package com.imooc.service.impl;

import java.util.List;

import com.imooc.domain.book.Book;

import com.imooc.service.BookService;

public class BookServiceImpl implements BookService {

/**

 * 添加图书信息

 */

@Override

public void addBook(List<Book> bookList, Book book) {

bookList.add(book);

}

/**

 * 修改图书信息

 */

@Override

public void updateBook(List<Book> bookList, Book book) {

Book book1=null;

for(Book b:bookList) {

if(book.getBookId().equals(b.getBookId())) {

book1=b;

break;

}

}

if(book1!=null) {

bookList.remove(book1);

bookList.add(book);

}

}

   /**

    * 删除图书信息

    */

@Override

public void deleteBook(List<Book> bookList, String bookId) {

Book book1=null;

for(Book book:bookList) {

if(book.getBookId().equals(bookId)) {

book1=book;

}

}

if(book1!=null) {

bookList.remove(book1);

}

}

@Override

public Book getBooksByBookId(List<Book> bookList, String bookID) {

// TODO Auto-generated method stub

return null;

}

/**

 * 通过图书分类名称显示图书信息

 */

@Override

public List<Book> getBooksByCategoryName(List<Book> bookList, String catgoryName) {

List<Book> bookList1=null;

for(Book book:bookList) {

if(catgoryName.equals(book.getCategoryName())) {

bookList1.add(book);

}

}

return bookList1;

}

}

****************************************

package com.imooc.web.servlet;

import java.io.IOException;

import java.util.List;

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 com.alibaba.fastjson.JSON;

import com.imooc.domain.book.Book;

import com.imooc.service.BookService;

import com.imooc.service.impl.BookServiceImpl;

/**

 * 通过图书分类名称显示图书信息

 * @author Administrator

 *

 */

@WebServlet("/SearchBook")

public class SearchBook extends HttpServlet {

private static final long serialVersionUID = 1L;

/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

*/

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

String catgoryName=request.getParameter("searchContent");

System.out.println(catgoryName);

List<Book> bookList=(List<Book>)request.getServletContext().getAttribute("bookList");

    BookService bookService =new BookServiceImpl();

List<Book> bookList1=bookService.getBooksByCategoryName(bookList, catgoryName);

if(bookList1==null) {

request.setAttribute("msk", "没有找到图书信息，请重新输入！");

request.getRequestDispatcher("/bookList.jsp").forward(request, response);

}else {String json=JSON.toJSONString(bookList1);

response.getWriter().println(json);

request.getRequestDispatcher("/bookList").forward(request, response);}

}

/**

* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

*/

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

// TODO Auto-generated method stub

doGet(request, response);

}

}

*****************************

三月 24, 2020 7:36:57 下午 org.apache.catalina.core.StandardWrapperValve invoke

严重: 在路径为[/Book-management]的上下文中，servlet[com.imooc.web.servlet.SearchBook]的Servlet.service()引发异常

java.lang.NullPointerException

at com.imooc.service.impl.BookServiceImpl.getBooksByCategoryName(BookServiceImpl.java:66)

at com.imooc.web.servlet.SearchBook.doGet(SearchBook.java:34)

at com.imooc.web.servlet.SearchBook.doPost(SearchBook.java:49)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

at com.imooc.web.filter.EncodeFilter.doFilter(EncodeFilter.java:44)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

at com.imooc.web.filter.AuthFilter.doFilter(AuthFilter.java:58)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)

at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:688)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)

at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:609)

at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)

at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:818)

at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1623)

at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)

at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)

at java.lang.Thread.run(Thread.java:745)