【转】js处理来自服务器的json数据

字数 1621阅读 1112评论 0赞 0

<div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">1.对于服务器返回的JSON字符串，如果jquery异步请求没做类型说明，或者以字符串方式接受，那么需要做一次对象化处理，方式不是太麻烦，就是将该字符串放于eval()中执行一次。这种方式也适合以普通javascipt方式获取json对象，以下举例说明：</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;"> </span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">var dataObj=eval("("+data+")");//转换为json对象</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;"> </span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">为什么要 eval这里要添加 “("("+data+")");//”呢？</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;"> </span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">原因在于：eval本身的问题。 由于json是以”{}”的方式来开始以及结束的，在JS中，它会被当成一个语句块来处理，所以必须强制性的将它转换成一种表达式。</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;"> </span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">加上圆括号的目的是迫使eval函数在处理JavaScript代码的时候强制将括号内的表达式（expression）转化为对象，而不是作为语句（statement）来执行。举一个例子，例如对象字面量{}，如若不加外层的括号，那么eval会将大括号识别为JavaScript代码块的开始和结束标记，那么{}将会被认为是执行了一句空语句。所以下面两个执行结果是不同的：</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">alert(eval("{}"); // return undefined</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">alert(eval("({})");// return object[Object]</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;"> </span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">对于这种写法，在JS中，可以到处看到。</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;"> </span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">如: (function()) {}();  做闭包操作时等。</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;"> </span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">alert(dataObj.root.length);//输出root的子对象数量</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">$.each(dataObj.root,fucntion(idx,item){</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">if(idx==0){</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">return true;</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">}</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">//输出每个root子对象的名称和值</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">alert("name:"+item.name+",value:"+item.value);</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">})</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">注：对于一般的js生成json对象，只需要将$.each()方法替换为for语句即可，其他不变。</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;"> </span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">2.对于服务器返回的JSON字符串，如果jquery异步请求将type（一般为这个配置属性）设为“json”，或者利用$.getJSON()方法获得服务器返回，那么就不需要eval（）方法了，因为这时候得到的结果已经是json对象了，只需直接调用该对象即可，这里以$.getJSON方法为例说明数据处理方法：</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">$.getJSON("http://www.phpzixue.cn/",{param:"gaoyusi"},function(data){</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">//此处返回的data已经是json对象</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">//以下其他操作同第一种情况</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">$.each(data.root,function(idx,item){</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">if(idx==0){</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">return true;//同countinue，返回false同break</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">}</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">alert("name:"+item.name+",value:"+item.value);</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">});</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">});</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">这里特别需要注意的是方式1中的eval()方法是动态执行其中字符串（可能是js脚本）的，这样很容易会造成系统的安全问题。所以可以采用一些规避了eval()的第三方客户端脚本库，比如JSON in JavaScript就提供了一个不超过3k的脚本库。</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;"> </span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">第二种解析方式就是使用Function对象来完成，它的典型应用就是在JQUERY中的AJAX方法下的success等对于返回数据data的解析</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;"> </span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">var json='{"name":"CJ","age":18}';</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;"> </span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">data =(new Function("", "return "+json))();</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">data =(new Function("return "+json))();</span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;"> </span></div><div style="margin: 0px; padding: 0px; font-family: verdana, 'ms song', 宋体, Arial, 微软雅黑, Helvetica, sans-serif; font-size: 12px; line-height: 21.6000003814697px; background-color: rgb(255, 255, 255);"><span style="margin: 0px; padding: 0px; line-height: 18px; font-family: 微软雅黑;">此时的data就是一个会解析成一个 json对象了.</span></div>

办公自动化

著作权归作者所有

如果觉得我的文章对您有用，请点赞。您的支持将鼓励我继续创作！

添加新评论0 条评论

Ctrl+Enter 发表

匿名评论

【转】js处理来自服务器的json数据

添加新评论0 条评论

作者其他文章

相关问题

相关资料