java - Dependencies and Library(JAR) 下载,概念

Question

很久以前我开发了一个 RESTFUL web 服务教程。现在我在我的 eclipse 中导入了相同的项目，但我不记得我是如何让这个项目早先运行的。我想知道更多关于POM.XML 和其他依赖项的重要性。

1.是否需要使用Maven build来构建项目？这将给出 pom.xml

2.如果是，pom.xml 是我们定义依赖关系的地方吗？就像读取一些 excel 文件所需的 jars 一样？这是我可以定义依赖项的同一个地方，它会自动下载。

3.我真的需要为此构建 Maven 吗？为此，我有简单的类以及 DAO 和 BEAN。

import java.io.IOException;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.MediaType;

import Bean.bookBean;
import Dao.bookDao;
@Path ("login")
public class bookPost {

@GET
@Path("validate")
@Produces(MediaType.TEXT_PLAIN)
    public String login(@QueryParam("frition")String un,@QueryParam("thriller")String pwd) throws IOException
{
    bookDao dao=new bookDao();
    bookBean tt=new bookBean();
    tt.setFrition(un);
    tt.setThriller(pwd);

    return dao.loginValidate(tt);
    }
}

我的书类

import javax.ws.rs.core.UriBuilder;
import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;
import Bean.bookBean;
import java.io.File;
import java.io.IOException;
import java.net.URI;
import jxl.Cell;
import jxl.CellType;
import jxl.Sheet;
import jxl.Workbook;
import jxl.read.biff.BiffException;

    public class BookCategories {

        private String inputFile;
        public void setInputFile(String inputFile) {
            this.inputFile = inputFile;
        }

        public void read() throws IOException  {
            File inputWorkbook = new File(inputFile);
            Workbook w;
            try {
                w = Workbook.getWorkbook(inputWorkbook);
                // Get the first sheet
                Sheet sheet = w.getSheet(0);
                // Loop over first 10 column and lines

                for (int j = 0; j < sheet.getColumns(); j++) {
                    for (int i = 0; i < sheet.getRows(); i++) {
                        Cell cell = sheet.getCell(j, i);
                        CellType type = cell.getType();

                        if (cell.getType() == CellType.LABEL) {
                            System.out.println("books "
                                    + cell.getContents());
                        }
            }
                }
            } catch (BiffException e) {
                e.printStackTrace();
            }



        }

        public static void main(String[] args) throws IOException {
            ClientConfig config = new DefaultClientConfig();
            Client client = Client.create(config);
            WebResource service = client.resource(getBaseURI());
            // Fluent interfaces
            bookBean lbean = new bookBean();
            lbean.setFrition("frition");
            lbean.setThriller("thriller");
            String cr =service.path("login").path("postvalidate").post(String.class,lbean);
            System.out.println(cr);
}

private static URI getBaseURI() {
    return UriBuilder.fromUri("http://localhost:8080/Services").build();
}

        }

4.我们什么时候真正需要 POM.XML？到目前为止，它显示了 poi jars 的错误。我已经手动下载了它们并将文件也添加到了项目中。不过，如果我在 APACHE TOMCAT 7 服务器上运行该项目，控制台中会出现以下错误。

Error May 13, 2014 2:44:05 PM com.sun.jersey.api.core.servlet.WebAppResourceConfig init
INFO: Scanning for root resource and provider classes in the Web app resource paths:
  /WEB-INF/lib
  /WEB-INF/classes
May 13, 2014 2:44:06 PM com.sun.jersey.api.core.ScanningResourceConfig init
INFO: No root resource classes found.
May 13, 2014 2:44:06 PM com.sun.jersey.api.core.ScanningResourceConfig logClasses
INFO: Provider classes found:
  class org.codehaus.jackson.jaxrs.JacksonJaxbJsonProvider
  class org.codehaus.jackson.jaxrs.JacksonJsonProvider
  class org.codehaus.jackson.jaxrs.JsonMappingExceptionMapper
  class org.codehaus.jackson.jaxrs.JsonParseExceptionMapper
May 13, 2014 2:44:06 PM com.sun.jersey.server.impl.application.WebApplicationImpl _initiate
INFO: Initiating Jersey application, version 'Jersey: 1.12 02/15/2012 04:51 PM'
May 13, 2014 2:44:06 PM com.sun.jersey.server.impl.application.RootResourceUriRules <init>
SEVERE: The ResourceConfig instance does not contain any root resource classes.
May 13, 2014 2:44:06 PM org.apache.catalina.core.ApplicationContext log
SEVERE: StandardWrapper.Throwable
com.sun.jersey.api.container.ContainerException: The ResourceConfig instance does not contain any root resource classes.
    at com.sun.jersey.server.impl.application.RootResourceUriRules.<init>(RootResourceUriRules.java:99)
    at com.sun.jersey.server.impl.application.WebApplicationImpl._initiate(WebApplicationImpl.java:1308)
    at com.sun.jersey.server.impl.application.WebApplicationImpl.access$700(WebApplicationImpl.java:171)
    at com.sun.jersey.server.impl.application.WebApplicationImpl$13.f(WebApplicationImpl.java:777)
    at com.sun.jersey.server.impl.application.WebApplicationImpl$13.f(WebApplicationImpl.java:773)
    at com.sun.jersey.spi.inject.Errors.processWithErrors(Errors.java:193)
    at com.sun.jersey.server.impl.application.WebApplicationImpl.initiate(WebApplicationImpl.java:773)
    at com.sun.jersey.server.impl.application.WebApplicationImpl.initiate(WebApplicationImpl.java:768)
    at com.sun.jersey.spi.container.servlet.ServletContainer.initiate(ServletContainer.java:488)
    at com.sun.jersey.spi.container.servlet.ServletContainer$InternalWebComponent.initiate(ServletContainer.java:318)
    at com.sun.jersey.spi.container.servlet.WebComponent.load(WebComponent.java:607)
    at com.sun.jersey.spi.container.servlet.WebComponent.init(WebComponent.java:208)
    at com.sun.jersey.spi.container.servlet.ServletContainer.init(ServletContainer.java:373)
    at com.sun.jersey.spi.container.servlet.ServletContainer.init(ServletContainer.java:556)
    at javax.servlet.GenericServlet.init(GenericServlet.java:160)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1133)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1087)
    at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:799)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:135)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:541)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:383)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:288)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

May 13, 2014 2:44:06 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Allocate exception for servlet Ebook
com.sun.jersey.api.container.ContainerException: The ResourceConfig instance does not contain any root resource classes.
    at com.sun.jersey.server.impl.application.RootResourceUriRules.<init>(RootResourceUriRules.java:99)
    at com.sun.jersey.server.impl.application.WebApplicationImpl._initiate(WebApplicationImpl.java:1308)
    at com.sun.jersey.server.impl.application.WebApplicationImpl.access$700(WebApplicationImpl.java:171)
    at com.sun.jersey.server.impl.application.WebApplicationImpl$13.f(WebApplicationImpl.java:777)
    at com.sun.jersey.server.impl.application.WebApplicationImpl$13.f(WebApplicationImpl.java:773)
    at com.sun.jersey.spi.inject.Errors.processWithErrors(Errors.java:193)
    at com.sun.jersey.server.impl.application.WebApplicationImpl.initiate(WebApplicationImpl.java:773)
    at com.sun.jersey.server.impl.application.WebApplicationImpl.initiate(WebApplicationImpl.java:768)
    at com.sun.jersey.spi.container.servlet.ServletContainer.initiate(ServletContainer.java:488)
    at com.sun.jersey.spi.container.servlet.ServletContainer$InternalWebComponent.initiate(ServletContainer.java:318)
    at com.sun.jersey.spi.container.servlet.WebComponent.load(WebComponent.java:607)
    at com.sun.jersey.spi.container.servlet.WebComponent.init(WebComponent.java:208)
    at com.sun.jersey.spi.container.servlet.ServletContainer.init(ServletContainer.java:373)
    at com.sun.jersey.spi.container.servlet.ServletContainer.init(ServletContainer.java:556)
    at javax.servlet.GenericServlet.init(GenericServlet.java:160)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1133)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1087)
    at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:799)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:135)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:541)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:383)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:288)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

我试图在其他论坛上找到这个。但我只是在中间迷路了，因为我有很多问题。花了大约 4 个小时，但没有继续前进。希望获得清晰明了的信息。

Answer 1

经过少量研究和与 MAVEN 的几天头脑 Storm 。我能够自己回答我的问题。

1。不，使用 maven build 或 ant build 或任何其他构建来构建项目不是强制性的。但是如果您使用 MAVEN，它肯定会有 pom.xml，您将在其中定义依赖项，打包 JAR 的详细信息。

构建过程通常意味着它将从您编写的源文件开始，并以可以部署在服务器上的 jar 或 war 之类的形式结束。

2。是的，您可以定义编译时和运行时依赖项。如果您想了解[编译时和运行时依赖项](http://stackoverflow.com/questions/4270950/compile-time-vs-run-time-dependency -java)。是的，它还为您提供了下载所需 jar 的功能，当您将在不同的机器上构建 jar，然后使用该 pom.xml 构建 jar。

3。如果你想将它打包在 jar 中并定义依赖关系，你需要 MAVEN。否则你不需要为此构建 maven。