点击阅读原文
介绍在SpringBoot中集成mybatis和druid以及自定义TypeHandler
创建数据库表
SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- 创建student表
-- ----------------------------
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '姓名',
`parent_phone` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '家长电话号码逗号分隔',
`city` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '居住城市json格式存储{\"province\":\"广东省\",\"city\":\"深圳市\",\"district\":\"南山区\"}',
`net_name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '网名逗号分隔',
PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 3 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
-- ----------------------------
-- 插入学生信息
-- ----------------------------
INSERT INTO `student` VALUES (1, '小英', '13222222222,13333333333,15777777777', '{\"province\":\"广东省\",\"city\":\"深圳市\",\"district\":\"南山区\"}', '会飞的鱼,小小雪,茉莉香果果');
INSERT INTO `student` VALUES (2, '小明', '13222222222,13333333333,15777777777', '{\"province\":\"广东省\",\"city\":\"深圳市\",\"district\":\"南山区\"}', '会飞的鱼2,小小雪2,茉莉香果果2');
SET FOREIGN_KEY_CHECKS = 1;
xml方式
在pom.xml添加mybatis,druid,mysql驱动配置
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.2</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.10</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
在application.yml中配置mybatis
# 使用druid数据源
spring:
datasource:
druid:
driver-class-name: com.mysql.jdbc.Driver
filters: stat
maxActive: 20
initialSize: 1
maxWait: 60000
minIdle: 1
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQuery: select 'x'
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: true
maxOpenPreparedStatements: 20
db-type: com.alibaba.druid.pool.DruidDataSource
thymeleaf:
cache: false
mybatis:
type-handlers-package: com.tiankonglanlande.cn.springboot.mybatis.typehandler
mapperLocations: classpath:mapper/**.xml
typeAliasesPackage: com.tiankonglanlande.cn.springboot.mybatis.bean
# 开启自动映射
configuration:
map-underscore-to-camel-case: true
lazy-loading-enabled: false
auto-mapping-behavior: full
数据库信息相关配置
spring.datasource.url = jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding-utf8&allowMultiQueries=true
spring.datasource.username= root
spring.datasource.password= root
启动文件相关配置
@SpringBootApplication
@MapperScan("com.tiankonglanlande.cn.springboot.mybatis.dao")
public class MybatisDruidApplication {
public static void main(String[] args) {
SpringApplication.run(MybatisDruidApplication.class, args);
}
}
说明:@MapperScan扫描注入指定的包名下Mapper接口注入容器
编写数据库表对应的Student实体类
/**
* 学生实体类
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class Student implements Serializable {
private String id;
private String name;
private String parentPhone;
private String city;
private String netName;
}
编写StudentDao Mapper接口
public interface StudentDao {
/**
* 查询所有的学生信息
* @return
*/
List<Student> selectStudentList();
}
编写StudentDao.xml Mapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.tiankonglanlande.cn.springboot.mybatis.dao.StudentDao" >
<select id="selectStudentList" resultType="Student">
SELECT * FROM student
</select>
</mapper>
编写StudentService
@Service
public class StudentService {
@Autowired
private StudentDao studentDao;
public List<Student> selectStudentList(){
return studentDao.selectStudentList();
}
}
编写StudentController
@RestController
public class StudentController {
@Autowired
private StudentService studentService;
@RequestMapping("/students")
public List<Student> selectStudentList(){
List<Student> students = studentService.selectStudentList();
return students;
}
}
在浏览器访问:http://localhost:8080/students得到结果
[
{
"id": "1",
"name": "小英",
"parentPhone": "13222222222,13333333333,15777777777",
"city": "{\"province\":\"广东省\",\"city\":\"深圳市\",\"district\":\"南山区\"}",
"netName": "会飞的鱼,小小雪,茉莉香果果"
},
{
"id": "2",
"name": "小明",
"parentPhone": "13222222222,13333333333,15777777777",
"city": "{\"province\":\"广东省\",\"city\":\"深圳市\",\"district\":\"南山区\"}",
"netName": "会飞的鱼2,小小雪2,茉莉香果果2"
}
]
使用纯注解方式
StudentDao添加方法selectStudentListByAnnotation
@Select("SELECT * FROM student")
List<Student> selectStudentListByAnnotation();
StudentService添加方法selectStudentListByAnnotation
public List<Student> selectStudentListByAnnotation(){
return studentDao.selectStudentListByAnnotation();
}
StudentController调用
@RequestMapping("/students2")
public List<Student> selectStudentListByAnnotation(){
List<Student> students = studentService.selectStudentListByAnnotation();
return students;
}
在浏览器访问:http://localhost:8080/students得到与xml访问相同的结果
[
{
"id": "1",
"name": "小英",
"parentPhone": "13222222222,13333333333,15777777777",
"city": "{\"province\":\"广东省\",\"city\":\"深圳市\",\"district\":\"南山区\"}",
"netName": "会飞的鱼,小小雪,茉莉香果果"
},
{
"id": "2",
"name": "小明",
"parentPhone": "13222222222,13333333333,15777777777",
"city": "{\"province\":\"广东省\",\"city\":\"深圳市\",\"district\":\"南山区\"}",
"netName": "会飞的鱼2,小小雪2,茉莉香果果2"
}
]
解决上面返回json数据的问题
从上面json的数据可以看出parentPhone和netName是多条数据通过逗号拼接成的一个字段,还有city是json字符串组成的文本
这样前端拿到数据可能还需要进行处理成集合再遍历出来;city是一个json字符串文本,要想转化成json还需要一番周折,
那么作为认真负责的后台开发的我们可以使用Mybatis的TypeHandler将parentPhone和netName转化成集合,将city转化成标准的json方便前端绑定数据。
处理逗号拼接的字符串为集合
首先我们看之前在application.yml中配置mybatis的一段代码
mybatis:
type-handlers-package: com.tiankonglanlande.cn.springboot.mybatis.typehandler
说明:这一段代码会扫描com.tiankonglanlande.cn.springboot.mybatis.typehandler包下面的TypeHandler注入到spring容器
修改一下Student实体属性为集合
/**
* 学生实体类
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class Student implements Serializable {
private String id;
private String name;
private String[] parentPhone;//此处修改为数组对象
private String city;
private String[] netName;//此处修改为数组对象
}
自定义typehandler
/**
* 字符串转int数组
*/
public class StringArrayTypeHandler extends BaseTypeHandler<String[]>{
private static final String delimiter=",";
@Override
public void setNonNullParameter(PreparedStatement preparedStatement, int i, String[] strings, JdbcType jdbcType) throws SQLException {
List<String> list=new ArrayList<>();
for (String item:strings){
list.add(String.valueOf(item));
}
preparedStatement.setString(i,String.join(delimiter,list));
}
@Override
public String[] getNullableResult(ResultSet resultSet, String s) throws SQLException {
String str=resultSet.getString(s);
if (resultSet.wasNull()){
return null;
}
return str.split(delimiter);
}
@Override
public String[] getNullableResult(ResultSet resultSet, int i) throws SQLException {
String str= resultSet.getString(i);
if (resultSet.wasNull()){
return null;
}
return str.split(delimiter);
}
@Override
public String[] getNullableResult(CallableStatement callableStatement, int i) throws SQLException {
String str= callableStatement.getString(i);
if (callableStatement.wasNull()){
return null;
}
return str.split(delimiter);
}
}
说明:setNonNullParameter方法会在保存数据库之前执行,我们在此方法将保存的数组使用逗号拼接还原数据库存储方式
其他方法是从数据库取出数据时mybatis将把数据映射成实体类执行,此时我们将逗号拼接的字符串转换为数组形式
验收逗号拼接字符串转换为数组成果
浏览器输入http://localhost:8080/students可以看到原先逗号拼接的字符串已经转换为集合对象
[
{
"id": "1",
"name": "小英",
"parentPhone": [
"13222222222",
"13333333333",
"15777777777"
],
"city": "{\"province\":\"广东省\",\"city\":\"深圳市\",\"district\":\"南山区\"}",
"netName": [
"会飞的鱼",
"小小雪",
"茉莉香果果"
]
},
{
"id": "2",
"name": "小明",
"parentPhone": [
"13222222222",
"13333333333",
"15777777777"
],
"city": "{\"province\":\"广东省\",\"city\":\"深圳市\",\"district\":\"南山区\"}",
"netName": [
"会飞的鱼2",
"小小雪2",
"茉莉香果果2"
]
}
]
解决最后一个问题:将city转化成标准的json方便前端绑定数据
定义CityBean
@Data
@AllArgsConstructor
@NoArgsConstructor
public class CityBean implements Serializable{
private String province;
private String city;
private String district;
}
修改Student将CityBean作为他的属性
/**
* 学生实体类
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class Student implements Serializable {
private String id;
private String name;
private String[] parentPhone;//此处修改为数组对象
private CityBean city;//修改为CityBean类
private String[] netName;//此处修改为数组对象
}
定义JsonCityBeanTypeHandler
public class JsonCityBeanTypeHandler extends BaseTypeHandler<CityBean> {
public ObjectMapper objectMapper=new ObjectMapper();
@Override
public void setNonNullParameter(PreparedStatement ps, int i, CityBean t, JdbcType jdbcType) throws SQLException {
try {
ps.setString(i,objectMapper.writeValueAsString(t));
} catch (JsonProcessingException e) {
e.printStackTrace();
}
}
@Override
public CityBean getNullableResult(ResultSet resultSet, String s) throws SQLException {
String str=resultSet.getString(s);
if (resultSet.wasNull()){
return null;
}
return getBean(str);
}
@Override
public CityBean getNullableResult(ResultSet resultSet, int i) throws SQLException {
return null;
}
@Override
public CityBean getNullableResult(CallableStatement callableStatement, int i) throws SQLException {
return null;
}
private CityBean getBean(String str){
if (StringUtils.isEmpty(str))
return null;
try {
return objectMapper.readValue(str,CityBean.class);
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}
如果是存储的是json集合字符串可以这样
修改student表添加一个visited字段(数据随便插入的不要当真哈!)
alter table student add visited varchar(256) COMMENT '去过的地方jsonarray存储[{"province":"广东省","city":"深圳市","district":"南山区"}]';
UPDATE student SET visited='[{"province":"四川省","city":"深圳市","district":"南山区"}]' WHERE id=1;
UPDATE student SET visited='[{"province":"四川省","city":"深圳市","district":"南山区"},{"province":"广东省","city":"成都市","district":"青羊区"}]' WHERE id=2;
定义VisitedBean
/**
* 去过的地方
*/
public class VisitedBean extends CityBean{
}
定义JsonListTypeHandler
/**
* json集合字符串转集合
* @param <T>
*/
public class JsonListTypeHandler<T> extends BaseTypeHandler<List<T>> {
public static ObjectMapper objectMapper = new ObjectMapper();
@Override
public void setNonNullParameter(PreparedStatement ps, int i, List<T> parameter, JdbcType jdbcType) throws SQLException {
try {
ps.setString(i, objectMapper.writeValueAsString(parameter));
} catch (JsonProcessingException e) {
e.printStackTrace();
}
}
@Override
public List<T> getNullableResult(ResultSet rs, String columnName) throws SQLException {
String str = rs.getString(columnName);
if (rs.wasNull())
return null;
return getBeanList(str);
}
@Override
public List<T> getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
String str = rs.getString(columnIndex);
if (rs.wasNull())
return null;
return getBeanList(str);
}
@Override
public List<T> getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
String str = cs.getString(columnIndex);
if (cs.wasNull())
return null;
return getBeanList(str);
}
private List<T> getBeanList(String str) {
if (StringUtils.isEmpty(str)){
return null;
}
try {
List<T> beanList =objectMapper.readValue(str,new TypeReference<List<T>>(){});
return beanList;
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
}
测试结果,浏览器输入:http://localhost:8080/students
结果如下:
[
{
"id": "1",
"name": "小英",
"parentPhone": [
"13222222222",
"13333333333",
"15777777777"
],
"city": {
"province": "广东省",
"city": "深圳市",
"district": "南山区"
},
"visited": [
{
"province": "四川省",
"city": "深圳市",
"district": "南山区"
}
],
"netName": [
"会飞的鱼",
"小小雪",
"茉莉香果果"
]
},
{
"id": "2",
"name": "小明",
"parentPhone": [
"13222222222",
"13333333333",
"15777777777"
],
"city": {
"province": "广东省",
"city": "深圳市",
"district": "南山区"
},
"visited": [
{
"province": "四川省",
"city": "深圳市",
"district": "南山区"
},
{
"province": "广东省",
"city": "成都市",
"district": "青羊区"
}
],
"netName": [
"会飞的鱼2",
"小小雪2",
"茉莉香果果2"
]
}
]
作者:天空蓝蓝的,版权所有,欢迎保留原文链接进行转载:)