Java_JDBC连接数据库_使用读取配置文件的方式

package com.homewoek3_4.dao;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

/**
* 数据库连接通用类
* @author Administrator
*/
public abstract class BaseDao {
private static final String path = "database.properties";
private static String DB_DRIVER;
private static String DB_URL;
private static String DB_USER;
private static String DB_PWD;

protected Connection conn = null;
protected PreparedStatement ps = null;
protected ResultSet rs = null;

static {
Properties pro = new Properties();
InputStream io = BaseDao.class.getClassLoader().getResourceAsStream(path);
try {
//读取配置文件
pro.load(io);
} catch (IOException e) {
e.printStackTrace();
}
DB_DRIVER = pro.getProperty("DB_DRIVER");
DB_URL = pro.getProperty("DB_URL");
DB_USER = pro.getProperty("DB_USER");
DB_PWD = pro.getProperty("DB_PWD");
try {
//加载驱动类
Class.forName(DB_DRIVER);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
/**
* 打开数据库连接
*/
protected void openConn() {
try {
conn = DriverManager.getConnection(DB_URL, DB_USER, DB_PWD);
} catch (SQLException e) {
e.printStackTrace();
}
}
/**
* 关闭数据库连接
*/
protected void closeConn() {
try {
if (rs != null) {
rs.close();
}
if (ps != null) {
ps.close();
}
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
/**
* 增删改
* @param sql
* @param obj
* @return
*/
protected int executeUpdate(String sql, Object...obj) {
int result = -1;
this.openConn();
try {
ps = conn.prepareStatement(sql);
if (obj != null) {
for (int i = 0; i < obj.length; i++) {
ps.setObject(i+1, obj[i]);
}
}
result = ps.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}
return result;
}
/**
* 查询
* @param sql
* @param obj
* @return
*/
protected void executeQuery(String sql, Object...obj) {
this.openConn();
try {
ps = conn.prepareStatement(sql);
if (obj != null) {
for (int i = 0; i < obj.length; i++) {
ps.setObject(i+1, obj[i]);
}
}
rs = ps.executeQuery();
} catch (SQLException e) {
e.printStackTrace();
}
}
}

创建database.properties文件，注意：后缀名一定是properties。此格式的文件在MyEclipse中图标会变，这点很容易写错，要注意。

DB_DRIVER=com.mysql.jdbc.Driver
DB_URL=jdbc:mysql://localhost:3306/Pet?useUnicode=true&characterEncoding=utf8&useSSL=true
DB_USER=root
DB_PWD=111111