QueryHelper

[1].[代码] QueryHelper.java 跳至 [1]
package my.db;
 
import java.io.Serializable;
import java.math.BigInteger;
import java.sql.*;
import java.util.*;
 
import my.cache.CacheManager;
import net.oschina.Configurations;
 
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.*;
import org.apache.commons.lang.ArrayUtils;
 
/**
 * 数据库查询助手
 * @author Winter Lau<br> */
@SuppressWarnings("unchecked")
public class QueryHelper {
     
    private final static QueryRunner _g_runner = new QueryRunner();
    private final static ColumnListHandler _g_columnListHandler = new ColumnListHandler(){
        @Override
        protected Object handleRow(ResultSet rs) throws SQLException {
            Object obj = super.handleRow(rs);
            if(obj instanceof BigInteger)
                return ((BigInteger)obj).longValue();
            return obj;
        }
         
    };
    private final static ScalarHandler _g_scaleHandler = new ScalarHandler(){
        @Override
        public Object handle(ResultSet rs) throws SQLException {
            Object obj = super.handle(rs);
            if(obj instanceof BigInteger)
                return ((BigInteger)obj).longValue();
            return obj;
        }       
    };
     
    private final static List<Class<?>> PrimitiveClasses = new ArrayList<Class<?>>(){{
        add(Long.class);
        add(Integer.class);
        add(String.class);
        add(java.util.Date.class);
        add(java.sql.Date.class);
        add(java.sql.Timestamp.class);
    }};
     
    private final static boolean _IsPrimitive(Class<?> cls) {
        return cls.isPrimitive() || PrimitiveClasses.contains(cls) ;
    }
     
    /**
     * 获取数据库连接
     * @return
     */
    public static Connection getConnection() {
        try{
            return Configurations.getConnection();
        }catch(SQLException e){
            throw new DBException(e);
        }
    }
 
    /**
     * 读取某个对象
     * @param sql
     * @param params
     * @return
     */
    @SuppressWarnings("rawtypes")
    public static <T> T read(Class<T> beanClass, String sql, Object...params) {
        try{
            return (T)_g_runner.query(getConnection(), sql, _IsPrimitive(beanClass)?_g_scaleHandler:new BeanHandler(beanClass), params);
        }catch(SQLException e){
            throw new DBException(e);
        }
    }
     
    public static <T> T read_cache(Class<T> beanClass, String cache, Serializable key, String sql, Object...params) {
        T obj = (T)CacheManager.get(cache, key);
        if(obj == null){
            obj = read(beanClass, sql, params);
            CacheManager.set(cache, key, (Serializable)obj);
        }
        return obj;
    }
     
    /**
     * 对象查询
     * @param <T>
     * @param beanClass
     * @param sql
     * @param params
     * @return
     */
    @SuppressWarnings("rawtypes")
    public static <T> List<T> query(Class<T> beanClass, String sql, Object...params) {
        try{
            return (List<T>)_g_runner.query(getConnection(), sql, _IsPrimitive(beanClass)?_g_columnListHandler:new BeanListHandler(beanClass), params);
        }catch(SQLException e){
            throw new DBException(e);
        }
    }
 
    /**
     * 支持缓存的对象查询
     * @param <T>
     * @param beanClass
     * @param cache_region
     * @param key
     * @param sql
     * @param params
     * @return
     */
    public static <T> List<T> query_cache(Class<T> beanClass, String cache_region, Serializable key, String sql, Object...params) {       
        List<T> objs = (List<T>)CacheManager.get(cache_region, key);
        if(objs == null){
            objs = query(beanClass, sql, params);
            CacheManager.set(cache_region, key, (Serializable)objs);
        }
        return objs;
    }
     
    /**
     * 分页查询
     * @param <T>
     * @param beanClass
     * @param sql
     * @param page
     * @param count
     * @param params
     * @return
     */
    public static <T> List<T> query_slice(Class<T> beanClass, String sql, int page, int count, Object...params) {
        if(page < 0 || count < 0) 
            throw new IllegalArgumentException("Illegal parameter of 'page' or 'count', Must be positive.");
        int from = (page - 1) * count;
        count = (count > 0) ? count : Integer.MAX_VALUE;
        return query(beanClass, sql + " LIMIT ?,?", ArrayUtils.addAll(params, new Integer[]{from,count}));      
    }
     
    /**
     * 支持缓存的分页查询
     * @param <T>
     * @param beanClass
     * @param cache
     * @param cache_key
     * @param cache_obj_count
     * @param sql
     * @param page
     * @param count
     * @param params
     * @return
     */
    public static <T> List<T> query_slice_cache(Class<T> beanClass, String cache, Serializable cache_key, int cache_obj_count, String sql, int page, int count, Object...params) {
        List<T> objs = (List<T>)CacheManager.get(cache, cache_key);
        if(objs == null) {
            objs = query_slice(beanClass, sql, 1, cache_obj_count, params);
            CacheManager.set(cache, cache_key, (Serializable)objs);
        }
        if(objs == null || objs.size()==0)
            return objs;
        int from = (page - 1) * count;
        if(from < 0)
            return null;
        if((from+count) > cache_obj_count)//超出缓存的范围
            return query_slice(beanClass, sql, page, count, params);
        int end = Math.min(from + count, objs.size());
        if(from >= end)
            return null;
        return objs.subList(from, end);
    }
     
    /**
     * 执行统计查询语句，语句的执行结果必须只返回一个数值
     * @param sql
     * @param params
     * @return
     */
    public static long stat(String sql, Object...params) {
        try{
            Number num = (Number)_g_runner.query(getConnection(), sql, _g_scaleHandler, params);
            return (num!=null)?num.longValue():-1;
        }catch(SQLException e){
            throw new DBException(e);
        }
    }
 
    /**
     * 执行统计查询语句，语句的执行结果必须只返回一个数值
     * @param cache_region
     * @param key
     * @param sql
     * @param params
     * @return
     */
    public static long stat_cache(String cache_region, Serializable key, String sql, Object...params) {
        Number value = (Number)CacheManager.get(cache_region, key);
        if(value == null){
            value = stat(sql, params);
            CacheManager.set(cache_region, key, value);
        }
        return value.longValue();
    }
 
    /**
     * 执行INSERT/UPDATE/DELETE语句
     * @param sql
     * @param params
     * @return
     */
    public static int update(String sql, Object...params) {
        try{
            return _g_runner.update(getConnection(), sql, params);
        }catch(SQLException e){
            throw new DBException(e);
        }
    }
     
    /**
     * 批量执行指定的SQL语句
     * @param sql
     * @param params
     * @return
     */
    public static int[] batch(String sql, Object[][] params) {
        try{
            return _g_runner.batch(getConnection(), sql, params);
        }catch(SQLException e){
            throw new DBException(e);
        }
    }
}