Spring MVC属于SpringFrameWork的后续产品，已经融合在Spring Web Flow里面。Spring 框架提供了构建 Web 应用程序的全功能 MVC 模块。使用 Spring 可插入的 MVC 架构，从而在使用Spring进行WEB开发时，可以选择使用Spring的Spring MVC框架或集成其他MVC开发框架，如Struts1(现在一般不用)，Struts 2(一般老项目使用)等。
springmvc工作流程图
搭建项目
pom 依赖
项目启动配置jetty插件
自定义注解
核心类 GpDispatcherServlet
package com.gupao.servlet.mvcframework;
import com.gupao.servlet.mvcframework.annotation.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
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 GpDispatcherServlet extends HttpServlet {
private static final Loggerlogger = LoggerFactory.getLogger(GpDispatcherServlet.class);
//保存配置文件扫描到的内容
private Properties contextConfig = new Properties();
//保存扫描到的类
private List classNameList = new ArrayList();
//ioc容器
private Map ioc = new HashMap();
//保存url对应的mapping
// private Map handMapping = new HashMap();
// 为啥不用map handmapping 本身的功能url methond对应 单一职责原则
private ListhandMapping =new ArrayList();
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)throws IOException {
//调用 运行阶段
try {
doDispatch(req, resp);
} catch (Exception e) {
e.printStackTrace();
resp.getWriter().write("500 exception " + Arrays.toString(e.getStackTrace()));
}
}
private void doDispatch(HttpServletRequest req, HttpServletResponse response)throws Exception{
HandMapping handMapping = getHandler(req);
if (handMapping ==null) {
response.getWriter().write("404 Not Found");
return;
}
//获得形参列表
Class [] paramTypes = handMapping.getParamTyps();
Object [] paramValues = new Object[paramTypes.length];
Map stringMap = req.getParameterMap();
for (Map.Entry param : stringMap.entrySet()) {
String value = Arrays.toString(param.getValue()).replaceAll("\\[|\\]", "")
.replaceAll("\\s", ",");
if (!handMapping.paramIndexMapping.containsKey(param.getKey())) {continue;}
int index = handMapping.paramIndexMapping.get(param.getKey());
paramValues[index] = convert(paramTypes[index], value);
}
//请求参数是否有httpservletRequest httpservletResponse
if (handMapping.paramIndexMapping.containsKey(HttpServletRequest.class.getName())) {
int reqIndex = handMapping.paramIndexMapping.get(HttpServletRequest.class.getName());
paramValues[reqIndex] = req;
}
if (handMapping.paramIndexMapping.containsKey(HttpServletResponse.class.getName())) {
int respIndex = handMapping.paramIndexMapping.get(HttpServletResponse.class.getName());
paramValues[respIndex] = response;
}
Object object = handMapping.method.invoke(handMapping.controller, paramValues);
if (object ==null) {return;}
response.getWriter().write(object.toString());
}
private HandMapping getHandler (HttpServletRequest req) {
if (handMapping.isEmpty()) {return null;}
String url = req.getRequestURI().replaceAll("/gupaospring", "");//绝对路径这里暂时写死
//处理成相对路径
String contextPath = req.getContextPath();
logger.info("contextPath : [{}]", contextPath);
url = url.replaceAll(contextPath, "").replaceAll("/+", "/");
for (HandMapping handMapping :this.handMapping) {
if (handMapping.getUrl().equals(url)) {
return handMapping;
}
}
return null;
}
//http基于string传输
private Object convert(Class type, String value) {
if (Integer.class == type) {
return Integer.valueOf(value);
} else if (Double.class == type) {
return Double.valueOf(value);
}
return value;
}
//配置阶段 初始化阶段
@Override
public void init(ServletConfig config)throws ServletException {
//加载配置文件 模板模式
logger.info("access init method.......");
doLoadConfig(config.getInitParameter("contextConfigLocation"));
//扫描相关类
doScanner(contextConfig.getProperty("scanPackage"));
//初始化相关类放到Ioc容器中
doInstance();
//完成依赖注入
doAutowired();
//初始化handmapping
initHandMapping();
logger.info("gp srpingframework complete");
}
private void initHandMapping() {
if (ioc.isEmpty()) {return;}
for (Map.Entry entry :ioc.entrySet()) {
Class clazz = entry.getValue().getClass();
if (!clazz.isAnnotationPresent(GpController.class)) {continue;}
String baseUrl ="";
if (clazz.isAnnotationPresent(GpRequestMapping.class)) {
GpRequestMapping requestMapping = clazz.getAnnotation(GpRequestMapping.class);
baseUrl = requestMapping.value().trim();//类上的url;
}
//默认获取所有的public方法
for (Method method : clazz.getMethods()) {
if (!method.isAnnotationPresent(GpRequestMapping.class)) {continue;}
GpRequestMapping requestMapping = method.getAnnotation(GpRequestMapping.class);
String url = (baseUrl +"/" + requestMapping.value().trim()).replaceAll("/+", "/");
// handMapping.put(url, method);
this.handMapping.add(new HandMapping(url, method, entry.getValue()));
System.out.println("url:" + url +"method:" + method +"controller:" + entry.getValue());
}
}
}
//自动注入
private void doAutowired() {
if (ioc.isEmpty()) {return;}
for (Map.Entry entry :ioc.entrySet()) {
//declared 所有的特定的 字段 包括private protected 等字段
Field [] fields = entry.getValue().getClass().getDeclaredFields();
for (Field field : fields) {
if (!field.isAnnotationPresent(GpAutowried.class)) {continue;}
GpAutowried autowried = field.getAnnotation(GpAutowried.class);
String beanName = autowried.value().trim();
if ("".equals(beanName)) {
//接口类型 作为key 到ioc容器中取值
beanName = field.getType().getName();
}
//如果是public 意外的修饰符 强制赋值
field.setAccessible(true);
//反射动态给字段赋值
try {
field.set(entry.getValue(), ioc.get(beanName));
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
}
}
//注入到ioc容器中去
private void doInstance() {
if (classNameList.isEmpty()) {return;}
try {
for (String className :classNameList) {
Class clazz = Class.forName(className);
if (clazz.isAnnotationPresent(GpController.class)) {
Object instance = clazz.newInstance();
String beanName = toLowerFirstCase(clazz.getSimpleName());
ioc.put(beanName, instance);
} else if (clazz.isAnnotationPresent(GpService.class)) {
GpService service = clazz.getAnnotation(GpService.class);
//beanName 为空
String beanName = service.value();
Object instance = clazz.newInstance();
if ("".equals(service.value())) {
beanName = toLowerFirstCase(clazz.getSimpleName());
}
ioc.put(beanName, instance);
//接口名称
for (Class i : clazz.getInterfaces()) {
if (ioc.containsKey(i.getName())) {
throw new Exception("the" + i.getName() +"is exits");
}
ioc.put(i.getName(), instance);
}
} else {
continue;
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
private String toLowerFirstCase(String simpleName) {
char [] chars = simpleName.toCharArray();
//加32是因为大小写字母的ascii相差32 大写字母的asci小于小写字母的ascII
chars[0] +=32;
return String.valueOf(chars);
}
private void doScanner(String scanPackage) {
//scanPackage=com.gupao.servlet包路径 变成文件路径
//classpath
URL url =this.getClass().getClassLoader().getResource("/" + scanPackage.replaceAll("\\.", "/"));
File classpath =new File(url.getFile());
for (File file : classpath.listFiles()) {
if (file.isDirectory()) {
doScanner(scanPackage +"." + file.getName());
} else {
if (!file.getName().endsWith(".class")){continue;}
String className = (scanPackage +"." + file.getName().replace(".class", ""));
classNameList.add(className);
}
}
}
private void doLoadConfig(String contextConfigLocation) {
//直接从类路径下 spring主配置文件的路径 读取放到properties中
//保存到内存中scanPackage=com.gupao.servlet
logger.info("acccess doLoadConfig method .......");
InputStream inputStream =null;
inputStream = this.getClass().getClassLoader().getResourceAsStream(contextConfigLocation);
try {
contextConfig.load(inputStream);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (inputStream !=null) {
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
//保存一个url和method对应关系handMapping策略模式
//解决多个参数问题不然参数容易错位
public class HandMapping {
private Stringurl;
private Methodmethod;
private Objectcontroller;
private Class []paramTyps;
//形参列表
private MapparamIndexMapping;
public StringgetUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public MethodgetMethod() {
return method;
}
public void setMethod(Method method) {
this.method = method;
}
public ObjectgetController() {
return controller;
}
public void setController(Object controller) {
this.controller = controller;
}
public Class[]getParamTyps() {
return paramTyps;
}
public void setParamTyps(Class[] paramTyps) {
this.paramTyps = paramTyps;
}
public HandMapping(String url, Method method, Object controller) {
this.url = url;
this.method = method;
this.controller = controller;
paramTyps = method.getParameterTypes();
paramIndexMapping =new HashMap();
putParamIndexMapping(method);
}
private void putParamIndexMapping(Method method) {
Annotation[][] pa = method.getParameterAnnotations();
for (int i =0; i < pa.length; i++) {
for (Annotation a : pa[i]) {
if (ainstanceof GpRequestParam) {//拿到参数注解的值
String paramName = ((GpRequestParam) a).value();
if (!"".equals(paramName.trim())) {//一个key对应一个数组 二维数组
paramIndexMapping.put(paramName, i);
}
}
}
}
Class[] paramType = method.getParameterTypes();
for (int i =0; i < paramType.length; i++) {
Class type = paramType[i];
if (type == HttpServletRequest.class || type == HttpServletResponse.class) {
paramIndexMapping.put(type.getName(), i);
}
}
}
}
}
看DemoAction方法
package com.gupao.servlet.action;
import com.gupao.servlet.mvcframework.annotation.GpAutowried;
import com.gupao.servlet.mvcframework.annotation.GpController;
import com.gupao.servlet.mvcframework.annotation.GpRequestMapping;
import com.gupao.servlet.mvcframework.annotation.GpRequestParam;
import com.gupao.servlet.service.IDemoService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@GpController
@GpRequestMapping(value ="/demo")
public class DemoAction {
private static final Loggerlogger = LoggerFactory.getLogger(DemoAction.class);
@GpAutowried
private IDemoServicedemoService;
@GpRequestMapping(value ="/query")
public void query(HttpServletRequest request, HttpServletResponse response,
@GpRequestParam("name") String name) {
logger.info("access query query");
try {
response.getWriter().write(name);
} catch (IOException e) {
e.printStackTrace();
}
}
@GpRequestMapping(value ="/add")
public void add(HttpServletRequest request, HttpServletResponse response,
@GpRequestParam("a") Integer a,
@GpRequestParam("b") Integer b) {
logger.info("access add add");
try {
response.getWriter().write("a + b = " + (a + b));
} catch (IOException e) {
e.printStackTrace();
}
}
@GpRequestMapping(value ="/sub")
public void sub(HttpServletRequest request, HttpServletResponse response,
@GpRequestParam("a") Double a,
@GpRequestParam("b") Double b) {
logger.info("access add sub");
try {
response.getWriter().write("a - b = " + (a - b));
} catch (IOException e) {
e.printStackTrace();
}
}
@GpRequestMapping(value ="/remove")
public String remove(@GpRequestParam("id") Integer id) {
logger.info("access add remove");
return "id = " + id;
}
}
测试：query 方法 存在当前参数
不存在当前参数 报异常
add 方法
sub方法
remove方法