Map转实体类

项目中遇到过这样一个问题，sql查询出来的结果是一个Map<String,Object>，需要将map中对应的值放置到对应的实体类中，map中的key与实体类中的属性名一样。在属性值很少的时候，我们可以简单的取出值在set进实体类中，但是项目中一个类属性值可能有几十个，一个一个set的话会很麻烦，于是简答写一个转换的工具。

1.Model类

package com.boai.springboot2_learning.Model;

import java.time.LocalDate;
import java.time.LocalDateTime;

public class Student {

    private Integer id;
    private String name;
    private Integer age;
    private LocalDate birth;
    private LocalDateTime updateTime;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public LocalDate getBirth() {
        return birth;
    }

    public void setBirth(LocalDate birth) {
        this.birth = birth;
    }

    public LocalDateTime getUpdateTime() {
        return updateTime;
    }

    public void setUpdateTime(LocalDateTime updateTime) {
        this.updateTime = updateTime;
    }

    @Override
    public String toString() {
        final StringBuilder sb = new StringBuilder("{");
        sb.append("\"id\":")
                .append(id);
        sb.append(",\"name\":\"")
                .append(name).append('\"');
        sb.append(",\"age\":")
                .append(age);
        sb.append(",\"birth\":")
                .append(birth);
        sb.append(",\"updateTime\":")
                .append(updateTime);
        sb.append('}');
        return sb.toString();
    }
}

2.反射方法类

package com.boai.springboot2_learning.Util;

import com.boai.springboot2_learning.Model.Student;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.Date;
import java.sql.Timestamp;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.*;

public class ReflectUtil {

    public static Object getFidleValueFromObject(Object object, String fieldName) {
        Class<?> clazz = object.getClass();
        String getterName = String.format("get%c%s",
                Character.toUpperCase(fieldName.charAt(0)), fieldName.substring(1));
        System.out.println("方法名：" + getterName);
        Object value = null;
        try {
            Method method = clazz.getMethod(getterName);
            value = method.invoke(object, null);
        } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
            e.printStackTrace();
        }
        return value;
    }

    private static String getSetterMethodName(String fieldName) {
        String setterName = String.format("set%c%s",
                Character.toUpperCase(fieldName.charAt(0)), fieldName.substring(1));
        return setterName;
    }

    public static void setObjectFieldValue(Object object, Object value, String fieldName) {
        Class<?> clazz = object.getClass();
        String methodName = getSetterMethodName(fieldName);
        Method method;
        try {
            if (value != null) {
                method = clazz.getMethod(methodName, value.getClass());
                method.invoke(object, value);
            }
        } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
            e.printStackTrace();
        }
    }

    public static List<String> getFieldNames(Class clazz) {
        Field[] fields = clazz.getDeclaredFields();
        ArrayList<String> fieldNames = new ArrayList<>();
        Arrays.stream(fields).forEach(field -> fieldNames.add(field.getName()));
        return fieldNames;
    }

    public static void mapToObject(Object object, Map<String, Object> map) {
        Class<?> clazz = object.getClass();
        List<String> fieldNames = getFieldNames(clazz);
        fieldNames.stream().forEach(fieldName -> {
            Object o = map.get(fieldName);
            if (o != null) {
                if (o instanceof java.sql.Date) {
                    o = ((Date) o).toLocalDate();
                } else if (o instanceof Timestamp) {
                    o = ((Timestamp) o).toLocalDateTime();
                }
                setObjectFieldValue(object, o, fieldName);
            }
        });
    }

    public static void main(String[] args) {
        Student student = new Student();
        Map<String, Object> map = new HashMap<String, Object>() {
            {
                put("id", 123);
                put("name", "newName");
                put("age", 23);
                put("birth", LocalDate.now());
                put("updateTime", LocalDateTime.of(2019, 3, 30, 16, 9, 8));
            }
        };
        mapToObject(student, map);
        System.out.println(student.toString());
        System.out.println(student.getUpdateTime().format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
    }
}

这里面只涉及到 部分值的类型转换，并没有写全部可能情况的类型转换，这里要根据实际情况进行处理;