DWR笔记2

来源：互联网发布：淘宝清仓活动方案编辑：程序博客网时间：2024/06/01 08:42

用javascript对象去匹配 java 对象
public class Remote {
public void setPerson(Person p) {
    this.person = p;
}
}

And Classes Person looks like this:
public Person {
private String name;
private int age;
private Date[] appointments;
// getters and setters ...一定要补上getter与setter
}

//Then you can call this from Javascript like this:
var p = {
name:"Fred Bloggs",
age:42,
appointments:[ new Date(), new Date("1 Jan 2008") ]
};
Remote.setPerson(p);

因为setPerson()使用 VOID 修饰所以在javascript中不不需要回调函数,即便你写了回调函数
,DWR也不会将任何值给传回来
当然你也可以这样写
Remote.setPerson(null,p);

异步Loading提示
DWR标准情况下是展现GMAIL样式的Loading消息提示,你可以在page loaded之后调用
loading消息提示,但不可以在page onload之前调用.因为loading的原理还是用一个hide
的层来包容loading消息.
在DWR中只要很简单的一步就可以完成GMAIL样式的loading设置
<head>
<script>
function init() {
    DWRUtil.useLoadingMessage();
}
</script>
...
</head>
<body onload="init();">

当然有些时候可能无法去修改<BODY>元素,那么你可以用CMS方式来修改
<script>
function init() {
DWRUtil.useLoadingMessage();
}

if (window.addEventListener) {
window.addEventListener("load", init, false);
}
else if (window.attachEvent) {
window.attachEvent("onload", init);
}
else {
window.onload = init;
}
</script>

你也可以动态的创建一个层(with id="disabledZone") ,它将包含提示消息
下面是2个改进的程序

第一个允许你修改属于你自己的提示消息
function useLoadingMessage(message) {
var loadingMessage;
if (message) loadingMessage = message;
else loadingMessage = "Loading";

DWREngine.setPreHook(function() {
    var disabledZone = $('disabledZone');
    if (!disabledZone) {
      disabledZone = document.createElement('div');
      disabledZone.setAttribute('id', 'disabledZone');
      disabledZone.style.position = "absolute";
      disabledZone.style.zIndex = "1000";
      disabledZone.style.left = "0px";
      disabledZone.style.top = "0px";
      disabledZone.style.width = "100%";
      disabledZone.style.height = "100%";
      document.body.appendChild(disabledZone);
      var messageZone = document.createElement('div');
      messageZone.setAttribute('id', 'messageZone');
      messageZone.style.position = "absolute";
      messageZone.style.top = "0px";
      messageZone.style.right = "0px";
      messageZone.style.background = "red";
      messageZone.style.color = "white";
      messageZone.style.fontFamily = "Arial,Helvetica,sans-serif";
      messageZone.style.padding = "4px";
      disabledZone.appendChild(messageZone);
      var text = document.createTextNode(loadingMessage);
      messageZone.appendChild(text);
    }
    else {
      $('messageZone').innerHTML = loadingMessage;
      disabledZone.style.visibility = 'visible';
    }
});

DWREngine.setPostHook(function() {
    $('disabledZone').style.visibility = 'hidden';
});
}

第2个你能使用图片作为提示消息
function useLoadingImage(imageSrc) {
var loadingImage;
if (imageSrc) loadingImage = imageSrc;
else loadingImage = "ajax-loader.gif";
DWREngine.setPreHook(function() {
    var disabledImageZone = $('disabledImageZone');
    if (!disabledImageZone) {
      disabledImageZone = document.createElement('div');
      disabledImageZone.setAttribute('id', 'disabledImageZone');
      disabledImageZone.style.position = "absolute";
      disabledImageZone.style.zIndex = "1000";
      disabledImageZone.style.left = "0px";
      disabledImageZone.style.top = "0px";
      disabledImageZone.style.width = "100%";
      disabledImageZone.style.height = "100%";
      var imageZone = document.createElement('img');
      imageZone.setAttribute('id','imageZone');
      imageZone.setAttribute('src',imageSrc);
      imageZone.style.position = "absolute";
      imageZone.style.top = "0px";
      imageZone.style.right = "0px";
      disabledImageZone.appendChild(imageZone);
      document.body.appendChild(disabledImageZone);
    }
    else {
      $('imageZone').src = imageSrc;
      disabledImageZone.style.visibility = 'visible';
    }
});
DWREngine.setPostHook(function() {
    $('disabledImageZone').style.visibility = 'hidden';
});
}

DWRUtil.toDescriptiveString()用于debug 页面上的任何Html控件
DWRUtil.toDescriptiveString(p1,p2)
其中p1 代表你将要bebug的控件id名称
p2 (int={0,1,2})
其中 0 返回单行调试信息
     1/2 返回多行调试信息