spring_(21)Spring _使用 JdbcTemplate和JdbcDaoSupport
阿新 • • 發佈：2018-12-09
JDBC Template簡介
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為了使JDBC更加易於使用，Spring在JDBC API上定義了一個抽象層，以此建立一個JDBC存取框架.
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作為SpringJDBC框架的核心，JDBC模板的設計目的是為不同型別的JDBC操作提供模板方法。每個模板都能控制整個過程，並允許覆蓋過程中的特定任務。通過這種方式，可以在儘可能保留靈活性的情況下，將資料庫存取的工作量降到最低。
使用JDBCTemplate更新資料庫
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用sql語句和引數更新資料庫：
update
public int update(String sql,Onject… args) throws DataAccessException
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批量更新資料庫：
batchUpdate
public int[] batchUpdate(String sql,List<Object[]> batchArgs)
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查詢單行：
queryForObject
public T queryForObject(String sql,ParameterizedRowMapper rm,Object… args) throws DataAccessException
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便利的BeanPropertyRowMapper 實現:
org.springframework.jdbc.core.simple
Class ParameterizedBeanPropertyRowMapper
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查詢多行:
query
public List query(String sql,ParameterizedRowMapper rm,Object… args) throws DataAccessException
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單值查詢:
queryForObject
public T queryForObject(String sql,Class requiredType,Object… args) throws DataAccessException
package com.spring.jdbc; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import org.springframework.jdbc.core.BeanPropertyRowMapper; import org.springframework.jdbc.core.JdbcTemplate; import org.springframework.jdbc.core.RowMapper; import java.util.ArrayList; import java.util.List; public class JDBCTest { private ApplicationContext ctx = null; private JdbcTemplate jdbcTemplate; { ctx = new ClassPathXmlApplicationContext("applicationContext.xml"); jdbcTemplate = (JdbcTemplate) ctx.getBean("jdbcTemplate"); } /** * 獲取單個列的值，或做統計查詢 * 使用 queryForObject(String sql,Class<Long> requiredType); */ public void testQueryForObject2(){ String sql = "SELECT count(id) FORM employees"; long count = jdbcTemplate.queryForObject(sql,Long.class); System.out.println(count); } /** * 查到實體類的集合 * 注意呼叫的不是queryForList方法 */ public void testQueryForList(){ String sql = "SELECT id,last_name lastname,email from employees where ID < ? "; RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<>(Employee.class); List<Employee> employees = jdbcTemplate.query(sql,rowMapper,5); System.out.println(employees); } /** * 從資料庫中獲取一條記錄，實際得到對應的一個物件 * 注意不是呼叫 queryForObject(String sql,Class<Employees> requiredType, Object...args)方法！ * 而需要呼叫 queryForObject(String sql,RowMapper<Emplyee> rowMapper, Object...args); * 1.其中的RowMapper 指定如何去對映結果集的行，常用的實現類為BeanPropertyMapper * 2.使用SQL中列的別名完成列名和類的屬性名的對映。例如last_name lastname * 3.不支援級聯屬性。JdbcTemplate 到底是一個JDBC的小工具，而不是ORM框架 */ public void testQueryForObject(){ String sql = "SELECT id,last_name lastname,email,dept_id \"department.id\" from employees where ID = ? "; RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<>(Employee.class); Employee employee = jdbcTemplate.queryForObject(sql,rowMapper,1); System.out.println(employee); } /** * 執行批量更新：批量的INSERT, UPDATE, DELETE * 最後一個引數是Object[] 的List 型別：因為修改一條記錄需要一個Object的陣列，那麼多條不就需要多個Object的陣列嗎 */ public void testBatchUpdate(){ String sql = "INSERT INTO employees(last_name,email,dept_id) values(?,?,?)"; List<Object[]> batchArgs = new ArrayList<>(); batchArgs.add(new Object[]{"AA","[email protected]",1}); batchArgs.add(new Object[]{"BB","[email protected]",2}); batchArgs.add(new Object[]{"CC","[email protected]",3}); batchArgs.add(new Object[]{"DD","[email protected]",3}); batchArgs.add(new Object[]{"EE","[email protected]",2}); jdbcTemplate.batchUpdate(sql,batchArgs); } public void testUpdate(){ String sql = "UPDATE employees SET last_name = ? WHERE id = ?"; jdbcTemplate.update(sql,"Jack",2); }
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簡化JDBC模板查詢
例子程式
基本結構
db.properties
jdbc.user=root
jdbc.password=****
jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.jdbcUrl=jdbc:mysql:///spring4
jdbc.initPoolSize=5
jdbc.maxPoolSize=50
applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<context:component-scan base-package="com.spring.jdbc"></context:component-scan>
<!-- 匯入資原始檔 -->
<context:property-placeholder location="classpath:db.properties"/>
<!-- 配置C3P0資料來源 -->
<bean id="dataSource"
class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="user" value="${jdbc.user}"></property>
<property name="password" value="${jdbc.password}"></property>
<property name="jdbcUrl" value="${jdbc.jdbcUrl}"></property>
<property name="driverClass" value="${jdbc.driverClass}"></property>
<property name="initialPoolSize" value="${jdbc.initPoolSize}"></property>
<property name="maxPoolSize" value="${jdbc.maxPoolSize}"></property>
</bean>
<!--配置Spring的JdbcTemplate-->
<bean id="jdbcTemplate"
class="org.springframework.jdbc.core.JdbcTemplate">
<property name="dataSource" ref="dataSource"></property>
</bean>
</beans>
Department.java
package com.spring.jdbc;
public class Department {
private Integer id;
private String name;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "Department{" +
"id=" + id +
", name='" + name + '\'' +
'}';
}
}
DepartmentDao.java
package com.spring.jdbc;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.support.JdbcDaoSupport;
import org.springframework.stereotype.Repository;
import javax.sql.DataSource;
/**
* 不推薦使用JdbcDaoSupport,而直接使用JdbcTemplate作為Dao類的成員變數
*/
@Repository
public class DepartmentDao extends JdbcDaoSupport {
@Autowired
public void setDataSource2(DataSource dataSource){
setDataSource(dataSource);
}
public Department get(Integer id){
String sql = "SELECT id, dept_name name FROM departments WHERE id = ?";
RowMapper<Department> rowMapper = new BeanPropertyRowMapper<>(Department.class);
return getJdbcTemplate().queryForObject(sql,rowMapper,id);
}
}
Employee.java
package com.spring.jdbc;
public class Employee {
private Integer id;
private String lastname;
private String email;
private Department department;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getLastname() {
return lastname;
}
public void setLastname(String last_name) {
this.lastname = last_name;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
@Override
public String toString() {
return "Employee{" +
"id=" + id +
", lastname='" + lastname + '\'' +
", email='" + email + '\'' +
", department=" + department +
'}';
}
}
EmployeeDao.java
package com.spring.jdbc;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Repository;
@Repository
public class EmployeeDao {
@Autowired
private JdbcTemplate jdbcTemplate;
public Employee get(Integer id){
String sql = "SELECT id,last_name lastname,email,dept_id \"department.id\" from employees where ID = ? ";
RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<>(Employee.class);
Employee employee = jdbcTemplate.queryForObject(sql,rowMapper,id);
return employee;
}
}
JDBCTest.java
package com.spring.jdbc;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import java.util.ArrayList;
import java.util.List;
public class JDBCTest {
private ApplicationContext ctx = null;
private JdbcTemplate jdbcTemplate;
private EmployeeDao employeeDao;
private DepartmentDao departmentDao;
{
ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
jdbcTemplate = (JdbcTemplate) ctx.getBean("jdbcTemplate");
employeeDao = ctx.getBean(EmployeeDao.class);
departmentDao = ctx.getBean(DepartmentDao.class);
}
public void testDepartmentDao(){
System.out.println(departmentDao.get(1));
}
public void testEmployeeDao(){
System.out.println(employeeDao.get(1));
}
/**
* 獲取單個列的值，或做統計查詢
* 使用 queryForObject(String sql,Class<Long> requiredType);
*/
public void testQueryForObject2(){
String sql = "SELECT count(id) FORM employees";
long count = jdbcTemplate.queryForObject(sql,Long.class);
System.out.println(count);
}
/**
* 查到實體類的集合
* 注意呼叫的不是queryForList方法
*/
public void testQueryForList(){
String sql = "SELECT id,last_name lastname,email from employees where ID < ? ";
RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<>(Employee.class);
List<Employee> employees = jdbcTemplate.query(sql,rowMapper,5);
System.out.println(employees);
}
/**
* 從資料庫中獲取一條記錄，實際得到對應的一個物件
* 注意不是呼叫 queryForObject(String sql,Class<Employees> requiredType, Object...args)方法！
* 而需要呼叫 queryForObject(String sql,RowMapper<Emplyee> rowMapper, Object...args);
* 1.其中的RowMapper 指定如何去對映結果集的行，常用的實現類為BeanPropertyMapper
* 2.使用SQL中列的別名完成列名和類的屬性名的對映。例如last_name lastname
* 3.不支援級聯屬性。JdbcTemplate 到底是一個JDBC的小工具，而不是ORM框架
*/
public void testQueryForObject(){
String sql = "SELECT id,last_name lastname,email,dept_id \"department.id\" from employees where ID = ? ";
RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<>(Employee.class);
Employee employee = jdbcTemplate.queryForObject(sql,rowMapper,1);
System.out.println(employee);
}
/**
* 執行批量更新：批量的INSERT, UPDATE, DELETE
* 最後一個引數是Object[] 的List 型別：因為修改一條記錄需要一個Object的陣列，那麼多條不就需要多個Object的陣列嗎
*/
public void testBatchUpdate(){
String sql = "INSERT INTO employees(last_name,email,dept_id) values(?,?,?)";
List<Object[]> batchArgs = new ArrayList<>();
batchArgs.add(new Object[]{"AA","[email protected]",1});
batchArgs.add(new Object[]{"BB","[email protected]",2});
batchArgs.add(new Object[]{"CC","[email protected]",3});
batchArgs.add(new Object[]{"DD","[email protected]",3});
batchArgs.add(new Object[]{"EE","[email protected]",2});
jdbcTemplate.batchUpdate(sql,batchArgs);
}
public void testUpdate(){
String sql = "UPDATE employees SET last_name = ? WHERE id = ?";
jdbcTemplate.update(sql,"Jack",2);
}
}
Main.java
package com.spring.jdbc;
public class Main {
public static void main(String[] args){
JDBCTest a = new JDBCTest();
a.testDepartmentDao();
}
}
執行結果
