import java.util.*;
import java.sql.*;

public class MySQL {
	private Connection con=null;
	private String host="jdbc:mysql://127.0.0.1:3306/";
	private String user;
	private String password;
	public MySQL(String db,String user,String password) {
		this.host=this.host+db;
		this.user=user;
		this.password=password;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			this.con=DriverManager.getConnection(host,user,password);
		} catch (Exception e) {
			System.err.println("数据库连接异常!");;
		}
	}
	
	
	/**
	 *	数据库查询
	 */
	public List<Map> selectAll(String table) {
		List<Map> list=new ArrayList<>();
		try {
			String sql="select * from "+table;
			PreparedStatement pre=this.con.prepareStatement(sql);
			ResultSet res=pre.executeQuery();
			ResultSetMetaData rsd = res.getMetaData();
			int cols=rsd.getColumnCount();
			while(res.next()) {
				HashMap<String,String> map=new HashMap<>();
				for (int i = 1; i <=cols; i++) {
					map.put(rsd.getColumnName(i),res.getString(i));
				}
				list.add(map);
			}
		} catch (SQLException e) {
			System.err.println("selectAll方法异常!");
		}
		return list;
	}
	
	/**
	 * 添加数据
	 */
	public boolean insert(String table,String paList1,String paList2) {
		boolean isSuc=false;
		try {
			String sql="insert into "+table+""+paList1+"values"+paList2;
			PreparedStatement pre=this.con.prepareStatement(sql);
			int resRow=pre.executeUpdate();
			if(resRow>=1) {
				isSuc=true;
			}
		} catch (SQLException e) {
			System.err.println("insert方法异常!");;
		}
		return isSuc;
	}
	
	
	/**
	 * 删除数据
	 */
	public boolean delete(String table,String key,String value) {
		boolean isSuc=false;
		try {
			String sql="delete from "+table+" where "+key+"="+value;
			PreparedStatement pre=this.con.prepareStatement(sql);
			int resRow=pre.executeUpdate();
			if(resRow>=1) {
				isSuc=true;
			}
		} catch (SQLException e) {
			System.err.println("delete方法异常!");;
		}
		return isSuc;
	}
	
	/**
	 * 条件查询
	 */
	public List<Map> selectIf(String table,String key,String value) {
		List<Map> list=new ArrayList<>();
		try {
			String sql="select * from "+table+" where "+key+"="+value;
			PreparedStatement pre=this.con.prepareStatement(sql);
			ResultSet res=pre.executeQuery();
			ResultSetMetaData rsd = res.getMetaData();
			int cols=rsd.getColumnCount();
			while(res.next()) {
				HashMap<String,String> map=new HashMap<>();
				for (int i = 1; i <=cols; i++) {
					map.put(rsd.getColumnName(i),res.getString(i));
				}
				list.add(map);
			}
		} catch (SQLException e) {
			System.err.println("selectIf方法异常!");
		}
		return list;
	}
	
	/**
	 * 数据更新
	 */
	
	public boolean updata(String table,String key,String Value,String newValue) {
		boolean isSuc=false;
		try {
			String sql="update "+table+" set "+key+"='"+newValue+"' where "+key+"='"+Value+"'";
			PreparedStatement pre=this.con.prepareStatement(sql);
			int resRow=pre.executeUpdate();
			if(resRow>=1) {
				isSuc=true;
			}
		} catch (SQLException e) {
			System.err.println("updata方法异常!");;
		}
		return isSuc;
	}

	
	/**
	 * 数据库关闭操作
	 */
	public void close() {
		if(con!=null) {
			try {
				con.close();
			} catch (SQLException e) {
				System.err.println("数据库关闭异常!");
			}
		}
	}
	
	/**
	 * 查看整张表(调试)
	 */
	public void selectShow(String table) {
		List<Map> list=selectAll(table);
		for (int i = 0; i < list.size(); i++) {
			Map<String,String> map=list.get(i);
			Set<String> set = map.keySet();
			Iterator<String> iter = set.iterator();
			while(iter.hasNext()) {
				String temp=iter.next();
				System.out.print(map.get(temp)+"("+temp+")"+"\t");
			}
			System.out.println();
		}
	}
}