Java注解动态解析获取方法参数值
/**
* @author wangdi
* @date 21-9-2
*/
@Component
@Slf4j
public class ResolverKit {
private static final String PREFIX = "#{";
private static final String SUBFIX = "}";
/**
* @param contextEL 带表达式的内容
* 举例："用户名：+#{}+，用户密码：+#{}+，用户年龄：+#{}+，手机号：+#{}"
* 注意：支持map对象获取key()，但是不支持在对象中嵌套map()
* @param proceedingJoinPoint
* @return
*/
public StringBuffer resolverContent(String contextEL, ProceedingJoinPoint proceedingJoinPoint) {
try {
StringBuffer context = new StringBuffer();
/**
* 文字+#{}+，+#{}+#{}+.
* 拆分
*
* 文字
* #{}
* ，
* #{}
* #{}
* .
*/
if (contextEL.contains(PREFIX) && contextEL.contains(SUBFIX) && contextEL.contains("+")) {
List<String> strings = Arrays.asList(contextEL.split("\\+"));
for (String s : strings) {
if (s.contains(PREFIX) && s.contains(SUBFIX)) {
// 解析表达式
String spel = s.substring(s.indexOf(PREFIX) + PREFIX.length(), s.lastIndexOf(SUBFIX));
context.append(resolverExpression(spel, proceedingJoinPoint));
} else {
// 不需要解析
context.append(s);
}
}
} else {
context.append(contextEL);
}
return context;
} catch (Exception e) {
log.error("表达式解析错误, 请检查@Log注解");
return null;
}
}
/**
* 解析表达式(可嵌套两层)
*
* @param expression 举例： #{} #{} #{}
* @param proceedingJoinPoint
* @return
*/
private String resolverExpression(String expression, ProceedingJoinPoint proceedingJoinPoint) throws NoSuchFieldException, IllegalAccessException {
String first = null;
String second = null;
String third = null;
if (expression.contains(".")) {
List<String> list = Arrays.asList(expression.split("\\."));
if (list.size() > 3) throw new RuntimeException("不支持三个变量以上的表达式: " + expression);
for (int i = 0; i < list.size(); i++) {
if (0 == i) first = list.get(i);
if (1 == i) second = list.get(i);
if (2 == i) third = list.get(i);
}
} else {
first = expression;
}
//获取参数值
Object[] args = proceedingJoinPoint.getArgs();
//获取运行时参数的名称
Method method = ((MethodSignature) proceedingJoinPoint.getSignature()).getMethod();
//获取参数值类型
Class<?>[] parameterTypes = method.getParameterTypes();
//获取参数值的数据
String[] parameterNames = new DefaultParameterNameDiscoverer().getParameterNames(method);
for (int i = 0; i < parameterNames.length; i++) {
Class<?> parameterType = parameterTypes[i];
String parameterName = parameterNames[i];
Object parameterValue = args[i];
if (first.equals(parameterName)) {
if (null == second) {
return (String) parameterValue;
}
if (null != second) {
//
if (parameterValue instanceof Map<?, ?>) {
return (String) ((Map) parameterValue).get(second);
} else {
return (String) getFieldValue(parameterValue, second + (null != third ? "." + third : ""));
}
}
}
}
return null;
}
/**
* 通过反射取对象指定字段(属性)的值
*
* @param target 目标对象
* @param fieldName 字段的名字
* @return 字段的值
*/
private Object getFieldValue(Object target, String fieldName) throws NoSuchFieldException, IllegalAccessException {
Class<?> clazz = target.getClass();
String[] fs = fieldName.split("\\.");
try {
for (int i = 0; i < fs.length - 1; i++) {
Field f = clazz.getDeclaredField(fs[i]);
f.setAccessible(true);
target = f.get(target);
if (null == target) {
// 嵌套内容中为null的返回null, 防止报错
return null;
}
clazz = target.getClass();
}
Field f = clazz.getDeclaredField(fs[fs.length - 1]);
f.setAccessible(true);
return f.get(target);
} catch (Exception e) {
throw e;
}
}
}