打印流以及Properties

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打印流以及Properties

字节打印流

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import java.io.*;
import java.nio.charset.StandardCharsets;

/**
 * @author zss
 */
public class Test {
    public static void main(String[] args) throws IOException  {
        PrintStream out=System.out;
        //默认打印在显示器上
        out.println("join,hello");
        //out底层调用的是write，所以可以直接调用write进行输出
        out.write("你好啊".getBytes(StandardCharsets.UTF_8));
        //我们也可以更改打印的位置
        System.setOut(new PrintStream("D:\\文件下载\\hello.txt"));
        //在文件中显示
        System.out.println("hello");
        out.close();
    }
}

字符打印流

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import java.io.*;
import java.nio.charset.StandardCharsets;

/**
 * @author zss
 */
public class Test {
    public static void main(String[] args) throws IOException  {
        PrintWriter printWriter=new PrintWriter(new FileWriter("D:\\文件下载\\hello.txt"));
        printWriter.println("你好啊");
        printWriter.close();
    }
}

Properties

传统方法

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import java.io.*;

/**
 * @author zss
 */
public class Test {
    public static void main(String[] args) throws IOException  {
        BufferedReader bufferedReader=new BufferedReader( new FileReader("src\\Information.properties"));
        String line;
        while ((line=bufferedReader.readLine())!=null){
            String []split=line.split("=");
            System.out.println(split[0]+"的值"+split[1]);
        }
        bufferedReader.close();
    }
}

image-20220703171201137

使用Properties类

专门用于读写配置文件的集合类，配置文件的格式：

键=值，键值对不需要有空格，值不需要用引号，默认为String类

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import java.io.*;
import java.util.Properties;

/**
 * @author zss
 */
public class Test {
    public static void main(String[] args) throws IOException  {
        //创建Properties类来读取文件
        Properties properties=new Properties();
        //加载指定配置的文件
        properties.load(new FileReader("src\\Information.properties"));
        //KV显示在控制台
        properties.list(System.out);
        //根据key获取相应的值
        String user= properties.getProperty("user");
        System.out.println(user);
        //修改相应的文件
        properties.setProperty("password","55555");
        properties.list(System.out);
        
    }
}

image-20220703171313929

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import java.io.*;
import java.util.Properties;

/**
 * @author zss
 */
public class Test {
    public static void main(String[] args) throws IOException  {
        //创建Properties类来读取文件
        Properties properties=new Properties();
        properties.setProperty("password","55555");
        properties.setProperty("user","zss");
        properties.setProperty("id","11");
        //注释效果
        properties.store(new FileOutputStream("src\\test.properties"),"hello");

    }

}

image-20220703171913787

练习

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import java.io.*;
import java.util.Properties;

/**
 * @author zss
 */
public class Test {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        Properties properties=new Properties();
        properties.load(new FileReader("src\\test.properties"));
        Employee employee=new Employee(properties.getProperty("user"),Integer.parseInt(properties.getProperty("id")), properties.getProperty("password") );
        System.out.println(employee);
        ObjectOutputStream objectOutputStream=new ObjectOutputStream(new FileOutputStream("D:\\文件下载\\test.dat"));
        objectOutputStream.writeObject(employee);
        objectOutputStream.close();
        ObjectInputStream objectInputStream=new ObjectInputStream(new FileInputStream("D:\\文件下载\\test.dat"));
        Employee employee1=(Employee) objectInputStream.readObject();
        System.out.println(employee1);
        objectInputStream.close();

    }
}
class  Employee implements Serializable{
    String user;
    int id;
    String password;

    public Employee(String user, int id, String password) {
        this.user = user;
        this.id = id;
        this.password = password;
    }

    @Override
    public String toString() {
        return "Employee{" +
                "user='" + user + '\'' +
                ", id=" + id +
                ", password='" + password + '\'' +
                '}';
    }
}


image-20220703171940795