实体类转Map、Map转实体类
1、创建entity（User.java）
package com.jeff.entity;
public class User {
private String userName;
private String password;
private Integer age;
public User() {
super();
}
public User(String userName, String password, Integer age) {
super();
this.userName = userName;
this.password = password;
this.age = age;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
@Override
public String toString() {
return "User [userName=" + userName + ", password=" + password + ", age=" + age + "]";
}
}2、创建utils（EntityUtils.java）
package com.jeff.utils;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;
public class EntityUtils {
public static Map<String, Object> entityToMap(Object object) {
Map<String, Object> map = new HashMap<>();
for (Field field : object.getClass().getDeclaredFields()) {
try {
boolean flag = field.isAccessible();
field.setAccessible(true);
Object o = field.get(object);
map.put(field.getName(), o);
field.setAccessible(flag);
} catch (Exception e) {
e.printStackTrace();
}
}
return map;
}
public static <T> T mapToEntity(Map<String, Object> map, Class<T> entity) {
T t = null;
try {
t = entity.newInstance();
for (Field field : entity.getDeclaredFields()) {
if (map.containsKey(field.getName())) {
boolean flag = field.isAccessible();
field.setAccessible(true);
Object object = map.get(field.getName());
if (object != null && field.getType().isAssignableFrom(object.getClass())) {
field.set(t, object);
}
field.setAccessible(flag);
}
}
return t;
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return t;
}
}3、创建Map转实体类（TestCopyObj3.java）
package com.jeff;
import java.util.HashMap;
import java.util.Map;
import com.jeff.entity.User;
import com.jeff.utils.EntityUtils;
public class TestCopyObj3 {
public static void main(String[] args) throws Exception {
Map<String, Object> map = new HashMap<String, Object>();
map.put("userName", "Jeff");
map.put("password", "123456");
map.put("age", 18);
System.out.println("Map对象：" + map);
User user = EntityUtils.mapToEntity(map, User.class);
System.out.println("User对象：" + user);
}
}4、控制台输出结果
5、创建实体类转Map（TestCopyObj4.java）
package com.jeff;
import java.util.Map;
import com.jeff.entity.User;
import com.jeff.utils.EntityUtils;
public class TestCopyObj4 {
public static void main(String[] args) throws Exception {
User user = new User("Jeff", "123456", 18);
System.out.println("User对象：" + user);
Map<String, Object> map = EntityUtils.entityToMap(user);
System.out.println("Map对象：" + map);
}
}
6、控制台输出结果
Map转实体类或List数组
因为做项目，需要取出复杂的map里的value转为实体类对象和List，在博客里找了很久没有找到合适的方法，于是只能默默探索。。。
map里包含了实体类，list数组，还有普通的key-value，取出我们想要的数据呢？直接取我是取不出来，后来想先转json，在从json里去出对象和list，然后就这么干，废话少说，撸代码！！！
1.先添加maven依赖，这里用alibaba的
<!--alibaba json -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.46</version>
</dependency>2.自己写的一个JsonUtil工具类
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import java.util.List;
import java.util.Map;
public class JsonUtil<T>{
public static JSONObject mapToJson(Map<String, Object> map) {
String data = JSON.toJSONString(map);
return JSON.parseObject(data);
}
public String mapToString(Map<String, Object> map, String key) {
JSONObject jsonObject = mapToJson(map);
return jsonObject.getString(key);
}
public static <T> T mapToObject(Map<String, Object> map, Class<T> clazz, String key) {
T t = null;
JSONObject jsonObject = mapToJson(map);
JSONObject object = jsonObject.getJSONObject(key);
t = object.toJavaObject(clazz);
return t;
}
public List<T> mapToList(Map<String, Object> map, Class<T> clazz, String key) {
List<T> t = null;
JSONObject jsonObject = mapToJson(map);
JSONArray array = jsonObject.getJSONArray(key);
t = array.toJavaList(clazz);
return t;
}
}3.用 postman 发送数据到后台
4.后台接收代码
@RequestMapping(value = "/subjects/subject", method = {RequestMethod.POST})
public Result addSubject(@RequestBody Map<String, Object> map) {
//使用json
JsonUtil jsonUtil = new JsonUtil();
//获取Subject对象
Subject subject = jsonUtil.mapToObject(map, Subject.class, "subject");
//获取List数组
List<Progress> progressList = jsonUtil.mapToList(map, Progress.class, "progress");
//获取key对应的值
String specid = jsonUtil.mapToString(map, "specid");
//打印输出
System.out.println(subject);
for(Progress progress : progressList) {
System.out.println(progress);
}
System.out.println(specid);
return null;
}5.后台输出
到此成功从map里取出对象，list，和key-value
以上为个人经验，希望能给大家一个参考，也希望大家多多支持编程网。
