DWR3.0实现对象的传递

在本例中，列举了从页面传递单个对象/对象集合/对象map集合到服务端；以及页面从服务端获取单个对象/对象集合/对象map集合/单个对象的string形式/多个对象的string形式的方法。关于使用多个对象的string形式，下文会有说明。

新建Dynamic Web Project工程，工程名为dwr3test。

复制DWR3最新的类库到/WEB-INF/lib内。

web.xml内容如下：

<?xml version="1.0" encoding="UTF-8"?>

<web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<description>DWR controller servlet</description>

<servlet-name>DWR controller servlet</servlet-name>

<servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class>

<init-param>

<param-name>classes</param-name>

<param-value>

entity.Student,

service.DwrService

</param-value>

</init-param>

<init-param>

<param-name>debug</param-name>

<param-value>true</param-value>

</init-param>

</servlet>

<servlet-mapping>

<servlet-name>DWR controller servlet</servlet-name>

<url-pattern>/dwr/*</url-pattern>

</servlet-mapping>

</web-app>

用于dwr传递的Student对象，内容如下：

package entity;

import java.io.Serializable;

import org.directwebremoting.annotations.DataTransferObject;

import org.directwebremoting.annotations.RemoteProperty;

@DataTransferObject

public class Student implements Serializable {

private static final long serialVersionUID = -5350994043280204179L;

public Student(){}

public Student(String oid,String name){

this.oid=oid;

this.name=name;

}

@RemoteProperty

private String oid;

@RemoteProperty

private String name;

public String getOid() {

return oid;

}

public void setOid(String oid) {

this.oid = oid;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

@Override

public String toString() {

StringBuilder sb=new StringBuilder();

sb.append("oid: ");

sb.append(this.oid);

sb.append("/nname:");

sb.append(this.name);

return sb.toString();

}

用于实现dwr的服务端内容如下：

package service;

import java.io.Serializable;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.LinkedHashMap;

import java.util.List;

import java.util.Map;

import java.util.Set;

import mydesign.dwr.DwrObjTransferManager;

import org.directwebremoting.annotations.RemoteMethod;

import org.directwebremoting.annotations.RemoteProxy;

import entity.Student;

@RemoteProxy

public class DwrService implements Serializable {

private static final long serialVersionUID = -3257953602189665211L;

@RemoteMethod

public Student addStudent(Student student){

return student;

}

@RemoteMethod

public String addAryStudents(List<Student> aryStu){

for(Student stu : aryStu){

System.out.println(stu);

}

return "成功";

}

@RemoteMethod

public String addMapStudents(LinkedHashMap<String,Student> mapStu){

Set<String> keys= mapStu.keySet();

Iterator<String>iterator= keys.iterator();

while(iterator.hasNext()){

String key=iterator.next();

Student stu=mapStu.get(key);

System.out.println("key: "+key);

System.out.println(stu);

}

return "成功";

}

@RemoteMethod

public Student getStudent(String oid) throws Exception{

if(oid.equals("1"))

throw new Exception("wwww wrong");

else

return genStudent();

}

@RemoteMethod

public List<Student> getLstStudents(){

List<Student>lst=new ArrayList<Student>();

lst.add(genStudent());

return lst;

}

@RemoteMethod

public Map<String,Student> getMapStudents(){

Map<String,Student> map=new LinkedHashMap<String,Student>();

map.put("first",genStudent());

return map;

}

@RemoteMethod

public String getArrayInString(){

Student[] studs=new Student[2];

studs[0]=new Student("1","abc");

studs[1]=new Student("2","xyz");

String result=DwrObjTransferManager.decorator(new String[]{"oid","name"}, studs);

return result;

}

@RemoteMethod

public String getSingleInString(){

return "{oid:'1',name:'abc'}";

}

@RemoteMethod

public String getDwrService(){

return this.toString();

}

private Student genStudent(){

return new Student("2","aaa");

}

DwrObjTransferManager对象是用于将一个对象数组生成字符串。返回到jsp页面时通过eval('('+ data + ')')的方式获取对象数组。它的好处在于如果对象的属性太多，但在页面只需要其中的几个属性，则无须通过DWR的反射方式来获取整个对象的信息。而且如果对象数组的量大时，DWR的方式会很耗时间的。现在人为的指定需要用到的属性，则会节约好多时间。它采用装饰者模式的设计思想。Decorate方法返回的格式是“[{ 属性名:属性值, 属性名:属性值...},{ 属性名:属性值, 属性名:属性值...}...]”,如果属性值是字符串,则将有’’套着属性值的内容。这个对象的内容如下：

package mydesign.dwr;

import java.lang.reflect.Field;

import entity.Student;

public class DwrObjTransferManager {

/**

* @param fieldNames:属性名

* @param objects:对象集合

* @return

public static String decorator(String[] fieldNames,Object[] objects){

if(fieldNames==null || fieldNames.length==0)

throw new IllegalArgumentException("you must offer an available string-array");

if(objects==null || objects.length==0)

throw new IllegalArgumentException("you must offer an available object-array");

AbstractDecorator former=null;

ObjectDecorator[] objDecorators=new ObjectDecorator[objects.length];

for(int i=0;i<objects.length;i++){

ObjectDecorator objDecorator=new ObjectDecorator(former, objects[i], fieldNames);

former=objDecorator;

objDecorators[i]=objDecorator;

}

//设置最后一个对象装修为上一个装修者

MapDecorator mapDecorator=new MapDecorator(objDecorators[objDecorators.length-1]);

return mapDecorator.decorate();

}

public static void main(String[] args){

Student[] studs=new Student[2];

studs[0]=new Student("1","abc");

studs[1]=new Student("2","xyz");

String result=DwrObjTransferManager.decorator(new String[]{"oid","name"}, studs);

System.out.println(result);

}

abstract class AbstractDecorator {

protected AbstractDecorator former;

public abstract String decorate();

}

class ObjectDecorator extends AbstractDecorator {

private Object object;

private String[] fieldNames;

public ObjectDecorator(AbstractDecorator former,Object object,String[] fieldNames){

this.former=former;

this.object=object;

this.fieldNames=fieldNames;

}

@Override

public String decorate() {

String result="";

if(former!=null)

result=former.decorate()+",";

result+=this.transfer();

return result;

}

private String transfer(){

String result="{";

StringBuffer tempString=new StringBuffer();

for(int i=0;i<fieldNames.length;i++){

Class clz=this.object.getClass();

Field fld;

try {

fld=clz.getDeclaredField(fieldNames[i]);

fld.setAccessible(true);

} catch (Exception e) {

e.printStackTrace();

throw new RuntimeException(fieldNames[i]+" is not existing in class: "+clz.getName());

}

String value;

try {

value=fld.get(this.object).toString();

} catch (Exception e) {

throw new RuntimeException(e.getMessage());

}

tempString.append(",")

.append(fieldNames[i]).append(":");

if(fld.getType().getName().equals(String.class.getName()))

tempString.append("'"+value+"'");

else

tempString.append(value);

}

result+=tempString.toString().substring(1)+"}";

return result;

}

class MapDecorator extends AbstractDecorator{

public MapDecorator(AbstractDecorator former){

this.former=former;

}

@Override

public String decorate() {

String result="[";

if(this.former!=null)

result+=this.former.decorate();

result+="]";

return result;

}

index.jsp的内容如下：

<%@ 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>

<title>Index</title>

</head>

<body>

</body>

var metaData={

callback:function(str,arg0) {

alert("oid: "+str.oid+" name: "+str.name);

alert("arg0:"+arg0);},

timeout:5000,

arg:"i am arg",//可用于callback的arg0,以及exceptionHandler的arg0

callbackArg:"i am callbackArg",//专用于callback的arg0,它的定义覆盖了arg在callback方法的arg0的值

errorHandler:function(message,exceptionObj) {

alert("in errorHandler: " + message);

alert("exceptionObj.javaClassName:"+ exceptionObj.javaClassName+" exceptionObj.message:"+exceptionObj.message);

exceptionHandler:function(message,exceptionObj,arg0) {

alert("in exceptionHandler: " + message);

alert("exceptionObj.javaClassName:"+ exceptionObj.javaClassName+" exceptionObj.message:"+exceptionObj.message);

alert("arg0:"+arg0);

}

};

function addStudent(){

var student={

oid:"111",

name:"fred"

};

DwrService.addStudent(student,metaData);

}

function addAryStudents(){

var ary=[];

var student1={

oid:"111",

name:"fred"

};

var student2={

oid:"222",

name:"tom"

};

ary[0]=student1;

ary[1]=student2;

DwrService.addAryStudents(ary,function(result){

alert("向后台传一个对象数组: "+result);

});

}

function addMapStudents(){

var ary={

"first":{oid:"111", name:"fred"},

"second":{oid:"222", name:"tom"}

};

DwrService.addMapStudents(ary,function(result){

alert("向后台传一个对象数组: "+result);

});

}

function getStudent(){

DwrService.getStudent("2",metaData);

}

function getLstStudents(){

DwrService.getLstStudents(function(result){

for(var index in result){

var stu=result[index];

alert("index: "+index+" oid: "+stu.oid+" name: "+stu.name);

}

});

}

function getMapStudents(){

DwrService.getMapStudents(function(result){

for(var index in result){

var stu=result[index];

alert("index: "+index+" oid: "+stu.oid+" name: "+stu.name);

}

});

}

function getArrayInString(){

DwrService.getArrayInString(function(data){

var datas = eval('('+ data + ')');

//alert("oid: "+datas.oid+" name: "+datas.name);

var result = (datas[0])['list'];

for(var index in result){

var stu=result[index];

alert("index: "+index+" oid: "+stu.oid+" name: "+stu.name);

}

for(var i=0;i<datas.length;i++){

var stu=datas[i];

alert("index: "+i+" oid: "+stu.oid+" name: "+stu.name);

}

});

}

function getSingleInString(){

DwrService.getSingleInString(function(data){

var datas = eval('('+ data + ')');

alert("oid: "+datas.oid+" name: "+datas.name);

});

}

function getDwrService(){

DwrService.getDwrService(function(result){

alert(result);

});

}

</script>

</html>

DWR3.0实现对象的传递

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