先来说一下模型驱动，在struts2的默认拦截器栈struts-default包中有一个 ModelDriverInterceptor拦截器，如果有我们的action实现ModerDriver接口，即可实现模型驱动。action如下代码
public abstract class BaseAction<T> extends ActionSupport implements ModelDriven<T>,SessionAware,ServletRequestAware{
/** model 的支持 */
protected T model;
public void setModel(T model) {
this.model = model;
}
public BaseAction() {
ParameterizedType genericSuperclass = (ParameterizedType) this.getClass().getGenericSuperclass();
Class<T> clazz=(Class<T>) (genericSuperclass.getActualTypeArguments()[0]);
try {
model=clazz.newInstance();
log.info("BaseAction model:"+model);
} catch (Exception e) {
//throw new RuntimeException(e);
}
}
@Override
public T getModel() {
return model;
}<br />//部分代码省略<br />}</pre>
从代码上看，每次都new了一个对象， 如果我们用 XXXService.update(model)的话，会将空值、默认值也会更新进去，显示这不是我们想要的。
，可以采用这一种方式：先通过id查找到这个对象，然后将model的非空属性赋值给这个对象，最后更新对象。
public String edit() throws Exception {
log.info("修改用户："+model);
User u=userService.getById(model.getId());
if (StrUtils.notNull(model.getPassword())) {
model.setPassword(DigestUtils.md5Hex(model.getPassword()));
}
BeanUtils.copyNotNullProperties(model, u);
userService.update(u);
//省略部分代码...
}
最后上一个BeanUtils工具类：
package core.utils;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.FatalBeanException;
import org.springframework.util.Assert;
/**
- 扩展 spring 的 BeanUtils，增加拷贝属性排除 null 值的功能(注：String 为 null 不考虑)
- 扩展 Apache Commons BeanUtils, 提供一些反射方面缺失功能的封装.
- @author shollin
/
public class BeanUtils extends org.springframework.beans.BeanUtils {
/* logger. */
private static Logger logger = LoggerFactory.getLogger(BeanUtils.class);
/** getter prefix length. */
public static final int LENGTH_GETTER_PREFIX = "get".length();
/** 保护的构造方法. */
protected BeanUtils() {
}
public static void copyNotNullProperties(Object source, Object target, String[] ignoreProperties) throws BeansException {
copyNotNullProperties(source, target, null, ignoreProperties);
}
public static void copyNotNullProperties(Object source, Object target, Class<?> editable) throws BeansException {
copyNotNullProperties(source, target, editable, null);
}
public static void copyNotNullProperties(Object source, Object target) throws BeansException {
copyNotNullProperties(source, target, null, null);
}
private static void copyNotNullProperties(Object source, Object target, Class<?> editable, String[] ignoreProperties) throws BeansException {
Assert.notNull(source, "Source must not be null");
Assert.notNull(target, "Target must not be null");
Class<?> actualEditable = target.getClass();
if (editable != null) {
if (!editable.isInstance(target)) {
throw new IllegalArgumentException("Target class [" + target.getClass().getName() + "] not assignable to Editable class [" + editable.getName() + "]");
}
actualEditable = editable;
}
PropertyDescriptor[] targetPds = getPropertyDescriptors(actualEditable);
List<String> ignoreList = (ignoreProperties != null) ? Arrays.asList(ignoreProperties) : null;
for (PropertyDescriptor targetPd : targetPds) {
if (targetPd.getWriteMethod() != null && (ignoreProperties == null || (!ignoreList.contains(targetPd.getName())))) {
PropertyDescriptor sourcePd = getPropertyDescriptor(source.getClass(), targetPd.getName());
if (sourcePd != null && sourcePd.getReadMethod() != null) {
try {
Method readMethod = sourcePd.getReadMethod();
if (!Modifier.isPublic(readMethod.getDeclaringClass().getModifiers())) {
readMethod.setAccessible(true);
}
Object value = readMethod.invoke(source);
if (value != null || readMethod.getReturnType().getName().equals("java.lang.String")) {// 这里判断以下value是否为空，当然这里也能进行一些特殊要求的处理 例如绑定时格式转换等等，如果是String类型，则不需要验证是否为空
boolean isEmpty = false;
if (value instanceof Set) {
Set s = (Set) value;
if (s == null || s.isEmpty()) {
isEmpty = true;
}
} else if (value instanceof Map) {
Map m = (Map) value;
if (m == null || m.isEmpty()) {
isEmpty = true;
}
} else if (value instanceof List) {
List l = (List) value;
if (l == null || l.size() < 1) {
isEmpty = true;
}
} else if (value instanceof Collection) {
Collection c = (Collection) value;
if (c == null || c.size() < 1) {
isEmpty = true;
}
}
if (!isEmpty) {
Method writeMethod = targetPd.getWriteMethod();
if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers())) {
writeMethod.setAccessible(true);
}
writeMethod.invoke(target, value);
}
}
} catch (Throwable ex) {
throw new FatalBeanException("Could not copy properties from source to target", ex);
}
}
}
}
}
/**
* 循环向上转型,获取对象的DeclaredField.
*
* @param object
* 对象实例
* @param propertyName
* 属性名
* @return 返回对应的Field
* @throws NoSuchFieldException
* 如果没有该Field时抛出
*/
public static Field getDeclaredField(Object object, String propertyName)
throws NoSuchFieldException {
Assert.notNull(object);
Assert.hasText(propertyName);
return getDeclaredField(object.getClass(), propertyName);
}
/**
* 循环向上转型,获取对象的DeclaredField.
*
* @param clazz
* 类型
* @param propertyName
* 属性名
* @return 返回对应的Field
* @throws NoSuchFieldException
* 如果没有该Field时抛出.
*/
public static Field getDeclaredField(Class clazz, String propertyName)
throws NoSuchFieldException {
Assert.notNull(clazz);
Assert.hasText(propertyName);
for (Class superClass = clazz; superClass != Object.class; superClass = superClass
.getSuperclass()) {
try {
return superClass.getDeclaredField(propertyName);
} catch (NoSuchFieldException ex) {
// Field不在当前类定义,继续向上转型
logger.debug(ex.getMessage(), ex);
}
}
throw new NoSuchFieldException("No such field: " + clazz.getName()
+ '.' + propertyName);
}
/**
* 暴力获取对象变量值,忽略private,protected修饰符的限制.
*
* @param object
* 对象实例
* @param propertyName
* 属性名
* @return 强制获得属性值
* @throws NoSuchFieldException
* 如果没有该Field时抛出.
*/
public static Object forceGetProperty(Object object, String propertyName)
throws NoSuchFieldException, IllegalAccessException {
return getFieldValue(object, propertyName, true);
}
public static Object safeGetFieldValue(Object object, String fieldName) {
return safeGetFieldValue(object, fieldName, true);
}
public static Object safeGetFieldValue(Object object, String fieldName,
boolean targetAccessible) {
try {
return getFieldValue(object, fieldName, targetAccessible);
} catch (NoSuchFieldException ex) {
logger.warn("", ex);
} catch (IllegalAccessException ex) {
logger.warn("", ex);
}
return null;
}
public static Object getFieldValue(Object object, String fieldName)
throws NoSuchFieldException, IllegalAccessException {
return getFieldValue(object, fieldName, false);
}
public static Object getFieldValue(Object object, String fieldName,
boolean targetAccessible) throws NoSuchFieldException,
IllegalAccessException {
Assert.notNull(object);
Assert.hasText(fieldName);
Field field = getDeclaredField(object, fieldName);
boolean accessible = field.isAccessible();
field.setAccessible(targetAccessible);
Object result = field.get(object);
field.setAccessible(accessible);
return result;
}
/**
* 暴力设置对象变量值,忽略private,protected修饰符的限制.
*
* @param object
* 对象实例
* @param propertyName
* 属性名
* @param newValue
* 赋予的属性值
* @throws NoSuchFieldException
* 如果没有该Field时抛出.
*/
public static void forceSetProperty(Object object, String propertyName,
Object newValue) throws NoSuchFieldException,
IllegalAccessException {
setFieldValue(object, propertyName, newValue, true);
}
public static void safeSetFieldValue(Object object, String fieldName,
Object newValue) {
safeSetFieldValue(object, fieldName, newValue, true);
}
public static void safeSetFieldValue(Object object, String fieldName,
Object newValue, boolean targetAccessible) {
try {
setFieldValue(object, fieldName, newValue, targetAccessible);
} catch (NoSuchFieldException ex) {
logger.warn("", ex);
} catch (IllegalAccessException ex) {
logger.warn("", ex);
}
}
public static void setFieldValue(Object object, String propertyName,
Object newValue, boolean targetAccessible)
throws NoSuchFieldException, IllegalAccessException {
Assert.notNull(object);
Assert.hasText(propertyName);
Field field = getDeclaredField(object, propertyName);
boolean accessible = field.isAccessible();
field.setAccessible(targetAccessible);
field.set(object, newValue);
field.setAccessible(accessible);
}
/**
* 暴力调用对象函数,忽略private,protected修饰符的限制.
*
* @param object
* 对象实例
* @param methodName
* 方法名
* @param params
* 方法参数
* @return Object 方法调用返回的结果对象
* @throws NoSuchMethodException
* 如果没有该Method时抛出.
*/
public static Object invokePrivateMethod(Object object, String methodName,
Object... params) throws NoSuchMethodException,
IllegalAccessException, InvocationTargetException {
return invokeMethod(object, methodName, true, params);
}
public static Object safeInvokeMethod(Object object, Method method,
Object... params) {
try {
return method.invoke(object, params);
} catch (IllegalAccessException ex) {
logger.warn("", ex);
} catch (InvocationTargetException ex) {
logger.warn("", ex);
}
return null;
}
public static Object safeInvokeMethod(Object object, String methodName,
Object... params) {
try {
return invokeMethod(object, methodName, params);
} catch (NoSuchMethodException ex) {
logger.warn("", ex);
} catch (IllegalAccessException ex) {
logger.warn("", ex);
} catch (InvocationTargetException ex) {
logger.warn("", ex);
}
return null;
}
public static Object invokeMethod(Object object, String methodName,
Object... params) throws NoSuchMethodException,
IllegalAccessException, InvocationTargetException {
return invokeMethod(object, methodName, false, params);
}
public static Object invokeMethod(Object object, String methodName,
boolean targetAccessible, Object... params)
throws NoSuchMethodException, IllegalAccessException,
InvocationTargetException {
Assert.notNull(object);
Assert.hasText(methodName);
Class[] types = new Class[params.length];
for (int i = 0; i < params.length; i++) {
types[i] = params[i].getClass();
}
Class clazz = object.getClass();
Method method = null;
for (Class superClass = clazz; superClass != Object.class; superClass = superClass
.getSuperclass()) {
try {
method = superClass.getDeclaredMethod(methodName, types);
break;
} catch (NoSuchMethodException ex) {
// 方法不在当前类定义,继续向上转型
logger.debug(ex.getMessage(), ex);
}
}
if (method == null) {
throw new NoSuchMethodException("No Such Method : "
+ clazz.getSimpleName() + "." + methodName
+ Arrays.asList(types));
}
boolean accessible = method.isAccessible();
method.setAccessible(targetAccessible);
Object result = method.invoke(object, params);
method.setAccessible(accessible);
return result;
}
/**
* 按Field的类型取得Field列表.
*
* @param object
* 对象实例
* @param type
* 类型
* @return 属性对象列表
*/
public static List<Field> getFieldsByType(Object object, Class type) {
List<Field> list = new ArrayList<Field>();
Field[] fields = object.getClass().getDeclaredFields();
for (Field field : fields) {
if (field.getType().isAssignableFrom(type)) {
list.add(field);
}
}
return list;
}
/**
* 按FieldName获得Field的类型.
*
* @param type
* 类型
* @param name
* 属性名
* @return 属性的类型
* @throws NoSuchFieldException
* 指定属性不存在时，抛出异常
*/
public static Class getPropertyType(Class type, String name)
throws NoSuchFieldException {
return getDeclaredField(type, name).getType();
}
/**
* 获得field的getter函数名称.
*
* @param type
* 类型
* @param fieldName
* 属性名
* @return getter方法名
* @throws NoSuchFieldException
* field不存在时抛出异常
*
* @todo: 使用reflectUtils里的方法更合适，这里的实现方式，必须先有field才能有method，逻辑上有问题 实际上，即使没有field也可以单独有method。
*/
public static String getGetterName(Class type, String fieldName)
throws NoSuchFieldException {
Assert.notNull(type, "Type required");
Assert.hasText(fieldName, "FieldName required");
Class fieldType = getDeclaredField(type, fieldName).getType();
if ((fieldType == boolean.class) || (fieldType == Boolean.class)) {
return "is" + StrUtils.capitalize(fieldName);
} else {
return "get" + StrUtils.capitalize(fieldName);
}
}
/**
* 获得field的getter函数,如果找不到该方法,返回null.
*
* @param type
* 类型
* @param fieldName
* 属性名
* @return getter方法对象
*/
public static Method getGetterMethod(Class type, String fieldName) {
try {
return type.getMethod(getGetterName(type, fieldName));
} catch (NoSuchMethodException ex) {
logger.error(ex.getMessage(), ex);
} catch (NoSuchFieldException ex) {
logger.error(ex.getMessage(), ex);
}
return null;
}
public static String getFieldName(String methodName) {
String fieldName = methodName.substring(LENGTH_GETTER_PREFIX);
return fieldName.substring(0, 1).toLowerCase() + fieldName.substring(1);
}
}
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