js implements front-end and back-end transmission of Json code examples

No matter what framework is used, there is the problem of passing data from the controller to the Html page or jsp page. The most common way is to pass Json string. I was a little vague about this piece of knowledge before, but now I’ve sorted it out and hope it can help everyone.

[Jquery basic method]

Jquery and internally encapsulated ajax are commonly used to achieve value transfer. First, take a look at jquery's get() and post() syntax. The get() method obtains data from the server. Its main parameters are to obtain the background request address and the callback function responsible for processing:

$.get(URL,callback);

$("button").click(function(){ 
 $.get("demo_test.php",function(data,status){ 
  alert("数据: " + data + "\n状态: " + status); 
 }); 
});

post passes HTTP post method requests data:

$.post(URL,data,callback);

$("button").click(function(){ 
  $.post("/try/ajax/demo_test_post.php", 
  { 
    name:"菜鸟教程", 
    url:"http://www.runoob.com" 
  }, 
    function(data,status){ 
    alert("数据: \n" + data + "\n状态: " + status); 
  }); 
});

[spring mvc framework+Jquery ajax]

The controller of spring mvc framework passes The annotation method returns Map type parameters to js.

@RequestMapping("update") 
@ResponseBody //此批注是ajax获取返回值使用 
public Map<String,Object> update(Long num,BigDecimal amount){ 
  map<string,Object> resultMap=new HashMap<string,Object>(); 
   
  if(num==null || agentId==null || amount==null){ 
    resultMap.put("result","参数不合法")； 
    return resultMap; 
  } 
  resultMap.put("result",result); 
   
}

jquery ajax gets the return value:

var params={}; 
params.num=num; 
params.id=id; 
params.amount=amount; 
$.ajax({ 
  async:false, 
  type:"post", 
  url:"uset/update", 
  data:params, 
  dataType:"json", 
  success:function(data){ 
    if(data.result=='success'){ 
      alert('修改成功'); 
    }else{ 
      alert('修改失败'); 
    } 
  }, 
  error:function(data){ 
    alert(data.result); 
  } 
   
})

If the parameters defined in js are consistent with the javabean defined by the persistence layer, the controller layer can also receive entities.

[MUI Binding Data Example]

It is easy to obtain the json value obtained by the controller using jquery. So how do we operate the json value and bind it to the page control? First, let’s briefly understand the structure of json:

var employees=[{"name":"Jon","age":12},{"name":"Tom","age":14}];

As the Json object defined above, {} represents the object, [] represents the array, "" represents the attribute or value, and : represents the latter as the value of the former.

Get the value in the json object: var name=employees[0].name;

Modify: employees[0].name="LiMing";

MUI Examples of applications in the framework, adding li tags to the list:

mui.init();
var url="queryUser"
mui.ajax(url,{
	data:{
		'type':1,
		'limit':10
	},
	dataType:'json',
	type:'post',
	success:function(data){
		var songs=data.result.songs;
		var list=document.getElementById("list");
		var fragment=document.creeateDocumentFramgment();
		
		var li;
		mui.each(songs,function(index,item){
			var id=item.id,
			name=item.album.name,
			author=item.artists[0].name;
			
			li=document.createElement('li');
			li.className="mui-table-view-cell mui-media";
			li.innerHTML=&#39;<a class="mui-navigate-right" id=&#39;+ id +&#39; data-audio=&#39;+ audio +&#39;>&#39;+&#39;<img class="mui-media-object mui-pull-left" srcload="&#39;+picUrl+&#39;">&#39;+&#39;<p class="mui-media-body">&#39;+name+&#39;<p class="mui-ellipsis">&#39;+author+&#39;</p>&#39;+&#39;</p>&#39;+&#39;</a>&#39;;
		fragment.appendChild(li);
		})
		
		list.appendChild(fragment);
		mui(document).imageLazyload({
			placeholder:&#39;../img/60*60.gif&#39;;
		});
		
	},erro:function(xhr,type,errorThrown){
		console.log(type);
	}
	
});
//列表点击事件
mui("#list").on(&#39;tap&#39;,&#39;li a&#39;,function(){
	var id=this.getAttribute(&#39;id&#39;);
	var audio=this.getAttribute(&#39;data-audio&#39;);
	mui.openWindow({
		url:&#39;music.html&#39;,
		id:&#39;music.html&#39;,
		extras:{
			musicId:id,
			audioUrl:audio
		}
	});
});

[Summary]

Compared with xml files, data in json format has a fast and stable transmission speed. In front-end design It's a very good choice.

Related recommendations:

How to transfer json array to php through ajax and insert data into the database through php

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