Spring MVC+JDBC 学习笔记

注解/xml配置

新建工程springmvcdemo即相应的包：

并将输出路径改为Tomcat的webapps下:

部署完毕后运行Tomcat，浏览器页面显示“Hello world！”，说明Tomcat工作正常。
在pom.xml中添加mysql、SpringMVC相关等依赖：

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.bit</groupId>
  <artifactId>SpringMVC2</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <name>SpringMVC2 Maven Webapp</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>


    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.38</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-aop</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-beans</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.springframework/spring-tx -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-web -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.0.1</version>
      <scope>provided</scope>
    </dependency>


    <!-- https://mvnrepository.com/artifact/javax.servlet/jstl -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/javax.el/javax.el-api -->
    <dependency>
      <groupId>javax.el</groupId>
      <artifactId>javax.el-api</artifactId>
      <version>3.0.0</version>
    </dependency>
  </dependencies>

  <build>
    <finalName>SpringMVC</finalName>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.1.0</version>
        </plugin>
        <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.22.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-war-plugin</artifactId>
          <version>3.2.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>

首先，写tools包下的DbManager类，该类用来连接数据库：其属性需要username、password、driver、url:

package com.bit.tools;

import java.sql.*;
//
public class DbManager {
    public String username="root";
    public String password="jdpy1229jiajia";
    public String driver="com.mysql.jdbc.Driver";
    public String url="jdbc:mysql://localhost:3306/ming";

public Connection connection=null;
public Statement statement=null;
public ResultSet resultSet=null;

//无参构造
public DbManager(){}

//获取数据库连接
public Connection getConnection()
{
    try {
        Class.forName(driver);
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
    System.out.println("加载数据库成功");

    try {
        connection=DriverManager.getConnection(url,username,password);
        System.out.println("数据库连接成功");
    } catch (SQLException e) {
        e.printStackTrace();
    }
return connection;
}

//执行全查query all of form user
    public ResultSet executeQueryForUser(String sql)
    {
        connection=this.getConnection();
        try {
            statement=connection.createStatement();
            resultSet=statement.executeQuery(sql);
        return resultSet;
        } catch (SQLException e) {
            e.printStackTrace();
        }
    return null;}


    //关闭连接
        public void closeConnection() throws SQLException {
            if(resultSet!=null) {
                try {
                    resultSet.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if(statement!=null)
                statement.close();
            if(connection!=null)
                connection.close();
        }
    }

在resources下新建SpringMVC的配置文件springmvcservlet.xml:
通过<context:component-scan base-package=<“com.bit.controller”/>可以扫描到控制器：

<?xml version="1.0" encoding="ISO-8859-1"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx" xmlns:p="http://www.springframework.org/schema/p"
       xmlns:util="http://www.springframework.org/schema/util"
       xmlns:cache="http://www.springframework.org/schema/cache"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/tx/spring-tx.xsd
    http://www.springframework.org/schema/cache
    http://www.springframework.org/schema/cache/spring-cache-3.1.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop.xsd
    http://www.springframework.org/schema/util
    http://www.springframework.org/schema/util/spring-util.xsd">
    

<context:component-scan base-package="com.bit.controller"/>
    <mvc:annotation-driven/>
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
        <property name="prefix" value="/jsps/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

在webapp下新建jsps文件夹，其中新建showuser,jsp:

<%--
  Created by IntelliJ IDEA.
  User: Lenovo
  Date: 2019/8/9
  Time: 20:23
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java"  isELIgnored="false" %>
<%@taglib prefix="c" uri="http://java.sun.com/jstl/core_rt" %>>

<html>
<head>
    <title>Title</title>
</head>
<body>
<table border="1" align="center" width="100%">
<tr>
    <th>
        UserId
    </th>
    <th>
        UserName
    </th>
    <th>
        UserAddr
    </th>
</tr>
<c:forEach items="${userListKey}" var="user">
    <tr>
        <td>${user.userId}</td>
        <td>${user.userName}</td
        <td>${user.userAddr}</td>
    </tr>


</c:forEach>
</table>
</body>
</html>

接下来，在web.xml中配置前端控制器:

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>


  <!--配置前端控制器-->
  <servlet>
    <servlet-name>myspringmvc</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springmvcservlet.xml</param-value>
    </init-param>
  </servlet>

  <servlet-mapping>
    <servlet-name>myspringmvc</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
</web-app>

接下来，写Controller，通过@Controller注解的方式:

import com.bit.po.User;
import com.bit.service.UserServiceImpl;
import com.bit.service.UserServive;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import java.util.List;


@Controller
public class UserController {

//自行维护UserController类与UserService类之间的关系
private UserServive userServive=new UserServiceImpl();

    //映射
@RequestMapping(value="/queryUser")


//接收请求，响应并跳转
    public ModelAndView queryUser() throws Exception {


        List<User> userList= userServive.queryUserService();


ModelAndView modelAndView=new ModelAndView();


//通过key与value进行转向
modelAndView.addObject("userListKey",userList);

//通过视图解析器来解析
modelAndView.setViewName("showuser");
return modelAndView;


}
}

在service包中需要一个UserService接口：

package com.bit.service;

import com.bit.po.User;

import java.util.List;

public interface UserServive
{public List<User> queryUserService() throws Exception;
}

在po包中新建User类，该类的属性需要与数据库中的表对应：

package com.bit.po;

public class User {
    private int userId;
    private String userName;
    private String userAddr;

    //默认的无参构造
    public User(){}

    @Override
    public String toString() {
        return "User{" +
                "userId=" + userId +
                ", userName='" + userName + '\'' +
                ", userAddr='" + userAddr + '\'' +
                '}';
    }

    public int getUserId() {
        return userId;
    }

    public void setUserId(int userId) {
        this.userId = userId;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getUserAddr() {
        return userAddr;
    }

    public void setUserAddr(String userAddr) {
        this.userAddr = userAddr;
    }
}

在service包中写实现类UserServiceImpl:

package com.bit.service;

import com.bit.dao.UserDao;
import com.bit.po.User;

import java.util.List;

public class UserServiceImpl implements UserServive{

private UserDao userDao=new UserDao();
    //Service层需要调用dao
    @Override
    public List<User> queryUserService() throws Exception {

      return userDao.queryUserDao();
    }
}

service层需要调用dao，dao需要访问数据库。在dao包中写UserDao类：

package com.bit.dao;

import com.bit.po.User;
import com.bit.tools.DbManager;

import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

//dao层需要访问数据库
public class UserDao {
    public List<User> queryUserDao()
    {List<User> userList=null;
        try{

String str="select * from user";
            ResultSet resultSet=new DbManager().executeQueryForUser(str);
            userList=new ArrayList<User>();
     while (resultSet.next())
     {User user=new User();
     user.setUserId(resultSet.getInt("userid"));
     user.setUserName(resultSet.getString("username"));
     user.setUserAddr(resultSet.getString("useraddr"));
     userList.add(user);}
        return userList;}
        catch (Exception ex)
        {ex.printStackTrace();}

        return userList;
    }


}

运行Tomcat，浏览器显示结果为：

上述代码存在问题：在controller类和service类中都用到了new关键字，应该让Spring容器去创建类、管理类与类之间的关系。拷贝一份UserController2.，并在resources中新建springmvcbeans.xml：
在web.xml中修改使Spring能扫描到新增加的xml：

 <param-value>classpath:springmvc*.xml</param-value>

并在springmvcbeans.xml中配置适配器和处理器：

  <!--配置适配器-->
    <bean id="simpleControllerHandlerAdapter" class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>
    
<!--配置处理器-->
<bean id="userController2"  name="/userController2" class="com.bit.controller.UserController2"/>
    
    <!--配置映射器-->
        <bean id="beanNameUrlHandlerMapping" class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>

那么UserContraller2类需要实现Controller接口：
接下来，在springmvcbeans.xml中声明servive、dao、po等层的bean，需要servive包下的UserServiveImpl类提供getter、setter方法，而不再是在该类中自行new UserDao类，修改UserDao类：

package com.bit.service;

import com.bit.dao.UserDao;
import com.bit.po.User;

import java.util.List;

public class UserServiceImpl implements UserServive {

    private UserDao userDao;

    public UserDao getUserDao() {
        return userDao;
    }

    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

    @Override
    public List<User> queryUserService() throws Exception {
        return userDao.queryUserDao();
    }
}

同理，UserController2类中不需要new UserServiveImpl,只需要提供setter、getter方法：
修改UserController2类：

package com.bit.controller;

import com.bit.po.User;
import com.bit.service.UserServiceImpl;
import com.bit.service.UserServive;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.List;



public class UserController2 implements Controller {
    private UserServive userServive;

    public UserServive getUserServive() {
        return userServive;
    }

    public void setUserServive(UserServive userServive) {
        this.userServive = userServive;
    }

    public ModelAndView handleRequest(HttpServletRequest var1, HttpServletResponse var2) throws Exception {
        List<User> userList=userServive.queryUserService();
        ModelAndView modelAndView=new ModelAndView();
        modelAndView.addObject("userListKey",userList);
        modelAndView.setViewName("showuser");
        return modelAndView;    }
}

那么这时UserController2类中拥有了UserServive属性，可以通过调用setter方法：

<!--配置处理器-->
<bean id="userController2"  name="/userController2" class="com.bit.controller.UserController2">
<property name="UserServive" ref="userServive">
</property>
</bean>

在springmvcbeans.xml中声明servive、dao、po等层的bean，

    <!--servive-->
    <bean id="userServive" class="com.bit.service.UserServiceImpl">
    <property name="userDao" ref="userDAo"/>
    </bean>>

    <!--Dao-->
    <bean id="userDAo" class="com.bit.dao.UserDao"/>

通过XML配置的方式，运行Tomcat,浏览器显示结果为：

在springmvcservlet.xml中添加：

<context:component-scan base-package="com.bit.service"/>

（！！！！！直接扫描整个com.bit包才行。否则会报500错误。）
这样Spring就可以扫描到service包，对service包中的UserServiveImpl类使用@Service注解，即可。而接下来需要让Controller找到这个Service，只需在UserController类中加上@Autowired注解。

接下来，给dao包下的UserDao类添加@Component注解：

UserServiveImpl类调用了UserDao，因此需要在UserDao属性前加@Autowired注解，这时就不再需要UserDao属性的getter、setter方法了：
配置与注解是不可以混用的。
推荐使用注解。