cn.easyutil.project.base.sqlExecuter.LamdbaUtil Maven / Gradle / Ivy
package cn.easyutil.project.base.sqlExecuter;
import cn.easyutil.project.base.bean.Page;
import cn.easyutil.project.base.sqlExecuter.annotation.TableField;
import cn.easyutil.util.javaUtil.StringUtil;
import java.io.Serializable;
import java.lang.invoke.SerializedLambda;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
public class LamdbaUtil {
public static void main(String[] args) {
SQLExecuter.build(null).eq(Page::getTotalPage,"123");
System.out.println();
}
/**
* 获取表达式方法中的字段名
* @param fun 表达式
* @return
*/
public static String getFieldName(LambdaFunction fun){
return getFieldName(fun,true);
}
/**
* 获取表达式方法中的字段名
* @param fun 表达式
* @param conver 是否驼峰转下划线
* @return
*/
public static String getFieldName(LambdaFunction fun, boolean conver) {
Field field = getField(fun);
if(field == null){
return null;
}
TableField an = field.getDeclaredAnnotation(TableField.class);
if(an != null){
if(!StringUtil.isEmpty(an.value())){
return an.value();
}
if(!StringUtil.isEmpty(an.name())){
return an.name();
}
}
if(conver){
return StringUtil.conversionMapUnderscore(field.getName());
}
return field.getName();
}
private static Field getField(LambdaFunction fun){
SerializedLambda lambda = getSerializedLambda(fun);
// 获取方法名
String methodName = lambda.getImplMethodName();
String fieldName = null;
if(methodName.startsWith("get")){
fieldName = methodName.substring(3);
}else if(methodName.startsWith("is")){
fieldName = methodName.substring(2);
}
if(fieldName == null){
return null;
}
fieldName = fieldName.toUpperCase();
String className = lambda.getImplClass().replace("/", ".");
Field field = null;
try {
Class aClass = Class.forName(className);
Class clazz = aClass;
while (clazz != Object.class){
Field[] fields = aClass.getDeclaredFields();
for (Field f : fields) {
if(f.getName().toUpperCase().equals(fieldName)){
return f;
}
}
clazz = clazz.getSuperclass();
}
}catch (Exception e){
e.printStackTrace();
}
return null;
}
/**
* 关键在于这个方法
*/
public static SerializedLambda getSerializedLambda(Serializable fn) {
// 提取SerializedLambda并缓存
try {
Method method = fn.getClass().getDeclaredMethod("writeReplace");
method.setAccessible(Boolean.TRUE);
return (SerializedLambda) method.invoke(fn);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
}