package com.zhuoer.qmaintance.utils;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class DBTools {
private static final String URL = "jdbc:mysql://127.0.0.1:3306/database?useUnicode=true&characterEncoding=UTF-8";
private static final String DRIVER = "com.mysql.jdbc.Driver";
private static final String USER = "root";
private static final String PASS = "123456";
private static Connection conn = null;
// 建立与数据库的Connection连接
public static Connection getConnection() {
try {
if (conn == null || conn.isClosed()) {
Class.forName(DRIVER);
conn = DriverManager.getConnection(URL, USER, PASS);
}
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
return conn;
}
}
package com.zhuoer.qmaintance.utils;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.zhuoer.qmaintance.beans.RepairInfo;
public class RepairInfoTools {
/**
* 所有查询工具类
* @param sql
* @param objects
* @return
*/
public static List executeQuary(String sql, Object... objects) {
List li=new ArrayList();
ResultSet rs;
try {
PreparedStatement ps=DBTools.getConnection().prepareStatement(sql);
if (objects != null) {
for (int i = 0; i < objects.length; i++) {
ps.setObject(i + 1, objects[i]);
}
}
rs= ps.executeQuery();
ResultSetMetaData md = rs.getMetaData();
int columnCount = md.getColumnCount();
while (rs.next()) {
Map rowData = new HashMap();
for (int i = 1; i <= columnCount; i++)
{
rowData.put(md.getColumnName(i), rs.getObject(i));
}
li.add(rowData);
}
rs.close();
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
return li;
}
/**
* 查询总页数
* @param sql
* @return
*/
public static int selectCount(String sql) {
int count=0;
try {
PreparedStatement ps = DBTools.getConnection().prepareStatement(sql);
ResultSet rs = ps.executeQuery();
if(rs.next())
{
count = rs.getInt(1);
}
rs.close();
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
return count;
}
/**
* 修改操作工具类(增删改)
* @param sql
* @param objects
* @return
*/
public static int executeUpdate(String sql, Object... objects) {
int s = -1;
try {
PreparedStatement ps=DBTools.getConnection().prepareStatement(sql);
if (objects != null)
for (int i = 0; i < objects.length; i++) {
ps.setObject(i + 1, objects[i]);
}
s= ps.executeUpdate();
ps.close();
return s;
} catch (SQLException e) {
e.printStackTrace();
}
return s;
}
}
hp>100 && damage<50
package charactor;
public class Hero implements Comparable<Hero>{
public String name;
public float hp;
public int damage;
public Hero(){
}
public Hero(String name) {
this.name =name;
}
//初始化name,hp,damage的构造方法
public Hero(String name,float hp, int damage) {
this.name =name;
this.hp = hp;
this.damage = damage;
}
@Override
public int compareTo(Hero anotherHero) {
if(damage<anotherHero.damage)
return 1;
else
return -1;
}
@Override
public String toString() {
return "Hero [name=" + name + ", hp=" + hp + ", damage=" + damage + "]\r\n";
}
}
package lambda;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import charactor.Hero;
public class TestLambda {
public static void main(String[] args) {
Random r = new Random();
List<Hero> heros = new ArrayList<Hero>();
for (int i = 0; i < 10; i++) {
heros.add(new Hero("hero " + i, r.nextInt(1000), r.nextInt(100)));
}
System.out.println("初始化后的集合:");
System.out.println(heros);
System.out.println("筛选出 hp>100 && damange<50的英雄");
filter(heros);
}
private static void filter(List<Hero> heros) {
for (Hero hero : heros) {
if(hero.hp>100 && hero.damage<50)
System.out.print(hero);
}
}
}