Java反射設置/獲取對象屬性值三種方式

更新時間：2023年11月07日 09:30:14 作者：zhuzicc

這篇文章主要給大家介紹了關于Java反射設置/獲取對象屬性值的三種方式,反射機制的用途非常多,比如獲取方法,屬性名和屬性值等,甚至可以獲取標簽等標簽屬性,需要的朋友可以參考下

設置/獲取屬性

實體類對象：

@AllArgsConstructor
@NoArgsConstructor
@Data
public class StudentScore {
    /**
     * 名稱
     */
    private String name;
    /**
     * 科目
     */
    private String subject;
    /**
     * 成績
     */
    private Integer score;
}

方式一

通過Field操作屬性：

public void method1() throws Exception {
        Class<StudentScore> cls = StudentScore.class;
        StudentScore obj = new StudentScore();
        StudentScore obj2 = new StudentScore();
        /*
         * 設置屬性
         */
        Field nameField = cls.getDeclaredField("name");
        nameField.setAccessible(true);
        nameField.set(obj, "張三");

        Field subjectField = cls.getDeclaredField("subject");
        subjectField.setAccessible(true);
        subjectField.set(obj, "語文");

        Field scoreField = cls.getDeclaredField("score");
        scoreField.setAccessible(true);
        scoreField.set(obj, 100);

        /*
         * 獲取屬性
         */
        Field[] fields = cls.getDeclaredFields();
        for (Field field : fields) {
            String s = Modifier.toString(field.getModifiers());
            // 排除final修飾的屬性
            if (!s.contains("final")) {
                field.setAccessible(true);
                // 通過filed獲取設置屬性
                System.out.printf("獲取屬性值，當前屬性：%s，值：%s%n", field.getName(), field.get(obj));
                // obj對象屬性值賦值給obj2
                field.set(obj2, field.get(obj));
            }
        }
        System.out.println("method1 obj：" + JSONObject.toJSONString(obj));
        System.out.println("method1 obj2：" + JSONObject.toJSONString(obj2));
    }

運行結果：

方式二

通過set方法：

public void method2() throws Exception {
        Class<StudentScore> cls = StudentScore.class;
        StudentScore obj = new StudentScore();

        /*
         * 設置屬性
         */
        Method setName = cls.getMethod("setName", String.class);
        setName.invoke(obj, "李四");

        Method setSubject = cls.getMethod("setSubject", String.class);
        setSubject.invoke(obj, "語文");

        Method setScore = cls.getMethod("setScore", Integer.class);
        setScore.invoke(obj, 114);

        /*
         * 獲取屬性
         */
        Method getName = cls.getMethod("getName");
        System.out.printf("獲取屬性值，當前屬性：%s，值：%s%n", "name", getName.invoke(obj));
        Method getSubject = cls.getMethod("getSubject");
        System.out.printf("獲取屬性值，當前屬性：%s，值：%s%n", "subject", getSubject.invoke(obj));
        Method getScore = cls.getMethod("getScore");
        System.out.printf("獲取屬性值，當前屬性：%s，值：%s%n", "score", getScore.invoke(obj));
        System.out.println("method2：" + JSONObject.toJSONString(obj));
    }

運行結果：

方式三

通過屬性名：

public void method3() throws Exception {
        Class<StudentScore> cls = StudentScore.class;
        StudentScore obj = new StudentScore();
        /*
         * 設置屬性
         */
        PropertyDescriptor namePd = new PropertyDescriptor("name", cls);
        Method writeMethod = namePd.getWriteMethod();
        writeMethod.invoke(obj, "王五");

        PropertyDescriptor subjectPd = new PropertyDescriptor("subject", cls);
        Method subjectMethod = subjectPd.getWriteMethod();
        subjectMethod.invoke(obj, "語文");

        PropertyDescriptor scorePd = new PropertyDescriptor("score", cls);
        Method scoreMethod = scorePd.getWriteMethod();
        scoreMethod.invoke(obj, 127);

        /*
         * 獲取屬性
         */
        Method nameRead = namePd.getReadMethod();
        System.out.printf("獲取屬性值，當前屬性：%s，值：%s%n", "name", nameRead.invoke(obj));
        Method subjectRead = subjectPd.getReadMethod();
        System.out.printf("獲取屬性值，當前屬性：%s，值：%s%n", "subject", subjectRead.invoke(obj));
        Method scoreRead = scorePd.getReadMethod();
        System.out.printf("獲取屬性值，當前屬性：%s，值：%s%n", "score", scoreRead.invoke(obj));
        System.out.println("method3：" + JSONObject.toJSONString(obj));
    }

運行結果：

場景案例

場景：學生查詢自己的語文考試成績；

學生成績對象實體類:

/**
 * 學生成績實體
 */
@AllArgsConstructor
@NoArgsConstructor
@Data
public class StudentScore {
    /**
     * 名稱
     */
    private String name;
    /**
     * 科目
     */
    private String subject;
    /**
     * 成績
     */
    private Integer score;
}

學生對象實體類：

/**
 * 學生-張三
 */
@Data
public class StudentZS extends StudentScore {
}
/**
 * 學生-李四
 *
 */
@Data
public class StudentLS extends StudentScore {
}
/**
 * 學生-王五
 */
@Data
public class StudentWW extends StudentScore {
}

測試：

@Test
public void testDemo() {
    StudentZS student1 = new StudentZS();
    student1.setName("張三");
    scoreSystem(student1, StudentZS.class);
    System.out.println("張三查詢成績結果：" + JSONObject.toJSONString(student1));

    StudentLS student2 = new StudentLS();
    student2.setName("李四");
    scoreSystem(student2, StudentLS.class);
    System.out.println("李四查詢成績結果：" + JSONObject.toJSONString(student2));

    StudentWW student3 = new StudentWW();
    student3.setName("王五");
    scoreSystem(student3, StudentWW.class);
    System.out.println("王五查詢成績結果：" + JSONObject.toJSONString(student3));
}

/**
  * 成績系統(tǒng)
  *
  * @param t   學生
  * @param cls 學生類
  * @param <T> 泛型
  */
public <T> void scoreSystem(T t, Class<T> cls) {
    // 給傳入對象賦值名稱
    try {
        Class<? super T> superclass = cls.getSuperclass();
        Field nameField = superclass.getDeclaredField("name");
        Type genericType = nameField.getGenericType();
        String typeName = genericType.getTypeName();
        assert "java.lang.String".equals(typeName);
        nameField.setAccessible(true);
        String studentName = nameField.get(t).toString();
        int schoolReport = 0;
        switch (studentName) {
            case "張三":
                schoolReport = 100;
                break;
            case "李四":
                schoolReport = 114;
                break;
            case "王五":
                schoolReport = 127;
                break;
        }
        Field subjectField = superclass.getDeclaredField("subject");
        subjectField.setAccessible(true);
        subjectField.set(t, "語文");
        Field scoreField = superclass.getDeclaredField("score");
        scoreField.setAccessible(true);
        scoreField.set(t, schoolReport);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

運行結果：