java键值对_Java 读写键值对

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Properties类(读入写出 键值对) 是Map子类Map方法都能用

public static void main(String[] args) throws IOException {

//读出

Properties pro=new Properties();

FileInputStream fis = new FileInputStream(“F:\\Demo.properties”);

//FileReader fr=new FileReader(“F:\\Demo.properties”);

pro.load(fis);//读取键值对 pro.load(fr);

String str=pro.getProperty(“name”);//取值

fis.close(); //fr.close();

//写入

Properties pro=new Properties();//创建集合

pro.setProperty(“name”,”lisi”);//写入键值对

pro.setProperty(“hobby”,”eat”);

pro.setProperty(“hobby”,”sleep”);//替换值

String str=pro.getProperty(“name”);//取值

Set set=pro.stringPropertyNames();//像keySet获取 键值集合

for(String key:set){//遍历

System.out.println(key+”…”+pro.getProperty(key));

}

FileOutputStream fos=new FileOutputStream(“F:\\aaa.properties”,true);

//FileWriter fw = new FileWriter(“F:\\aaa.properties”,true);

pro.store(fos, “person information”); //(文件路径,添加理由)

//pro.store(fw,”save data”);

fos.close();//5，关闭流

}

//父类方法：

Properties prop = new Properties();

prop.put(“CZBK001”, “zhangsan”);//添加映射关系

Set keys = prop.keySet();

for (Object key : keys) {

Object value = prop.get(key);

System.out.println(key + “=” + value);

}

Set> entrys = prop.entrySet();

for (Map.Entry entry : entrys) {

Object key = entry.getKey();

Object value = entry.getValue();

System.out.println(key + “=” + value);

}

PrintWriter pw = new PrintWriter(“d.txt”);//打印流对象

prop.list(pw);

pw.close();//释放资源

Properties类JDBC从文件读取信息

public static Connection getConn(){

Connection conn=null; //不是局部

Properties pro=new Properties();

try{

FileInputStream fis=new FileInputStream(“src/pro.properties”);

pro.load(fis); //相对路径 正斜杠

Class.forName(pro.getProperty(“driverClass”));//点出try catch

String url=pro.getProperty(“url”);

String username=pro.getProperty(“username”);

String password=pro.getProperty(“password”);// 空

conn=DriverManager.getConnection(url, username, password);//点add catch

}

catch (ClassNotFoundException e) {e.printStackTrace();}

catch (SQLException e) {e.printStackTrace();}

catch (IOException e) {e.printStackTrace();}

return conn;

}

src/pro.properties文件：//无空格 密码空串(空格)

driverClass=com.mysql.jdbc.Driver

url=jdbc:mysql://localhost:3306/guanjiapo?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull

username=root

password=

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