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本文总结:Java 通过反射设置对象属性值,或者获取对象属性值,编码过程中反射结合泛型使用可以代码复用,减少冗余代码;
食用建议:配合场景案例食用更佳;
设置/获取属性
实体类对象:
@AllArgsConstructor
@NoArgsConstructor
@Data
public class StudentScore {
/**
* 名称
*/
private String name;
/**
* 科目
*/
private String subject;
/**
* 成绩
*/
private Integer score;
}
方式一
通过Field操作属性:
public void method1() throws Exception {
Class<StudentScore> cls = StudentScore.class;
StudentScore obj = new StudentScore();
StudentScore obj2 = new StudentScore();
/*
* 设置属性
*/
Field nameField = cls.getDeclaredField("name");
nameField.setAccessible(true);
nameField.set(obj, "张三");
Field subjectField = cls.getDeclaredField("subject");
subjectField.setAccessible(true);
subjectField.set(obj, "语文");
Field scoreField = cls.getDeclaredField("score");
scoreField.setAccessible(true);
scoreField.set(obj, 100);
/*
* 获取属性
*/
Field[] fields = cls.getDeclaredFields();
for (Field field : fields) {
String s = Modifier.toString(field.getModifiers());
// 排除final修饰的属性
if (!s.contains("final")) {
field.setAccessible(true);
// 通过filed获取设置属性
System.out.printf("获取属性值,当前属性:%s,值:%s%n", field.getName(), field.get(obj));
// obj对象属性值赋值给obj2
field.set(obj2, field.get(obj));
}
}
System.out.println("method1 obj:" + JSONObject.toJSONString(obj));
System.out.println("method1 obj2:" + JSONObject.toJSONString(obj2));
}
运行结果:
方式二
通过set方法:
public void method2() throws Exception {
Class<StudentScore> cls = StudentScore.class;
StudentScore obj = new StudentScore();
/*
* 设置属性
*/
Method setName = cls.getMethod("setName", String.class);
setName.invoke(obj, "李四");
Method setSubject = cls.getMethod("setSubject", String.class);
setSubject.invoke(obj, "语文");
Method setScore = cls.getMethod("setScore", Integer.class);
setScore.invoke(obj, 114);
/*
* 获取属性
*/
Method getName = cls.getMethod("getName");
System.out.printf("获取属性值,当前属性:%s,值:%s%n", "name", getName.invoke(obj));
Method getSubject = cls.getMethod("getSubject");
System.out.printf("获取属性值,当前属性:%s,值:%s%n", "subject", getSubject.invoke(obj));
Method getScore = cls.getMethod("getScore");
System.out.printf("获取属性值,当前属性:%s,值:%s%n", "score", getScore.invoke(obj));
System.out.println("method2:" + JSONObject.toJSONString(obj));
}
运行结果:
方式三
通过属性名:
public void method3() throws Exception {
Class<StudentScore> cls = StudentScore.class;
StudentScore obj = new StudentScore();
/*
* 设置属性
*/
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, "语文");
PropertyDescriptor scorePd = new PropertyDescriptor("score", cls);
Method scoreMethod = scorePd.getWriteMethod();
scoreMethod.invoke(obj, 127);
/*
* 获取属性
*/
Method nameRead = namePd.getReadMethod();
System.out.printf("获取属性值,当前属性:%s,值:%s%n", "name", nameRead.invoke(obj));
Method subjectRead = subjectPd.getReadMethod();
System.out.printf("获取属性值,当前属性:%s,值:%s%n", "subject", subjectRead.invoke(obj));
Method scoreRead = scorePd.getReadMethod();
System.out.printf("获取属性值,当前属性:%s,值:%s%n", "score", scoreRead.invoke(obj));
System.out.println("method3:" + JSONObject.toJSONString(obj));
}
运行结果:
场景案例
场景:学生查询自己的语文考试成绩;
学生成绩对象实体类:
/**
* 学生成绩实体
*/
@AllArgsConstructor
@NoArgsConstructor
@Data
public class StudentScore {
/**
* 名称
*/
private String name;
/**
* 科目
*/
private String subject;
/**
* 成绩
*/
private Integer score;
}
学生对象实体类:
/**
* 学生-张三
*/
@Data
public class StudentZS extends StudentScore {
}
/**
* 学生-李四
*
*/
@Data
public class StudentLS extends StudentScore {
}
/**
* 学生-王五
*/
@Data
public class StudentWW extends StudentScore {
}
测试:文章来源:https://www.toymoban.com/news/detail-732210.html
@Test
public void testDemo() {
StudentZS student1 = new StudentZS();
student1.setName("张三");
scoreSystem(student1, StudentZS.class);
System.out.println("张三查询成绩结果:" + JSONObject.toJSONString(student1));
StudentLS student2 = new StudentLS();
student2.setName("李四");
scoreSystem(student2, StudentLS.class);
System.out.println("李四查询成绩结果:" + JSONObject.toJSONString(student2));
StudentWW student3 = new StudentWW();
student3.setName("王五");
scoreSystem(student3, StudentWW.class);
System.out.println("王五查询成绩结果:" + JSONObject.toJSONString(student3));
}
/**
* 成绩系统
*
* @param t 学生
* @param cls 学生类
* @param <T> 泛型
*/
public <T> void scoreSystem(T t, Class<T> cls) {
// 给传入对象赋值名称
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 "张三":
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, "语文");
Field scoreField = superclass.getDeclaredField("score");
scoreField.setAccessible(true);
scoreField.set(t, schoolReport);
} catch (Exception e) {
e.printStackTrace();
}
}
运行结果:
文章来源地址https://www.toymoban.com/news/detail-732210.html
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