package com.jdk.annotation.demo;
public class Person {
private String name;
private int age;
//入学日期
@ReqAnnotation(isDateType=true)
private String entranceDate;
//数学分数
private double mathScore;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getEntranceDate() {
return entranceDate;
}
public void setEntranceDate(String entranceDate) {
this.entranceDate = entranceDate;
}
public double getMathScore() {
return mathScore;
}
public void setMathScore(double mathScore) {
this.mathScore = mathScore;
}
}
package com.jdk.annotation.demo;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface ReqAnnotation {
//传入参数的名称
String name() default "";
//是否为dateString类型
boolean isDateType() default false;
//时间格式
String dateFormat() default "yyyy-MM-dd HH:mm:ss";
}
package com.jdk.annotation.demo;
import java.lang.reflect.Field;
import javax.servlet.http.HttpServletRequest;
//request转换成bean工具类
public class ConvertHelper {
//将request中的值转换成bean对象
@SuppressWarnings("unchecked")
public static <T> T convertRequestToBean(HttpServletRequest request, Class<T> clazz) throws InstantiationException, IllegalAccessException{
Object object = clazz.newInstance();
//获取目标类所有的字段
Field [] fields = clazz.getDeclaredFields();
for (Field field : fields) {
//取消语言的检查，能够访问非公有的属性
field.setAccessible(true);
String reqName = field.getName();
ReqAnnotation reqAnnotation = field.getAnnotation(ReqAnnotation.class);
//判断这个字段是否添加了注解
boolean isDate = false;
String dateFormat = "";
if (reqAnnotation != null) {
if (StringHelper.isNotEmpty(reqAnnotation.name())) {
/**
* 这步操作是避免，当页面的变量名称与bean中的变量名称不一致的时候，
* 在bean字段上的用@RequestAnnotation(name=页面变量名称)
*/
reqName = reqAnnotation.name();
}
if (StringHelper.isNotEmpty(reqAnnotation.dateFormat())) {
/**
* 当日期的格式转换成非"yyyy-MM-dd HH:mm:ss"格式时，
* 只需要在日期字段上添加@RequestAnnotation(dateFormat=需要的格式)
*/
dateFormat = reqAnnotation.dateFormat();
}
//如果bean中的这个字段注释为isDateType=true,在数据填充是将进行时间格式化做铺垫
isDate = reqAnnotation.isDateType();
}
//获取字段的类型
Class<?> clazzType = field.getType();
String dateValue = request.getParameter(reqName);
if (StringHelper.isNotEmpty(dateValue)) {
if (clazzType == String.class) {
if (isDate) {
/*
* 当字段中使用@RequestAnnotation(isDateType=true)
*/
field.set(object, ConvertTypeHelper.getDate(dateValue, dateFormat));
} else {
field.set(object, dateValue);
}
} else if (clazzType == Integer.class) {
field.set(object, ConvertTypeHelper.getInteger(dateValue));
} else if (clazzType == int.class) {
field.set(object, ConvertTypeHelper.getInt(dateValue));
} else if (clazzType == double.class) {
field.set(object, ConvertTypeHelper.getDouble(dateValue));
} else if (clazzType == Double.class) {
field.set(object, ConvertTypeHelper.getDDoubleWapper(dateValue));
} else if (clazzType == long.class) {
field.set(object, ConvertTypeHelper.getLong(dateValue));
} else if (clazzType == Long.class) {
field.set(object, ConvertTypeHelper.getLongWapper(dateValue));
} else if (clazzType == float.class) {
field.set(object, ConvertTypeHelper.getFloat(dateValue));
} else if (clazzType == Float.class) {
field.set(object, ConvertTypeHelper.getFloatWapper(dateValue));
}
}
}
return (T)object;
}
}
package com.jdk.annotation.demo;
public class StringHelper {
public static boolean isNotEmpty(String str) {
boolean bool = false;
if (str != null && str.trim().length() > 0) {
bool = true;
}
return bool;
}
}
package com.jdk.annotation.demo;
import java.text.ParseException;
import java.text.SimpleDateFormat;
/**
*
* 字段类型转换工具类
*
*/
public class ConvertTypeHelper {
public static String getDate(String date, String dateFormat) {
SimpleDateFormat format = new SimpleDateFormat(dateFormat);
String retDate = null;
try {
retDate = format.format(format.parse(date));
} catch (ParseException e) {
e.printStackTrace();
}
return retDate;
}
public static Integer getInteger(String str) {
return Integer.valueOf(str);
}
public static int getInt(String str) {
return Integer.parseInt(str);
}
public static long getLong(String str) {
return Long.parseLong(str);
}
public static Long getLongWapper(String str) {
return Long.valueOf(str);
}
public static double getDouble(String str) {
return Double.parseDouble(str);
}
public static Double getDDoubleWapper(String str) {
return Double.valueOf(str);
}
public static float getFloat(String str) {
return Float.parseFloat(str);
}
public static float getFloatWapper(String str) {
return Float.valueOf(str);
}
}
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>将requst转换为bean demo</title>
<style type="text/css">
tr {
width: 100px;
}
</style>
</head>
<body>
<form action="../annoServlet" method="post">
<table>
<tr>
<td>姓名</td>
<td><input type="text" name="name"/></td>
</tr>
<tr>
<td>年龄</td>
<td><input type="text" name="age"/></td>
</tr>
<tr>
<td>入学日期</td>
<td><input type="text" name="entranceDate"/></td>
</tr>
<tr>
<td>数学分数</td>
<td><input type="text" name="mathScore"/></td>
</tr>
<tr>
<td>提交</td>
<td><input type="submit"/></td>
</tr>
</table>
</form>
</body>
</html>
package com.jdk.annotation.demo;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class annoServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
Person person = ConvertHelper.convertRequestToBean(request, Person.class);
System.out.println("name:"+person.getName()+"\r\n age:"+person.getAge()+"\r\n entranceDate:"+
person.getEntranceDate()+"\r\n mathScore:"+person.getMathScore());
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
}
前段输入和后端打印结果
1、当如果后端的接受日期格式要换成yyyy-MM-dd时，只需要在person类中在entranceDate字段上加上dateFormat="yyyy-MM-dd"，并不需要在手动去转换
//入学日期 @ReqAnnotation(isDateType=true, dateFormat="yyyy-MM-dd") private String entranceDate;
2.当jsp中的名称与bean的名称不一致（比如jsp中personName表示人的名称，而person类中name字段表示人的名称），前段的personName值是不能赋给person中name上
但是这里可以通过在person类中name字段上添加@ReqAnnotation(name="personName")，这样就能成功将前段输入personName值赋值给person中name字段上
@ReqAnnotation(name="personName") private String name;
评论