SpringBoot數據庫訪問
關系型數據庫訪問（RDBMS）
采用JdbcTemplate、MyBatis、JPA、Hibernate等技術。
一、JdbcTemplate工具
1.在pom.xml添加boot-starter-jdbc定義<dependencies> 數據庫驅動
<dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId><version>2.0.1.RELEASE</version></dependency>
<dependency> <groupId>com.oracle</groupId> <artifactId>ojdbc6</artifactId> <version>11.2.0.3</version> </dependency> </dependencies>
2.在application.properties添加鏈接參數定義
spring.datasource.username=SCOTT
spring.datasource.password=TIGER
spring.datasource.url=jdbc:oracle:thin:@localhost:1521:XE
spring.datasource.driverClassName=oracle.jdbc.OracleDriver3.根據DEPT表編寫Dept實體類
public class Dept implements Serializable{
private Integer deptno;
private String dname;
private String loc;
//set和get省略
}
4.定義DeptDao接口
public interface DeptDao {
public List<Dept> findAll();
}
5.定義JdbcDeptDao實現類
@Repository("deptDao")
public class JdbcDeptDao implements DeptDao {
@Autowired
private JdbcTemplate jdbcTemplate;
public List<Dept> findAll() {
String sql = "select * from DEPT";
//BeanPropertyRowMapper功能同名加載。查詢結果集列名和實體類屬性名一致
RowMapper<Dept> rowMapper = new BeanPropertyRowMapper<Dept>(Dept.class);
List<Dept> list = jdbcTemplate.query(sql, rowMapper);
return list;
}
}
6.定義主啟動類，開啟自動配置和掃描等功能
@SpringBootApplication
public class MyBootApplication {
}
7.測試程序
public static void main(String[] args) {
ApplicationContext ac =
SpringApplication.run(MyBootApplication.class);
DeptDao deptDao = ac.getBean("deptDao",DeptDao.class);
List<Dept> list = deptDao.findAll();
for(Dept dept:list){
System.out.println(dept.getDeptno()
+" "+dept.getDname()+" "+dept.getLoc());
}
}
二、MyBatis工具
-
在pom.xml添加boot-starter-jdbc、mybatis-boot定義
<parent>
<-- 設置boot版本--> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.1.RELEASE</version> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency>
<!--數據庫訪問基於jdbc --> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency> <dependency>
<!-- 數據庫驅動包 --> <groupId>com.oracle</groupId> <artifactId>ojdbc6</artifactId> <version>11.2.0.3</version> </dependency> <!-- mybatis、mybatis-spring、autocofigurer --> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.3.0</version> </dependency> </dependencies>
2.在application.properties添加數據庫連接參數定義
spring.datasource.username=SCOTT
spring.datasource.password=TIGER
spring.datasource.url=jdbc:oracle:thin:@localhost:1521:XE
spring.datasource.driverClassName=oracle.jdbc.OracleDriver3.根據DEPT表定義Dept實體類
同上4.定義Mapper映射器DeptDao接口、利用注解定義SQL
public interface DeptDao {
@Select("select * from DEPT")
public List<Dept> selectAll();
@Select("select * form DEPT where DEPTNO=#{no}")
public Dept selectById(int id);
@Insert("insert into DEPT(DEPTNO,DNAME,LOC) values (#{deptno},#{dname},#{loc})")
public void save(Dept dept);
}
5.定義主啟動類，添加MapperScan標記
@SpringBootApplication
@MapperScan(basePackages={"cn.xdl.dao"})
public class MyBootApplication {
}
6.測試程序
public static void main(String[] args) {
ApplicationContext ac =
SpringApplication.run(MyBootApplication.class, args);
DeptDao deptDao = ac.getBean("deptDao",DeptDao.class);
List<Dept> list = deptDao.selectAll();
for(Dept dept:list){
System.out.println(dept.getDeptno()+" "+dept.getDname());
}
}7.追加pageHelper分頁處理
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper-spring-boot-starter</artifactId>
<version>1.2.3</version>
</dependency>
然后在調用查詢方法前，執行下PageHelper.startPage()方法即可
PageHelper.startPage(2, 3);
List<Dept> list = deptDao.selectAll();Mybatis使用注意問題：
-
SQL參數使用#{}和${}的區別
- 采用#{}格式，預編譯SQL執行機制，SQL發送時采用?
- ${}采用Statement執行機制，參數值拼到SQL中
- SQL字段值位置使用#{}，字段名或表名位置使用${}
-
異常："無效列類型:1111"
參數#{}遇到null值情況，會提示上述異常。在可能為null參數位置，使用#{}時，需要指定jdbcType屬性，例如#{xx,jdbcType=XXX}
三、Hibernate工具（略）
四、JPA工具
1.在pom.xml追加boot-jdbc、boot-data-jpa包定義 、數據庫驅動
<parent>
<!-- 設置boot版本控制 -->
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.1.RELEASE</version>
</parent>
<properties>
<!-- 設置字符集utf-8 jre版本1.8-->
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<!-- jpa基於jdbc -->
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<!-- 數據庫驅動 -->
<groupId>com.oracle</groupId>
<artifactId>ojdbc6</artifactId>
<version>11.2.0.3</version>
</dependency>
<dependency>
<!-- jpa -->
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
</dependencies>
2.在application.properties文件追加數據庫連接參數定義
spring.datasource.username=SCOTT
spring.datasource.password=TIGER
spring.datasource.url=jdbc:oracle:thin:@localhost:1521:XE
spring.datasource.driverClassName=oracle.jdbc.OracleDriver
3.根據DEPT表編寫Dept實體類，並追加映射注解標記（可用jpa逆向生成工程）
@Entity
@Table(name="DEPT")
public class Dept implements Serializable{
@Id
@Column(name="DEPTNO")
private Integer deptno;
@Column(name="DNAME")
private String dname;
@Column(name="LOC")
private String loc;
//省略set和get方法
}
4.定義DeptDao接口，可以繼承JpaRepository
public interface DeptDao extends JpaRepository<Dept, Integer>{ //Dept 為eitity類型 Integer為主鍵類型
}
Repository：頂級接口，無任何操作
CrudRepository：繼承了Repository，增加了增刪改查操作方法
PagingAndSortingRepository：繼承CrudRepository，增加了分頁和排序操作
JpaRepository：繼承了PagingAndSortingRepository，增加批處理操作
5.測試程序
public static void main(String[] args) {
ApplicationContext ac =
SpringApplication.run(MyBootApplication.class, args);
DeptDao deptDao = ac.getBean("deptDao",DeptDao.class);
List<Dept> list = deptDao.findAll();
for(Dept dept:list){
System.out.println(dept.getDeptno()+" "+dept.getDname());
}
}