Use JS to send Json between front-end and back-end

This time I will introduce to you the use of JS to transmit Json in the front end and the backend. What are the precautions for using JS to transmit Json in the front end and the backend? The following is a practical case, let's take a look.

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, so I’ll sort it out now.

[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 mvc framework 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 implementation 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
		}
	});
});

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

Recommended reading:

Convert json and array key values ​​to upper and lower case

How to use the diff algorithm in vue

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