引言
Java中常用的ORM框架主要是mybatis, hibernate, JPA等框架。
国内又以Mybatis用的多，基于mybatis上的增强框架，又有mybatis plus和TK mybatis等。
今天我们介绍一个新的mybatis增强框架 fluent mybatis,
那既然JDBC --> Mybatis或Mybatis Plus无疑简化了开发者的工作，而今天我们所讲的 Fluent MyBatis又起到什么作用呢？
初识Fluent MyBatis
Fluent MyBatis是一个 MyBatis 的增强工具，他只做了mybatis的语法糖封装，没有对mybatis做任何修改。
通过编译手段，提供了一系列辅助类来帮助开发简化开发、提高效率。
入门初体验
创建一个示例的数据库表
```sql
DROP TABLE IF EXISTS `your_table`;
create table `your_table`
(
id bigint auto_increment comment '主键ID' primary key,
name varchar(30) charset utf8 null comment '姓名',
age int null comment '年龄',
email varchar(50) charset utf8 null comment '邮箱',
gmt_create datetime null comment '记录创建时间',
gmt_modified datetime null comment '记录最后修改时间',
is_deleted tinyint(2) default 0 null comment '逻辑删除标识'
);
```
初始化 SpringBoot 项目
设置项目依赖
1. spring boot: 基于spring boot开发，肯定是必须的
2. lombok: 省略get, set, toString代码的神器，个人比较喜欢；你也可以手动生成get set方法
3. mysql-connector-java: 数据库驱动
4. fluent-mybatis: fluent-mybatis运行时依赖
5. fluent-mybatis-processor: fluent-mybatis编译时依赖
6. fluent-mybatis-generator: fluent-mybatis代码生成依赖
6. 测试依赖的jar包: spring-test, junit
配置数据库信息
```properties
spring.datasource.username=root
spring.datasource.password=password
spring.datasource.url=jdbc:mysql://localhost:3306/fluent_mybatis_demo?useSSL=false&useUnicode=true&characterEncoding=utf-8
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
```
创建（生成）实体类
可以手工创建Entity类，或者任何手段创建的Entity类，然后加上注解
1. 在Entity类上加上 @FluentMybatis注解
2. 在主键字段加 @TableId注解
3. 在一般字段加 @TableField注解
这里直接使用fluent mybatis提供的工具类生成代码
```java
public class AppEntityGenerator {
static final String url = "jdbc:mysql://localhost:3306/fluent_mybatis_demo?useSSL=false&useUnicode=true&characterEncoding=utf-8";
public static void main(String[] args) {
FileGenerator.build(Abc.class);
}
@Tables(
/** 数据库连接信息 **/
url = url, username = "root", password = "password",
/** Entity类parent package路径 **/
basePack = "cn.org.fluent.mybatis.springboot.demo",
/** Entity代码源目录 **/
srcDir = "spring-boot-demo/src/main/java",
/** Dao代码源目录 **/
daoDir = "spring-boot-demo/src/main/java",
/** 如果表定义记录创建，记录修改，逻辑删除字段 **/
gmtCreated = "gmt_create", gmtModified = "gmt_modified", logicDeleted = "is_deleted",
/** 需要生成文件的表 **/
tables = @Table(value = {"your_table"})
)
static class Abc {
}
}
```
这里有3个特殊字段
1. gmt_create, 记录创建时间，会设置记录插入的默认值，对应生成Entity字段上的注解 @TableField(insert="now()")
2. gmt_modified, 记录最后更新时间，会设置记录插入和更新默认值，对应生成代码Entity字段上注解 @TableField(insert="now()", update="now()")
3. is_deleted, 记录逻辑删除标识，字段类型为Boolean，且设置记录插入的默认值，对应注解 @TableField(insert="0")
执行生成代码main函数, 在工程main/src/java目录下产出 Entity, DaoIntf, DaoImpl文件；
观察YourEntity的主键 id, gmt_create, gmt_modified, is_deleted这几个字段的注解
```java
@Data
@Accessors(chain = true)
@FluentMybatis(table = "your_table")
public class YourEntity implements IEntity{
private static final long serialVersionUID = 1L;
@TableId(value = "id")
private Long id;
@TableField(value = "gmt_create", insert = "now()")
private Date gmtCreate;
@TableField(value = "gmt_modified", insert = "now()", update = "now()")
private Date gmtModified;
@TableField(value = "is_deleted", insert = "0")
private Boolean isDeleted;
@TableField(value = "age")
private Integer age;
@TableField(value = "email")
private String email;
@TableField(value = "name")
private String name;
@Override
public Serializable findPk() {
return id;
}
}
```
生成的Dao文件，引用到了YourTableBaseDao类，这个类需要根据Entity类编译生成，在重新编译前会有编译错误，所以生成代码后需要重新Rebuild下
```java
@Repository
public class YourDaoImpl extends YourBaseDao implements YourDao {
// 在这里添加你自己的业务逻辑代码
}
```
在Rebuild后，会在target目录下就会多出几个文件, 重新刷新一下工程把target/generated-sources加到源目录上即可。
启动SpringBoot测试，验证效果
这时工程已经具备fluent mybatis强大的增删改查功能了。我们创建一个测试类来验证一下，在测试类中注入 YourMapper，这里演示一个查询所有的方法，所以使用了 listEntity ，其参数是一个Query对象。
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void contextLoads() {
List<YourEntity> list = yourMapper.listEntity(yourMapper.query());
for (YourEntity entity : list) {
System.out.println(entity);
}
}
}
```
你可以手工往数据库中插入几条记录，验证一下效果。
Entity对应的Mapper提供的数据操作方法
下面我们分别介绍FluentMybatis提供的insert, select, update和delete方法，内容的介绍基本按4部分解析
1. 方法的Mapper定义（**编译生成的代码**）
2. Mapper对应的动态SQL组装SQLProvider（**编译生成的代码**）
3. 一个验证测试例子
4. 根据例子打印的SQL语句和信息输出，对照查看
FluentMybatis提供的insert方法
insert：单条插入操作
-Mapper方法
```java
public interface YourMapper extends IEntityMapper<YourEntity> {
/**
* 插入一条记录
*
* @param entity
* @return
*/
@Override
@InsertProvider(
type = YourSqlProvider.class,
method = "insert"
)
@Options(
useGeneratedKeys = true,
keyProperty = "id",
keyColumn = "id"
)
int insert(YourEntity entity);
}
```
- 动态SQL组装
```java
public class YourSqlProvider {
public String insert(YourEntity entity) {
assertNotNull("entity", entity);
MapperSql sql = new MapperSql();
sql.INSERT_INTO("your_table");
List<String> columns = new ArrayList<>();
List<String> values = new ArrayList<>();
if (entity.getId() != null) {
columns.add("id");
values.add("#{id}");
}
columns.add("gmt_create");
if (entity.getGmtCreate() != null) {
values.add("#{gmtCreate}");
} else {
values.add("now()");
}
columns.add("gmt_modified");
if (entity.getGmtModified() != null) {
values.add("#{gmtModified}");
} else {
values.add("now()");
}
columns.add("is_deleted");
if (entity.getIsDeleted() != null) {
values.add("#{isDeleted}");
} else {
values.add("0");
}
if (entity.getAge() != null) {
columns.add("age");
values.add("#{age}");
}
if (entity.getEmail() != null) {
columns.add("email");
values.add("#{email}");
}
if (entity.getName() != null) {
columns.add("name");
values.add("#{name}");
}
sql.INSERT_COLUMNS(columns);
sql.VALUES();
sql.INSERT_VALUES(values);
return sql.toString();
}
}
```
组装过程中，对对应了 @TableField(insert="默认值")的3个字段：gmt_crate, gmt_modified, is_deleted做了特殊判断。
- 编写insert test验证下
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void insert() {
// 构造一个对象
YourEntity entity = new YourEntity();
entity.setName("Fluent Mybatis");
entity.setAge(1);
entity.setEmail("darui.wu@163.com");
entity.setIsDeleted(false);
// 插入操作
int count = yourMapper.insert(entity);
System.out.println("count:" + count);
System.out.println("entity:" + entity);
}
}
```
- 执行insert测试方法, 查看控制台输出log信息
```text
DEBUG - ==> Preparing: INSERT INTO your_table(gmt_create, gmt_modified, is_deleted, age, email, name) VALUES (now(), now(), ?, ?, ?, ?)
DEBUG - ==> Parameters: false(Boolean), 1(Integer), darui.wu@163.com(String), Fluent Mybatis(String)
DEBUG - <== Updates: 1
count:1
entity:YourEntity(id=18, gmtCreate=null, gmtModified=null, isDeleted=false, age=1, email=darui.wu@163.com, name=Fluent Mybatis)
```
- 这里有几个需要注意的地方
1. Entity主键值的自增和回写
根据控制台输出，可以看到Entity的id属性已经是根据数据库自增主键值回写过的。
自增主键的设置是通过 @TableId 注解来的，其属性方法auto()默认值是true。
2. fluent mybatis根据@TableId注解生成的Mapper类上@Options注解如下：
``` java
@Options(
useGeneratedKeys = true,
keyProperty = "id",
keyColumn = "id"
)
```
3. gmt_created, gmt_modified, is_deleted 默认值插入处理
我们先看一下Entity上这3个字段的@TableField注解, 他们都定义了一个属性方法insert，设置了insert的默认值（即程序编码insert时，如果没有设置该字段，则使用默认值）
``` java
@TableField(value = "gmt_create", insert = "now()")
private Date gmtCreate;
@TableField(value = "gmt_modified", insert = "now()", update = "now()")
private Date gmtModified;
@TableField(value = "is_deleted", insert = "0")
private Boolean isDeleted;
```
在测试例子中，gmt_created和gmt_modified在初始化Entity时，没有设置任何值; is_deleted设置了值false。
在构建sql是，gmt_created, gmt_modified直接使用默认值 "now()", is_deleted使用预编译变量(?)设置(实际值false)。
```sql
INSERT INTO your_table
(gmt_create, gmt_modified, is_deleted, age, email, name)
VALUES
(now(), now(), ?, ?, ?, ?)
```
我们再看一下对应的SQLProvider的SQL构造, 我们只看着3个字段的构造
```java
public class YourSqlProvider {
public String insert(YourEntity entity) {
List<String> columns = new ArrayList<>();
List<String> values = new ArrayList<>();
// 省略 ... ...
columns.add("gmt_create");
if (entity.getGmtCreate() != null) {
values.add("#{gmtCreate}");
} else {
values.add("now()");
}
columns.add("gmt_modified");
if (entity.getGmtModified() != null) {
values.add("#{gmtModified}");
} else {
values.add("now()");
}
columns.add("is_deleted");
if (entity.getIsDeleted() != null) {
values.add("#{isDeleted}");
} else {
values.add("0");
}
if (entity.getAge() != null) {
columns.add("age");
values.add("#{age}");
}
// 省略... ...
return sql.toString();
}
}
```
我们看到，没有 insert属性的字段，只判断了是否为空; 有insert属性的字段，如果entity不为空，则把默认值赋值给sql语句。
insertBatch：批量插入
- 查看Mapper对应的SqlProvider中insertBatch动态SQL的构造
```java
public class YourSqlProvider {
public String insertBatch(Map map) {
assertNotEmpty("map", map);
MapperSql sql = new MapperSql();
List<YourEntity> entities = getParas(map, "list");
sql.INSERT_INTO("your_table");
sql.INSERT_COLUMNS(ALL_ENTITY_FIELDS);
sql.VALUES();
for (int index = 0; index < entities.size(); index++) {
if (index > 0) {
sql.APPEND(", ");
}
sql.INSERT_VALUES(
"#{list[" + index + "].id}",
entities.get(index).getGmtCreate() == null ? "now()" : "#{list[" + index + "].gmtCreate}",
entities.get(index).getGmtModified() == null ? "now()" : "#{list[" + index + "].gmtModified}",
entities.get(index).getIsDeleted() == null ? "0" : "#{list[" + index + "].isDeleted}",
"#{list[" + index + "].age}",
"#{list[" + index + "].email}",
"#{list[" + index + "].name}"
);
}
return sql.toString();
}
}
```
SQL构造语句是通过一个for循环遍历实体列表，构造出下列SQL语句, 其中对有insert默认值属性处理方式同单条insert一样, 这里就不再重复。
```sql
INSERT INTO your_table ('Entity对应的字段列表') VALUES ('实例1值'), ('实例2值')
```
- 写个测试看看具体效果
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
void insertBatch(){
List<YourEntity> entities = new ArrayList<>();
entities.add(new YourEntity().setName("Fluent Mybatis").setEmail("darui.wu@163.com"));
entities.add(new YourEntity().setName("Fluent Mybatis Demo").setEmail("darui.wu@163.com"));
entities.add(new YourEntity().setName("Test4J").setEmail("darui.wu@163.com"));
int count = yourMapper.insertBatch(entities);
System.out.println("count:" + count);
System.out.println("entity:" + entities);
}
}
```
- 执行测试，查看控制台输出
```text
DEBUG - ==> Preparing: INSERT INTO your_table(id, gmt_create, gmt_modified, is_deleted, age, email, name) VALUES (?, now(), now(), 0, ?, ?, ?) , (?, now(), now(), 0, ?, ?, ?) , (?, now(), now(), 0, ?, ?, ?)
DEBUG - ==> Parameters: null, null, darui.wu@163.com(String), Fluent Mybatis(String), null, null, darui.wu@163.com(String), Fluent Mybatis Demo(String), null, null, darui.wu@163.com(String), Test4J(String)
DEBUG - <== Updates: 3
count:3
entity:[YourEntity(id=null, gmtCreate=null, gmtModified=null, isDeleted=null, age=null, email=darui.wu@163.com, name=Fluent Mybatis), YourEntity(id=null, gmtCreate=null, gmtModified=null, isDeleted=null, age=null, email=darui.wu@163.com, name=Fluent Mybatis Demo), YourEntity(id=null, gmtCreate=null, gmtModified=null, isDeleted=null, age=null, email=darui.wu@163.com, name=Test4J)]
```
FluentMybatis提供的select查询方法
findById：根据id查找单条数据
- 系统生成的Mapper方法定义
```java
public interface YourMapper extends IEntityMapper<YourEntity> {
String ResultMap = "YourEntityResultMap";
@SelectProvider(
type = YourSqlProvider.class,
method = "findById"
)
@Results(
id = ResultMap,
value = {
@Result(column = "id", property = "id", javaType = Long.class, id = true),
@Result(column = "gmt_create", property = "gmtCreate", javaType = Date.class),
@Result(column = "gmt_modified", property = "gmtModified", javaType = Date.class),
@Result(column = "is_deleted", property = "isDeleted", javaType = Boolean.class),
@Result(column = "age", property = "age", javaType = Integer.class),
@Result(column = "email", property = "email", javaType = String.class),
@Result(column = "name", property = "name", javaType = String.class)
}
)
YourEntity findById(Serializable id);
}
```
在findById上，除了定义了提供动态SQL语句的SQLProvider类和方法外，还定义的数据映射关系 @Results。
这个ResultMap映射在单个Mapper里是通用的，其他的查询方法返回Entity对象时也会用到。
- 系统生成的动态sql构造方法
```java
public class YourSqlProvider {
public String findById(Serializable id) {
assertNotNull("id", id);
MapperSql sql = new MapperSql();
sql.SELECT("your_table", ALL_ENTITY_FIELDS);
sql.WHERE("id = #{id}");
return sql.toString();
}
}
```
这个SQL拼接比较简单
1. 根据Entity字段拼接了查询字段列表
2. 设置 id = #{id}
- 写个测试实际使用下
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void findById(){
YourEntity entity = yourMapper.findById(8L);
System.out.println(entity);
}
}
```
- 查看控制台输出log
```text
DEBUG - ==> Preparing: SELECT id, gmt_create, gmt_modified, is_deleted, age, email, name FROM your_table WHERE id = ?
DEBUG - ==> Parameters: 8(Long)
DEBUG - <== Total: 1
YourEntity(id=8, gmtCreate=null, gmtModified=null, isDeleted=false, age=1, email=darui.wu@163.com, name=Fluent Mybatis)
```
listByIds：根据id列表批量查询实例
- Mapper定义
```java
public interface YourMapper extends IEntityMapper<YourEntity> {
String ResultMap = "YourEntityResultMap";
@Override
@SelectProvider(
type = YourSqlProvider.class,
method = "listByIds"
)
@ResultMap(ResultMap)
List<YourEntity> listByIds(@Param(Param_Coll) Collection ids);
}
```
输入是一个id列表集合，返回是一个Entity列表, 数据的映射复用了findById中定义的ResultMap。
- 动态SQL提供方法
```java
public class YourSqlProvider {
public String listByIds(Map map) {
Collection ids = getParas(map, "coll");
MapperSql sql = new MapperSql();
sql.SELECT("your_table", ALL_ENTITY_FIELDS);
sql.WHERE_PK_IN("id", ids.size());
return sql.toString();
}
}
```
1. 根据Entity字段拼接了查询字段列表
2. 根据传入的id数量(size), 设置 id IN (#{coll[0]}, ..., #{coll[size - 1]})
- 写测试验证下
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void listByIds() {
List<YourEntity> entities = yourMapper.listByIds(Arrays.asList(8L, 9L));
System.out.println(entities);
}
}
```
- 查看控制台输出
```text
DEBUG - ==> Preparing: SELECT id, gmt_create, gmt_modified, is_deleted, age, email, name FROM your_table WHERE id IN (?, ?)
DEBUG - ==> Parameters: 8(Long), 9(Long)
DEBUG - <== Total: 2
[YourEntity(id=8, gmtCreate=null, gmtModified=null, isDeleted=false, age=1, email=darui.wu@163.com, name=Fluent Mybatis),
YourEntity(id=9, gmtCreate=null, gmtModified=null, isDeleted=false, age=1, email=darui.wu@163.com, name=Fluent Mybatis)]
```
findOne：根据自定义条件查询单条记录
- Mapper方法定义
```java
public interface YourMapper extends IEntityMapper<YourEntity> {
@SelectProvider(
type = YourSqlProvider.class,
method = "findOne"
)
@ResultMap(ResultMap)
YourEntity findOne(@Param(Param_EW) IQuery query);
}
```
- 动态sql组装
```java
public class YourSqlProvider {
public String findOne(Map map) {
WrapperData data = getWrapperData(map, "ew");
MapperSql sql = new MapperSql();
sql.SELECT("your_table", data, ALL_ENTITY_FIELDS);
sql.WHERE_GROUP_ORDER_BY(data);
return byPaged(DbType.MYSQL, data, sql.toString());
}
}
```
动态SQL组装做了以下几件事：
1. 根据query是否显式设置了查询字段，设置select字段列表，如果未设置，则取默认拼装Entity全字段。
2. 根据query里面的where, group by, having by和order by设置查询条件: sql.WHERE_GROUP_ORDER_BY(data)
3. 根据是否设置了分页信息和数据库类型，组装分页查询语法: byPaged(DbType.MYSQL, data, sql.toString())
- 写个测试验证下
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void findOne() {
YourEntity entity = yourMapper.findOne(new YourQuery()
.where.id().eq(4L).end()
);
}
}
```
查看控制台的输出:
```text
DEBUG - ==> Preparing: SELECT id, gmt_create, gmt_modified, is_deleted, age, email, name FROM your_table WHERE id = ?
DEBUG - ==> Parameters: 4(Long)
DEBUG - <== Total: 1
YourEntity(id=4, gmtCreate=null, gmtModified=null, isDeleted=false, age=1, email=darui.wu@163.com, name=Fluent Mybatis)
```
这种情况下，数据库中满足条件的数据有一条或0条；如果符合条件的数据大于一条，情况会怎样呢，我们再写一个测试实验一下。
- 如果findOne，符合条件数据大于2条
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void findOne2() {
YourEntity entity = yourMapper.findOne(new YourQuery()
.where.name().eq("Fluent Mybatis").end()
);
System.out.println(entity);
}
}
```
因为数据库中有多条name='Fluent Mybatis'的数据，调用这个方法会抛出异常
```text
DEBUG - ==> Preparing: SELECT id, gmt_create, gmt_modified, is_deleted, age, email, name FROM your_table WHERE name = ?
DEBUG - ==> Parameters: Fluent Mybatis(String)
DEBUG - <== Total: 14
org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions
.TooManyResultsException: Expected one result (or null) to be returned by selectOne(),
but found: 14
```
listByMap
- Mapper方法定义
```java
public interface YourMapper extends IEntityMapper<YourEntity> {
String ResultMap = "YourEntityResultMap";
@SelectProvider(
type = YourSqlProvider.class,
method = "listByMap"
)
@ResultMap(ResultMap)
List<YourEntity> listByMap(@Param(Param_CM) Map<String, Object> columnMap);
}
```
入参Map<String, Object>, 用来表示查询数据的条件。具体条件是 key = value 的AND关系。
- 动态SQL拼接
```java
public class YourSqlProvider {
public String listByMap(Map map) {
Map<String, Object> where = getParas(map, "cm");
MapperSql sql = new MapperSql();
sql.SELECT("your_table", ALL_ENTITY_FIELDS);
sql.WHERE("cm", where);
return sql.toString();
}
}
```
1. 查询Entity所有字段
2. 组装map条件, (key1 = value1) AND (key2 = value2)
- 写个测试demo验证下
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void listByMap() {
List<YourEntity> entities = yourMapper.listByMap(new HashMap<String, Object>() {
{
this.put("name", "Fluent Mybatis");
this.put("is_deleted", false);
}
});
System.out.println(entities);
}
}
```
- 查看控制台输出
```text
DEBUG - ==> Preparing: SELECT id, gmt_create, gmt_modified, is_deleted, age, email, name FROM your_table WHERE is_deleted = ? AND name = ?
DEBUG - ==> Parameters: false(Boolean), Fluent Mybatis(String)
DEBUG - <== Total: 5
[YourEntity(id=4, gmtCreate=null, gmtModified=null, isDeleted=false, age=1, email=darui.wu@163.com, name=Fluent Mybatis),
YourEntity(id=5, gmtCreate=null, gmtModified=null, isDeleted=false, age=1, email=darui.wu@163.com, name=Fluent Mybatis),
YourEntity(id=6, gmtCreate=null, gmtModified=null, isDeleted=false, age=1, email=darui.wu@163.com, name=Fluent Mybatis),
YourEntity(id=7, gmtCreate=null, gmtModified=null, isDeleted=false, age=1, email=darui.wu@163.com, name=Fluent Mybatis),
YourEntity(id=8, gmtCreate=null, gmtModified=null, isDeleted=false, age=1, email=darui.wu@163.com, name=Fluent Mybatis)]
```
listEntity：根据自定义条件查询数据，并把数据映射为对应的Entity类
- Mapper方法定义
```java
public interface YourMapper extends IEntityMapper<YourEntity> {
@SelectProvider(
type = YourSqlProvider.class,
method = "listEntity"
)
@ResultMap(ResultMap)
List<YourEntity> listEntity(@Param(Param_EW) IQuery query);
}
```
- 动态SQL组装
```java
public class YourSqlProvider {
public String listEntity(Map map) {
WrapperData data = getWrapperData(map, "ew");
MapperSql sql = new MapperSql();
sql.SELECT("your_table", data, ALL_ENTITY_FIELDS);
sql.WHERE_GROUP_ORDER_BY(data);
return byPaged(DbType.MYSQL, data, sql.toString());
}
}
```
同findOne方法, 动态SQL组装做了下面几件事:
1. 根据query是否显式设置了查询字段，设置select字段列表，如果未设置，则取默认拼装Entity全字段。
2. 根据query里面的where, group by, having by和order by设置查询条件: sql.WHERE_GROUP_ORDER_BY(data)
3. 根据是否设置了分页信息和数据库类型，组装分页查询语法: byPaged(DbType.MYSQL, data, sql.toString())
- 写个测试看下效果
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void listEntity() {
List<YourEntity> entities = yourMapper.listEntity(new YourQuery()
.select.name().age().email().end()
.where.id().lt(6L)
.and.name().like("Fluent").end()
.orderBy.id().desc().end()
);
System.out.println(entities);
}
}
```
- 查看控制台log
```text
DEBUG - ==> Preparing: SELECT name, age, email FROM your_table WHERE id < ? AND name LIKE ? ORDER BY id DESC
DEBUG - ==> Parameters: 6(Long), %Fluent%(String)
DEBUG - <== Total: 2
[YourEntity(id=null, gmtCreate=null, gmtModified=null, isDeleted=null, age=1, email=darui.wu@163.com, name=Fluent Mybatis),
YourEntity(id=null, gmtCreate=null, gmtModified=null, isDeleted=null, age=1, email=darui.wu@163.com, name=Fluent Mybatis)]
```
自定义查询定义了
1. 要查询的字段: name, age, email3个字段
2. 定义了具体条件: id < ? AND name LIKE ?
3. 定义了按id倒序排
listMaps
listMaps参数构造和listEntity一样，不同的时返回时不映射为Entity，而且映射成Map对象
- 写个测试验证下
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void listMaps() {
List<Map<String,Object>> maps = yourMapper.listMaps(new YourQuery()
.select.name().age().email().end()
.where.id().lt(6L)
.and.name().like("Fluent").end()
.orderBy.id().desc().end()
);
System.out.println(maps);
}
}
```
- 查看控制台输出信息
```text
DEBUG - ==> Preparing: SELECT name, age, email AS EMail FROM your_table WHERE id < ? AND name LIKE ? ORDER BY id DESC
DEBUG - ==> Parameters: 6(Long), %Fluent%(String)
DEBUG - <== Total: 2
[{name=Fluent Mybatis, EMail=darui.wu@163.com},
{name=Fluent Mybatis, EMail=darui.wu@163.com}]
```
listObjs
listObjs查询参数构造和listEntity、listMaps一样，但只返回查询对象的第一列，其余列被舍弃。
- 验证例子
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void listObjs() {
List<String> ids = yourMapper.listObjs(new YourQuery()
.select.name().age().email().end()
.where.id().lt(6L)
.and.name().like("Fluent").end()
.orderBy.id().desc().end()
);
System.out.println(ids);
}
}
```
- 查看控制台输出信息
```text
DEBUG - ==> Preparing: SELECT name, age, email AS EMail FROM your_table WHERE id < ? AND name LIKE ? ORDER BY id DESC
DEBUG - ==> Parameters: 6(Long), %Fluent%(String)
DEBUG - <== Total: 2
[Fluent Mybatis, Fluent Mybatis]
```
我们看到，控制台只打印出了查询字段的第一列name： [Fluent Mybatis, Fluent Mybatis]
count
count, 返回符合条件的记录数
- Mapper定义
```java
public interface YourMapper extends IEntityMapper<YourEntity> {
@SelectProvider(
type = YourSqlProvider.class,
method = "count"
)
Integer count(@Param(Param_EW) IQuery query);
}
```
- 验证示例
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void count() {
int count = yourMapper.count(new YourQuery()
.where.id().lt(1000L)
.and.name().like("Fluent").end()
.limit(0, 10)
);
System.out.println(count);
}
}
```
- 查看控制台输出信息
```text
DEBUG - ==> Preparing: SELECT COUNT(*) FROM your_table WHERE id < ? AND name LIKE ? LIMIT ?, ?
DEBUG - ==> Parameters: 1000(Long), %Fluent%(String), 0(Integer), 10(Integer)
DEBUG - <== Total: 1
5
```
countNoLimit
使用方法同count,只是SQL语句部分舍弃了limit设置（如果你设置了）
- 验证示例
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void countNoLimit() {
int count = yourMapper.countNoLimit(new YourQuery()
.where.id().lt(1000L)
.and.name().like("Fluent").end()
.limit(0, 10)
);
System.out.println(count);
}
}
```
- 查看控制台输出
```text
DEBUG - ==> Preparing: SELECT COUNT(*) FROM your_table WHERE id < ? AND name LIKE ?
DEBUG - ==> Parameters: 1000(Long), %Fluent%(String)
DEBUG - <== Total: 1
5
```
我们看到打印出的SQL语句和count方法相比，少了limit部分。
FluentMybatis提供的update更新方法
updateById
updateById 根据Entity id值，更新Entity中非空属性
- Mapper定义
```java
public interface YourMapper extends IEntityMapper<YourEntity> {
@UpdateProvider(
type = YourSqlProvider.class,
method = "updateById"
)
int updateById(@Param(Param_ET) YourEntity entity);
}
```
入参是Entity对象， 出参是更新记录数，这里返回值只可能是0: 不存在id记录,更新失败；1: 更新id记录成功。
- 动态SQL组装
```java
public class YourSqlProvider {
public String updateById(Map<String, Object> map) {
YourEntity entity = getParas(map, "et");
MapperSql sql = new MapperSql();
sql.UPDATE("your_table");
List<String> sets = new ArrayList<>();
if (entity.getGmtCreate() != null) {
sets.add("gmt_create = #{et.gmtCreate}");
}
if (entity.getGmtModified() != null) {
sets.add("gmt_modified = #{et.gmtModified}");
} else {
sets.add("gmt_modified = now()");
}
if (entity.getIsDeleted() != null) {
sets.add("is_deleted = #{et.isDeleted}");
}
if (entity.getAge() != null) {
sets.add("age = #{et.age}");
}
if (entity.getEmail() != null) {
sets.add("email = #{et.email}");
}
if (entity.getName() != null) {
sets.add("name = #{et.name}");
}
sql.SET(sets);
sql.WHERE("id = #{et.id}");
return sql.toString();
}
}
```
我们看到，在设置set时，会判断entity对象是否为null；但如果在Entity对象上设置了 @TableField( update = 'update默认值')，
则entity属性是空的情况下，会使用默认值代替，比如上面gmtModified属性
``` java
if (entity.getGmtModified() != null) {
sets.add("gmt_modified = #{et.gmtModified}");
} else {
sets.add("gmt_modified = now()");
}
```
where条件部分则比较简单: id = #{et.id}
- 演示验证例子
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void updateById() {
int count = yourMapper.updateById(new YourEntity()
.setId(2L)
.setName("Powerful Fluent Mybatis")
);
System.out.println(count);
}
}
```
- 查看控制台输出
```text
DEBUG - ==> Preparing: UPDATE your_table SET gmt_modified = now(), name = ? WHERE id = ?
DEBUG - ==> Parameters: Powerful Fluent Mybatis(String), 2(Long)
DEBUG - <== Updates: 1
1
```
我们看到update set部分，除了设置了name=?，还设置了 gmt_modified = now()
updateBy
updateBy, 根据自定义set语句，where条件执行更新操作
- Mapper定义
```java
public interface YourMapper extends IEntityMapper<YourEntity> {
@UpdateProvider(
type = YourSqlProvider.class,
method = "updateBy"
)
int updateBy(@Param(Param_EW) IUpdate update);
}
```
入参是一个IUpdate对象，出参是更新成功的记录数。
- 动态SQL构造
```java
public class YourSqlProvider {
public String updateBy(Map<String, Object> map) {
WrapperData data = getWrapperData(map, "ew");
MapperSql sql = new MapperSql();
Map<String, String> updates = data.getUpdates();
assertNotEmpty("updates", updates);
sql.UPDATE("your_table");
List<String> sets = new ArrayList<>();
if (!updates.containsKey("gmtModified")) {
sets.add("gmt_modified = now()");
}
sets.add(data.getUpdateStr());
sql.SET(sets);
sql.WHERE_GROUP_ORDER_BY(data);
sql.LIMIT(data, true);
return sql.toString();
}
}
```
动态构造语句中对 @TableField( update = 'update默认值')字段（这里是gmtModified）做了单独判断,
如果条件中不包含gmtModified，则追加默认值更新。
- 写个例子验证
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void updateBy() {
int count = yourMapper.updateBy(new YourUpdate()
.update.name().is("Powerful Fluent mybatis")
.set.email().is("darui.wu@163.com")
.set.age().is(1).end()
.where.id().eq(2).end()
);
System.out.println(count);
}
}
```
- 查看控制台输出
```text
DEBUG - ==> Preparing: UPDATE your_table SET gmt_modified = now(), name = ?, email = ?, age = ? WHERE id = ?
DEBUG - ==> Parameters: Powerful Fluent mybatis(String), darui.wu@163.com(String), 1(Integer), 2(Integer)
DEBUG - <== Updates: 1
1
```
注意 gmt_modified = now()更新默认值部分
FluentMybatis提供的delete方法
deleteById：根据主键Id物理删除记录
- 查看deleteById对应的SqlProvider语句构造方法
```java
public class YourSqlProvider {
public String deleteById(Serializable id) {
MapperSql sql = new MapperSql();
sql.DELETE_FROM("your_table");
sql.WHERE("id = #{id}");
return sql.toString();
}
}
```
- deleteById的SQL构造比较简单，我们直接看测试演示例子
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void deleteById(){
int count = yourMapper.deleteById(3L);
System.out.println("count:" + count);
}
}
```
- 查看控制台输出log:
```text
DEBUG - ==> Preparing: DELETE FROM your_table WHERE id = ?
DEBUG - ==> Parameters: 3(Long)
DEBUG - <== Updates: 1
count:1
```
deleteByIds：按id列表批量删除, 用法同deleteById
- 直接写个测试验证下
``` java
@Test
void deleteByIds() {
int count = yourMapper.deleteByIds(Arrays.asList(1L, 2L, 3L));
System.out.println("count:" + count);
}
```
- 控制台输出
```text
DEBUG - ==> Preparing: DELETE FROM your_table WHERE id IN (?, ?, ?)
DEBUG - ==> Parameters: 1(Long), 2(Long), 3(Long)
```
#### delete
delete, 按自定义Query条件删除记录
- Mapper定义
```java
public interface YourMapper extends IEntityMapper<YourEntity> {
@DeleteProvider(
type = YourSqlProvider.class,
method = "delete"
)
int delete(@Param(Param_EW) IQuery wrapper);
}
```
入参是一个IQuery对象，出参是删除记录数
- 验证示例
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void delete() {
int count = yourMapper.delete(new YourQuery()
.where.id().in(new int[]{1, 2, 3}).end()
);
System.out.println("count:" + count);
}
}
```
- 查看控制台输出
```text
DEBUG - ==> Preparing: DELETE FROM your_table WHERE id IN (?, ?, ?)
DEBUG - ==> Parameters: 1(Integer), 2(Integer), 3(Integer)
DEBUG - <== Updates: 3
count:3
```
deleteByMap: 根据map中key=value条件集更新记录
- Mapper定义
```java
public interface YourMapper extends IEntityMapper<YourEntity> {
@DeleteProvider(
type = YourSqlProvider.class,
method = "deleteByMap"
)
int deleteByMap(@Param(Param_CM) Map<String, Object> cm);
}
```
- 测试演示例子
```java
@SpringBootTest(classes = QuickStartApplication.class)
public class FluentMybatisApplicationTest {
@Autowired
private YourMapper yourMapper;
@Test
void deleteByMap() {
int count = yourMapper.deleteByMap(new HashMap<String, Object>() {
{
this.put("name", "Fluent Mybatis");
this.put("email", "darui.wu@163.com");
}
});
System.out.println("count:" + count);
}
}
```
- 查看控制台输出
```text
DEBUG - ==> Preparing: DELETE FROM your_table WHERE name = ? AND email = ?
DEBUG - ==> Parameters: Fluent Mybatis(String), darui.wu@163.com(String)
DEBUG - <== Updates: 2
count:2
```
总结
本篇文章介绍完FluentMuybatis提供Mapper内置方法，我们后面接着介绍如何通过IQuery和IUpdate定义强大的动态SQL语句。
文章中提到示例验证例子可以在 [FluentMybatis gitee docs上找到](https://gitee.com/fluent-mybatis/fluent-mybatis-docs/blob/master/spring-boot-demo/src/test/java/cn/org/fluent/mybatis/springboot/demo/FluentMybatisApplicationTest.java)
