotation(WolfGetMapping.class);
requestUrl = requestUrl + "/" + wolfGetMapping.value();//拼成完成的请求路径
//不考虑正则匹配路径/xx/* 的情况，只考虑完全匹配的情况
if (handlerMappingMap.containsKey(requestUrl)){
System.out.println("重复路径");
continue;
}
Annotation[][] annotationArr = method.getParameterAnnotations();//获取方法中参数的注解
Map<Integer,String> methodParam = new HashMap<>();//存储参数的顺序和参数名
retryParam:
for (int i=0;i<annotationArr.length;i++){
for (Annotation annotation : annotationArr[i]){
if (annotation instanceof WolfRequestParam){
WolfRequestParam wolfRequestParam = (WolfRequestParam) annotation;
methodParam.put(i,wolfRequestParam.value());//存储参数的位置和注解中定义的参数名
continue retryParam;
}
}
}
requestUrl = this.formatUrl(requestUrl);//主要是防止路径多了/导致路径匹配不上
HandlerMapping handlerMapping = new HandlerMapping();
handlerMapping.setRequestUrl(requestUrl);//请求路径
handlerMapping.setMethod(method);//请求方法
handlerMapping.setTarget(entry.getValue());//请求方法所在controller对象
handlerMapping.setMethodParams(methodParam);//请求方法的参数信息
handlerMappingMap.put(requestUrl,handlerMapping);//存入hashmap
}
}
}
/**
* 初始化类，并放入容器iocContainerMap内
*/
private void doInitializedClass() {
if (classNameList.isEmpty()){
return;
}
for (String className : classNameList){
if (StringUtils.isEmpty(className)){
continue;
}
Class clazz;
try {
clazz = Class.forName(className);//反射获取对象
if (clazz.isAnnotationPresent(WolfController.class)){
String value = ((WolfController)clazz.getAnnotation(WolfController.class)).value();
//如果直接指定了value则取value，否则取首字母小写类名作为key值存储类的实例对象
iocContainerMap.put(StringUtils.isBlank(value) ? toLowerFirstLetterCase(clazz.getSimpleName()) : value,clazz.newInstance());
}else if(clazz.isAnnotationPresent(WolfService.class)){
String value = ((WolfService)clazz.getAnnotation(WolfService.class)).value();
iocContainerMap.put(StringUtils.isBlank(value) ? toLowerFirstLetterCase(clazz.getSimpleName()) : value,clazz.newInstance());
}else{
System.out.println("不考虑其他注解的情况");
}
} catch (Exception e) {
e.printStackTrace();
System.out.println("初始化类失败，className为" + className);
}
}
}
/**
* 将首字母转换为小写
* @param className
* @return
*/
private String toLowerFirstLetterCase(String className) {
if (StringUtils.isBlank(className)){
return "";
}
String firstLetter = className.substring(0,1);
return firstLetter.toLowerCase() + className.substring(1);
}
/**
* 扫描包下所有文件获取全限定类名
* @param basePackages
*/
private void doScanPacakge(String basePackages) {
if (StringUtils.isBlank(basePackages)){
return;
}
//把包名的.替换为/
String scanPath = "/" + basePackages.replaceAll("\\.","/");
URL url = this.getClass().getClassLoader().getResource(scanPath);//获取到当前包所在磁盘的全路径
File files = new File(url.getFile());//获取当前路径下所有文件
for (File file : files.listFiles()){//开始扫描路径下的所有文件
if (file.isDirectory()){//如果是文件夹则递归
doScanPacakge(basePackages + "." + file.getName());
}else{//如果是文件则添加到集合。因为上面是通过类加载器获取到的文件路径，所以实际上是class文件所在路径
classNameList.add(basePackages + "." + file.getName().replace(".class",""));
}
}
}
/**
* 加载配置文件
* @param configPath - 配置文件所在路径
*/
private void doLoadConfig(String configPath) {
InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream(configPath);
Properties properties = new Properties();
try {
properties.load(inputStream);
} catch (IOException e) {
e.printStackTrace();
System.out.println("加载配置文件失败");
}
properties.forEach((k, v) -> {
try {
Field field = myConfig.getClass().getDeclaredField((String)k);
field.setAccessible(true);
field.set(myConfig,v);
} catch (Exception e) {
e.printStackTrace();
System.out.println("初始化配置类失败");
return;
}
});
}
}

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package com.lonely.wolf.mini.spring.v1;
import java.lang.reflect.Method;
import java.util.Map;
//省略了getter/setter方法
public class HandlerMapping {
private String requestUrl;
private Object target;//保存方法对应的实例
private Method method;//保存映射的方法
private Map<Integer,String> methodParams;//记录方法参数
}

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package com.lonely.wolf.mini.spring.controller;
import com.lonely.wolf.mini.spring.annotation.WolfAutowired;
import com.lonely.wolf.mini.spring.annotation.WolfController;
import com.lonely.wolf.mini.spring.annotation.WolfGetMapping;
import com.lonely.wolf.mini.spring.annotation.WolfRequestParam;
import com.lonely.wolf.mini.spring.service.HelloService;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WolfController
public class HelloController {
@WolfAutowired
private HelloService helloService;
@WolfGetMapping("/hello")
public void query(HttpServletRequest request,HttpServletResponse response, @WolfRequestParam("name") String name) throws IOException {
response.setContentType("text/html;charset=utf-8");
response.getWriter().write("Hello：" + name);
}
}
package com.lonely.wolf.mini.spring.service;
import com.lonely.wolf.mini.spring.annotation.WolfService;
@WolfService(value = "hello_service")//为了演示能否正常取value属性
public class HelloService {
}

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