多条件复杂查询，不知具体有多少个条件，一个一个判断代码冗长，只想取出有值的条件，拼接到sql上，比如有个User类，有属性name,id， 当只有id有值时，返回"and id =xxxx"
用法，将自己的bean对象继承ParameterBaseUtils，用this.gainConditionFromObjectByField()即可
package cn.com.suntree.cmp.utils;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
public class ParameterBaseUtils {
/**
* 返回有的值条件,比如有个User类，有属性name,id
* 当只有id有值时，返回and id ={id的值}
*
* @return
* @throws
* @author ld
* @date 2019/02/11 14:13
*/
public String gainConditionFromObjectByField() {
StringBuffer sb = new StringBuffer();
Field[] fields = this.getClass().getDeclaredFields();//取出所有属性
for (int i = 0; i < fields.length; i++) {
Field f = fields[i];
String fieldName = f.getName();
Object value = getFieldValue(this, fieldName);//取属性值
if (CommonUtil.check(value)) {
Class<?> type = f.getType();
if ("class java.lang.String".equals(type.toString())) {
sb.append(" and " + fieldName + "='" + value + "'");
} else {
sb.append(" and " + fieldName + "=" + value);
}
}
continue;
}
return sb.toString();
}
private String getFieldValue(Object owner, String fieldName) {
Object o = invokeMethod(owner, fieldName, null);
if (CommonUtil.check(o)) {
return o.toString();
}
return null;
}
/**
* 执行某个Field的getField方法
*
* @param owner 类
* @param fieldName 类的属性名称
* @param args 参数，默认为null
* @return
*/
private Object invokeMethod(Object owner, String fieldName, Object[] args) {
Class<? extends Object> ownerClass = owner.getClass();
//fieldName -> FieldName
String methodName = fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1);
Method method = null;
try {
method = ownerClass.getMethod("get" + methodName);
} catch (SecurityException e) {
//e.printStackTrace();
} catch (NoSuchMethodException e) {
// e.printStackTrace();
return "";
}
//invoke getMethod
try {
return method.invoke(owner);
} catch (Exception e) {
return "";
}
}
}
