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import javax.servlet.GenericServlet;
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import javax.servlet.ServletException;
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import javax.servlet.ServletRequest;
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import javax.servlet.ServletResponse;
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import javax.servlet.annotation.WebServlet;
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import java.io.IOException;
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/**
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 * @author stone
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 * @date 2023/01/12 22:44
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 */
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@WebServlet("/user/login")
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public class UserServlet extends GenericServlet {
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    @Override
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    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
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        servletResponse.getWriter().write("LOGIN SUCCESS");
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    }
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}

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/**
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 * 继承GenericServlet
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 *  实现其抽象方法service
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 *  localhost:8080/demo1/servlet1
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 *  控制台里打印hello servlet1
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 * @author stone
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 * @date 2023/02/02 17:29
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 */
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@WebServlet("/servlet1")
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public class Servlet1 extends GenericServlet {
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    @Override
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    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
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        System.out.println("hello servlet1");
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    }
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}
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/**
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 * 继承HttpServletServlet
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 *  重写其doGet、doPost方法
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 *  localhost:8080/demo1/servlet2
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 *  控制台里打印hello servlet2
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 * @author stone
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 * @date 2023/02/02 17:29
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 */
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@WebServlet("/servlet2")
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public class Servlet2 extends HttpServlet {
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    @Override
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    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
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        // 接下来会使用浏览器方法，通过浏览器的地址栏发送的请求是GET请求
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        System.out.println("hello servlet2");
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    }
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    @Override
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    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
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        // 自己写业务
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    }
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}

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@Target({ElementType.TYPE}) // 该注解可以写在类上
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@Retention(RetentionPolicy.RUNTIME) // 该注解运行时生效
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@Documented
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public @interface WebServlet {
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    String name() default "";
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    String[] value() default {}; // 该Servlet的路径，通过该路径可以访问到这个servlet的service或doGet、doPost方法
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    String[] urlPatterns() default {}; // 和value属性的功能是一致的
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    int loadOnStartup() default -1; // 默认值是负数；如果为负数的话，意味着放访问该servlet路径的时候，该Servlet才初始化；如果不为负数，则Tomcat启动的时候就初始化，并且会按照数字的顺序来初始化不同的Servlet
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    WebInitParam[] initParams() default {}; // 提供初始化参数，当前基本不用
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    boolean asyncSupported() default false;
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    String smallIcon() default "";
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    String largeIcon() default "";
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    String description() default "";
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    String displayName() default "";
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}

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/**
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 * 1.合法写法
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 *   (1) /xxx 比如/first、/second、/hello1、/hello/world → 最左边要有/
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 *   (2) *.xxx 比如*.do、*.action  如果访问localhost:8080/demo3/hello/world.do
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 * 2.优先级 路径匹配 ＞ 类型匹配   匹配度越高优先级越高
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 * 3.默认Servlet → tomcat有提供默认的Servlet 它的url-pattern是/ ，缺省匹配
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 * → 没有找到与之对应的Servlet的话，找的就是缺省Servlet
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 * @date 2023/03/30 14:40
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 */
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@WebServlet("/urlpattern1")
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public class UrlPatternServlet extends HttpServlet {
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    @Override
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    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
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        System.out.println("/xxxx的形式");
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    }
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}

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@WebServlet(value = "/parameter",loadOnStartup = 1)
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public class ParameterServlet extends HttpServlet {
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    Map<String,String> map = new HashMap<>();
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    @Override
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    public void init() throws ServletException {
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        InputStream inputStream = ParameterServlet.class.getClassLoader().getResourceAsStream("param.properties");
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        Properties properties = new Properties();
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        try {
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            properties.load(inputStream);
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        } catch (IOException e) {
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            e.printStackTrace();
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        }
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        String username = properties.getProperty("username");
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        String password = properties.getProperty("password");
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        map.put("username", username);
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        map.put("password", password);
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    }
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    @Override
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    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
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        String username = map.get("username");
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        System.out.println("username = " + username);
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    }
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}

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@WebServlet(value = "/properties",loadOnStartup = 1)
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public class PropertiesServlet extends HttpServlet {
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    @Override
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    public void init() throws ServletException {
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        Properties properties = new Properties();
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        try {
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            properties.load(PropertiesServlet.class.getClassLoader().getResourceAsStream("param.properties"));
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        } catch (IOException e) {
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            e.printStackTrace();
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        }
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        getServletContext().setAttribute("properties", properties);
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        String username = properties.getProperty("username");
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        String password = properties.getProperty("password");
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        //User user = new User();
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        String clazz = properties.getProperty("clazz");
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        Class<?> aClass = null;
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        User user = null;
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        try {
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            aClass = Class.forName(clazz);
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            user = (User) aClass.newInstance();
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        } catch (InstantiationException e) {
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            e.printStackTrace();
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        } catch (IllegalAccessException e) {
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            e.printStackTrace();
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        } catch (ClassNotFoundException e) {
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            e.printStackTrace();
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        }
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        getServletContext().setAttribute("user",user);
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    }
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}