前言

前面几章介绍了一些基础，但都是静态的，还不足以构建一个动态的应用。本篇开始就要介绍数据交互了，为了演示效果更加好，博主花了大把时间整合了一个后端模板框架，基于Bootstrap3的ACE模板，并实现了一个基本的增删改查分页功能。让我们一起动手，学技术的同时，顺便把我们的项目完善起来，这样跟着博主学到最后，你就有了一个属于自己的Spring Boot项目啦。

正文

本文介绍在Spring Boot基础下配置数据源和通过JdbcTemplate编写数据访问的示例。

添加依赖

这里需要添加spring-boot-starter-jdbc依赖跟mysql依赖

<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
 <groupId>mysql</groupId>
 <artifactId>mysql-connector-java</artifactId>
</dependency>

数据源配置

在src/main/resources/application.properties中配置数据源信息。

spring.datasource.url = jdbc:mysql://localhost:3306/spring?useUnicode=true&characterEncoding=utf-8
spring.datasource.username = root
spring.datasource.password = root
spring.datasource.driver-class-name = com.mysql.jdbc.Driver

自定义数据源

spring-boot-starter-jdbc 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,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>

修改Application.java

@SpringBootApplication
public class Application {
	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
	}
	@Autowired
	private Environment env;
	//destroy-method="close"的作用是当数据库连接不使用的时候,就把该连接重新放到数据池中,方便下次使用调用.
	@Bean(destroyMethod = "close")
	public DataSource dataSource() {
		DruidDataSource dataSource = new DruidDataSource();
		dataSource.setUrl(env.getProperty("spring.datasource.url"));
		dataSource.setUsername(env.getProperty("spring.datasource.username"));//用户名
		dataSource.setPassword(env.getProperty("spring.datasource.password"));//密码
		dataSource.setDriverClassName(env.getProperty("spring.datasource.driver-class-name"));
		dataSource.setInitialSize(2);//初始化时建立物理连接的个数
		dataSource.setMaxActive(20);//最大连接池数量
		dataSource.setMinIdle(0);//最小连接池数量
		dataSource.setMaxWait(60000);//获取连接时最大等待时间，单位毫秒。
		dataSource.setValidationQuery("SELECT 1");//用来检测连接是否有效的sql
		dataSource.setTestOnBorrow(false);//申请连接时执行validationQuery检测连接是否有效
		dataSource.setTestWhileIdle(true);//建议配置为true，不影响性能，并且保证安全性。
		dataSource.setPoolPreparedStatements(false);//是否缓存preparedStatement，也就是PSCache
		return dataSource;
	}
}

ok这样就算自己配置了一个DataSource，Spring Boot会智能地选择我们自己配置的这个DataSource实例。

脚本初始化

CREATE DATABASE /*!32312 IF NOT EXISTS*/`spring` /*!40100 DEFAULT CHARACTER SET utf8 */;
USE `spring`;
DROP TABLE IF EXISTS `learn_resource`;
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=1029 DEFAULT CHARSET=utf8;
insert into `learn_resource`(`id`,`author`,`title`,`url`) values (999,'官方SpriongBoot例子','官方SpriongBoot例子','https://github.com/spring-projects/spring-boot/tree/master/spring-boot-samples');
insert into `learn_resource`(`id`,`author`,`title`,`url`) values (1000,'龙果学院','Spring Boot 教程系列学习','http://www.roncoo.com/article/detail/124661');
insert into `learn_resource`(`id`,`author`,`title`,`url`) values (1001,'嘟嘟MD独立博客','Spring Boot干货系列','http://tengj.top/');
insert into `learn_resource`(`id`,`author`,`title`,`url`) values (1002,'后端编程嘟','Spring Boot视频教程','http://www.toutiao.com/m1559096720023553/');

开始使用JdbcTemplate

Spring的JdbcTemplate是自动配置的，你可以直接使用@Autowired来注入到你自己的bean中来使用。这里博主做了一套基本的增删改查操作。

实体对象

public class LearnResouce {
 private Long id;
 private String author;
 private String title;
 private String url;
	// SET和GET方法
}

Controller层

@Controller
@RequestMapping("/learn")
public class LearnController {
 @Autowired
 private LearnService learnService;
 private Logger logger = LoggerFactory.getLogger(this.getClass());
 @RequestMapping("")
 public String learn(){
 return "learn-resource";
 }
 @RequestMapping(value = "/queryLeanList",method = RequestMethod.POST,produces="application/json;charset=UTF-8")
 @ResponseBody
 public void queryLearnList(HttpServletRequest request ,HttpServletResponse response){
 String page = request.getParameter("page"); // 取得当前页数,注意这是jqgrid自身的参数
 String rows = request.getParameter("rows"); // 取得每页显示行数，,注意这是jqgrid自身的参数
 String author = request.getParameter("author");
 String title = request.getParameter("title");
 Map<String,Object> params = new HashMap<String,Object>();
 params.put("page", page);
 params.put("rows", rows);
 params.put("author", author);
 params.put("title", title);
 Page pageObj =learnService.queryLearnResouceList(params);
 List<Map<String, Object>> learnList=pageObj.getResultList();
 JSONObject jo=new JSONObject();
 jo.put("rows", learnList);
 jo.put("total", pageObj.getTotalPages());
 jo.put("records", pageObj.getTotalRows());
 ServletUtil.createSuccessResponse(200, jo, response);
 }
 /**
 * 新添教程
 * @param request
 * @param response
 */
 @RequestMapping(value = "/add",method = RequestMethod.POST)
 public void addLearn(HttpServletRequest request , HttpServletResponse response){
 JSONObject result=new JSONObject();
 String author = request.getParameter("author");
 String title = request.getParameter("title");
 String url = request.getParameter("url");
 if(StringUtil.isNull(author)){
 result.put("message","作者不能为空!");
 result.put("flag",false);
 ServletUtil.createSuccessResponse(200, result, response);
 return;
 }
 if(StringUtil.isNull(title)){
 result.put("message","教程名称不能为空!");
 result.put("flag",false);
 ServletUtil.createSuccessResponse(200, result, response);
 return;
 }
 if(StringUtil.isNull(url)){
 result.put("message","地址不能为空!");
 result.put("flag",false);
 ServletUtil.createSuccessResponse(200, result, response);
 return;
 }
 LearnResouce learnResouce = new LearnResouce();
 learnResouce.setAuthor(author);
 learnResouce.setTitle(title);
 learnResouce.setUrl(url);
 int index=learnService.add(learnResouce);
 System.out.println("结果="+index);
 if(index>0){
 result.put("message","教程信息添加成功!");
 result.put("flag",true);
 }else{
 result.put("message","教程信息添加失败!");
 result.put("flag",false);
 }
 ServletUtil.createSuccessResponse(200, result, response);
 }
 /**
 * 修改教程
 * @param request
 * @param response
 */
 @RequestMapping(value = "/update",method = RequestMethod.POST)
 public void updateLearn(HttpServletRequest request , HttpServletResponse response){
 JSONObject result=new JSONObject();
 String id = request.getParameter("id");
 LearnResouce learnResouce=learnService.queryLearnResouceById(Long.valueOf(id));
 String author = request.getParameter("author");
 String title = request.getParameter("title");
 String url = request.getParameter("url");
 if(StringUtil.isNull(author)){
 result.put("message","作者不能为空!");
 result.put("flag",false);
 ServletUtil.createSuccessResponse(200, result, response);
 return;
 }
 if(StringUtil.isNull(title)){
 result.put("message","教程名称不能为空!");
 result.put("flag",false);
 ServletUtil.createSuccessResponse(200, result, response);
 return;
 }
 if(StringUtil.isNull(url)){
 result.put("message","地址不能为空!");
 result.put("flag",false);
 ServletUtil.createSuccessResponse(200, result, response);
 return;
 }
 learnResouce.setAuthor(author);
 learnResouce.setTitle(title);
 learnResouce.setUrl(url);
 int index=learnService.update(learnResouce);
 System.out.println("修改结果="+index);
 if(index>0){
 result.put("message","教程信息修改成功!");
 result.put("flag",true);
 }else{
 result.put("message","教程信息修改失败!");
 result.put("flag",false);
 }
 ServletUtil.createSuccessResponse(200, result, response);
 }
 /**
 * 删除教程
 * @param request
 * @param response
 */
 @RequestMapping(value="/delete",method = RequestMethod.POST)
 @ResponseBody
 public void deleteUser(HttpServletRequest request ,HttpServletResponse response){
 String ids = request.getParameter("ids");
 System.out.println("ids==="+ids);
 JSONObject result = new JSONObject();
 //删除操作
 int index = learnService.deleteByIds(ids);
 if(index>0){
 result.put("message","教程信息删除成功!");
 result.put("flag",true);
 }else{
 result.put("message","教程信息删除失败!");
 result.put("flag",false);
 }
 ServletUtil.createSuccessResponse(200, result, response);
 }
}

Service层

public interface LearnService {
 int add(LearnResouce learnResouce);
 int update(LearnResouce learnResouce);
 int deleteByIds(String ids);
 LearnResouce queryLearnResouceById(Long learnResouce);
 Page queryLearnResouceList(Map<String,Object> params);
}

实现类

@Service
public class LearnServiceImpl implements LearnService {
 @Autowired
 LearnDao learnDao;
 @Override
 public int add(LearnResouce learnResouce) {
 return this.learnDao.add(learnResouce);
 }
 @Override
 public int update(LearnResouce learnResouce) {
 return this.learnDao.update(learnResouce);
 }
 @Override
 public int deleteByIds(String ids) {
 return this.learnDao.deleteByIds(ids);
 }
 @Override
 public LearnResouce queryLearnResouceById(Long id) {
 return this.learnDao.queryLearnResouceById(id);
 }
 @Override
 public Page queryLearnResouceList(Map<String,Object> params) {
 return this.learnDao.queryLearnResouceList(params);
 }
}

Dao层

public interface LearnDao {
 int add(LearnResouce learnResouce);
 int update(LearnResouce learnResouce);
 int deleteByIds(String ids);
 LearnResouce queryLearnResouceById(Long id);
 Page queryLearnResouceList(Map<String,Object> params);
}

实现类,这里注入我们需要的JdbcTemplate

@Repository
public class LearnDaoImpl implements LearnDao{
 @Autowired
 private JdbcTemplate jdbcTemplate;
 @Override
 public int add(LearnResouce learnResouce) {
 return jdbcTemplate.update("insert into learn_resource(author, title,url) values(?, ?, ?)",learnResouce.getAuthor(),learnResouce.getTitle(),learnResouce.getUrl());
 }
 @Override
 public int update(LearnResouce learnResouce) {
 return jdbcTemplate.update("update learn_resource set author=?,title=?,url=? where id = ?",new Object[]{learnResouce.getAuthor(),learnResouce.getTitle(),learnResouce.getUrl(),learnResouce.getId()});
 }
 @Override
 public int deleteByIds(String ids){
 return jdbcTemplate.update("delete from learn_resource where id in("+ids+")");
 }
 @Override
 public LearnResouce queryLearnResouceById(Long id) {
 List<LearnResouce> list = jdbcTemplate.query("select * from learn_resource where id = ?", new Object[]{id}, new BeanPropertyRowMapper(LearnResouce.class));
 if(null != list && list.size()>0){
 LearnResouce learnResouce = list.get(0);
 return learnResouce;
 }else{
 return null;
 }
 }
 @Override
 public Page queryLearnResouceList(Map<String,Object> params) {
 StringBuffer sql =new StringBuffer();
 sql.append("select * from learn_resource where 1=1");
 if(!StringUtil.isNull((String)params.get("author"))){
 sql.append(" and author like '%").append((String)params.get("author")).append("%'");
 }
 if(!StringUtil.isNull((String)params.get("title"))){
 sql.append(" and title like '%").append((String)params.get("title")).append("%'");
 }
 Page page = new Page(sql.toString(), Integer.parseInt(params.get("page").toString()), Integer.parseInt(params.get("rows").toString()), jdbcTemplate);
 return page;
 }
}

上面介绍的JdbcTemplate只是最基本的几个操作，更多其他数据访问操作的使用请参考：JdbcTemplate API

到此为止，后端交互代码都写好了，这里博主整合的bootstrap模板就不展示了，各位可以自行下载本篇对应的源码跑起来看看，效果很棒咯，如下：

总结

SpringBoot下访问数据库还是很简单的，只要添加依赖，然后在application.properties中配置连接信息。下一篇博主将介绍下Spring Boot对mybatis的整合

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