<?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>org.springframework</groupId><artifactId>gs-relational-data-access</artifactId><version>0.1.0</version><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.5.8.RELEASE</version></parent><properties><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-jdbc</artifactId></dependency><dependency><groupId>com.h2database</groupId><artifactId>h2</artifactId></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

package hello;public class Customer {private long id;private String firstName, lastName;public Customer(long id, String firstName, String lastName) {this.id = id;this.firstName = firstName;this.lastName = lastName;}@Overridepublic String toString() {return String.format("Customer[id=%d, firstName='%s', lastName='%s']",id, firstName, lastName);}public long getId() {return id;}public void setId(long id) {this.id = id;}public String getFirstName() {return firstName;}public void setFirstName(String firstName) {this.firstName = firstName;}public String getLastName() {return lastName;}public void setLastName(String lastName) {this.lastName = lastName;}}

package hello;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.jdbc.core.JdbcTemplate;import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;@SpringBootApplication
public class Application implements CommandLineRunner {private static final Logger log = LoggerFactory.getLogger(Application.class);public static void main(String args[]) {SpringApplication.run(Application.class, args);}@AutowiredJdbcTemplate jdbcTemplate;@Overridepublic void run(String... strings) throws Exception {log.info("Creating tables");jdbcTemplate.execute("DROP TABLE customers IF EXISTS");jdbcTemplate.execute("CREATE TABLE customers(" +"id SERIAL, first_name VARCHAR(255), last_name VARCHAR(255))");// Split up the array of whole names into an array of first/last namesList<Object[]> splitUpNames = Arrays.asList("John Woo", "Jeff Dean", "Josh Bloch", "Josh Long").stream().map(name -> name.split(" ")).collect(Collectors.toList());// Use a Java 8 stream to print out each tuple of the listsplitUpNames.forEach(name -> log.info(String.format("Inserting customer record for %s %s", name[0], name[1])));// Uses JdbcTemplate's batchUpdate operation to bulk load datajdbcTemplate.batchUpdate("INSERT INTO customers(first_name, last_name) VALUES (?,?)", splitUpNames);log.info("Querying for customer records where first_name = 'Josh':");jdbcTemplate.query("SELECT id, first_name, last_name FROM customers WHERE first_name = ?", new Object[] { "Josh" },(rs, rowNum) -> new Customer(rs.getLong("id"), rs.getString("first_name"), rs.getString("last_name"))).forEach(customer -> log.info(customer.toString()));}
}

该main()方法使用Spring Boot的SpringApplication.run()方法来启动应用程序。您是否注意到没有一行XML？也没有web.xml文件。此Web应用程序是100％纯Java，您无需处理配置任何管道或基础结构。

Spring Boot支持H2，一种内存中的关系数据库引擎，并自动创建连接。因为我们使用的是spring-jdbc，Spring Boot会自动创建一个JdbcTemplate。该@Autowired JdbcTemplate字段自动加载它并使其可用。

这个Application类实现了Spring Boot CommandLineRunner，这意味着它将run()在加载应用程序上下文后执行该方法。

首先，使用JdbcTemplate’s `execute方法安装一些DDL 。

其次，您获取字符串列表并使用Java 8流，将它们拆分为Java数组中的firstname / lastname对。

然后使用JdbcTemplate’s `batchUpdate方法在新创建的表中安装一些记录。方法调用的第一个参数是查询字符串，最后一个参数（Objects 的数组）包含要替换为“？”字符的查询的变量。

补充说明:

Java 8 lambdas很好地映射到单个方法接口，如Spring的RowMapper。如果您使用的是Java 7或更早版本，则可以轻松插入匿名接口实现，并具有与lambda expresion正文所包含的相同的方法体，并且它可以毫不费力地使用Spring。