问题[servlet]

当我尝试访问 localhost:61687/hello（或类似的）处的 servlet 时，出现 404 错误。

细节：

服务器本身可以正常工作，因为 http://localhost:61687/ 上会出现一个页面，确认了这一点：

端口61687，因为 8080 忙。

使用 gradle 命令收集 .war 文件

./gradle war

使用以下命令从控制台启动服务器：

./asadmin start-domain newDomain1

对于部署，我使用了以下命令

./asadmin deploy --force /Users/dima/Documents/projects/Java/JavaEE/build/libs/JavaEE-1.0-SNAPSHOT.war

Servlet 代码：

package servlets;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

@WebServlet(name="firstservlet", urlPatterns = "/hello")
public class servlet1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html");
        PrintWriter printWriter = resp.getWriter();
        printWriter.write("Hello!");
        printWriter.close();
    }
}

构建.gradle 文件：

plugins {
    id 'java'
    id 'war'
}

group 'org.example'
version '1.0-SNAPSHOT'

repositories {
    mavenCentral()
}

dependencies {
    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.1'
    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.8.1'
    compileOnly group: 'org.glassfish', name: 'javax.servlet', version: '3.2-b06'

}

test {
    useJUnitPlatform()
}

我如何尝试修复错误

我尝试了地址http://localhost:61687/JavaEE-1.0-SNAPSHOT/hello - 情况没有改变。

我尝试使用不带包的 servlet 类

尝试使用带有一个参数的注释： @WebServlet("/hello")

这是一个用于演示的简单记录器调用示例

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@WebServlet(LOGIN_PATH)
public class LoginServlet extends HttpServlet {
    static final Logger logger = LoggerFactory.getLogger(LoginServlet.class);

    public static final String ERROR_ATTRIBUTE = "error";

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        logger.info("Example log from {}", LoginServlet.class.getSimpleName());
        logger.error("Example log from {}", LoginServlet.class.getSimpleName());
        logger.debug("Example log from {}", LoginServlet.class.getSimpleName());
        logger.warn("Example log from {}", LoginServlet.class.getSimpleName());

        req.getRequestDispatcher(LOGIN_VIEW).forward(req, resp);
    }
    }

对于配置，我在资源文件夹中创建了 log4j.properties

# Logger option
log4j.rootLogger = TRACE, console, file

log4j.appender.console = org.apache.log4j.ConsoleAppender
log4j.appender.console.layout = org.apache.log4j.EnhancedPatternLayout
log4j.appender.console.layout.ConversionPattern = %d{yyyy-MM-dd HH:mm:ss} [%X{CorrelationId}] %-5p %X{method} %X{uri} %c{1} - %m%n

# console is set to be a ConsoleAppender.
log4j.appender.file = org.apache.log4j.RollingFileAppender

log4j.appender.file.File = D:\\log\\logging.log
log4j.appender.file.MaxFileSize = 10MB
log4j.appender.file.MaxBackupIndex = 10
log4j.appender.file.layout = org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern = %d{yyyy-MM-dd HH:mm:ss} [%X{CorrelationId}] %-5p %X{method} %X{uri} %c{1} - %m%n

这是我在 pom xml 中与日志记录相关的依赖项。

    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.36</version>
      </dependency>
      <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-simple</artifactId>
        <version>1.7.21</version>
      </dependency>
  <dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
  </dependency>

问题是文件没有创建，我只在控制台看到这个输出

大家好。伙计们可以举例说明在 servlet 应用程序中限制对页面的访问。因此，当我以用户身份登录时，我无法使用 /admin url 转到管理页面。

这是登录 servlet 代码：

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;


public class LoginServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {

        req.getRequestDispatcher("index.jsp").forward(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        PrintWriter pw = response.getWriter();
        response.setContentType("text/html");

        String user = request.getParameter("userName");
        String pass = request.getParameter("userPassword");

        if (user.equals("admin") && pass.equals("admin")) {
            response.sendRedirect("/admin");
        }
        if (user.equals("user") && pass.equals("user")) {
            response.sendRedirect("/user");
        }
        if (user.equals("page3") && pass.equals("page3")) {
            response.sendRedirect("page3.jsp");
        }
        else
            pw.println("Login Failed...!");
        pw.close();

    }


}

需要将图像保存到服务器。可以吃朴实无华的图书馆吗？当我停在 oracle 教程上时。但问题是文件保存在服务器的什么位置，如何创建路径呢？

该示例使用String path = request.getParameter("MyPath");但我未在此处指定返回的null 内容还有另一个选项path = request.getServletContext().getRealPath("");返回项目的父目录。是否可以在服务器上使用此选项？

@MultipartConfig
public class FileUploadServlet extends HttpServlet {

    private final static Logger LOGGER =
            Logger.getLogger(FileUploadServlet.class.getCanonicalName());
    private static final long serialVersionUID = 7908187011456392847L;

    /**
     * Processes requests for both HTTP
     * <code>GET</code> and
     * <code>POST</code> methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");

        // Create path components to save the file
        final String path = request.getParameter("destination");
        final Part filePart = request.getPart("file");
        final String fileName = getFileName(filePart);

        OutputStream out = null;
        InputStream filecontent = null;
        final PrintWriter writer = response.getWriter();

        try {
            out = new FileOutputStream(new File(path + File.separator
                    + fileName));
            filecontent = filePart.getInputStream();

            int read;
            final byte[] bytes = new byte[1024];

            while ((read = filecontent.read(bytes)) != -1) {
                out.write(bytes, 0, read);
            }
            writer.println("New file " + fileName + " created at " + path);
            LOGGER.log(Level.INFO, "File {0} being uploaded to {1}",
                    new Object[]{fileName, path});

        } catch (FileNotFoundException fne) {
            writer.println("You either did not specify a file to upload or are "
                    + "trying to upload a file to a protected or nonexistent "
                    + "location.");
            writer.println("<br/> ERROR: " + fne.getMessage());

            LOGGER.log(Level.SEVERE, "Problems during file upload. Error: {0}",
                    new Object[]{fne.getMessage()});
        } finally {
            if (out != null) {
                out.close();
            }
            if (filecontent != null) {
                filecontent.close();
            }
            if (writer != null) {
                writer.close();
            }
        }
    }

    private String getFileName(final Part part) {
        final String partHeader = part.getHeader("content-disposition");
        LOGGER.log(Level.INFO, "Part Header = {0}", partHeader);
        for (String content : part.getHeader("content-disposition").split(";")) {
            if (content.trim().startsWith("filename")) {
                return content.substring(
                        content.indexOf('=') + 1).trim().replace("\"", "");
            }
        }
        return null;
    }

    /**
     * Handles the HTTP
     * <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP
     * <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Servlet that uploads files to a user-defined destination";
    }
}