mybatis注解方式使用示例

映射注解，操作数据库表

public interface UtilMapper {

    //检查表是否存在，注意表名 用 $
    @Select("SELECT  case when  count(name)=0 then 'false' else 'true' end    FROM   sysobjects   where   name= '${tableName}'")
    boolean existsTable(@Param("tableName") String tableName);

    //执行sql语句
    @Update("${sql}")
    @Options(statementType = StatementType.STATEMENT)
    void execute(@Param("sql") String sql);
}

映射注解，操作数据

public interface UserMapper {
    @Insert("insert into sys_user(name,passWord) " +
            "values(#{name},#{passWord})")
    void add(UserEntity entity);

    //使用其他方法生成sql
    @UpdateProvider(type=UserProvider.class,method = "updateSql")
    void update(UserEntity entity);

    @Delete("delete from sys_user where id=#{id}")
    void del(int id);

    @Select("select * from sys_user where id=#{id}")
    UserEntity get(int id);
    
 @SelectProvider(type=UserProvider.class,method = "listSql")
    List<Map<String,Object>> list(String key, int rows, int page);

    @SelectProvider(type=UserProvider.class,method="countSql")
    int count(String key);

}

sql语句生成，用于复杂sql的拼接与生成，其中有like 用法，使用concat连接
like CONCAT(’%’,#{key},’%’)

public class UserProvider {
    public String updateSql(UserEntity entity){
        return new SQL(){{
            UPDATE("sys_user");
            SET("name=#{name}");
            if(StringUtils.isNotBlank( entity.getPassWord())){
                SET("passWord=#{passWord}");
            }
            WHERE("id=#{id}");
        }}.toString();
    }

private String listWhere(String key){
        String where="";
        if(StringUtils.isNotBlank(key)){
            where =" where name like CONCAT('%',#{key},'%') ";
        }
        return where;
    }

//分页sql
    public String listSql(String key,int rows,int page){
        String where = listWhere(key);
        Map<String,Integer> pObj = DataGridJson.compuPage(rows,page);
        String sql =String.format("select * from " +
                "(select ROW_NUMBER() over(order by id) rowid,id,name,dislog,dislogreason,dislogtime " +
                "from sys_user %s)t where rowid between %d and %d",where,pObj.get("start"),pObj.get("end"));
        return sql;
//        return new SQL(){{
//            SELECT("ROW_NUMBER() over(order by id) rowid,id,name,dislog,dislogreason,dislogtime");
//            FROM("sys_user");
//            if(StringUtils.isNotBlank(key)){
//                WHERE("name like CONCAT('%',#{key},'%')");
//            }
//        }}.toString();
    }

    public String countSql(String key){
        String where = listWhere(key);
        String sql = String.format("select count(id) from sys_user %s",where);
        return sql;
    }
}

返回json列表对象封装

public class DataGridJson {
    int total;
    Object rows;

    public int getTotal() {
        return total;
    }

    public Object getRows() {
        return rows;
    }

    public void setRows(Object rows) {
        this.rows = rows;
    }

    public void setTotal(int total) {
        this.total = total;
    }

    public DataGridJson(List list) {
        this.total = list.size();
        rows = list;
    }

    public DataGridJson(int total,List list){
        this.total = total;
        rows = list;
    }

    /**
     * 计算分页
     * @param rows
     * @param page
     * @return
     */
    public static Map<String, Integer> compuPage(int rows, int page){
        if (page == 0)
        {
            page = 1;
        }
        if (rows == 0)
        {
            rows = 20;
        }
        int start = (page - 1) * rows;
        int end = start + rows;
        start = page == 1 ? start : start + 1;
        Map<String,Integer> result = new HashMap<String,Integer>();
        result.put("start",start);
        result.put("end",end);
        return result;
    }
}

分页查询调用方法：

 @Override
    public DataGridJson listUser(String key, int rows, int page) {
        List list = userMapper.list(key,rows,page);
        int count =userMapper.count(key);
        DataGridJson obj = new DataGridJson(count,list);
        return obj;
    }