java stream filter 包含name等于l 或者等li

可以使用如下代码实现：

List<Person> people = ... // 假设这里有一个Person对象的列表
List<Person> filteredPeople = people.stream()
        .filter(person -> person.getName().matches("l(i)?"))
        .collect(Collectors.toList());

这段代码会筛选出`name`属性为"l"或者"li"的`Person`对象，并将它们放入一个新的列表中。其中，`matches()`方法用于判断字符串是否匹配正则表达式，正则表达式`"l(i)?"`表示匹配以"l"开头，后面跟0个或1个"i"的字符串。当然，你需要将代码中的`Person`替换成你自己的实体类名，并根据实际情况修改属性名和正则表达式。

相关问题

用户能进行个人文件管理，能上传和下载图片、文档，可以对相册图片和文档进行查看、删除等操作的Javaweb代码

以下是一个简单的 Javaweb 文件管理系统的代码示例，包括上传、下载、查看、删除功能：

1. 首先，在项目的 web.xml 文件中配置以下 servlet 和 filter：

<servlet>
    <servlet-name>FileUploadServlet</servlet-name>
    <servlet-class>com.example.FileUploadServlet</servlet-class>
</servlet>

<servlet-mapping>
    <servlet-name>FileUploadServlet</servlet-name>
    <url-pattern>/file/upload</url-pattern>
</servlet-mapping>

<filter>
    <filter-name>LoginFilter</filter-name>
    <filter-class>com.example.LoginFilter</filter-class>
</filter>

<filter-mapping>
    <filter-name>LoginFilter</filter-name>
    <url-pattern>/file/*</url-pattern>
</filter-mapping>

2. 创建一个 FileUploadServlet 类，用于处理文件上传请求：

public class FileUploadServlet extends HttpServlet {
    
    private static final long serialVersionUID = 1L;
    private static final String UPLOAD_DIRECTORY = "uploads";
    
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // 创建文件上传工厂
        DiskFileItemFactory factory = new DiskFileItemFactory();

        // 设置缓冲区大小
        factory.setSizeThreshold(1024 * 1024);

        // 设置上传目录
        File uploadDir = new File(getServletContext().getRealPath("") + File.separator + UPLOAD_DIRECTORY);
        if (!uploadDir.exists()) {
            uploadDir.mkdir();
        }
        factory.setRepository(uploadDir);

        // 创建文件上传处理器
        ServletFileUpload upload = new ServletFileUpload(factory);

        // 设置上传文件大小限制
        upload.setFileSizeMax(1024 * 1024 * 10); // 10 MB

        // 解析请求
        List<FileItem> items = null;
        try {
            items = upload.parseRequest(request);
        } catch (FileUploadException e) {
            e.printStackTrace();
        }

        // 处理上传的文件
        for (FileItem item : items) {
            if (!item.isFormField()) {
                String fileName = new File(item.getName()).getName();
                String filePath = getServletContext().getRealPath("") + File.separator + UPLOAD_DIRECTORY + File.separator + fileName;
                File uploadedFile = new File(filePath);
                try {
                    item.write(uploadedFile);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }

        response.sendRedirect(request.getContextPath() + "/file/list");
    }
}

3. 创建一个 FileListServlet 类，用于显示文件列表和处理文件下载请求：

public class FileListServlet extends HttpServlet {
    
    private static final long serialVersionUID = 1L;
    private static final String UPLOAD_DIRECTORY = "uploads";
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // 获取上传目录的绝对路径
        String uploadPath = getServletContext().getRealPath("") + File.separator + UPLOAD_DIRECTORY;

        // 创建上传目录文件对象
        File uploadDir = new File(uploadPath);

        // 获取上传目录下的所有文件对象
        File[] files = uploadDir.listFiles();

        // 将文件对象数组转换为文件名数组
        String[] fileNames = new String[files.length];
        for (int i = 0; i < files.length; i++) {
            fileNames[i] = files[i].getName();
        }

        // 将文件名数组存入请求属性中
        request.setAttribute("fileNames", fileNames);

        // 转发到文件列表页面
        request.getRequestDispatcher("/file/list.jsp").forward(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // 获取下载文件名
        String fileName = request.getParameter("fileName");

        // 获取下载文件对象
        String filePath = getServletContext().getRealPath("") + File.separator + UPLOAD_DIRECTORY + File.separator + fileName;
        File downloadFile = new File(filePath);

        // 设置响应头，告诉浏览器下载文件
        response.setContentType("application/octet-stream");
        response.setHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
        response.setHeader("Content-Length", String.valueOf(downloadFile.length()));

        // 将文件内容写入响应输出流中
        FileInputStream in = new FileInputStream(downloadFile);
        OutputStream out = response.getOutputStream();
        byte[] buffer = new byte[1024];
        int length = 0;
        while ((length = in.read(buffer)) > 0) {
            out.write(buffer, 0, length);
        }
        in.close();
        out.flush();
    }
}

4. 创建一个 LoginFilter 类，用于检查用户是否已登录：

public class LoginFilter implements Filter {
    
    public void init(FilterConfig filterConfig) throws ServletException {}

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest httpRequest = (HttpServletRequest) request;
        HttpServletResponse httpResponse = (HttpServletResponse) response;

        HttpSession session = httpRequest.getSession(false);

        boolean isLoggedIn = (session != null && session.getAttribute("user") != null);
        String loginURI = httpRequest.getContextPath() + "/login.jsp";

        boolean isLoginRequest = httpRequest.getRequestURI().equals(loginURI);
        boolean isLoginPage = httpRequest.getRequestURI().endsWith("login.jsp");

        if (isLoggedIn && (isLoginRequest || isLoginPage)) {
            httpResponse.sendRedirect(httpRequest.getContextPath() + "/file/list");
        } else if (isLoggedIn || isLoginRequest || isLoginPage) {
            chain.doFilter(request, response);
        } else {
            httpResponse.sendRedirect(loginURI);
        }
    }

    public void destroy() {}
}

5. 创建一个文件列表页面 list.jsp，用于显示文件列表和处理文件上传和下载：

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>文件列表</title>
</head>
<body>
    <h1>文件列表</h1>

    <% if (request.getAttribute("fileNames") != null) { %>
        <ul>
        <% for (String fileName : (String[]) request.getAttribute("fileNames")) { %>
            <li>
                <%= fileName %>
                <form method="post" action="<%= request.getContextPath() %>/file/download">
                    <input type="hidden" name="fileName" value="<%= fileName %>">
                    <button type="submit">下载</button>
                </form>
                <form method="post" action="<%= request.getContextPath() %>/file/delete">
                    <input type="hidden" name="fileName" value="<%= fileName %>">
                    <button type="submit">删除</button>
                </form>
            </li>
        <% } %>
        </ul>
    <% } else { %>
        <p>没有上传的文件</p>
    <% } %>

    <h2>上传文件</h2>

    <form method="post" action="<%= request.getContextPath() %>/file/upload" enctype="multipart/form-data">
        <input type="file" name="file">
        <button type="submit">上传</button>
    </form>
</body>
</html>

6. 创建一个文件删除页面 delete.jsp，用于处理文件删除请求：

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>删除文件</title>
</head>
<body>
    <h1>删除文件</h1>

    <p>确定要删除文件 <%= request.getParameter("fileName") %> 吗？</p>

    <form method="post" action="<%= request.getContextPath() %>/file/do_delete">
        <input type="hidden" name="fileName" value="<%= request.getParameter("fileName") %>">
        <button type="submit">是</button>
        <a href="<%= request.getContextPath() %>/file/list">否</a>
    </form>
</body>
</html>

7. 创建一个 FileDeleteServlet 类，用于处理文件删除请求：

public class FileDeleteServlet extends HttpServlet {
    
    private static final long serialVersionUID = 1L;
    private static final String UPLOAD_DIRECTORY = "uploads";
    
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // 获取要删除的文件名
        String fileName = request.getParameter("fileName");

        // 获取要删除的文件对象
        String filePath = getServletContext().getRealPath("") + File.separator + UPLOAD_DIRECTORY + File.separator + fileName;
        File deleteFile = new File(filePath);

        // 删除文件
        if (deleteFile.exists()) {
            deleteFile.delete();
        }

        response.sendRedirect(request.getContextPath() + "/file/list");
    }
}

这个文件管理系统包括上传、下载、查看、删除文件的功能，可以根据需要进行扩展和修改。