Java 获取Object对象中的某个List对象,并获取里面的值
java">package com.java;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
public class test1 {
public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {
User user = new User(1,"张三");
User user2 = new User(2,"李四");
List<User> users = new ArrayList<>();
users.add(user);
users.add(user2);
Teacher teacher = new Teacher(1,users);
System.out.println(teacher.toString());
test1 test1 = new test1();
test1.getUserList(teacher);
}
public void getUserList(Object object) throws NoSuchFieldException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {
Field field = object.getClass().getDeclaredField("users");
field.setAccessible(true);
Class clazz = field.get(object).getClass();
Method m= clazz.getDeclaredMethod("size");
int size = (Integer) m.invoke(field.get(object));
for (int i = 0; i < size; i++) {//遍历list,调用get方法,获取list中的对象实例
Method getM= clazz.getDeclaredMethod("get", int.class);
if(!getM.isAccessible()){
getM.setAccessible(true);
}
Object invoke = getM.invoke(field.get(object), i);
Field id = invoke.getClass().getDeclaredField("id");
Field username = invoke.getClass().getDeclaredField("username");
id.setAccessible(true);
username.setAccessible(true);
System.out.println(id.get(invoke).toString());
System.out.println(username.get(invoke).toString());
}
}
}
class Teacher{
private int id;
private List<User> users;
public Teacher() {
}
public Teacher(int id, List<User> users) {
this.id = id;
this.users = users;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public List<User> getUsers() {
return users;
}
public void setUsers(List<User> users) {
this.users = users;
}
@Override
public String toString() {
return "Teacher{" +
"id=" + id +
", users=" + users +
'}';
}
}
class User{
private int id;
private String username;
public User(int id, String username) {
this.id = id;
this.username = username;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
'}';
}
}