第二节：Java代码审计零点五基础系统学习之JavaWeb快速入门-1

+---------+       +----------------+       +------------------+|         |       |                |       |                  ||  用户   +------>+   控制器(C)   +------>+    模型(M)      ||         |   用  |                |   处理|                  ||         |  户   +----------------+       +------------------+|         |       |                |       |                  ||         +<------+    视图(V)     +<------+    业务逻辑      ||         |       |                |       |                  |+---------+       +----------------+       +------------------+

| 注解                | 参数                      | 含义                                                                                      ||---------------------|---------------------------|-------------------------------------------------------------------------------------------|| `@WebServlet`       | `name`                    | Servlet 的名称。||                     | `urlPatterns` / `value`   | 映射到 Servlet 的 URL 模式。||                     | `initParams`              | 初始化参数，类型为 `WebInitParam[]`。||                     | `loadOnStartup`           | 指定 Servlet 的加载顺序。||                     | `asyncSupported`          | 指定 Servlet 是否支持异步处理。||---------------------|---------------------------|-------------------------------------------------------------------------------------------|| `@WebFilter`        | `filterName`              | 过滤器的名称。||                     | `urlPatterns` / `value`   | 映射到过滤器的 URL 模式。||                     | `servletNames`            | 映射到过滤器的 Servlet 名称。||                     | `dispatcherTypes`         | 过滤器的分发类型，类型为 `DispatcherType[]`。||                     | `initParams`              | 初始化参数，类型为 `WebInitParam[]`。||                     | `asyncSupported`          | 指定过滤器是否支持异步处理。||---------------------|---------------------------|-------------------------------------------------------------------------------------------|| `@WebListener`      | 无                        | 用于定义监听器。||---------------------|---------------------------|-------------------------------------------------------------------------------------------|| `@MultipartConfig`  | `location`                | 用于存储上传文件的目录。||                     | `fileSizeThreshold`       | 文件大小超过该值时，文件内容将被写入磁盘。||                     | `maxFileSize`             | 单个上传文件的最大大小。||                     | `maxRequestSize`          | 总的上传文件的最大大小。||---------------------|---------------------------|-------------------------------------------------------------------------------------------|| `@ServletSecurity`  | `value`                   | 安全性约束，类型为 `HttpConstraint`。||                     | `httpMethodConstraints`   | 为特定 HTTP 方法定义安全约束，类型为 `HttpMethodConstraint[]`。||---------------------|---------------------------|-------------------------------------------------------------------------------------------|| `@WebInitParam`     | `name`                    | 初始化参数的名称。||                     | `value`                   | 初始化参数的值。||                     | `description`             | 初始化参数的描述。||---------------------|---------------------------|-------------------------------------------------------------------------------------------|| `@HandlesTypes`     | `value`                   | 指定 Servlet 容器在启动时应该扫描和处理的类型。||---------------------|---------------------------|-------------------------------------------------------------------------------------------|| `@ServletComponentScan` | `basePackageClasses`  | 基础包类。||                     | `basePackages`            | 基础包名称。||---------------------|---------------------------|-------------------------------------------------------------------------------------------|| `@HttpConstraint`   | `value`                   | 安全性约束，类型为 `ServletSecurity.EmptyRoleSemantic`。||                     | `rolesAllowed`            | 允许访问的角色。||                     | `transportGuarantee`      | 传输保证，类型为 `ServletSecurity.TransportGuarantee`。||---------------------|---------------------------|-------------------------------------------------------------------------------------------|| `@HttpMethodConstraint` | `value`              | HTTP 方法名称。||                     | `rolesAllowed`            | 允许访问的角色。||                     | `transportGuarantee`      | 传输保证，类型为 `ServletSecurity.TransportGuarantee`。||                     | `emptyRoleSemantic`       | 空角色语义，类型为 `ServletSecurity.EmptyRoleSemantic`。|
      
import javax.servlet.annotation.WebServlet;import javax.servlet.annotation.WebInitParam;import javax.servlet.http.HttpServlet;
@WebServlet(    name = "MyServlet",    urlPatterns = {"/myServlet"},    initParams = {        @WebInitParam(name = "param1", value = "value1", description = "Parameter 1 description"),        @WebInitParam(name = "param2", value = "value2", description = "Parameter 2 description")    },    loadOnStartup = 1,    asyncSupported = true)public class MyServlet extends HttpServlet {    // Servlet implementation}import javax.servlet.annotation.WebFilter;import javax.servlet.annotation.WebInitParam;import javax.servlet.*;
@WebFilter(    filterName = "MyFilter",    urlPatterns = {"/myServlet"},    servletNames = {"MyServlet"},    dispatcherTypes = {DispatcherType.REQUEST, DispatcherType.FORWARD},    initParams = {        @WebInitParam(name = "filterParam1", value = "value1", description = "Filter Parameter 1")    },    asyncSupported = true)public class MyFilter implements Filter {    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)            throws IOException, ServletException {        // Filter implementation        chain.doFilter(request, response);    }}

import javax.servlet.annotation.WebFilter;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import java.io.IOException;
@WebFilter(urlPatterns = "/path/*")public class MyFilter implements Filter {// Filter 的逻辑代码}

| 注解参数              | 含义                                  ||----------------------|---------------------------------------|| `@WebFilter`         |                                       || `filterName`         | 过滤器的名称                          || `urlPatterns` / `value` | 过滤器映射到的 URL 模式            || `servletNames`       | 过滤器映射到的 Servlet 名称           || `dispatcherTypes`    | 过滤器的分发类型，类型为 `DispatcherType[]` || `initParams`         | 初始化参数，类型为 `WebInitParam[]`  || `asyncSupported`     | 指定过滤器是否支持异步处理            |

public void init(FilterConfig filterConfig) throws ServletException {     // 初始化操作，读取配置等}

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)        throws IOException, ServletException {    // 请求处理前的操作    chain.doFilter(request, response); // 继续请求处理    // 请求处理后的操作}

public void destroy() { 2 // 清理资源，关闭连接等 3 }

<%!    private Integer id;    private String name;    private static Map map = new HashMap<>();%><%!    //声明 static 静态代码块    static {        map.put("key1",1);        map.put("key2",2);        map.put("key3",3);        map.put("key4",4);    }%>

<%=12 %><%=12.12 %><%="我是字符串" %><%=map %><%=request.getParameter("username") %>

<%    int i =12;    if (i == 12){        System.out.println("好厉害" );    }else {        System.out.println("家的啊");    }%><%    for (int i1 = 0; i1 < 10; i1++) {        System.out.println(i1);    }%><%    String username = request.getParameter("username");    System.out.println(username);%>

<%    request.setAttribute("key","key1");%>表达式脚本输出: <%=request.getAttribute("key1")%>EL表达式输出: ${key1}

<%    Person person = new Person();    person.setName("tom");    person.setPhones(new String[]{"186515151","156295654","123521888"});    ArrayList cities = new ArrayList<>();    cities.add("北京");    cities.add("南京");    cities.add("上海");    cities.add("深圳");    person.setCities(cities);    Map map = new HashMap<>();    map.put("key1","values1");    map.put("key2","values2");    map.put("key3","values3");    map.put("key4","values4");    map.put("key5","values5");    person.setMap(map);    pageContext.setAttribute("person",person);%>
输出person的属性:${person}输出person的name属性: ${person.name}输出person的phones1数组属性: ${person.phones[0]}输出person的phones2数组属性: ${person.phones[1]}输出person的phones3数组属性: ${person.phones[2]}输出person的cities集合1的属性: ${person.cities[0]}输出person的cities集合2的属性: ${person.cities[1]}输出person的map集合的属性: ${person.map}输出person的map集合1的属性: ${person.map.key2}

pageScope ====== pageContext 域requestScope ====== Request 域sessionScope ====== Session 域applicationScope ====== ServletContext 域<%--    ${pageContext}--%>    <%=request.getScheme()%>     1.协议：${pageContext.request.scheme}     2.服务器ip: ${pageContext.request.serverName}    3.服务器端口号 : ${pageContext.request.serverPort}    4.获取工程路径：${pageContext.request.contextPath}    5.获取请求的方法: ${pageContext.request.method}    6.获取客户端IP: ${pageContext.request.remoteHost}    7.获取会话的id: ${pageContext.session.id}

// 获取请求参数String username = req.getParameter("username");//1 先以 iso8859-1 进行编码//2 再以 utf-8 进行解码username = new String(username.getBytes("iso-8859-1"), "UTF-8");

@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException,IOException{    // 设置请求体的字符集为 UTF-8，从而解决 post 请求的中文乱码问题    req.setCharacterEncoding("UTF-8");    System.out.println("-------------doPost------------");        //要在获取参数设置字符编码        // 获取请求参数    String username = req.getParameter("username");    String password = req.getParameter("password");    String[] hobby = req.getParameterValues("hobby");    System.out.println("用户名：" + username);    System.out.println("密码：" + password);    System.out.println("兴趣爱好：" + Arrays.asList(hobby));}

/**************************Servlet1代码***************************/public class Servlet1 extends HttpServlet {    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException,            IOException {// 获取请求的参数（办事的材料）查看        String username = req.getParameter("username");        System.out.println("在 Servlet1（柜台 1）中查看参数（材料）：" + username);// 给材料 盖一个章，并传递到 Servlet2（柜台 2）去查看        req.setAttribute("key1","柜台 1 的章");// 问路：Servlet2（柜台 2）怎么走/** * 请求转发必须要以斜杠打头，/ 斜杠表示地址为：http://ip:port/工程名/ , 映射到 IDEA 代码的 web 目录 <br/> * */        RequestDispatcher requestDispatcher = req.getRequestDispatcher("/servlet2");// RequestDispatcher requestDispatcher = req.getRequestDispatcher("http://www.baidu.com");// 走向 Sevlet2（柜台 2）        requestDispatcher.forward(req,resp);}}
//为了方面也写成：req.getRequestDispatcher("/servlet2").forward(req,resp);
/***********************Servlet2 代码***********************/    public class Servlet2 extends HttpServlet {    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException,            IOException {// 获取请求的参数（办事的材料）查看        String username = req.getParameter("username");        System.out.println("在 Servlet2（柜台 2）中查看参数（材料）：" + username);// 查看 柜台 1 是否有盖章        Object key1 = req.getAttribute("key1");        System.out.println("柜台 1 是否有章：" + key1);// 处理自己的业务        System.out.println("Servlet2 处理自己的业务 ");    }}

/*请求重定向的第一种方案：*/        // 设置响应状态码 302 ，表示重定向，（已搬迁）        resp.setStatus(302);// 设置响应头，说明 新的地址在哪里        resp.setHeader("Location", "http://localhost:8080");
/*-----------------------------------------------------*/
        //请求重定向的第二种方案（推荐使用）：resp.sendRedirect("http://localhost:8080");

/*解决响应中文乱码方案一（不推荐使用）：*/        // 设置服务器字符集为 UTF-8        resp.setCharacterEncoding("UTF-8");// 通过响应头，设置浏览器也使用 UTF-8 字符集        resp.setHeader("Content-Type", "text/html; charset=UTF-8");
/*-----------------------------------------------------------------------------*/
          /*解决响应中文乱码方案二（推荐）：*/        // 它会同时设置服务器和客户端都使用 UTF-8 字符集，还设置了响应头// 此方法一定要在获取流对象之前调用才有效        resp.setContentType("text/html; charset=UTF-8");