自定义通用mapper
由于mapper做了分层结构,我们的mapper接口可不继承Mapper
封装好的方法:
1-编写自定义通用mapper接口并选择性的继承封装好的方法。
public interface MyMapper<T> extends
SelectAllMapper<T>,
SelectByExampleMapper<T>{
}
2-个人mapper接口继承自定义通用mapper
public interface EmployeeMapper extends MyMapper<Employee>{
}
3-测试
@Autowired
EmployeeMapper employeeMapper;
@RequestMapping(value = "/selectByExample",method = RequestMethod.GET)
public List<Employee> selectByExample(Employee employee) {
// 创建example对象
Example example = new Example(Employee.class);
//通过example设置查询条件
Example.Criteria criteria1 = example.createCriteria();
Example.Criteria criteria2 = example.createCriteria();
criteria1.andGreaterThan("empSalary",3000)
.andLessThan("empAge",25);
criteria2.andLessThan("empSalary",5000)
.andGreaterThan("empAge",30);
example.or(criteria2);// 组装查询条件
example.orderBy("empSalary").asc().orderBy("empAge").desc();// 排序
example.setDistinct(true);//去重
// 执行查询
List<Employee> employees = employeeMapper.selectByExample(example);
return employees;
}
扩展通用mapper接口
个人mapper接口:普通dao层接口
通用mapper接口或自定义通用mapper接口:已封装好相关sql操作的接口,拿来即用那种
扩展通用mapper接口:个人自定义的sql操作接口
1-定义【扩展接口】,使用相关注解注释并指定type和method(值为dynamicSQL),如: @UpdateProvider 加上@RegisterMapper
@RegisterMapper
public interface MyBatchUpdateMapper<T> {
@UpdateProvider(type = MyBatchUpdateProvider.class ,method = "dynamicSQL")
void batchUpdate(List<T> list);
}
2-定义【接口方法实现类】,返回相关拼接好的sql语句
public class MyBatchUpdateProvider extends MapperTemplate{
public MyBatchUpdateProvider(Class<?> mapperClass, MapperHelper mapperHelper) {
super(mapperClass, mapperHelper);
}
/**
* <foreach collection="list" item="record" separator=";" >
UPDATE tabple_emp
SET emp_name=#f{record.empName},
emp_age=#{record.empAge},
emp_salary=#{record.empSalary}
where emp_id=#{record.empId}
</foreach>
* @param statement
*/
public String batchUpdate(MappedStatement statement){ //方法名和接口需要保持一致
StringBuilder builder = new StringBuilder();
builder.append("<foreach collection=\"list\" item=\"record\" separator=\";\" >");
Class<?> entityClass = super.getEntityClass(statement);
String tableName = super.tableName(entityClass);
String updateClause = SqlHelper.updateTable(entityClass, tableName);
builder.append(updateClause);
builder.append("<set>");
Set<EntityColumn> columns = EntityHelper.getColumns(entityClass);
String idColumn = null;
String idHodler = null;
for (EntityColumn entityColumn : columns){
boolean isPrimaryKey = entityColumn.isId();
if (isPrimaryKey){
idColumn = entityColumn.getColumn();
idHodler = entityColumn.getColumnHolder("record");
}else {
String column = entityColumn.getColumn();
String columnHolder = entityColumn.getColumnHolder("record");
builder.append(column).append("=").append(columnHolder).append(",");
}
}
builder.append("</set>");
builder.append("WHERE ").append(idColumn).append("=").append(idHodler);
builder.append("</foreach>");
return builder.toString();
}
}
3-【自定义通用mapper接口继承扩展接口】以及个人mapper接口继承自定义通用mapper接口
public interface MyMapper<T> extends
SelectAllMapper<T>,
SelectByExampleMapper<T> ,
MyBatchUpdateMapper<T> {
}
public interface EmployeeMapper extends MyMapper<Employee>{}
或者【个人mapper接口直接继承扩展接口】
public interface EmployeeMapper extends MyMapper<Employee> ,
MyBatchUpdateMapper<Employee> {
}
4-测试
@Autowired
EmployeeMapper employeeMapper;
@RequestMapping(value = "/batchUpdate",method = RequestMethod.GET)
public void batchUpdate() {
List<Employee> employees = new ArrayList<>();
employees.add(new Employee(4,"newName01",111.11,11));
employees.add(new Employee(5,"newName02",222.22,22));
employees.add(new Employee(6,"newName03",222.22,33));
employeeMapper.batchUpdate(employees);
}