How does the front end transmit Json data to the backend?

This time I will show you how the front-end transmits Json data to the background. What are the precautions for transmitting Json data from the front-end to the background? The following is a practical case, let's take a look.

[Jquery basic method]

Jquery and internally encapsulated ajax are commonly used to implement 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 requests data through the HTTP post method:

$.post(URL,data,callback);

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

[spring mvcFramework Jquery ajax]

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

@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 get the json value obtained by the controller using jquery, so how do we operate the json value, let What about binding 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";

Application example in MUI framework, add li tag to 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='<a class="mui-navigate-right" id=&#39;+ id +&#39; data-audio=&#39;+ audio +&#39;>'+'<img class="mui-media-object mui-pull-left" srcload="&#39;+picUrl+&#39;">'+'<p class="mui-media-body">'+name+'<p class="mui-ellipsis">'+author+'</p>'+'</p>'+'</a>';
		fragment.appendChild(li);
		})
		
		list.appendChild(fragment);
		mui(document).imageLazyload({
			placeholder:'../img/60*60.gif';
		});
		
	},erro:function(xhr,type,errorThrown){
		console.log(type);
	}
	
});
//列表点击事件
mui("#list").on('tap','li a',function(){
	var id=this.getAttribute('id');
	var audio=this.getAttribute('data-audio');
	mui.openWindow({
		url:'music.html',
		id:'music.html',
		extras:{
			musicId:id,
			audioUrl:audio
		}
	});
});

[Summary]

Compared to xml files, data in json format has fast and stable transmission speed, and is a very good choice in front-end design.

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

Recommended reading:

Use jQuery to preview locally when uploading images

vue.JS to make a shopping cart and Address matching

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