通過輸入流輸出流,反射對log4j對象獲取

新建女孩類
public class Girl implements Serializable {

//transient修飾的屬性不能被序列化
private transient String name;
private String gender;
private int age;

public Girl() {
}

public Girl(String name, String gender, int age) {
    this.name = name;
    this.gender = gender;
    this.age = age;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getGender() {
    return gender;
}

public void setGender(String gender) {
    this.gender = gender;
}

public int getAge() {
    return age;
}

public void setAge(int age) {
    this.age = age;
}

@Override
public String toString() {
    return "Girl{" +
            "name='" + name + '\'' +
            ", gender='" + gender + '\'' +
            ", age=" + age +
            '}';
}

}
從Properties文件中讀數據

  @Test
void test1() throws IOException {
    // Properties類:對 Properties文件操作的類
    Properties properties = new Properties();
    //加載文件//路徑
    FileReader fileReader = new           FileReader("src/main/resources/a.properties");
    properties.load(fileReader);
    //獲取數據
    String name = properties.getProperty("a.name");
    System.out.println("name=" + name);
    //獲取數據,如果key不存在,返回默認值
    System.out.println(properties.getProperty("height", "180"));

    System.out.println(properties.propertyNames());
    //獲取所有的key
    System.out.println(properties.stringPropertyNames());
    //遍歷properties文件的內容
    for (String Key : properties.stringPropertyNames()) {
        String value = properties.getProperty(Key);
        System.out.printf("%s=%s\n", Key, value);
    }
}

通過Properties生成對象,默認log4j 通過配置文件產生對象

@Test
void test2() throws IOException {
    // Properties類:對 Properties文件操作的類
    final Properties properties = new Properties();
    //加載文件//路徑
    FileReader fileReader = new FileReader("src/main/resources/log4j.properties");
    properties.load(fileReader);

獲取指定key的value值

      String zoo = properties.getProperty("zoo");
    System.out.println(zoo);

獲取所有動物的名,用逗號隔開

    String[] strings = zoo.split(",");
    System.out.println(Arrays.toString(strings));
    Stream.of(strings).skip(1).forEach(x -> {
        String classname = properties.getProperty(x + ".class");
        try {
            Class<?> aClass = Class.forName(classname);
            Constructor<?> constructor = aClass.getConstructor();
            Object o = constructor.newInstance();
            String nickname = properties.getProperty(x + ".nickname");
            //
            Method nicknameMethod = aClass.getMethod("setNickname", String.class);
            nicknameMethod.invoke(o, nickname);

            int weight = Integer.parseInt(properties.getProperty(x + ".weight"));
            Method weightMethod = aClass.getMethod("setWeight", int.class);
            weightMethod.invoke(o, weight);
            System.out.println(o);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();

        }
    });
    
}

//

向Properties文件中寫數據

@Test
void test3() throws IOException {
    Properties properties = new Properties();
    properties.setProperty("a", "456");
    properties.setProperty("b", "56");

    FileWriter fileWriter = new FileWriter("src/main/resources/b.properties", true);//在後面添加,不是覆蓋
    properties.store(fileWriter, "第一次提交:");
}

@Test
void test4() throws IOException {
    //創建一個Girl對象,並把對象存入文件666
    Girl girl = new Girl("李若彤", "女", 19);

    ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("src/main/resources/666"));
    objectOutputStream.writeObject(girl);
}

@Test
void Test5() throws IOException, ClassNotFoundException {
    FileInputStream fileInputStream = new FileInputStream("src/main/resources/666");
    ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
    Object o = objectInputStream.readObject();
    if (o instanceof Girl) {
        Girl girl = (Girl) o;
        System.out.println(girl);
    }

}