mybatis抽取基類BaseMapper(通用增/刪/改/查)
阿新 • • 發佈：2018-12-15
目前專案當中使用mapper.xml檔案方式對資料庫進行操作,但是每個裡邊都有增/刪/改/查,為了方便開發,把這些公共的程式碼提取出來,不用當做基類,不用每個Mapper檔案都寫了
準備工作:
1:資料庫表
CREATE TABLE `t_permission` ( `id` int(11) NOT NULL AUTO_INCREMENT COMMENT '許可權ID', `type` int(11) NOT NULL COMMENT '許可權型別', `name` varchar(255) NOT NULL COMMENT '許可權名稱', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=24 DEFAULT CHARSET=utf8 COMMENT='許可權表';
2:準備實體類
public class TPermissionEntity {
@PrimaryKey //下面步驟2中自定義註解
private Integer id;//許可權ID
private Integer type;//許可權型別
private String name;//許可權名稱
//省略了get,set方法....
}
步驟1:編寫工具類Tools:作用:用於駝峰和資料庫欄位的轉換
因為類的名稱用的是駝峰命名,所以這裡需要轉換一下
import java.util.regex.Matcher; import java.util.regex.Pattern; /* * 駝峰名稱和下劃線名稱的相互轉換 */ public class Tool { private static Pattern linePattern = Pattern.compile("_(\\w)"); /** 下劃線轉駝峰 */ 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]"); /** 駝峰轉下劃線,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(); } }
步驟2:自定義兩個註解,分別用於類欄位的排除和字義主鍵
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface Exclude {
}@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface PrimaryKey {
String value() default "";
} 步驟3:自定義動態sql生成類BaseSqlProvider<T>
作用:根據傳入的物件動態獲取表名和欄位名生成動態的sql語句,再執行
@Insert,@Select,@update,@Delete是直接配置SQL語句，而@InsertProvider,@UpdateProvider,@SelectProvider,@DeleteProvider則是通過SQL工廠類及對應的方法生產SQL語句
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<T> {
@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<Field> 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<Field> 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("物件中未包含PrimaryKey屬性");
}
return sql.toString();
}
private List<Field> getPrimarkKeyFields(Class clazz) {
List<Field> primaryKeyField = new ArrayList<>();
List<Field> 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<Field> getFields(Class clazz) {
List<Field> 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<Field> 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("物件中未包含PrimaryKey屬性");
}
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<Field> 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<Field> 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("物件中未包含PrimaryKey屬性");
}
System.out.println("updateSql:"+sql.toString());
return sql.toString();
}
}
步驟4:編寫BaseMapper基類介面
public interface BaseMapper<T> {
//新增一條資料
@InsertProvider(method = "add",type=BaseSqlProvider.class)
@Options(useGeneratedKeys=true)
public int add(T bean);
//根據主鍵刪除一條資料
@DeleteProvider(method = "delete",type=BaseSqlProvider.class)
public int delete(T bean);
//根據主鍵獲取一條資料
@SelectProvider(method = "get",type=BaseSqlProvider.class)
public T get(T bean);
//修改一條資料
@UpdateProvider(method = "update",type=BaseSqlProvider.class)
public int update(T bean);
}說明：@InsertProvider註解中的type指明自定義的SQL工廠類，method是工廠類裡對應的方法,方法返回的是對方的sql語句
到這裡基類以及它的配置就完成了,接下來,可以使用了
舉例:
編寫一個TPermissionMapper介面,實現BaseMapper類,並傳入一個泛型引數,此時這個TPermissionMapper介面已經具備了,BaseMapper中基本的增/刪/改/查功能.同時TPermissionMapper還可以再寫自己獨有的方法和mapper.xml檔案對功能進行擴充套件
public interface TPermissionMapper extends BaseMapper<TPermissionEntity>{
//List<TPermissionEntity> queryByPage();
}
在controller當中的應用:
@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;
}
//查詢
@ResponseBody
@RequestMapping(value = "/query")
public TPermissionEntity query() {
TPermissionEntity tPermissionEntity = new TPermissionEntity();
tPermissionEntity.setId(23);
tPermissionEntity= (TPermissionEntity) tPermissionMapper.get(tPermissionEntity);
return tPermissionEntity;
}
//刪除
@ResponseBody
@RequestMapping(value = "/delete")
public Integer delete() {
TPermissionEntity permissionEntiry = new TPermissionEntity();
permissionEntiry.setId(22);
Integer num = tPermissionMapper.delete(permissionEntiry);
return num;
}
}