About JdbcTemplate
Spring in the operation of the database jdbc did a deep package, using the spring injection feature, you can register the DataSource into JdbcTemplate.
JdbcTemplate located 
in. Its fully qualified name org.springframework.jdbc.core.JdbcTemplate. To use JdbcTemlate need a 
package that contains a bit Affairs and exception control
JdbcTemplate method provides the following five categories:
-
execute method: it can be used to execute any SQL statement, typically used to execute DDL statements;
-
update method and batchUpdate method: update methods for performing add, modify and delete statements; batchUpdate methods for performing batch related statements;
-
query methods and queryForXXX method: to perform a query related statements;
-
Method call: for executing stored procedures, functions related statements.
The following cases were analyzed
In the src attribute below to create a new configuration file
1 jdbc.user=root 2 jdbc.password=123456 3 jdbc.driverClass=com.mysql.jdbc.Driver 4 jdbc.jdbcUrl=jdbc\:mysql\:///test
We usually configuration information into a single database file, so also in order to facilitate later maintenance
Spring configuration profiles applicationContext.xml
1 <context:property-placeholder location="classpath:db.properties"/>
2 <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
3 <property name="user" value="${jdbc.user}"></property>
4 <property name="password" value="${jdbc.password}"></property>
5 <property name="driverClass" value="${jdbc.driverClass}"></property>
6 <property name="jdbcUrl" value="${jdbc.jdbcUrl}"></property>
7 </bean>
8
9 <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
10 <property name="dataSource" ref="dataSource"></property>
11 </bean>
The first line of code: db.properties to read the data file.
Second line: to configure a data source, where the data from the implementation class property of a class of C3P0. Wherein the value of the attribute is derived from db.properties
Ninth line of code: Configure a JdbcTemplate example, data source and inject a dataSource
Test code
1, update () method
a, by inserting data update
1 //启动IoC容器
2 ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");
3 //获取IoC容器中JdbcTemplate实例
4 JdbcTemplate jdbcTemplate=(JdbcTemplate) ctx.getBean("jdbcTemplate");
5 String sql="insert into user (name,deptid) values (?,?)";
6 int count= jdbcTemplate.update(sql, new Object[]{"caoyc",3});
7 System.out.println(count);
Here update method, the second parameter may be a variable parameter. Can be seen in the database, the data to be inserted correctly
b, modify the data update
1 String sql="update user set name=?,deptid=? where id=?";
2 jdbcTemplate.update(sql,new Object[]{"zhh",5,51});
c, delete data update
1 String sql="delete from user where id=?"; 2 jdbcTemplate.update(sql,51);
2, batchUpdate () bulk insert, update and delete methods
a, bulk insert
1 String sql="insert into user (name,deptid) values (?,?)";
2
3 List<Object[]> batchArgs=new ArrayList<Object[]>();
4 batchArgs.add(new Object[]{"caoyc",6});
5 batchArgs.add(new Object[]{"zhh",8});
6 batchArgs.add(new Object[]{"cjx",8});
7
8 jdbcTemplate.batchUpdate(sql, batchArgs);
The second parameter is a method batchUpdate elements Object [] List of the collection array type
3, to read data from the data entity object
First set a User entity class
1 package com.proc;
2
3 public class User {
4 private Integer id;
5 private String name;
6 private Integer deptid;
7 public Integer getId() {
8 return id;
9 }
10 public void setId(Integer id) {
11 this.id = id;
12 }
13 public String getName() {
14 return name;
15 }
16 public void setName(String name) {
17 this.name = name;
18 }
19 public Integer getDeptid() {
20 return deptid;
21 }
22 public void setDeptid(Integer deptid) {
23 this.deptid = deptid;
24 }
25
26 public String toString() {
27 return "User [id=" + id + ", name=" + name + ", deptid=" + deptid + "]";
28 }
29 }
a, reading a single object
1 String sql="select id,name,deptid from user where id=?"; 2 3 RowMapper<User> rowMapper=new BeanPropertyRowMapper<User>(User.class); 4 User user= jdbcTemplate.queryForObject(sql, rowMapper,52); 5 System.out.println(user);
Output:
User [id=52, name=caoyc, deptid=6]
[Note]: 1, BeanProperytRowMapper requirements sql query data out of the column and entity attributes required correspondence. If not specify the property name and data in sql statements need to re-use as an alias
2, the object can not be obtained using JdbcTemplate associated objects
b, reading the plurality of objects
1 String sql="select id,name,deptid from user";
2
3 RowMapper<User> rowMapper=new BeanPropertyRowMapper<User>(User.class);
4 List<User> users= jdbcTemplate.query(sql, rowMapper);
5 for (User user : users) {
6 System.out.println(user);
7 }
Output
...
User [id=49, name=姓名49, deptid=5]
User [id=50, name=姓名50, deptid=8]
User [id=52, name=caoyc, deptid=6]
User [id=53, name=zhh, deptid=8]
User [id=54, name=cjx, deptid=8]
---
c, obtaining a record or a column count, avg, sum and other unique function return value
1 String sql="select count(*) from user"; 2 3 int count= jdbcTemplate.queryForObject(sql, Integer.class); 4 System.out.println(count);
In the actual development of how you can use
UserDao.java
1 package com.proc;
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 UserDao {
11
12 @Autowired
13 private JdbcTemplate jdbcTemplate;
14
15 public User get(int id){
16 String sql="select id,name,deptid from user where id=?";
17 RowMapper<User> rowMapper=new BeanPropertyRowMapper<User>(User.class);
18 return jdbcTemplate.queryForObject(sql, rowMapper,id);
19 }
20 }
xml configuration:
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:aop="http://www.springframework.org/schema/aop"
5 xmlns:context="http://www.springframework.org/schema/context"
6 xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
7 http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
8 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd">
9
10 <context:component-scan base-package="com.proc"></context:component-scan>
11 <context:property-placeholder location="classpath:db.properties"/>
12 <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
13 <property name="user" value="${jdbc.user}"></property>
14 <property name="password" value="${jdbc.password}"></property>
15 <property name="driverClass" value="${jdbc.driverClass}"></property>
16 <property name="jdbcUrl" value="${jdbc.jdbcUrl}"></property>
17 </bean>
18
19 <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
20 <property name="dataSource" ref="dataSource"></property>
21 </bean>
22 </beans>
Code Testing
1 UserDao userDao=(UserDao) ctx.getBean("userDao");
2 System.out.println(userDao.get(53));
original: