反射应用！

public static String getUpdate(Object obj) throws IllegalArgumentException, IllegalAccessException{
Class<? extends Object>classll=obj.getClass();
String sql="Update "+classll.getSimpleName()+" set ";
String sql2=" ";
String sql3=" where ";
Field[] field=classll.getDeclaredFields();
for(Field f:field){
f.setAccessible(true);
Object value = f.get(obj);

if(f.isAnnotationPresent(PrimaryKey.class)){

if(value instanceof String){
sql3 +=f.getName()+"='"+value+"'";
}else{
sql3 +=f.getName()+"="+value+"";
}
}else if(!f.isAnnotationPresent(NonField.class)){
if(value instanceof String){
sql2 +=f.getName()+"='"+value+"',";
}else{
sql2 +=f.getName()+"="+value+", ";
}
}
}
sql2 = sql2.substring(0,sql2.length()-2);
sql=sql+sql2+sql3;
return sql;
}

Userinfo u=new Userinfo();
u.setUsername(" 成都");
u.setUserpwd(" 张山");
u.setUserquan("123");
String userInfoSQL = null;
try {
userInfoSQL = BeanUtil.getUpdate(u);
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(userInfoSQL);

package com.gxa.bj.util;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface NonField {

}

//通过反射区获取相应的类的一些定义
Class classzz=Person.class;
//另外一种获取Class对象的方法
Person p=new Person();
Class classzz2=p.getClass();
System.out.println("类的名称:"+classzz.getSimpleName());
Field[] fields=classzz.getDeclaredFields();//获取定义的字段
for(Field f : fields){
Class c=f.getType();//字段
if(c.getPackage()!=null){
if(c.getPackage().getName().equals("com.gxa.bj.test")){
System.out.println(c.getPackage().getName());
System.out.println("字段类型:"+c.getName());
System.out.println("该字段的名字:"+f.getName());
}
}
}

public static void main(String[] args) {
// TODO Auto-generated method stub
Person p=new Person();
p.setAge(12);
p.setName(" 张三 ");
Class<? extends Object> classzz = p.getClass();
//通过反射去获取字段的值
Field[] f = classzz.getDeclaredFields();
for(Field field :f){
String methodName="get"+field.getName().substring(0,1).toUpperCase()+field.getName().substring(1);
try {
Method m=classzz.getDeclaredMethod(methodName);
Object o = null;
try {
o = m.invoke(p);
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if(o!=null){
System.out.println("方法名:"+methodName+",方法值:"+o);
}
} catch (NoSuchMethodException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

}