map与java bean相互转换

1. 使用org.apache.commons.beanutils转换

pom.xml

<dependency>
    <groupId>commons-beanutilsgroupId>
    <artifactId>commons-beanutilsartifactId>
    <version>1.9.4version>
dependency>

//map转java对象
public static Object mapToObject(Map<String, Object> map, Class<?> beanClass)
			throws Exception {
		if (map == null) {
			return null;
		}
		Object obj = beanClass.newInstance();
		BeanUtils.populate(obj, map);
		return obj;
	}
 
//java对象转map
public static Map<?, ?> objectToMap(Object obj) {
		if (obj == null)
			return null;
		return new BeanMap(obj);
	}

可能出现的错误
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/collections/Transformer
解决方法案例

package com.example2.pojo;
 
import java.util.Map;
import java.util.Set;
 
import org.apache.commons.beanutils.BeanMap;
 
public class PojoToMap {
 
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		Employee employee = new Employee();
		employee.setName("张三");
		employee.setAge(30);
		Map map;
		try {
			map = objectToMap(employee);
			Set<Map.Entry<String, Object>> set = map.entrySet();
			for (Map.Entry<String, Object> entry : set) {
				System.out.println(entry.getKey() + " : " + entry.getValue());
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	public static Map<?, ?> objectToMap(Object obj) {
		if (obj == null)
			return null;
		return new BeanMap(obj);
	}
}

package com.example2.pojo;
 
public class Employee {
 
	private String name;
	private Integer age;
	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;
	}
}

从报错信息上看，是缺少了org.apache.commons.collections.Transformer类，网上下载了commons-collections-3.2.1.jar包，引入后，重新执行，即可。

2. 使用Introspector转换

//map转java对象
public static Object mapToObject(Map<String, Object> map, Class<?> beanClass) throws Exception {
        if (map == null)
            return null;
        Object obj = beanClass.newInstance();
        BeanInfo beanInfo = Introspector.getBeanInfo(obj.getClass());
        PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
        for (PropertyDescriptor property : propertyDescriptors) {
            Method setter = property.getWriteMethod();
            if (setter != null) {
                setter.invoke(obj, map.get(property.getName()));
            }
        }
        return obj;
    }
 
//java对象转map
public static Map<String, Object> objectToMap(Object obj) throws Exception {
	if (obj == null) {
		return null;
	}
	Map<String, Object> map = new HashMap<String, Object>();
	BeanInfo beanInfo = Introspector.getBeanInfo(obj.getClass());
	PropertyDescriptor[] propertyDescriptors = beanInfo
				.getPropertyDescriptors();
	for (PropertyDescriptor property : propertyDescriptors) {
		String key = property.getName();
		if (key.compareToIgnoreCase("class") == 0) {
			continue;
		}
		Method getter = property.getReadMethod();
		Object value = getter != null ? getter.invoke(obj) : null;
		map.put(key, value);
	}
	return map;
}

3. 使用reflect转换

//map转java对象
public static Object mapToObject(Map<String, Object> map, Class<?> beanClass) throws Exception {
        if (map == null) {
            return null;
        }
        Object object = beanClass.newInstance();
        Field[] fields = beanClass.getDeclaredFields();
        for (Field field : fields) {
            int mod = field.getModifiers();
            if (Modifier.isFinal(mod) || Modifier.isStatic(mod)) {
                continue;
            }
            field.setAccessible(true);
            field.set(object, map.get(field.getName()));
        }
        return object;
    }
 
//java对象转map
public static Map<String, Object> objectToMap(Object obj) throws Exception {
	if (obj == null) {
		return null;
	}
	Map<String, Object> map = new HashMap<String, Object>();
	Field[] declaredFields = obj.getClass().getDeclaredFields();
	for (Field field : declaredFields) {
		field.setAccessible(true);
		map.put(field.getName(), field.get(obj));
	}
	return map;
}

4. 使用net.sf.cglib.beans.BeanMap转换

//map转java对象
public static Object mapToObject(Map<String, Object> map, Class<?> beanClass) throws Exception {
    Object object = beanClass.newInstance();
    BeanMap beanMap = BeanMap.create(object);
    beanMap.putAll(map);
    return object;
}
 
//java对象转map
public static Map<String, Object> objectToMap(Object obj) {
    Map<String, Object> map = Maps.newHashMap();
    if (obj != null) {
        BeanMap beanMap = BeanMap.create(obj);
        for (Object key : beanMap.keySet()) {
            map.put(key + "", beanMap.get(key));
        }
    }
    return map;
}

可能出现的错误
Exception in thread "main" java.lang.NoClassDefFoundError: org/objectweb/asm/Type
解决案例

package com.example2.pojo;
 
import java.util.HashMap;
import java.util.Map;
 
import net.sf.cglib.beans.BeanMap;
 
public class MapToPojo {
 
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		Map<String, Object> map = new HashMap<String, Object>();
		map.put("name", "张三");
		map.put("age", 30);
		try {
			Employee employee = (Employee) mapToBean(map, Employee.class);
			System.out.print(employee.toString());
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
    public static Object mapToBean(Map<String, Object> map, Class<?> beanClass) throws Exception {
    	Object object = beanClass.newInstance();
        BeanMap beanMap = BeanMap.create(object);
        beanMap.putAll(map);
        return object;
    }
 
}

package com.example2.pojo;
 
public class Employee {
 
	private String name;
	private Integer age;
	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;
	}
	@Override
	public String toString() {
		return "Employee [name=" + name + ", age=" + age + "]";
	}
}

从错误信息上看，是缺少了org.objectweb.asm.Type类，那么找一个就OK了，从网上下载了com.springsource.org.objectweb.asm-3.2.0.jar包，引入后，再次执行，即可。
补充：其实项目中已引入的spring-core-4.1.7.RELEASE.jar包中也已经集成了cglib模块，如图：

引用这个包里的BeanMap类也可以，
import org.springframework.cglib.beans.BeanMap;
执行后，达到同样效果。

5. 使用fastjson转换

pom.xml

<dependency>
    <groupId>com.alibabagroupId>
    <artifactId>fastjsonartifactId>
    <version>1.2.78version>
dependency>

//map转java对象
public static Object mapToObject(Map<String, Object> map, Class<?> beanClass) throws Exception {
    String jsonStr = JSONObject.toJSONString(map);
    return JSONObject.parseObject(jsonStr, beanClass);
}
 
//java对象转map
public static Map<String, Object> objectToMap(Object obj) {
    String jsonStr = JSONObject.toJSONString(obj);
    return JSONObject.parseObject(jsonStr);
}