spring boot01,spring完全注解(零配置)编程方式

Posted 2021-01-31 chao123

前言：

 

　　spring boot就是整合了很多优秀的框架，不用我们自己手动的去写一堆xml配置然后进行配置。有了它， 你可以更加敏捷地开发Spring应用程序，专注于应用程序的功能，不用在Spring的配置上多花功 夫，甚至完全不用配置。

一  spring4.x的java注解方式编程

　Java注解是Spring4.x推荐的配置方式，可以完全替代xml配置。Spring的Java注解方式是通过 @Configuration和 @Bean这两个注解实现的：

　　　　　1、@Configuration 作用于类上，相当于一个xml配置文件；

   　　　　 2、@Bean 作用于方法上，相当于xml配置中的<bean>；

　　　上案例！！！

　　　开发环境:spring4.3.9+jdk1.7+maven3.6+eclipse mars.2+mysql

　　　　结构图：

　　　　　　

　　pom.xml配置如下:

<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>org.lzq</groupId>
    <artifactId>springboot</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <properties>
        <!-- jar包统一升级管理 -->
        <spring.version>4.3.9.RELEASE</spring.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!-- 日志包 -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <!-- mysql连接驱动包 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.26</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                    <encoding>utf-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

　　实体类:UserEntity.java

package org.lzq.entity;

import java.io.Serializable;

public class UserEntity implements Serializable {
    
    private static final long serialVersionUID = -5425731832559669953L;
    private Integer userId;
    private String userName;
    private String passWord;

    public UserEntity() {
        super();
    }

    public UserEntity(Integer userId, String userName, String passWord) {
        super();
        this.userId = userId;
        this.userName = userName;
        this.passWord = passWord;
    }

    public Integer getUserId() {
        return userId;
    }

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

    public String getUserName() {
        return userName;
    }

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

    public String getPassWord() {
        return passWord;
    }

    public void setPassWord(String passWord) {
        this.passWord = passWord;
    }

}

　　dao层代码:

　　IUserDao.java

package com.accp.dao;

import java.util.List;

import org.lzq.entity.UserEntity;

public interface IUserDao {
    //查询所有
    List<UserEntity> queryAll();
}

　　UserDaoImpl.java

package com.lyc.dao;


import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import org.springframework.stereotype.Repository;

import com.lyc.entity.UserEntity;


@Repository("userDao")
public class UserDaoImpl extends BaseDao implements IUserDao{

    @Override
    public List<UserEntity> queryAll() {
        
        List<UserEntity> list = new ArrayList<UserEntity>();
        String sql= "select * from users";
        rs = executeQuery(sql);
         try {
                UserEntity user=null;
                while(rs.next()){
                    user=new UserEntity();
                    user.setUserId(rs.getInt("userId"));
                    user.setUserName(rs.getString("userName"));
                    user.setPassWord(rs.getString("passWord"));
                    list.add(user);
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }finally{
                closeAll();
            }
            return list;

    }

}

业务层代码

UserService.java

package com.lyc.service;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service;

import com.lyc.dao.IUserDao;
import com.lyc.entity.UserEntity;


@Service("userService")
public class UserService {
    //Autowired默认根据类型进行装配，加上Qualifier注解则变成根据名称装配
    @Autowired
    @Qualifier("userDao")
    private IUserDao userDao;
    
    public List<UserEntity> queryAll() {
        return userDao.queryAll();
    }
}    

配置类

SpringConfig.java

package com.lyc.configs;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

import com.lyc.dao.IUserDao;
import com.lyc.dao.UserDaoImpl;

//通过该注解来表明该类是一个Spring的配置，相当于一个传统的ApplicationContext.xml
@Configuration
//相当于配置文件里面的<context:component-scan/>标签
@ComponentScan(basePackages="com.lyc.dao,com.lyc.service")
public class SpringConfig {
        // 通过该注解来表明是一个Bean对象，相当于xml中的<bean>
        //bean的id值默认是方法名userDao
        /*
        @Bean
        public IUserDao userDao(){
            return new UserDaoImpl();
        }
        */

}

测试类代码　　

Test01.java

package com.lyc.test;

import java.util.List;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import com.lyc.configs.SpringConfig;
import com.lyc.entity.UserEntity;
import com.lyc.service.UserService;



public class Test01 {

    public static void main(String[] args) {
        //通过java配置来实例化spring容器
        AnnotationConfigApplicationContext acac = 
                new AnnotationConfigApplicationContext(SpringConfig.class);
        //在spring容器中获取bean对象
        //名称userService是注解根据类UserService自动生成的
        UserService userService = (UserService) acac.getBean("userService");
        //或者采取下面的方式
        //UserService userService = acac.getBean(UserService.class);
        
        List<UserEntity> list = userService.queryAll();
        for (UserEntity u : list) {
            System.out.println(u.getUserName()+"---"+u.getPassWord());
        }
        //销毁容器
        acac.destroy();
    }

}

 感觉还是挺简单的哈！！！