Web Front-end
JS Tutorial
Detailed code explanation of jquery ajax passing arrays to the background and how to receive arrays in the background
Detailed code explanation of jquery ajax passing arrays to the background and how to receive arrays in the background
The array in JS is weakly typed and can contain any type (object, basic type). However, if the array contains an object type, only objects will be displayed when passed to the background. String --[object Object], the reasons are as follows:
When receiving in the background, you can only use request to receive. The request.getParameterValues() method returns a String[], so , it should be that the toString() method of the object is called during the foreground transmission, so what if you still want to pass the object? But it can be implemented using JSON strings, and the JSON strings are parsed into JAVA objects in the background.
Perhaps, you want to say what to do if it is a composite object, such as the following:
public class Person {
private String username;
private String password;
private Address addr;
}The Person object has an addr attribute of Address type. It doesn’t matter. The attribute values ultimately used by any object are basicData type, you only need to use the corresponding packaging type parseInt or parseXXX to parse.
Implementation:
OK, this is the principle. Let’s first look at how to write JS:
var as = [];
var temp = [];
for ( var int = 0; int < 5; int++) {
temp.push('{"k":');
temp.push(int);
temp.push(',"v":');
temp.push(int);
temp.push('}');
as.push(temp.join(""));
}
//Jquery中的方法，具体参考Jquery API
$.post( "servlet/AjaxServlet?m=putWarningRule",{"aa":as} );The final string is the following style, (for example only)
{"k":0,"v":0}Background reception, no framework is discussed, only HttpServletRequest is required
String[] jsonArr = request.getParameterValues("aa[]");One thing to note is that when passing parameters in js, the parameter name is "aa", but when receiving it in the background, it is "aa[]". Jquery should have done the conversion here, so the best way is Just change it to "aa[]" in JS. The reason why "[]" is not written here is to illustrate the problem. You can use the following method to print all parameters in the request
Enumeration<String> names = request.getParameterNames();
while (names.hasMoreElements()) {
String string = (String) names.nextElement();
System.out.println(string);
}OK. At this point, the reception has been completed. The only thing left is how to convert a JSON string into a POJO.
/**
* 将对象转换为JSON格式的字符串
* @param obj
* @return 返回JSON字符串
*/
public
static
String toJSONAsString(Object obj){
try {
return JSONMapper.toJSON(obj).render(false);
} catch (Mapper
Exception
e) {
e.printStackTrace();
}
return null;
}
@SuppressWarnings("unchecked")
public static <T> T jsonToObject(String jsonStr, Class<T> targetClass) throws TokenStreamException, RecognitionException, MapperException{
JSONValue jv = new JSONParser(new StringReader(jsonStr)).nextValue();
return (T) JSONMapper.toJava(jv,targetClass);
}
//test
public static void main(String[] args) throws Exception {
Person p = new Person();
p.setK("a");
p.setV("v");
String json = toJSONAsString(p);
Person np = jsonToObject(json,Person.class);
System.out.println(np.getK()+"=="+np.getV());
}After the request gets the value, traverse the array and convert one by one
Person p = JSONUtils.jsonToObject(jsonArr[0], Person.class);
The Person class is as follows:
public class Person {
private String k;
private String v;
public String getK() {
return k;
}
public void setK(String k) {
this.k = k;
}
public String getV() {
return v;
}
public void setV(String v) {
this.v = v;
}
}Sometimes there will be problems, the background reception less than this value.
Solution:
Set the tradional attribute of jQuery.ajax
$.ajax({
url: "/xxx",
type: "GET",
data: {
"boxIds": boxIds,
"boxType": 0,
"time": new Date().getTime()
},
traditional: true,//这里设置为true
success: function(data) {
//do sth...
}
});This time parameters Without "[]", the array can be successfully received in the background.
The above is the detailed content of Detailed code explanation of jquery ajax passing arrays to the background and how to receive arrays in the background. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
How to remove duplicate elements from PHP array using foreach loop?
Apr 27, 2024 am 11:33 AM
The method of using a foreach loop to remove duplicate elements from a PHP array is as follows: traverse the array, and if the element already exists and the current position is not the first occurrence, delete it. For example, if there are duplicate records in the database query results, you can use this method to remove them and obtain results without duplicate records.
The Art of PHP Array Deep Copy: Using Different Methods to Achieve a Perfect Copy
May 01, 2024 pm 12:30 PM
Methods for deep copying arrays in PHP include: JSON encoding and decoding using json_decode and json_encode. Use array_map and clone to make deep copies of keys and values. Use serialize and unserialize for serialization and deserialization.
PHP and Ajax: Building an autocomplete suggestion engine
Jun 02, 2024 pm 08:39 PM
Build an autocomplete suggestion engine using PHP and Ajax: Server-side script: handles Ajax requests and returns suggestions (autocomplete.php). Client script: Send Ajax request and display suggestions (autocomplete.js). Practical case: Include script in HTML page and specify search-input element identifier.
PHP array key value flipping: Comparative performance analysis of different methods
May 03, 2024 pm 09:03 PM
The performance comparison of PHP array key value flipping methods shows that the array_flip() function performs better than the for loop in large arrays (more than 1 million elements) and takes less time. The for loop method of manually flipping key values takes a relatively long time.
PHP array multi-dimensional sorting practice: from simple to complex scenarios
Apr 29, 2024 pm 09:12 PM
Multidimensional array sorting can be divided into single column sorting and nested sorting. Single column sorting can use the array_multisort() function to sort by columns; nested sorting requires a recursive function to traverse the array and sort it. Practical cases include sorting by product name and compound sorting by sales volume and price.
Best Practices for Deep Copying PHP Arrays: Discover Efficient Methods
Apr 30, 2024 pm 03:42 PM
The best practice for performing an array deep copy in PHP is to use json_decode(json_encode($arr)) to convert the array to a JSON string and then convert it back to an array. Use unserialize(serialize($arr)) to serialize the array to a string and then deserialize it to a new array. Use the RecursiveIteratorIterator to recursively traverse multidimensional arrays.
Application of PHP array grouping function in data sorting
May 04, 2024 pm 01:03 PM
PHP's array_group_by function can group elements in an array based on keys or closure functions, returning an associative array where the key is the group name and the value is an array of elements belonging to the group.
The role of PHP array grouping function in finding duplicate elements
May 05, 2024 am 09:21 AM
PHP's array_group() function can be used to group an array by a specified key to find duplicate elements. This function works through the following steps: Use key_callback to specify the grouping key. Optionally use value_callback to determine grouping values. Count grouped elements and identify duplicates. Therefore, the array_group() function is very useful for finding and processing duplicate elements.
