最近剛?cè)腴T后端，對不起，我背叛了游戲【哭】
跟著寫了一個這樣的案例
網(wǎng)頁界面是這樣的
?沒寫刪除，里面帶有增加行和修改表單數(shù)據(jù)的功能
?
?web方面就三個頁面，里面涉及到了Mybatis，Tomcat，JSP，Servlet，Maven，前端三劍客等知識，東西比較雜，我也是速通選手，掌握不太穩(wěn)固，所以寫個文章鞏固一下知識點，以便自己能夠更好地理解代碼以及運行邏輯。
項目結(jié)構(gòu)是這樣的，需要配置mybatis-config.xml文件，pom.xml需要引入tomcat、Servlet，mybatis，JSP，Maven寫個標(biāo)識就能自動下載了，Maven好方便
以及Mapper配置文件和web配置文件，不是很復(fù)雜。
我們的代碼方面
一、前端頁面
三個前端頁面分別是這樣的
brand：主頁面
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<input type="button" value="新增" id="add"><br>
<hr>
<table border="1" cellspacing="0" width="80%">
<tr>
<th>序號</th>
<th>品牌名稱</th>
<th>企業(yè)名稱</th>
<th>排序</th>
<th>品牌介紹</th>
<th>狀態(tài)</th>
<th>操作</th>
</tr>
<c:forEach items="${brands}" var="brand" varStatus="status">
//items：被遍歷的容器
//var：遍歷產(chǎn)生的臨時變量
//varStatus：遍歷狀態(tài)對象
//我們這里是從SelectAllServlet跳轉(zhuǎn)過來的，所以接收了request域，我們只管調(diào)brand對象輸出數(shù)據(jù)就行
<tr align="center">
<%--<td>${brand.id}</td>--%>
<td>${status.count}</td>
<td>${brand.brandName}</td>
<td>${brand.companyName}</td>
<td>${brand.ordered}</td>
<td>${brand.description}</td>
<c:if test="${brand.status == 1}">//這里是JSP，就是if判斷
<td>啟用</td>
</c:if>
<c:if test="${brand.status != 1}">
<td>禁用</td>
</c:if>
<td><a href="/brandDemo/selectByIdServlet?id=${brand.id}">修改</a> <a href="#">刪除</a></td>
</tr>
</c:forEach>
</table>
<script>
document.getElementById("add").onclick = function (){
location.href = "/brandDemo/addBrand.jsp";
}//這里使用getElementById設(shè)置了按鈕的點擊事件。
</script>
</body>
</html>?addBrand：新增數(shù)據(jù)
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>添加品牌</title>
</head>
<body>
<h3>添加品牌</h3>
<form action="/brandDemo/addServlet" method="post">//這里我們提交到addServlet服務(wù)，還是以POST形式，然后addServlet再轉(zhuǎn)發(fā)到brand.jsp頁面
品牌名稱：<input name="brandName"><br>
企業(yè)名稱：<input name="companyName"><br>
排序：<input name="ordered"><br>
描述信息：<textarea rows="5" cols="20" name="description"></textarea><br>
狀態(tài)：
<input type="radio" name="status" value="0">禁用
<input type="radio" name="status" value="1">啟用<br>
<input type="submit" value="提交">
</form>
</body>
</html>update：修改數(shù)據(jù)
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>修改品牌</title>
</head>
<body>
<h3>修改品牌</h3>
<form action="/brandDemo/updateServlet" method="post">//這里還是一樣的，提交到updateServlet服務(wù)當(dāng)中
//這里跟新增表單頁面沒什么大的不同，但是Servlet方面就要先查詢再修改，還是比新增麻煩的
<%--隱藏域，提交id--%>
<input type="hidden" name="id" value="${brand.id}">
品牌名稱：<input name="brandName" value="${brand.brandName}"><br>
企業(yè)名稱：<input name="companyName" value="${brand.companyName}"><br>
排序：<input name="ordered" value="${brand.ordered}"><br>
描述信息：<textarea rows="5" cols="20" name="description">${brand.description} </textarea><br>
狀態(tài)：
<c:if test="${brand.status == 0}">
<input type="radio" name="status" value="0" checked>禁用
<input type="radio" name="status" value="1">啟用<br>
</c:if>
<c:if test="${brand.status == 1}">
<input type="radio" name="status" value="0" >禁用
<input type="radio" name="status" value="1" checked>啟用<br>
</c:if>
<input type="submit" value="提交">
</form>
</body>
</html>二、mybatis操作方面
既然處理數(shù)據(jù)肯定是要學(xué)習(xí)mybatis的
操作不難，寫幾個接口就行
這里則是使用到mapper的知識，不得不說，javaweb學(xué)的東西是真的雜，學(xué)的時候天天導(dǎo)包配文件，累。
BrandMapper:
package com.itheima.mapper;
import com.itheima.pojo.Brand;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.ResultMap;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import java.util.List;
public interface BrandMapper {//這里也沒啥好說的，以注解形式操縱數(shù)據(jù)庫，都是一些基礎(chǔ)操作語句
//唯一值得注意的是當(dāng)我們兩種模式命名有沖突的時候我們要配置ResultMap
//使得我們Brand查詢的時候能找到對應(yīng)的變量
/*
查詢所有
@return
*/
@Select("select * from tb_brand")
@ResultMap("brandResultMap")
List<Brand> selectAll();
@Insert("insert into tb_brand values(null,#{brandName},#{companyName},#{ordered},#{description},#{status})")
void add(Brand brand);
/**
* 根據(jù)id查詢
* @param id
* @return
*/
@Select("select * from tb_brand where id = #{id}")
@ResultMap("brandResultMap")
Brand selectById(int id);
/**
* 修改
* @param brand
*/
@Update("update tb_brand set brand_name = #{brandName},company_name = #{companyName},ordered = #{ordered},description = #{description},status = #{status} where id = #{id}")
void update(Brand brand);
}
brand數(shù)據(jù)類：
package com.itheima.pojo;
public class Brand {
// id 主鍵
private Integer id;
// 品牌名稱
private String brandName;
// 企業(yè)名稱
private String companyName;
// 排序字段
private Integer ordered;
// 描述信息
private String description;
// 狀態(tài)：0：禁用 1：啟用
private Integer status;
//提供了三種構(gòu)造方法以備不同情況，是一些面向?qū)ο蟮奶匦?，Java學(xué)過的都能懂
public Brand() {
}
public Brand(Integer id, String brandName, String companyName, String description) {
this.id = id;
this.brandName = brandName;
this.companyName = companyName;
this.description = description;
}
public Brand(Integer id, String brandName, String companyName, Integer ordered, String description, Integer status) {
this.id = id;
this.brandName = brandName;
this.companyName = companyName;
this.ordered = ordered;
this.description = description;
this.status = status;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getBrandName() {
return brandName;
}
public void setBrandName(String brandName) {
this.brandName = brandName;
}
public String getCompanyName() {
return companyName;
}
public void setCompanyName(String companyName) {
this.companyName = companyName;
}
public Integer getOrdered() {
return ordered;
}
public void setOrdered(Integer ordered) {
this.ordered = ordered;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public Integer getStatus() {
return status;
}
public void setStatus(Integer status) {
this.status = status;
}
@Override
public String toString() {
return "Brand{" +
"id=" + id +
", brandName='" + brandName + '\'' +
", companyName='" + companyName + '\'' +
", ordered=" + ordered +
", description='" + description + '\'' +
", status=" + status +
'}';
}
}
三、Servlet服務(wù)
這里就是處理數(shù)據(jù)的大頭了
因為創(chuàng)建工廠類只用一次就能最節(jié)省資源，所以我們用一個SqlSessionFactoryUtils靜態(tài)類來封裝好，下次直接調(diào)函數(shù)就行了，這里還是操作mybatis的東西
package com.itheima.util;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.InputStream;
public class SqlSessionFactoryUtils {
private static SqlSessionFactory sqlSessionFactory;//靜態(tài)對象
static {
try{//這里是數(shù)據(jù)庫連接必寫的三句
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}catch (IOException e){
e.printStackTrace();
}
}
public static SqlSessionFactory getSqlSessionFactory(){
return sqlSessionFactory;//用的時候直接調(diào)這個方法
}
}
隨后寫B(tài)randService，這里是將對數(shù)據(jù)的操作全都封裝好，免得到時候麻煩
代碼是這樣的
package com.itheima.service;
import com.itheima.mapper.BrandMapper;
import com.itheima.pojo.Brand;
import com.itheima.util.SqlSessionFactoryUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import java.util.List;
public class BrandService {
SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();//這里獲取工廠類
/*
查詢所有
@return
*/
public List<Brand> selectAll(){//查詢所有
//調(diào)用BrandMapper.selectAll()
//2.獲取SqlSession
SqlSession sqlSession = factory.openSession();
//3.獲取BrandMapper
BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
//4.調(diào)用方法
List<Brand> brands = mapper.selectAll();//這里就是操作數(shù)據(jù)庫，然后封裝到一個brands列表里
sqlSession.close();
return brands;//返回查詢到的值
}
/**
* 添加
* @param brand
*/
public void add(Brand brand){//這里是添加
//2. 獲取SqlSession
SqlSession sqlSession = factory.openSession();
//3. 獲取BrandMapper
BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
//4. 調(diào)用方法
mapper.add(brand);//往數(shù)據(jù)庫里添加一個brand對象
//提交事務(wù)
sqlSession.commit();
//釋放資源
sqlSession.close();
}
/**
* 根據(jù)id查詢
* @return
*/
public Brand selectById(int id){//依靠id查詢對象
//調(diào)用BrandMapper.selectAll()
//2. 獲取SqlSession
SqlSession sqlSession = factory.openSession();
//3. 獲取BrandMapper
BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
//4. 調(diào)用方法
Brand brand = mapper.selectById(id);
sqlSession.close();
return brand;
}
/**
* 修改
* @param brand
*/
public void update(Brand brand){//修改值
//2. 獲取SqlSession
SqlSession sqlSession = factory.openSession();
//3. 獲取BrandMapper
BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
//4. 調(diào)用方法
mapper.update(brand);
//提交事務(wù)
sqlSession.commit();
//釋放資源
sqlSession.close();
}
}
然后是Servlet服務(wù)類
通過這些服務(wù)我們來操作網(wǎng)頁里的數(shù)據(jù)
SelectAllServlet：
package com.itheima.web;
import com.itheima.pojo.Brand;
import com.itheima.service.BrandService;
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.util.List;
@WebServlet("/selectAllServlet")//這里我們通過標(biāo)簽訪問Servlet
public class SelectAllServlet extends HttpServlet {
private BrandService service = new BrandService();//先創(chuàng)建一個Brand服務(wù)對象
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1、調(diào)用BrandService完成查詢
List<Brand> brands = service.selectAll();//這里我們直接調(diào)用查詢
//2、存入request域中
req.setAttribute("brands",brands);//存入request域，到時候發(fā)出去的就是這個，要查詢的話只要調(diào)用鍵查值就行了，request域都是鍵值對。
//3、轉(zhuǎn)發(fā)到brand.jsp
req.getRequestDispatcher("/brand.jsp").forward(req,resp);//這里我們調(diào)用getrequestDispatcher方法轉(zhuǎn)發(fā)到brand.jsp頁面中，再通過JSP代碼把數(shù)據(jù)顯示出來。
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req,resp);//這樣寫能同時響應(yīng)POST請求和GET請求
}
}
AddServlet:
package com.itheima.web;
import com.itheima.pojo.Brand;
import com.itheima.service.BrandService;
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;
@WebServlet("/addServlet")
public class AddServlet extends HttpServlet {
private BrandService service = new BrandService();
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//處理POST請求的亂碼問題
request.setCharacterEncoding("utf-8");
//1. 接收表單提交的數(shù)據(jù)，封裝為一個Brand對象
String brandName = request.getParameter("brandName");
String companyName = request.getParameter("companyName");
String ordered = request.getParameter("ordered");
String description = request.getParameter("description");
String status = request.getParameter("status");
//封裝為一個Brand對象
Brand brand = new Brand();
brand.setBrandName(brandName);
brand.setCompanyName(companyName);
brand.setOrdered(Integer.parseInt(ordered));
brand.setDescription(description);
brand.setStatus(Integer.parseInt(status));
//2. 調(diào)用service 完成添加
service.add(brand);
//3. 轉(zhuǎn)發(fā)到查詢所有Servlet
request.getRequestDispatcher("/selectAllServlet").forward(request,response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
}
SelectById:
package com.itheima.web;
import com.itheima.pojo.Brand;
import com.itheima.service.BrandService;
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;
@WebServlet("/selectByIdServlet")
public class SelectByIdServlet extends HttpServlet {
private BrandService service = new BrandService();
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1、接受id
String id = req.getParameter("id");
//2、調(diào)用service查詢
Brand brand = service.selectById(Integer.parseInt(id));
//3、存儲到request中
req.setAttribute("brand",brand);
//4、轉(zhuǎn)發(fā)到update.jsp
req.getRequestDispatcher("/update.jsp").forward(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req, resp);
}
}
Updateservlet:
package com.itheima.web;
import com.itheima.pojo.Brand;
import com.itheima.service.BrandService;
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;
@WebServlet("/updateServlet")
public class UpdateServlet extends HttpServlet {
private BrandService service = new BrandService();
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//處理POST請求的亂碼問題
req.setCharacterEncoding("utf-8");
//1、接受表單提交的數(shù)據(jù)
String id = req.getParameter("id");
String brandName = req.getParameter("brandName");
String companyName = req.getParameter("companyName");
String ordered = req.getParameter("ordered");
String description = req.getParameter("description");
String status = req.getParameter("status");
//封裝為一個Brand對象
Brand brand = new Brand();
brand.setId(Integer.parseInt(id));
brand.setBrandName(brandName);
brand.setCompanyName(companyName);
brand.setOrdered(Integer.parseInt(ordered));
brand.setDescription(description);
brand.setStatus(Integer.parseInt(status));
//2、調(diào)用serice完成修改
service.update(brand);
//3、轉(zhuǎn)發(fā)到查詢所有Servlet
req.getRequestDispatcher("/selectAllServlet").forward(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req, resp);
}
}
代碼差不多就這樣了，做完發(fā)現(xiàn)東西還挺多的，面向?qū)ο笠獙懙臇|西還是挺多的。
?
下面是邏輯的梳理，說實話梳理邏輯確實是要花上一些時間
展現(xiàn)brand頁面：通過查詢tb_brand和JSP以及HTML、CSS來展現(xiàn)出數(shù)據(jù)庫里的數(shù)據(jù)
訪問順序：SelectAll.class->brand.jsp
新增數(shù)據(jù)：填寫表單數(shù)據(jù)->在數(shù)據(jù)庫中實現(xiàn)添加->addServlet->selectAllServlet->發(fā)送到brand.jsp->展現(xiàn)數(shù)據(jù)
訪問順序：brand.jsp->AddServlet.class->update.jsp->SelectAllServlet.class->brand.jsp
修改數(shù)據(jù)：通過查詢當(dāng)前id所對應(yīng)的表將其發(fā)送到update.jsp0界面->填寫修改后的數(shù)據(jù)->提交表單數(shù)據(jù)->在數(shù)據(jù)庫中實現(xiàn)修改->查詢所有->brand.jsp展現(xiàn)數(shù)據(jù)文章來源：http://www.zghlxwxcb.cn/news/detail-461798.html
訪問順序：brand.jsp->SelectByIdServlet->update.jsp->updateServlet->SelectAllServlet->brand.jsp文章來源地址http://www.zghlxwxcb.cn/news/detail-461798.html
到了這里，關(guān)于【后端】黑馬MVC案例詳解的文章就介紹完了。如果您還想了解更多內(nèi)容，請在右上角搜索TOY模板網(wǎng)以前的文章或繼續(xù)瀏覽下面的相關(guān)文章，希望大家以后多多支持TOY模板網(wǎng)！
