一、需求描述
我们开发过程中遇到过JSON字符串数据赋值到实体对象的属性，一个实体类中可能包含我们之前封装好的实体对象，比如Person.java里面包含Home home，Home.java有String Address，有自定义的Room room属性，然后需要一个这样的字符串给Person赋值
String jsonString = "name:李明,higher:12,age:32,date:2022-04-09 10-20-21,home.room.size:12,home.address:河北省邯郸市";
之前单级别的类我们可以通过ObjectMapper、Gson去转化到实体类，但是现在是是多级的赋值，我们可以做一个赋值的工厂
二、实际操作一下
Person类
package com.attributeAssignMent;
import java.util.Date;
/**
* @author zhr_java@163.com
* @date 2022/4/9 17:01
*/
public class Person {
private String name;
private String higher;
private Integer age;
private Date date;
private Home home;
@Override
public String toString() {
return "Person{" +
"name='" + name + '\'' +
", higher='" + higher + '\'' +
", age=" + age +
", date=" + date +
", home=" + home +
'}';
}
public Home getHome() {
return home;
}
public void setHome(Home home) {
this.home = home;
}
public Date getDate() {
return date;
}
public void setDate(Date date) {
this.date = date;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getHigher() {
return higher;
}
public void setHigher(String higher) {
this.higher = higher;
}
}
Home类
package com.attributeAssignMent;
/**
* @author zhr_java@163.com
* @date 2022/4/10 17:39
*/
public class Home {
private String address;
private Room room;
@Override
public String toString() {
return "Home{" +
"address='" + address + '\'' +
", room=" + room +
'}';
}
public Room getRoom() {
return room;
}
public void setRoom(Room room) {
this.room = room;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
Room类
package com.attributeAssignMent;
/**
* @author zhr_java@163.com
* @date 2022/4/10 17:40
*/
public class Room {
private String size;
@Override
public String toString() {
return "Room{" +
"size='" + size + '\'' +
'}';
}
public String getSize() {
return size;
}
public void setSize(String size) {
this.size = size;
}
}
StringUtils类
package com.attributeAssignMent;
/**
* @author zhr_java@163.com
* @date 2022/4/9 17:03
*/
public class StringUtils {
public static String initcap(String string) {
if (string.equals("") || string == null) {
return string;
}
if (string.length() == 1) {
return string.toUpperCase();
} else {
return string.substring(0, 1).toUpperCase() + string.substring(1);
}
}
}
BeanUtils类
package com.attributeAssignMent;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
* @author zhr_java@163.com
* @date 2022/4/9 17:07
*/
public class BeanUtils {
public static void setValue(Object obj, String value) {
String result[] = value.split(",");
for (int i = 0; i < result.length; i++) {
Object currentObj = obj;
Object currentObjBefore = obj;
String attribute[] = result[i].split(":");
// 添加try防止获取不到属性对象而终止操作
try {
// 判断属性名称里面是否有点，如果有点的话就应该是联级
if (attribute[0].contains(".")) {
String temp[] = attribute[0].split("\\.");
// 最后一个该赋值了
for (int o = 0; o < temp.length - 1; o++) {
Field field = currentObj.getClass().getDeclaredField(temp[o]);
Method getMethod =
currentObj.getClass().getDeclaredMethod("get" + StringUtils.initcap(temp[o]));
Method setMethod =
currentObj
.getClass()
.getDeclaredMethod("set" + StringUtils.initcap(temp[o]), field.getType());
// 判断该属性未实例化
if (getMethod.invoke(currentObj) == null) {
// 创建一个实例
currentObj = field.getType().getDeclaredConstructor().newInstance();
setMethod.invoke(currentObjBefore, currentObj);
currentObjBefore = currentObj;
} else {
currentObj = getMethod.invoke(currentObj);
}
}
// 获取成员，这里是为了要获取属性的类型
Field field = currentObj.getClass().getDeclaredField(temp[temp.length - 1]);
System.out.println(field);
Method method =
currentObj
.getClass()
.getDeclaredMethod(
"set" + StringUtils.initcap(temp[temp.length - 1]), field.getType());
System.out.println(method);
Object attributeValue = BeanUtils.convertParam(field.getType().getName(), attribute[1]);
// 调用方法
method.invoke(currentObj, attributeValue);
} else {
// 根据属性名获取属性对象
Field field = obj.getClass().getDeclaredField(attribute[0]);
// 获取属性对应的set方法
Method method =
obj.getClass()
.getDeclaredMethod("set" + StringUtils.initcap(attribute[0]), field.getType());
Object attributeValue = convertParam(field.getType().getName(), attribute[1]);
// 给对象里面的属性赋值
method.invoke(obj, attributeValue);
}
} catch (Exception e) {
}
}
}
/**
* 根据类中的属性更改传入属性的类型,此处建议根据实际开发来扩展，建议先把基本的八大类型扩展出来
*
* @param attType 属性类型
* @param value 属性值
* @return
*/
public static Object convertParam(String attType, String value) {
if ("double".equals(attType) || "java.lang.Double".equals(attType)) {
return Double.parseDouble(value);
} else if ("int".equals(attType) || "java.lang.Integer".equals(attType)) {
return Integer.parseInt(value);
} else if ("java.util.Date".equals(attType)) {
SimpleDateFormat time;
if (value.matches("\\d{4}-\\d{2}-\\d{2}")) {
time = new SimpleDateFormat("yyyy-MM-dd");
} else if (value.matches("\\d{2}-\\d{2}-\\d{2}")) {
time = new SimpleDateFormat("HH-mm-ss");
} else if (value.matches("\\d{4}-\\d{2}-\\d{2} \\d{2}-\\d{2}-\\d{2}")) {
time = new SimpleDateFormat("yyyy-MM-dd HH-mm-ss");
} else {
return new Date();
}
try {
return time.parse(value);
} catch (ParseException e) {
e.printStackTrace();
return new Date();
}
} else {
return value;
}
}
}
ClassInstanceFactory类
package com.attributeAssignMent;
/**
* @author zhr_java@163.com
* @date 2022/4/9 17:20
*/
public class ClassInstanceFactory {
public ClassInstanceFactory() {}
/**
* 实例化对象的创建方法：该对象可以根据传入的字符串结构"属性：内容，属性：内容"
*
* @param clazz 要被赋值的目标对象
* @param value 目标对象被赋的值
* @param <T> 所有类型对象
* @return 已经被赋值后的目标对象
*/
public static <T> T create(Class<?> clazz, String value) {
try {
// 通过目标对象的无参构造实例化
Object obj = clazz.getDeclaredConstructor().newInstance();
//通过反射设置属性
BeanUtils.setValue(obj,value);
return (T) obj;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
}
Test类
package com.attributeAssignMent;
/**
* @author zhr_java@163.com
* @date 2022/4/9 17:33
*/
public class Test {
public static void main(String[] args) {
//测试单级赋值
String jsonString = "name:李明,higher:12,age:32,date:2022-04-09 10-20-21,home.room.size:12,home.address:河北省邯郸市";
Person person = ClassInstanceFactory.create(Person.class,jsonString);
System.out.println(person.toString());
}
}
效果图：
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