jdbc

首先配置maven包

org.springframework.boot

spring-boot-starter-jdbc

org.mybatis.spring.boot

mybatis-spring-boot-starter

2.1.0

注意pom.xml中配置结点

src/main/java

**/*.xml

false

src/main/resources

static/*.*

templates/*.*

**/*.xml

**/*.yml

**/*.properties

false

针对不同的数据库，引入对应的包：SqlServer-sqljdbc4，DB2-db2jcc4，以SqlServer为例

在com.cmb.**.mapper.sqlserver目录下新建接口文件

@Repository

public interface SqlserverMapper {

List function_name();

}

同时在resources/mapperconfig/sqlserver目录下新建xml文件

select ... from ...

数据源类和工厂类配置如下

@MapperScan(basePackages = "com.cmb.**.mapper.sqlserver", sqlSessionFactoryRef = "sqlserverSqlSessionFactoryBean")

@SpringBootConfiguration

public class SqlserverDataSourceConfiguration {

private static String jdbcUrl, jdbcUser, jdbcPassword, maximumPoolSize;

static { ... }

@Bean(name = "sqlserverDataSource")

public DataSource createDataSource() {

return DataSourceConfig.getHikariDataSourceInstance(jdbcUrl, jdbcUser, jdbcPassword, maximumPoolSize);

}

}

@Configuration

public class SqlserverSessionFactoryConfiguration {

@Autowired

@Qualifier(value = "sqlserverDataSource")

private DataSource sqlserverDataSource;

private String mapperXmlConfigPath = "/mapperconfig/sqlserver/**.xml", mapperPackagePath = "com.cmb.**.mapper.sqlserver";

@Bean(name = "sqlserverSqlSessionFactoryBean")

public SqlSessionFactoryBean createSqlSessionFactory() throws Exception {

return DataSourceConfig.getSqlSessionFactoryBeanInstance(mapperXmlConfigPath, mapperPackagePath, sqlserverDataSource);

}

}

如需事务操作，上述配置类中分别新增

@Bean(name = "sqlserverTransactionManager")

@Primary

public DataSourceTransactionManager createTransactionManager(@Qualifier("sqlserverDataSource") DataSource dataSource) {

return new DataSourceTransactionManager(dataSource);

}

@Bean(name = "sqlserverSqlSessionTemplate")

@Primary

public SqlSessionTemplate createSqlSessionTemplate(@Qualifier("sqlserverSqlSessionFactoryBean") SqlSessionFactory sqlSessionFactory) {

return new SqlSessionTemplate(sqlSessionFactory);

}

public static HikariDataSource getHikariDataSourceInstance(String jdbcUrl, String jdbcUser, String jdbcPassword, String maximumPoolSize) {

HikariDataSource source = new HikariDataSource();

source.setJdbcUrl(jdbcUrl);

source.setUsername(jdbcUser);

source.setPassword(jdbcPassword);

source.setMaximumPoolSize(Integer.valueOf(maximumPoolSize));

return source;

}

public static SqlSessionFactoryBean getSqlSessionFactoryBeanInstance(String mapperXmlConfigPath, String mapperPackagePath, DataSource ds) throws Exception {

SqlSessionFactoryBean bean = new SqlSessionFactoryBean();

PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();

String xmlConfigPath = PathMatchingResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX + mapperXmlConfigPath;

bean.setMapperLocations(resolver.getResources(xmlConfigPath));//设置mapper对应的XML文件的路径

bean.setDataSource(ds);//设置数据源

bean.setTypeAliasesPackage(mapperPackagePath);//设置mapper接口所在的包

bean.getObject().getConfiguration().setMapUnderscoreToCamelCase(true);

return bean;

}

附上配置文件

- name: afvapp_hikari_sql_jdbcUrl

value: "jdbc:sqlserver://55.14.18.118:1433;DatabaseName=Business"

- name: afvapp_hikari_sql_username

value: "sa"

- name: afvapp_hikari_sql_password

value: "cmbzephyr"

- name: afvapp_hikari_sql_maximumPoolSize

value: "25"

若是mysql库，记得追加?Unicode=true&characterEncoding=UTF-8，否则部分数据库会中文乱码

mybatis

★₯₰☆ SpringBoot中设置返回类型map，值为空时字段不显示

查了几种方法，均无效...

application.properties中配置 mybatis.configuration.call-setters-on-nulls=true

最后通过配置SqlSessionFactoryBean实现：高铁直达

org.apache.ibatis.session.Configuration config = new org.apache.ibatis.session.Configuration();

config.setCallSettersOnNulls(true);

bean.setConfiguration(config);

对于字段送默认值的问题，同时设置config.setJdbcTypeForNull(JdbcType.NULL);

★₯₰☆ #{}和${}备忘

对sql语句预编译前，会动态解析为一个BoundSql对象，#{}被解析为一个参数占位符?，${}直接被纯碎的string替换

考虑到性能问题和防sql注入：

能使用#{}的地方就用#{}

表名作为变量时，必须用${}

传入数值时，select top等也建议${}

#{}：创建预处理语句属性从而设置安全的值，常用作查询条件的值、指定一个确切的数据类型

${}：不会修改或转义字符串，直接在SQL语句中插入一个不改变的字符串，常用于拼凑sql的实体部分

详情参见：动态sql中的#与$

★₯₰☆ 动态sql

先来一个mybatis的案例热热身：mybatis遇坑填坑

数据库字段binary8的问题

//sqlserver

sql语句：where UniqueID=${uniqueID}，代码入参送值："0x22CE15DD10F7F70F"

预编译后：where UniqueID=0x22CE15DD10F7F70F

//db2

sql语句：where UniqueID=x${uniqueID}，代码入参送值："'2213C85A0004376B'"

预编译后：where VerifyID=x'2213C85A0004376B'

定义resultMap通常需类型转换，须引入mybatis-typehandlers-jsr310，并配置属性typeHandler，注意要以全局限定绝对路径。通常无需指定，mybatis会自动探测。建议同时引入jackson-datatype-jsr310。

实体类字段Java.sql.Date、java.sql.Timestamp、java.util.Date映射数据库的date、timestamp、datetime字段

对mybatis返回的时间戳作格式化处理，可在ObjectMapper反序列化时统一处理，与具体数据库解耦

@Component

public class JacksonConfig {

@Bean

@Primary

public ObjectMapper objectMapper() {

ObjectMapper mapper = new ObjectMapper();

mapper.registerModule(new JSR310Module());

mapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"));

return mapper;

}

}

问题：sqlserver列类型datetime，实体类字段为java.time.LocalDateTime，mybatis映射报错

1、java.util.Date可以，或直接用String

2、typeHandler="org.apache.ibatis.type.LocalDateTimeTypeHandler"无效

3、mybatis-3.5.0直接可以，无需typeHandler

第2种：mybatis-spring-boot-starter-2.1默认引入的mybatis-3.5.2抛异常且捕获不到，请求返回结果报错：3.5.x>=1均不行：mybatis 3.5.X的特性与bug

"status": 500,

"error": "Internal Server Error",

"message": "Method com/microsoft/sqlserver/jdbc/SQLServerResultSet.getObject(Ljava/lang/String;Ljava/lang/Class;)Ljava/lang/Object; is abstract",

此时需自定义TypeHandler，并typeHandler="com.cmb.afvapp.common.handler.MyLocalDateTimeTypeHandler"

public class MyLocalDateTimeTypeHandler extends LocalDateTimeTypeHandler {

@Override

public LocalDateTime getResult(ResultSet rs, String columnName) throws SQLException {

Object object = rs.getObject(columnName);

System.out.println(columnName + ": " + object);

if(object instanceof java.sql.Timestamp){//强转，将sql的时间转为LocalDateTime

return LocalDateTime.ofInstant(((Timestamp)object).toInstant(), ZoneOffset.ofHours(0));//按需转化

}

return super.getResult(rs, columnName);

}

}

关于typehandler的映射问题，参见：mybatis-typeHandlers

若遇到type-aliases-package、type-handlers-package等不起作用，导致类加载失败问题，解决：

sqlSessionFactoryBean.setVfs(SpringBootVFS.class);

★₯₰☆ 全局日期格式化问题

LocalDateTime默认ISO时间：'2011-11-03T10:15:30'，提供几种格式化方法：好文参见

可以采用注解方式

@JsonSerialize(using = LocalDateTimeSerializer.class)

@JsonDeserialize(using = LocalDateTimeDeserializer.class)

@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")

若序列化后有小时差，需json序列化时指定时区为GMT+8。

或在配置类里定义两个Bean，可完成全局日期格式化处理，同时兼顾Date和LocalDateTime并存

@Configuration

public class LocalDateTimeSerializerConfig {

@org.springframework.beans.factory.annotation.Value("${spring.jackson.date-format:yyyy-MM-dd HH:mm:ss}")

private String pattern_format;

@Bean

public LocalDateTimeSerializer localDateTimeDeserializer() {

return new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(pattern_format));

}

@Bean

public Jackson2ObjectMapperBuilderCustomizer jackson2ObjectMapperBuilderCustomizer() {

return builder -> builder.serializerByType(LocalDateTime.class, localDateTimeDeserializer());

}

}

或者采用

@Bean(name = "mapperObject")

public ObjectMapper getObjectMapper() {

ObjectMapper om = new ObjectMapper();

JavaTimeModule javaTimeModule = new JavaTimeModule();

javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));

javaTimeModule.addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));

javaTimeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern("HH:mm:ss")));

om.registerModule(javaTimeModule);

return om;

}

springboot以注解引入mybatis

注解：去XML化

★₯₰☆ 快速生成映射结果集方法

public static String getResultsStr(Class origin) {

StringBuilder stringBuilder = new StringBuilder();

stringBuilder.append("@Results({\n");

for (Field field : origin.getDeclaredFields()) {

String property = field.getName();

//映射关系：对象属性(驼峰)->数据库字段(下划线)

String column = new PropertyNamingStrategy.SnakeCaseStrategy().translate(field.getName()).toUpperCase();

stringBuilder.append(String.format("@Result(property = \"%s\", column = \"%s\"),\n", property, column));

}

stringBuilder.append("})");

return stringBuilder.toString();

}