spring boot整合mybatis数据库内容为null不显示怎么解决 springboot mybatis jndi

1.新建项目 springbootmybatis

2.在resources下面的application.properties配置文件中添加mysql数据库的配置参数

# mysql驱动配置
spring.datasource.url = jdbc:mysql://localhost:3306/aslan?useUnicode=true&characterEncoding=utf-8
spring.datasource.username = root
spring.datasource.password = root
spring.datasource.driverClassName = com.mysql.jdbc.Driver

3.在数据库中创建表结构

CREATE TABLE `learn_resource` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT 'ID',
  `author` varchar(20) DEFAULT NULL COMMENT '作者',
  `title` varchar(100) DEFAULT NULL COMMENT '描述',
  `url` varchar(100) DEFAULT NULL COMMENT '地址链接',
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=1035 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of learn_resource
-- ----------------------------
INSERT INTO `learn_resource` VALUES ('999', '官方SpriongBoot例子', '官方SpriongBoot例子', 'https://github.com/spring-www.google.comboot/tree/master/spring-boot-samples');
INSERT INTO `learn_resource` VALUES ('1000', '龙果学院', 'Spring Boot 教程系列学习', 'www.google.com');
INSERT INTO `learn_resource` VALUES ('1001', '测试博客', 'Spring Boot干活', 'www.google.com');
INSERT INTO `learn_resource` VALUES ('1002', '后端编程嘟', 'Spring Boot视频教程', 'www.google.com');
INSERT INTO `learn_resource` VALUES ('1034', '后端编程嘟', 'Spring 屌屌的视频教程', 'www.google.com');

4.使用阿里的数据库连接池

Spring Boot默认使用tomcat-jdbc数据源，如果你想使用其他的数据源，比如这里使用了阿里巴巴的数据池管理,除了在application.properties配置数据源之外，你应该额外添加以下依赖：

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.0.19</version>
</dependency>

在resources下面的application.properties配置文件中添加druid的相关参数

#连接池的配置信息
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.initialSize=5  
spring.datasource.minIdle=5  
spring.datasource.maxActive=20  
spring.datasource.maxWait=60000  
spring.datasource.timeBetweenEvictionRunsMillis=60000  
spring.datasource.minEvictableIdleTimeMillis=300000  
spring.datasource.validationQuery=SELECT 1 FROM DUAL  
spring.datasource.testWhileIdle=true  
spring.datasource.testOnBorrow=false  
spring.datasource.testOnReturn=false  
spring.datasource.poolPreparedStatements=true  
spring.datasource.maxPoolPreparedStatementPerConnectionSize=20  
spring.datasource.filters=stat,wall,log4j  
spring.datasource.connectionProperties=druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000

目前Spring Boot中默认支持的连接池有dbcp,dbcp2, tomcat, hikari三种连接池。 由于Druid暂时不在Spring Boot的直接支持，故需要进行配置信息的定制：

package com.example.demo.config;


import com.alibaba.druid.pool.DruidDataSource;
import org.slf4j.LoggerFactory;
import org.slf4j.Logger;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

import javax.sql.DataSource;
import java.sql.SQLException;


/**
 * Created by Administrator on 2018/1/4 0004.
 */
@Configuration
public class DruidDBConfig {

    private Logger logger = LoggerFactory.getLogger(DruidDBConfig.class);

    @Value("${spring.datasource.url}")
    private String dbUrl;

    @Value("${spring.datasource.username}")
    private String username;

    @Value("${spring.datasource.password}")
    private String password;

    @Value("${spring.datasource.driverClassName}")
    private String driverClassName;

    @Value("${spring.datasource.initialSize}")
    private int initialSize;

    @Value("${spring.datasource.minIdle}")
    private int minIdle;

    @Value("${spring.datasource.maxActive}")
    private int maxActive;

    @Value("${spring.datasource.maxWait}")
    private int maxWait;

    @Value("${spring.datasource.timeBetweenEvictionRunsMillis}")
    private int timeBetweenEvictionRunsMillis;

    @Value("${spring.datasource.minEvictableIdleTimeMillis}")
    private int minEvictableIdleTimeMillis;

    @Value("${spring.datasource.validationQuery}")
    private String validationQuery;

    @Value("${spring.datasource.testWhileIdle}")
    private boolean testWhileIdle;

    @Value("${spring.datasource.testOnBorrow}")
    private boolean testOnBorrow;

    @Value("${spring.datasource.testOnReturn}")
    private boolean testOnReturn;

    @Value("${spring.datasource.poolPreparedStatements}")
    private boolean poolPreparedStatements;

    @Value("${spring.datasource.maxPoolPreparedStatementPerConnectionSize}")
    private int maxPoolPreparedStatementPerConnectionSize;

    @Value("${spring.datasource.filters}")
    private String filters;

    @Value("{spring.datasource.connectionProperties}")
    private String connectionProperties;

    @Bean     //声明其为Bean实例
    @Primary  //在同样的DataSource中，首先使用被标注的DataSource
    public DataSource dataSource(){
        DruidDataSource datasource = new DruidDataSource();

        datasource.setUrl(this.dbUrl);
        datasource.setUsername(username);
        datasource.setPassword(password);
        datasource.setDriverClassName(driverClassName);

        //configuration
        datasource.setInitialSize(initialSize);
        datasource.setMinIdle(minIdle);
        datasource.setMaxActive(maxActive);
        datasource.setMaxWait(maxWait);
        datasource.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);
        datasource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        datasource.setValidationQuery(validationQuery);
        datasource.setTestWhileIdle(testWhileIdle);
        datasource.setTestOnBorrow(testOnBorrow);
        datasource.setTestOnReturn(testOnReturn);
        datasource.setPoolPreparedStatements(poolPreparedStatements);
        datasource.setMaxPoolPreparedStatementPerConnectionSize(maxPoolPreparedStatementPerConnectionSize);
        try {
            datasource.setFilters(filters);
        } catch (SQLException e) {
            logger.error("druid configuration initialization filter", e);
        }
        datasource.setConnectionProperties(connectionProperties);

        return datasource;
    }
}

DruidDBConfig类被@Configuration标注，用作配置信息；

DataSource对象被@Bean声明，为Spring容器所管理，

@Primary表示这里定义的DataSource将覆盖其他来源的DataSource。

5.实体对象

public class LearnResouce {
    private Long id;
    private String author;
    private String title;
    private String  url;
    
    ---get---set--方法
  }

6.Controller层

@Controller
@RequestMapping("/learn")
public class LearnController {

    private Logger logger = LoggerFactory.getLogger(LearnController.class);

    @Autowired
    LearnService learnService;
    
    //添加
    @RequestMapping("/add")
    public void addLearn(HttpServletRequest request, HttpServletResponse response){
        LearnResouce learnResouce = new LearnResouce();

        learnResouce.setAuthor("aslan");
        learnResouce.setTitle("test title");
        learnResouce.setUrl("www.baidu.com");
        learnService.add(learnResouce);
    }

    @GetMapping("/query/{id}")
    public void queryLearnResource(@PathVariable Long id){

        LearnResouce learnResouce =  learnService.queryLearnResouceById(id);
        if (learnResouce == null){
            System.out.println("not find ");
        }else {
            System.out.println(learnResouce.getAuthor());
            logger.debug(learnResouce.getAuthor());
            logger.info("in here");
            logger.info(learnResouce.getAuthor());
        }
    }

    @GetMapping("/update/{id}")
    public void  update(@PathVariable Long id){
        LearnResouce learnResouce = learnService.queryLearnResouceById(id);
        learnResouce.setUrl("www.google.com");
        learnService.update(learnResouce);
        System.out.println("update over!");
    }

    @GetMapping("/delete/{idstring}")
    public void deleteIds(@PathVariable String idstring){

        String[] ids = idstring.split(",");
        learnService.deleteByIds(ids);
        System.out.println("over");
    }
}

7.Service层

public interface LearnService {

    int add(LearnResouce learnResouce);

    LearnResouce queryLearnResouceById(Long id);

    int deleteByIds(String[] ids);

    int update(LearnResouce learnResouce);
    
    public List<LearnResouce> queryLearnResouceList(Map<String, Object> params);

}

8.Service 实现类

@Service
public class LearnServiceImpl implements LearnService {

    @Autowired
    LearnMapper learnMapper;

    @Override
    public int add(LearnResouce learnResouce) {
        return this.learnMapper.add(learnResouce);
    }

    @Override
    public LearnResouce queryLearnResouceById(Long id) {
        return this.learnMapper.queryLearnResourceById(id);
    }

    @Override
    public int deleteByIds(String[] ids) {
        return this.learnMapper.deleteByIds(ids);
    }

    @Override
    public int update(LearnResouce learnResouce) {
        return this.learnMapper.update(learnResouce);
    }
    
    @Override
    public List<LearnResouce> queryLearnResouceList(Map<String, Object> params) {
        return this.learnMapper.queryLearnResouceList(params);
    }
}

9.Mybatis集成

9.1 方式1，注解方式

package com.example.demo.dao;

import com.example.demo.domain.LearnResouce;
import org.apache.ibatis.annotations.*;
import org.springframework.stereotype.Component;

/**
 * Created by Administrator on 2018/1/3 0003.
 */
@Component
@Mapper
public interface LearnMapper {

    @Insert("insert into learn_resource(author,title,url) values(#{author},#{title},#{url})")
    int add(LearnResouce learnResouce);

    @Select("select * from learn_resource where id = #{id}")
    LearnResouce queryLearnResourceById(@Param("id") Long id);

    @Update("update learn_resource set author=#{author},title=#{title},url=#{url} where id = #{id}")
    int update(LearnResouce learnResouce);

    @DeleteProvider(type = LearnSqlBuilder.class,method = "deleteByids")
    int deleteByIds(@Param("ids") String[] ids);

     @SelectProvider(type = LearnSqlBuilder.class, method = "queryLearnResouceByParams")
    List<LearnResouce> queryLearnResouceList(Map<String, Object> params);



    class LearnSqlBuilder {

        public String queryLearnResouceByParams(final Map<String, Object> params) {
            StringBuffer sql =new StringBuffer();
            sql.append("select * from learn_resource where 1=1");
            return sql.toString();
        }

        public String deleteByids(@Param("ids") final String[] ids){
            StringBuilder sql = new StringBuilder();
            sql.append("DELETE FROM learn_resource WHERE id in(");
            for (int i = 0 ; i < ids.length; i++){
                if (i == ids.length - 1){
                    sql.append(ids[i]);
                }else {
                    sql.append(ids[i]).append(",");
                }
            }
            sql.append(")");
            return sql.toString();
        }
    }

}

9.2 XML配置方式

暂无

10.分页插件

在pom.xml中添加依赖

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.1.0</version>
</dependency>

然后你只需在查询list之前使用PageHelper.startPage(int pageNum, int pageSize)方法即可。pageNum是第几页，pageSize是每页多少条。

@Override
    public List<LearnResouce> queryLearnResouceList(Map<String, Object> params) {
        PageHelper.startPage(Integer.parseInt(params.get("page").toString()), Integer.parseInt(params.get("rows").toString()));
        return this.learnMapper.queryLearnResouceList(params);
    }

Controller中的用法:

@GetMapping("/qlist/{page}/{rows}")
    public void qlist(@PathVariable Integer page,@PathVariable Integer rows){

        Map<String,Object> params = new HashMap<>();
        params.put("page",page);
        params.put("rows",rows);

        List<LearnResouce> list =  learnService.queryLearnResouceList(params);

        for (LearnResouce learn : list) {
            System.out.println(learn.getTitle());
        }
    }

11.总结

到此为止，Spring Boot与Mybatis的初步整合就完成了

12. Mybatis 注解@Select 和 @SelectProvider 的区别

@Select

同@select功能类似的还有@insert,@delete,@update，对应于数据库语句的CRUD。使用@select很方便，不用写配置文件

@SelectProvider

优点，可以实现动态SQL语句。