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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：

   
     
    
     4.0.0
      
    
     com.bit
      
    
     SpringMVC2
      
    
     1.0-SNAPSHOT
      
    
     war
      
    
     SpringMVC2 Maven Webapp
      
      
    
     http://www.example.com
      
        
     
      UTF-8
         
     
      1.7
         
     
      1.7
       
      
        
           
      
       junit
            
      
       junit
            
      
       4.11
            
      
       test
          
         
           
      
       mysql
            
      
       mysql-connector-java
            
      
       5.1.38
          
         
         
           
      
       org.springframework
            
      
       spring-context
            
      
       5.1.5.RELEASE
          
         
           
      
       org.springframework
            
      
       spring-core
            
      
       5.1.5.RELEASE
          
         
           
      
       org.springframework
            
      
       spring-aop
            
      
       5.1.5.RELEASE
          
         
           
      
       org.springframework
            
      
       spring-beans
            
      
       5.1.5.RELEASE
          
         
         
           
      
       org.springframework
            
      
       spring-tx
            
      
       5.1.5.RELEASE
          
         
         
           
      
       org.springframework
            
      
       spring-webmvc
            
      
       5.1.5.RELEASE
          
         
         
           
      
       org.springframework
            
      
       spring-web
            
      
       5.1.5.RELEASE
          
         
         
           
      
       javax.servlet
            
      
       javax.servlet-api
            
      
       3.0.1
            
      
       provided
          
         
         
           
      
       javax.servlet
            
      
       jstl
            
      
       1.2
          
         
         
           
      
       javax.el
            
      
       javax.el-api
            
      
       3.0.0
          
       
      
        
     
      SpringMVC
         
     
            
              
                 
        
         maven-clean-plugin
                  
        
         3.1.0
                
               
               
                 
        
         maven-resources-plugin
                  
        
         3.0.2
                
               
                 
        
         maven-compiler-plugin
                  
        
         3.8.0
                
               
                 
        
         maven-surefire-plugin
                  
        
         2.22.1
                
               
                 
        
         maven-war-plugin
                  
        
         3.2.2
                
               
                 
        
         maven-install-plugin
                  
        
         2.5.2
                
               
                 
        
         maven-deploy-plugin
                  
        
         2.8.2
                
             
          
       
    
   

    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：

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" %>>    
       
   
   
    
     
          
        UserId    
          
        UserName    
          
        UserAddr    
     
     
              
${   user.userId}
              
${   user.userName}
      
${   user.userAddr}
         
    
   

    接下来，在web.xml中配置前端控制器:

     
    
     Archetype Created Web Application
      
      
        
     
      myspringmvc
       
     
      org.springframework.web.servlet.DispatcherServlet
         
           
      
       contextConfigLocation
            
      
       classpath:springmvcservlet.xml
          
       
      
        
     
      myspringmvc
         
     
      /
       
    
   

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;@Controllerpublic 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
   
     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
   
     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
   
     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
   
     queryUserDao()    {   List
    
      userList=null;        try{   String str="select * from user";            ResultSet resultSet=new DbManager().executeQueryForUser(str);            userList=new ArrayList
     
      ();     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：

   
    classpath:springmvc*.xml
   

并在springmvcbeans.xml中配置适配器和处理器：

     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
   
     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
   
     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：

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

       
       
        
   >    
       
   

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：

（！！！！！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。