这篇文章主要介绍了java 动态生成bean的案例,具有很好的参考价值,希望对大家有所帮助。一起跟随小编过来看看吧
最近做一个需求,需求中的bean只用于生成一次json使用,所以想通过配置来动态的生成,查了一下,java还真有这个实现。
java动态的生成javabean,只能生成属性和对应的set/get方法,不能生成其他的方法。import org.assertj.core.internal.cglib.beans.BeanGenerator;
import org.assertj.core.internal.cglib.beans.BeanMap;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
/**
* Created by wangpengzhi1 on 2018/1/2.
*/
public class BeanCeater {
public static void main(String[] args) throws ClassNotFoundException {
System.out.println("Generate JavaBean");
Map properties = new HashMap();
properties.put("id", Class.forName("java.lang.Integer"));
properties.put("name", Class.forName("java.lang.String"));
properties.put("address", Class.forName("java.lang.String"));
Object stu = generateObject(properties);
System.out.println("Set values");
setValue(stu, "id", 123);
setValue(stu, "name", "454");
setValue(stu, "address", "789");
System.out.println("Get values");
System.out.println(">> " + getValue(stu, "id"));
System.out.println(">> " + getValue(stu, "name"));
System.out.println(">> " + getValue(stu, "address"));
System.out.println("Show all methods");
Method[] methods = stu.getClass().getDeclaredMethods();
for(Method method : methods) {
System.out.println(">> " + method.getName());
}
System.out.println("Show all properties");
Field[] fields = stu.getClass().getDeclaredFields();
for(Field field : fields) {
System.out.println(">> " + field.getName());
}
}
private static Object generateObject(Map properties) {
BeanGenerator generator = new BeanGenerator();
Set keySet = properties.keySet();
for(Iterator i = keySet.iterator(); i.hasNext();) {
String key = (String)i.next();
generator.addProperty(key, (Class)properties.get(key));
}
return generator.create();
}
private static Object getValue(Object obj, String property) {
BeanMap beanMap = BeanMap.create(obj);
return beanMap.get(property);
}
private static void setValue(Object obj, String property, Object value) {
BeanMap beanMap = BeanMap.create(obj);
beanMap.put(property, value);
}
} 代码不难懂,有需要的自己复制。
补充:spring 工具类 ReflectionUtils 获取bean所有字段
以前遇到要获取当前类以及所有父类的的field的时候,都是递归一直往上找,一直到Object ,个人觉得这种方法是不是太low了,有没有更好的办法?或者jdk其实是有这种方法的,只是我不知道,今天看了下spring中的实现,也是一样的,真没有更好的办法?public static void doWithFields(Class<?> clazz, ReflectionUtils.FieldCallback fc, @Nullable ReflectionUtils.FieldFilter ff) {
Class targetClass = clazz;
do {
Field[] fields = getDeclaredFields(targetClass);
Field[] var5 = fields;
int var6 = fields.length;
for(int var7 = 0; var7 < var6; ++var7) {
Field field = var5[var7];
if (ff == null || ff.matches(field)) {
try {
fc.doWith(field);
} catch (IllegalAccessException var10) {
throw new IllegalStateException("Not allowed to access field '" + field.getName() + "': " + var10);
}
}
}
targetClass = targetClass.getSuperclass();
} while(targetClass != null && targetClass != Object.class);
}
private static Field[] getDeclaredFields(Class<?> clazz) {
Assert.notNull(clazz, "Class must not be null");
Field[] result = (Field[])declaredFieldsCache.get(clazz);
if (result == null) {
try {
result = clazz.getDeclaredFields();
declaredFieldsCache.put(clazz, result.length == 0 ? NO_FIELDS : result);
} catch (Throwable var3) {
throw new IllegalStateException("Failed to introspect Class [" + clazz.getName() + "] from ClassLoader [" + clazz.getClassLoader() + "]", var3);
}
}
return result;
} 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CodeAE代码之家。如有错误或未考虑完全的地方,望不吝赐教。
原文链接:https://blog.csdn.net/wangpengzhi19891223/article/details/78949572
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