Java数据库语句拼凑

两个类分别是Sql和Where，支持hql语句和支持sql语句拼凑，当你传入的参数为空时，拼凑的这个条件就会自动的换成“1=1”，使用方法：Sql sql = Sql.start("select * from tbl_name").add(Where.newIntance().like("property", value), "where")（这里拼接很灵活大家可以看代码）获取sql语句直接可以sql.toString()，如果获取所有参数可以通过sql.getParams()。

Sql.java

package com.fbtt.axst.utils;

import java.util.ArrayList;
import java.util.List;

public class Sql {
	private Sql(String hql) {
		this.hql = hql;
	}
	public static Sql start(String hql){
		return new Sql(hql);
	}
	//所有的参数
	private List params = new ArrayList();
	//最终的hql语句
	private String hql = null;
	/**
	 * 向当前hql语句追加语句
	 * Example:
	 * hql = Hql.start("from Employee a ");
	 * hql.add("order by a.name")
	 * String str = hql.toString();
	 * 此处str为：from Employee a order by a.name;
	 */
	public Sql add(String str){
		hql = hql + " " + str;
		return this;
	}
	/**
	 * 向当前hql语句追加语句，其它的参数
	 * Example:
	 * hql = Hql.start("from Employee a ");
	 * hql.add("where a.name like ?", new Serializable[]{"张三"});
	 * String str = hql.toString();
	 * str为：from Employee a where a.name like ?
	 * Serializable[] params = hql.getParams();
	 * params为：["张三"]
	 * @param hql
	 * @param params
	 */
	@SuppressWarnings("unchecked")
	public Sql add(String str, Object[] params){
		this.add(str);
		if(params != null){
			for(Object obj : params){
				this.params.add(obj);
			}
		}
		return this;
	}
	public Sql add(String str, Object param){
		this.add(str, new Object[]{param});
		return this;
	}
	
	//获取所有参数
	public Object[] getParams(){
		return params.toArray();
	}
	/**
	 * 添加where条件
	 * Example:
	 * WhereHql wh = WhereHql.newInstance();
	 * wh.eq("a.name", "张三");
	 * Hql hql = Hql.start("from Employee a ");
	 * hql.add(wh, "where");
	 * hql.toString();
	 * 此时得到：from Employee a where a.name = '张三' 
	 * @param wh
	 * @param prefix 当wh.toString不为空时在其前添加的前缀
	 * @return
	 */
	public Sql add(Where wh, String prefix){
		String wstr = wh.toString();
		if(prefix == null)prefix = "";
		if(wstr != null){
			this.add(prefix + " " + wstr, wh.getParams());
		}
		return this;
	}
	/**
	 * 获取生成的hql语句
	 */
	@Override
	public String toString() {
		return hql;
	}
}

Where.java

package com.fbtt.axst.utils;

import java.util.ArrayList;
import java.util.List;
public class Where {
	private Where(){
		
	}
	public static Where newInstance(){
		return new Where();
	}
	//所有的参数
	private List params = new ArrayList();
	//最终的hql语句
	private String hql = null;
	/**
	 * 向当前hql语句追加语句，及它的参数
	 * @param params
	 */
	@SuppressWarnings("unused")
	private Where addNotNull(String str, Object param, String prefix){
		if(param == null || param.equals(""))return this;
		this.add(str, param, prefix);
		return this;
	}
	private Where addAndNotNull(String str, Object param){
		if(param == null || param.equals(""))return this;
		this.add(str, param, "and");
		return this;
	}
	@SuppressWarnings("unchecked")
	public Where add(String str, Object param, String prefix){
		if(prefix == null)prefix = "and";
		if(hql == null)
			hql = str;
		else
			hql = hql + " " + prefix + " " + str;
		if(param != null){
			this.params.add(param);
		}
		return this;
	}
	
	
	@Override
	public String toString() {
		return hql;
	}
	//获取所有参数
	public Object[] getParams(){
		return this.params.toArray();
	}
	//=
	public Where eq(String prop, Object param){
		if(param == null || param.equals(""))return this;
		this.addAndNotNull(prop + "=?", param);
		return this;
	}
	//<
	public Where lt(String prop, Object param){
		if(param == null || param.equals(""))return this;
		this.addAndNotNull(prop + " < ?", param);
		return this;
	}
	//<=
	public Where le(String prop, Object param){
		if(param == null || param.equals(""))return this;
		this.addAndNotNull(prop + " <= ?", param);
		return this;
	}

	//like
	public Where like(String prop, Object param){
		if(param == null || param.equals(""))return this;
		this.addAndNotNull(prop + " like ?", "%" + param + "%");
		return this;
	}
	//>
	public Where gt(String prop, Object param){
		if(param == null || param.equals(""))return this;
		this.addAndNotNull(prop + " > ?", param);
		return this;
	}
	//>=
	public Where ge(String prop, Object param){
		if(param == null || param.equals(""))return this;
		this.addAndNotNull(prop + " >= ?", param);
		return this;
	}
		
}