JdbcTemplate简介
- 为了使JDBC更加易于使用，Spring在JDBC API上定义了一个抽象层，以此建立一个JDBC存取框架
- 作为Spring JDBC框架的核心，JDBC模板的设计目的是为不同类型的JDBC操作提供模板方法，每个模板方法都能控制整个过程，并允许覆盖过程中的特定任务。通过这种方式，可以在尽可能保留灵活性的情况下，将数据库存取的工作量降到最低。
代码示例：
首先是数据库的配置。数据库中包含employee和department两张表。
1 jdbc.user=scott 2 jdbc.password=tiger 3 jdbc.driverClass=oracle.jdbc.driver.OracleDriver 4 jdbc.jdbcUrl=jdbc:oracle:thin:@localhost:1521:orcl 5 6 jdbc.initialPoolSize=5 7 jdbc.maxPoolSize=10
然后是spring的配置文件
1 <?xml version="1.0" encoding="UTF-8"?>
2 <beans xmlns="http://www.springframework.org/schema/beans"
3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4 xmlns:context="http://www.springframework.org/schema/context"
5 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
6 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd">
7
8 <context:component-scan base-package="com.yl.spring.jdbc"></context:component-scan>
9
10 <!-- 导入属性文件 -->
11 <context:property-placeholder location="classpath:db.properties"/>
12 <!-- 配置c3p0数据源 -->
13 <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
14 <property name="user" value="${jdbc.user}"></property>
15 <property name="password" value="${jdbc.password}"></property>
16 <property name="driverClass" value="${jdbc.driverClass}"></property>
17 <property name="jdbcUrl" value="${jdbc.jdbcUrl}"></property>
18
19 <property name="initialPoolSize" value="${jdbc.initialPoolSize}"></property>
20 <property name="maxPoolSize" value="${jdbc.maxPoolSize}"></property>
21 </bean>
22
23 <!-- 配置Spring的JdbcTemplate -->
24 <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
25 <property name="dataSource" ref="dataSource"></property>
26 </bean>
27 </beans>
然后是两个实体类:Employee和Department
1 package com.yl.spring.jdbc;
2
3 public class Employee {
4 private Integer id;
5 private String lastName;
6 private String email;
7
8 private Department department;
9
10 public Integer getId() {
11 return id;
12 }
13
14 public void setId(Integer id) {
15 this.id = id;
16 }
17
18 public String getLastName() {
19 return lastName;
20 }
21
22 public void setLastName(String lastName) {
23 this.lastName = lastName;
24 }
25
26 public String getEmail() {
27 return email;
28 }
29
30 public void setEmail(String email) {
31 this.email = email;
32 }
33
34 public Department getDepartment() {
35 return department;
36 }
37
38 public void setDepartment(Department department) {
39 this.department = department;
40 }
41
42 @Override
43 public String toString() {
44 return "Employee [id=" + id + ", lastName=" + lastName + ", email="
45 + email + ", department=" + department + "]";
46 }
47
48
49 }
1 package com.yl.spring.jdbc;
2
3 public class Department {
4 private Integer id;
5 private String name;
6 public Integer getId() {
7 return id;
8 }
9 public void setId(Integer id) {
10 this.id = id;
11 }
12 public String getName() {
13 return name;
14 }
15 public void setName(String name) {
16 this.name = name;
17 }
18 @Override
19 public String toString() {
20 return "Department [id=" + id + ", name=" + name + "]";
21 }
22
23
24 }
然后是测试类
1 package com.yl.spring.jdbc;
2
3
4 import java.sql.SQLException;
5 import java.util.ArrayList;
6 import java.util.List;
7
8 import javax.sql.DataSource;
9
10 import org.junit.Test;
11 import org.springframework.context.ApplicationContext;
12 import org.springframework.context.support.ClassPathXmlApplicationContext;
13 import org.springframework.jdbc.core.BeanPropertyRowMapper;
14 import org.springframework.jdbc.core.JdbcTemplate;
15 import org.springframework.jdbc.core.RowMapper;
16
17 public class JDBCTest {
18
19 private ApplicationContext ctx = null;
20 private JdbcTemplate jdbcTemplate;
21 private EmployeeDao employeeDao;
22
23 {
24 ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
25 jdbcTemplate = (JdbcTemplate)ctx.getBean("jdbcTemplate");
26 employeeDao = ctx.getBean(EmployeeDao.class);
27 }
28
29 @Test
30 public void testEmployeeDao() {
31 System.out.println(employeeDao.get(1));
32 }
33
34 /**
35 * 获取单个列的值，或做统计查询
36 */
37 @Test
38 public void testQueryForObject2() {
39 String sql = "SELECT count(id) FROM employee";
40 long count = jdbcTemplate.queryForObject(sql, Long.class);
41 System.out.println(count);
42 }
43
44 /**
45 * 查到实体类的集合
46 */
47 @Test
48 public void testQueryForList() {
49 String sql = "SELECT id, last_name, email FROM employee WHERE id > ?";
50 RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<Employee>(Employee.class);
51 List<Employee> employees = jdbcTemplate.query(sql, rowMapper, 5);
52 System.out.println(employees);
53 }
54
55 /**
56 * 从数据库中获取一条记录，实际得到对应的一个对象
57 * 1.RowMapper指定如何映射结果集的行，常用的实现类为BeanPropertyRowMapper
58 * 2.使用SQL中列的别名完成列名和类的属性名的映射。例如last_name和lastName
59 * 3.不支持级联属性。JdbcTemplate到底是一个JDBC工具，不是ORM框架。
60 */
61 @Test
62 public void TestForQueryObject() {
63 String sql = "SELECT id, last_name, email FROM employee WHERE id = ?";
64 RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<Employee>(Employee.class);
65
66 Employee employee = jdbcTemplate.queryForObject(sql, rowMapper, 1);
67 System.out.println(employee);
68 }
69
70 /**
71 * 批量执行更新：批量的INSERT, UPDATE, DELETE
72 * 最后一个参数是Object[]的list类型：因为修改一条记录需要一个Object的数组，那么多条就是需要多个Object的数组
73 */
74 @Test
75 public void testBatchUpdate() {
76 String sql = "INSERT INTO employee(id, last_name, email, dept_id) VALUES(?, ?, ?, ?)";
77 List<Object[]> batchArgs = new ArrayList<Object[]>();
78 batchArgs.add(new Object[]{6, "AA", "[email protected]", 1});
79 batchArgs.add(new Object[]{7, "BB", "[email protected]", 2});
80 batchArgs.add(new Object[]{8, "CC", "[email protected]", 3});
81 batchArgs.add(new Object[]{9, "DD", "[email protected]", 3});
82 batchArgs.add(new Object[]{10, "EE", "[email protected]", 2});
83 jdbcTemplate.batchUpdate(sql, batchArgs);
84 }
85
86 /**
87 * 执行INSERT, UPDATE, DELETE
88 */
89 @Test
90 public void testUpdate() {
91 String sql = "UPDATE employee SET last_name=? WHERE id=?";
92 jdbcTemplate.update(sql, "Jack", 5);
93 }
94
95 @Test
96 public void test() throws SQLException {
97 DataSource dataSource = (DataSource)ctx.getBean("dataSource");
98 System.out.println(dataSource.getConnection());
99 }
100
101 }
如果在项目中使用JdbcTemplate，那么可以参考下面的写法来写对应的dao：
1 package com.yl.spring.jdbc;
2
3 import org.springframework.beans.factory.annotation.Autowired;
4 import org.springframework.jdbc.core.BeanPropertyRowMapper;
5 import org.springframework.jdbc.core.JdbcTemplate;
6 import org.springframework.jdbc.core.RowMapper;
7 import org.springframework.stereotype.Repository;
8
9 @Repository
10 public class EmployeeDao {
11
12 @Autowired
13 private JdbcTemplate jdbcTemplate;
14
15 public Employee get(Integer id) {
16 String sql = "SELECT id, last_name, email FROM employee WHERE id = ?";
17 RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<Employee>(Employee.class);
18
19 Employee employee = jdbcTemplate.queryForObject(sql, rowMapper, id);
20
21 return employee;
22 }
23 }
时间： 2024-08-09 04:16:37