准备工作:

创新互联公司网站建设公司是一家服务多年做网站建设策划设计制作的公司,为广大用户提供了成都网站制作、成都网站设计，成都网站设计，1元广告，成都做网站选创新互联公司，贴合企业需求，高性价比，满足客户不同层次的需求一站式服务欢迎致电。

1:数据库表

CREATE TABLE `t_permission` (

`id` int(11) NOT NULL AUTO_INCREMENT COMMENT '权限ID',

`type` int(11) NOT NULL COMMENT '权限类型',

`name` varchar(255) NOT NULL COMMENT '权限名称',

PRIMARY KEY (`id`)

) ENGINE=InnoDB AUTO_INCREMENT=24 DEFAULT CHARSET=utf8 COMMENT='权限表';

2:准备实体类

public class TPermissionEntity {

@PrimaryKey //下面步骤2中自定义注解

private Integer id;//权限ID

private Integer type;//权限类型

private String name;//权限名称

//省略了get,set方法....

}

步骤1:编写工具类Tools:作用:用于驼峰和数据库字段的转换

因为类的名称用的是驼峰命名,所以这里需要转换一下

import java.util.regex.Matcher;

import java.util.regex.Pattern;

/*

* 驼峰名称和下划线名称的相互转换

*/

public class Tool {

private static Pattern linePattern = Pattern.compile("_(\\w)");

/** 下划线转驼峰 */

public static String lineToHump(String str) {

str = str.toLowerCase();

Matcher matcher = linePattern.matcher(str);

StringBuffer sb = new StringBuffer();

while (matcher.find()) {

matcher.appendReplacement(sb, matcher.group(1).toUpperCase());

}

matcher.appendTail(sb);

return sb.toString();

}

private static Pattern humpPattern = Pattern.compile("[A-Z]");

/** 驼峰转下划线,效率比上面高 */

public static String humpToLine(String str) {

Matcher matcher = humpPattern.matcher(str);

StringBuffer sb = new StringBuffer();

while (matcher.find()) {

matcher.appendReplacement(sb, "_" + matcher.group(0).toLowerCase());

}

matcher.appendTail(sb);

return sb.toString();

}

}

步骤2:自定义两个注解,分别用于类字段的排除和字义主键

@Target({ElementType.FIELD})

@Retention(RetentionPolicy.RUNTIME)

public @interface Exclude {

}

@Target({ElementType.FIELD})

@Retention(RetentionPolicy.RUNTIME)

public @interface PrimaryKey {

String value() default "";

}

步骤3:自定义动态sql生成类BaseSqlProvider

作用:根据传入的对象动态获取表名和字段名生成动态的sql语句,再执行

@Insert,@Select,@update,@Delete是直接配置SQL语句，而@InsertProvider,@UpdateProvider,@SelectProvider,@DeleteProvider则是通过SQL工厂类及对应的方法生产SQL语句

import java.lang.reflect.Field;

import java.util.ArrayList;

import java.util.List;

import org.apache.ibatis.annotations.Options;

import org.apache.ibatis.jdbc.SQL;

import com.example.demo.common.utils.Tool;

public class BaseSqlProvider {

@Options

public String add(T bean) {

SQL sql = new SQL();

Class clazz = bean.getClass();

String tableName = clazz.getSimpleName();

String realTableName = Tool.humpToLine(tableName).replaceAll("_entity", "").substring(1);

sql.INSERT_INTO(realTableName);

List fields = getFields(clazz);

for (Field field : fields) {

field.setAccessible(true);

String column = field.getName();

System.out.println("column:" + Tool.humpToLine(column));

sql.VALUES(Tool.humpToLine(column), String.format("#{" + column + ",jdbcType=VARCHAR}"));

}

return sql.toString();

}

public String delete(T bean) {

SQL sql = new SQL();

Class clazz = bean.getClass();

String tableName = clazz.getSimpleName();

String realTableName = Tool.humpToLine(tableName).replaceAll("_entity", "").substring(1);

sql.DELETE_FROM(realTableName);

List primaryKeyField = getPrimarkKeyFields(clazz);

if (!primaryKeyField.isEmpty()) {

for (Field pkField : primaryKeyField) {

pkField.setAccessible(true);

sql.WHERE(pkField.getName() + "=" + String.format("#{" + pkField.getName() + "}"));

}

} else {

sql.WHERE(" 1= 2");

throw new RuntimeException("对象中未包含PrimaryKey属性");

}

return sql.toString();

}

private List getPrimarkKeyFields(Class clazz) {

List primaryKeyField = new ArrayList<>();

List fields = getFields(clazz);

for (Field field : fields) {

field.setAccessible(true);

PrimaryKey key = field.getAnnotation(PrimaryKey.class);

if (key != null) {

primaryKeyField.add(field);

}

}

return primaryKeyField;

}

private List getFields(Class clazz) {

List fieldList = new ArrayList<>();

Field[] fields = clazz.getDeclaredFields();

for (Field field : fields) {

field.setAccessible(true);

Exclude key = field.getAnnotation(Exclude.class);

if (key == null) {

fieldList.add(field);

}

}

return fieldList;

}

public String get(T bean) {

SQL sql = new SQL();

Class clazz = bean.getClass();

String tableName = clazz.getSimpleName();

String realTableName = Tool.humpToLine(tableName).replaceAll("_entity", "").substring(1);

sql.SELECT("*").FROM(realTableName);

List primaryKeyField = getPrimarkKeyFields(clazz);

if (!primaryKeyField.isEmpty()) {

for (Field pkField : primaryKeyField) {

pkField.setAccessible(true);

sql.WHERE(pkField.getName() + "=" + String.format("#{" + pkField.getName() + "}"));

}

} else {

sql.WHERE(" 1= 2");

throw new RuntimeException("对象中未包含PrimaryKey属性");

}

System.out.println("getSql:"+sql.toString());

return sql.toString();

}

public String update(T bean) {

SQL sql = new SQL();

Class clazz = bean.getClass();

String tableName = clazz.getSimpleName();

String realTableName = Tool.humpToLine(tableName).replaceAll("_entity", "").substring(1);

sql.UPDATE(realTableName);

List fields = getFields(clazz);

for (Field field : fields) {

field.setAccessible(true);

String column = field.getName();

if (column.equals("id")) {

continue;

}

System.out.println(Tool.humpToLine(column));

sql.SET(Tool.humpToLine(column) + "=" + String.format("#{" + column + ",jdbcType=VARCHAR}"));

}

List primaryKeyField = getPrimarkKeyFields(clazz);

if (!primaryKeyField.isEmpty()) {

for (Field pkField : primaryKeyField) {

pkField.setAccessible(true);

sql.WHERE(pkField.getName() + "=" + String.format("#{" + pkField.getName() + "}"));

}

} else {

sql.WHERE(" 1= 2");

throw new RuntimeException("对象中未包含PrimaryKey属性");

}

System.out.println("updateSql:"+sql.toString());

return sql.toString();

}

}

步骤4:编写BaseMapper基类接口

public interface BaseMapper {

//新增一条数据

@InsertProvider(method = "add",type=BaseSqlProvider.class)

@Options(useGeneratedKeys=true)

public int add(T bean);

//根据主键删除一条数据

@DeleteProvider(method = "delete",type=BaseSqlProvider.class)

public int delete(T bean);

//根据主键获取一条数据

@SelectProvider(method = "get",type=BaseSqlProvider.class)

public T get(T bean);

//修改一条数据

@UpdateProvider(method = "update",type=BaseSqlProvider.class)

public int update(T bean);

}

说明：@InsertProvider注解中的type指明自定义的SQL工厂类，method是工厂类里对应的方法,方法返回的是对方的sql语句

到这里基类以及它的配置就完成了,接下来,可以使用了

举例:无锡看妇科的医院 http://www.ytsg120.cn/

编写一个TPermissionMapper接口,实现BaseMapper类,并传入一个泛型参数,此时这个TPermissionMapper接口已经具备了,BaseMapper中基本的增/删/改/查功能.同时TPermissionMapper还可以再写自己独有的方法和mapper.xml文件对功能进行扩展

public interface TPermissionMapper extends BaseMapper{

//List queryByPage();

}

在controller当中的应用:

@Controller

public class LoginController {

@Autowired

private TPermissionMapper tPermissionMapper;

//新增

@ResponseBody

@RequestMapping(value = "/add")

public Integer add() {

TPermissionEntity permissionEntiry = new TPermissionEntity();

permissionEntiry.setName("test");

permissionEntiry.setType(3);

Integer num = tPermissionMapper.add(permissionEntiry);

return num;

}

//修改

@ResponseBody

@RequestMapping(value = "/update")

public Integer update() {

TPermissionEntity permissionEntiry = new TPermissionEntity();

permissionEntiry.setId(23);

permissionEntiry.setName("test");

permissionEntiry.setType(3);

Integer num = tPermissionMapper.update(permissionEntiry);

return num;

}

//查询

@ResponseBody

@RequestMapping(value = "/query")

public TPermissionEntity query() {

TPermissionEntity tPermissionEntity = new TPermissionEntity();

tPermissionEntity.setId(23);

tPermissionEntity= (TPermissionEntity) tPermissionMapper.get(tPermissionEntity);

return tPermissionEntity;

}

//删除

@ResponseBody

@RequestMapping(value = "/delete")

public Integer delete() {

TPermissionEntity permissionEntiry = new TPermissionEntity();

permissionEntiry.setId(22);

Integer num = tPermissionMapper.delete(permissionEntiry);

return num;

}

文章标题：mybatis抽取基类BaseMapper
网站链接：http://scyanting.com/article/phdsos.html