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。
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
|
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？
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
|
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服务器之家。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