Customize some elements in the MVC framework
Some annotations
@Documented
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface Controller {
String value () default "";
}
@Documented
@Target({ElementType.TYPE,ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface RequestMapping {
String value () default "";
}
@Documented
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface Service {
String value () default "";
}
@Documented
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface Autowired {
String value () default "";
}
Copy the codeHandling object encapsulation
public class Handler { private Object controller; //Controller class private Method Method; Private Pattern Pattern; //uri private Map<String,Integer> paramIndexMapping; Public Handler(Object controller, Method Method, Pattern Pattern) {this.controller = controller; this.method = method; this.pattern = pattern; this.paramIndexMapping = new HashMap<>(); } public Object getController() { return controller; } public void setController(Object controller) { this.controller = controller; } public Method getMethod() { return method; } public void setMethod(Method method) { this.method = method; } public Pattern getPattern() { return pattern; } public void setPattern(Pattern pattern) { this.pattern = pattern; } public Map<String, Integer> getParamIndexMapping() { return paramIndexMapping; } public void setParamIndexMapping(Map<String, Integer> paramIndexMapping) { this.paramIndexMapping = paramIndexMapping; }}Copy the codeCustom DisptchServelet handler code
public class DispatchServelet extends HttpServlet {
private Properties properties = new Properties();
private List<String> classNames = new ArrayList<>();
private Map<String,Object> ioc =new HashMap<>();
private List<Handler> handlerMapping = new ArrayList<>();
@Override
public void init(ServletConfig config) throws ServletException {
//加载配置文件
String contextConfigLocation = config.getInitParameter("contextConfigLocation");
doLoadConfig(contextConfigLocation);
//扫描相关的类，扫描注解
doScan(properties.getProperty("scanPackage"));
//初始化bean,基于注解
doInstance();
//实现依赖注入
doAutoWired();
//实现处理器映射器，将url和method进行关联
initHandlerMapping();
System.out.println("mvc 初始化完成");
}
//执行的是方法和url方法映射
private void initHandlerMapping() {
if (ioc.isEmpty()){
return;
}
for (Map.Entry<String,Object> entry :ioc.entrySet()){
Class<?> aClass = entry.getValue().getClass();
if (!aClass.isAnnotationPresent(Controller.class)){
continue;
}
String baseUrl = "";
if (aClass.isAnnotationPresent(RequestMapping.class)){
RequestMapping requestMapping = aClass.getAnnotation(RequestMapping.class);
baseUrl=requestMapping.value();
}
Method[] methods= aClass.getMethods();
for (int i=0;i<methods.length;i++){
Method method = methods[i];
if (!method.isAnnotationPresent(RequestMapping.class)){
continue;
}
RequestMapping requestMapping = method.getAnnotation(RequestMapping.class);
String methodUrl = requestMapping.value();
String url = baseUrl+methodUrl;
Handler handler = new Handler(entry.getValue(),method, Pattern.compile(url));
Parameter[] parameters = method.getParameters();
for (int j=0;j<parameters.length;j++){
Parameter parameter = parameters[j];
if (parameter.getType().equals(HttpServletRequest.class)||parameter.getType().equals(HttpServletResponse.class)){
handler.getParamIndexMapping().put(parameter.getType().getSimpleName(),j);
}else {
handler.getParamIndexMapping().put(parameter.getName(),j);
}
}
//完成方法和url的映射关系
handlerMapping.add(handler);
}
}
}
//执行注入部分，同样是做的ioc的部分功能
private void doAutoWired() {
if (ioc.isEmpty()){
return;
}
for (Map.Entry<String,Object> entry :ioc.entrySet()){
Field[] declareFields = entry.getValue().getClass().getDeclaredFields();
for (int i=0;i<declareFields.length;i++){
Field declareField = declareFields[i];
if (!declareField.isAnnotationPresent(Autowired.class)){
continue;
}
Autowired autowired = declareField.getAnnotation(Autowired.class);
String beanName = autowired.value();
if ("".equals(beanName.trim())){
beanName=declareField.getType().getName();
}
declareField.setAccessible(true);
try {
//直接将这个字段的值设置为ioc中已经示例化的类，
// 即是完成了ioc中的实例化交给容器来管理的情况
declareField.set(entry.getValue(),ioc.get(beanName));
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
}
}
//执行的是符合要求的类的初始化，实际上是实现的一部分ioc的功能
private void doInstance() {
if (classNames.size()==0){
return;
}
try {
for (int i=0;i<classNames.size();i++){
String className = classNames.get(i);
Class<?> clazz = Class.forName(className);
if (clazz.isAnnotationPresent(Controller.class)){
String simpleName = clazz.getSimpleName();
String lowerFirst = lowerFirst(simpleName);
Object o = clazz.newInstance();
//因为controller无别名，所以简单设置成首字母小写就行
ioc.put(lowerFirst,o);
}else if (clazz.isAnnotationPresent(Service.class)){
Service service = clazz.getAnnotation(Service.class);
String beanName =service.value();
if (!"".equals(beanName.trim())){
ioc.put(beanName,clazz.newInstance());
}else {
beanName = lowerFirst(clazz.getSimpleName());
ioc.put(beanName,clazz.newInstance());
}
Class<?>[] interfaces = clazz.getInterfaces();
for (int j=0;j<interfaces.length;j++){
Class<?> ainterface = interfaces[j];
System.out.println(ainterface.getName());
//将实现类和接口进行绑定
ioc.put(ainterface.getName(),clazz.newInstance());
}
}else {
continue;
}
}
}catch (Exception e){
e.printStackTrace();
}
}
private String lowerFirst(String className){
char[] chars = className.toCharArray();
if ('A'<chars[0]&&chars[0]<'Z'){
chars[0]+=32;
}
return new String(chars);
}
private void doScan(String basePackage) {
//获取到指定包下的所有类的类名
String scanPackagePath= Thread.currentThread().getContextClassLoader().getResource("").getPath()+basePackage.replaceAll("\\.","/");
File pack = new File(scanPackagePath);
File [] files = pack.listFiles();
for (File file:files){
if (file.isDirectory()){
doScan(basePackage+"."+file.getName());
}else if (file.getName().endsWith(".class")){
String className = basePackage+"."+file.getName().replaceAll(".class","");
classNames.add(className);
}
}
}
//实现加载web.xml中配置的文件的路径
private void doLoadConfig(String contextConfigLocation) {
InputStream inputStream =this.getClass().getClassLoader().getResourceAsStream(contextConfigLocation);
try {
properties.load(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
Handler handler = getHander(req);
if (handler==null){
resp.getWriter().write("404 not found");
return;
}
Class<?> [] parameterTypes = handler.getMethod().getParameterTypes();
Object[] paraValues = new Object[parameterTypes.length];
Map<String,String[]> parameterMap = req.getParameterMap();
for (Map.Entry<String,String[]> param:parameterMap.entrySet()){
String value = StringUtils.join(param.getValue(),",");
if (!handler.getParamIndexMapping().containsKey(param.getKey())){
continue;
}
//对应实际参数的位置
Integer index = handler.getParamIndexMapping().get(param.getKey());
paraValues[index]=value;
}
//对应上req,和resp参数的位置
int reqIndex = handler.getParamIndexMapping().get(HttpServletRequest.class.getSimpleName());
paraValues[reqIndex]=req;
int respIndex = handler.getParamIndexMapping().get(HttpServletResponse.class.getSimpleName());
paraValues[respIndex]=resp;
try {
//实际执行的是controller中的方法
handler.getMethod().invoke(handler.getController(),paraValues);
System.out.println("执行controller方法成功");
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
}
private Handler getHander(HttpServletRequest req) {
if (handlerMapping.isEmpty()){
return null;
}
String url =req.getRequestURI();
for (Handler handler:handlerMapping){
Matcher matcher = handler.getPattern().matcher(url);
if (!matcher.matches()){
continue;
}
return handler;
}
return null;
}
}
Copy the codeThe test code
public interface DemoService { String getName(String name); } @Service("demoService") public class DemoServiceImpl implements DemoService { @Override public String getName(String name) { return name; } } @Controller @RequestMapping("/demo") public class DemoController { @Autowired private DemoService demoService; @RequestMapping("/query") public String query(HttpServletRequest req, HttpServletResponse resp,String name){ return demoService.getName(name); }}Copy the codeThe web.xml configuration
<! DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc., / / DTD Web Application / 2.3 / EN "" http://java.sun.com/dtd/web-app_2_3.dtd" > < Web - app > < the display - the name > Archetype Created Web Application</display-name> <servlet> <servlet-name>mvc</servlet-name> <servlet-class>com.zhao.mvcframework.servelet.DispatchServelet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>mvc.properties</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>mvc</servlet-name> <url-pattern>/*</url-pattern> </servlet-mapping> </web-app>Copy the codeMVC. The properties of the configuration
scanPackage=com.zhao.mvcdemo
Copy the codeConfigure POM files
<? The 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" > The < modelVersion > 4.0.0 < / modelVersion > < groupId > com. Zhao < / groupId > < artifactId > MVC < / artifactId > <version> 1.0-snapshot </version> <packaging> WAR </packaging> <name> MVC 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.com piler. Source > 1.8 < / maven.com piler source > </properties> <dependencies> <dependency> <groupId> </groupId> <artifactId>junit</artifactId> <version>4.11</version> <scope>test</scope> </dependency> <dependency> < groupId > javax.mail. Servlet < / groupId > < artifactId > javax.mail. The servlet API - < / artifactId > < version > 3.1.0 < / version > <scope>provided</scope> </dependency> <dependency> <groupId>org.apache.commons</groupId> <artifactId> Commons -lang3</artifactId> <version>3.10</version> </dependency> </dependencies> <build> <plugins> <plugin> < the groupId > org, apache tomcat. Maven < / groupId > < artifactId > tomcat7 maven - plugin < / artifactId > < version > 2.2 < / version > <configuration> <port>8080</port> <path>/</path> </configuration> </plugin> <plugin> . < groupId > org, apache maven plugins < / groupId > < artifactId > maven - compiler - plugin < / artifactId > < version > 3.1 < / version > The < configuration > < source > 1.8 < / source > < target > 1.8 < / target > < encoding > utf-8 < / encoding > <compilerArgs>-parameters</compilerArgs> </configuration> </plugin> </plugins> </build> </project>Copy the codeTest access specifichttp://localhost:8080/demo/query?name=zhaozhenThere is no problem
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