# XML Parsing and Generation

> **NOTE**
>
> The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.


## Modules to Import

```
import xml from '@ohos.xml';
```

## XmlSerializer


### constructor

constructor(buffer: ArrayBuffer | DataView, encoding?: string)

A constructor used to create an **XmlSerializer** instance.

**System capability**: SystemCapability.Utils.Lang

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| buffer | ArrayBuffer \| DataView | Yes| **ArrayBuffer** or **DataView** for storing the XML information to write.|
| encoding | string | No| Encoding format.|

**Example**

```js
var arrayBuffer = new ArrayBuffer(1024);
var bufView = new DataView(arrayBuffer);
var thatSer = new xml.XmlSerializer(bufView);
```


### setAttributes

setAttributes(name: string, value: string): void

Sets an attribute.

**System capability**: SystemCapability.Utils.Lang

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| name | string | Yes| Key of the attribute.|
| value | string | Yes| Value of the attribute.|

**Example**

```js
var arrayBuffer = new ArrayBuffer(1024);
var bufView = new DataView(arrayBuffer);
var thatSer = new xml.XmlSerializer(bufView);
thatSer.setAttributes("importance", "high");  
```


### addEmptyElement

addEmptyElement(name: string): void

Adds an empty element.

**System capability**: SystemCapability.Utils.Lang

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| name | string | Yes| Name of the empty element to add.|

**Example**

```js
var arrayBuffer = new ArrayBuffer(1024);
var bufView = new DataView(arrayBuffer);
var thatSer = new xml.XmlSerializer(bufView);
thatSer.addEmptyElement("b"); // => <b/>
```


### setDeclaration

setDeclaration(): void

Sets a declaration.

**System capability**: SystemCapability.Utils.Lang

**Example**

```js
var arrayBuffer = new ArrayBuffer(1024);
var bufView = new DataView(arrayBuffer);
var thatSer = new xml.XmlSerializer(bufView);
thatSer.setDeclaration() // => <?xml version="1.0" encoding="utf-8"?>;
```


### startElement

startElement(name: string): void

Writes the start tag based on the given element name.

**System capability**: SystemCapability.Utils.Lang

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| name | string | Yes| Name of the element.|

**Example**

```js
var arrayBuffer = new ArrayBuffer(1024);
var thatSer = new xml.XmlSerializer(arrayBuffer);
thatSer.startElement("notel");
thatSer.endElement();// => '<notel/>';
```


### endElement

endElement(): void

Writes the end tag of the element.

**System capability**: SystemCapability.Utils.Lang

**Example**

```js
var arrayBuffer = new ArrayBuffer(1024);
var bufView = new DataView(arrayBuffer);
var thatSer = new xml.XmlSerializer(bufView);
thatSer.setNamespace("h", "http://www.w3.org/TR/html4/");
thatSer.startElement("table");
thatSer.setAttributes("importance", "high");
thatSer.setText("Happy");
thatSer.endElement(); // => <h:table importance="high" xmlns:h="http://www.w3.org/TR/html4/">Happy</h:table>
```


### setNamespace

setNamespace(prefix: string, namespace: string): void

Sets the namespace for an element tag.

**System capability**: SystemCapability.Utils.Lang

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| prefix | string | Yes| Prefix of the element and its child elements.|
| namespace | string | Yes| Namespace to set.|

**Example**

```js
var arrayBuffer = new ArrayBuffer(1024);
var thatSer = new xml.XmlSerializer(arrayBuffer);
thatSer.setDeclaration();
thatSer.setNamespace("h", "http://www.w3.org/TR/html4/");
thatSer.startElement("note");
thatSer.endElement();// = >'<?xml version="1.0" encoding="utf-8"?>\r\n<h:note xmlns:h="http://www.w3.org/TR/html4/"/>';
```

### setComment

setComment(text: string): void

Sets the comment.

**System capability**: SystemCapability.Utils.Lang

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| text | string | Yes| Comment to set.|

**Example**

```js
var arrayBuffer = new ArrayBuffer(1024);
var thatSer = new xml.XmlSerializer(arrayBuffer);
thatSer.startElement("note");
thatSer.setComment("Hi!");
thatSer.endElement(); // => '<note>\r\n  <!--Hi!-->\r\n</note>';
```


### setCDATA

setCDATA(text: string): void

Sets CDATA attributes.

**System capability**: SystemCapability.Utils.Lang

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| text | string | Yes| CDATA attribute to set.|

**Example**

```js
var arrayBuffer = new ArrayBuffer(1028);
var thatSer = new xml.XmlSerializer(arrayBuffer);
thatSer.setCDATA('root SYSTEM') // => '<![CDATA[root SYSTEM]]>';
```


### setText

setText(text: string): void

Sets **Text**.

**System capability**: SystemCapability.Utils.Lang

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| text | string | Yes| Content of the **Text** to set.|

**Example**

```js
var arrayBuffer = new ArrayBuffer(1024);
var thatSer = new xml.XmlSerializer(arrayBuffer);
thatSer.startElement("note");
thatSer.setAttributes("importance", "high");
thatSer.setText("Happy1");
thatSer.endElement(); // => '<note importance="high">Happy1</note>';
```


### setDocType

setDocType(text: string): void

Sets **DocType**.

**System capability**: SystemCapability.Utils.Lang

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| text | string | Yes| Content of **DocType** to set.|

**Example**

```js
var arrayBuffer = new ArrayBuffer(1024);
var thatSer = new xml.XmlSerializer(arrayBuffer);
thatSer.setDocType('root SYSTEM'); // => '<!DOCTYPE root SYSTEM>';
```


## XmlPullParser


### XmlPullParser

constructor(buffer: ArrayBuffer | DataView, encoding?: string)

Creates and returns an **XmlPullParser** object. The **XmlPullParser** object passes two parameters. The first parameter is the memory of the **ArrayBuffer** or **DataView** type, and the second parameter is the file format (UTF-8 by default).

**System capability**: SystemCapability.Utils.Lang

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| buffer | ArrayBuffer&nbsp;\|&nbsp;DataView | Yes| **ArrayBuffer** or **DataView** that contains XML text information.|
| encoding | string | No| Encoding format. Only UTF-8 is supported.|

**Example**

```js
var strXml =
            '<?xml version="1.0" encoding="utf-8"?>' +
            '<note importance="high" logged="true">' +
            '    <title>Happy</title>' +
            '    <todo>Work</todo>' +
            '    <todo>Play</todo>' +
            '</note>';
var arrayBuffer = new ArrayBuffer(strXml.length*2);
var bufView = new Uint8Array(arrayBuffer);
var strLen = strXml.length;
for (var i = 0; i < strLen; ++i) {
    bufView[i] = strXml.charCodeAt(i);// Set the ArrayBuffer mode.
}
var that = new xml.XmlPullParser(arrayBuffer);
```


### parse

parse(option: ParseOptions): void

Parses XML information.

**System capability**: SystemCapability.Utils.Lang

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| option | [ParseOptions](#parseoptions) | Yes| Options for controlling and obtaining the parsed information.|

**Example**

```js
var strXml =
            '<?xml version="1.0" encoding="utf-8"?>' +
            '<note importance="high" logged="true">' +
            '    <title>Happy</title>' +
            '    <todo>Work</todo>' +
            '    <todo>Play</todo>' +
            '</note>';
var arrayBuffer = new ArrayBuffer(strXml.length*2);
var bufView = new Uint8Array(arrayBuffer);
var strLen = strXml.length;
for (var i = 0; i < strLen; ++i) {
    bufView[i] = strXml.charCodeAt(i);
}
var that = new xml.XmlPullParser(arrayBuffer);
var arrTag = {};
var str = "";
var i = 0;
function func(key, value){
    arrTag[i] = 'key:'+key+' value:'+ value.getDepth();
    str += arrTag[i];
    i++;
    return true; // Determines whether to continuely parse, which is used to continue or terminate parsing.
}
var options = {supportDoctype:true, ignoreNameSpace:true, tokenValueCallbackFunction:func}
that.parse(options);
console.log(str);
// Output:
// key:0 value:0key:2 value:1key:10 value:1key:2 value:2key:4 value:2key:3 value:2key:10 value:1key:2 value:2key:4 value:2key:3 value:2key:10 value:1key:2 value:2key:4 value:2key:3 value:2key:3 value:1key:1 value:0
// Notes:
// The key represents the current event type, and the value represents the depth of the current parsing. You can know the parsed event according to EVENTTYPE. For example, the result 'key: value' in this example means:
// 0(START_DOCUMENT):0(Parse to the START_DOCUMENT, and the depth is 0), 2(START_TAG):1(Parse to the START_TAG node, and the depth is 1), 10(WHITESPACE):1(Parse to the WHITESPACE space, and the depth is 1), 2(START_TAG):2(Parse to the START_TAG title, and the depth is 2), ...
```


## ParseOptions

Defines the XML parsing options.

**System capability**: SystemCapability.Utils.Lang


| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| supportDoctype | boolean | No| Whether to ignore **Doctype**. The default value is **false**.|
| ignoreNameSpace | boolean | No| Whether to ignore **Namespace**. The default value is **false**.|
| tagValueCallbackFunction | (name:&nbsp;string,&nbsp;value:&nbsp;string)=&gt;&nbsp;boolean | No| Callback used to return **tagValue**.|
| attributeValueCallbackFunction | (name:&nbsp;string,&nbsp;value:&nbsp;string)=&gt;&nbsp;boolean | No| Callback used to return **attributeValue**.|
| tokenValueCallbackFunction | (eventType:&nbsp;[EventType](#eventtype),&nbsp;value:&nbsp;[ParseInfo](#parseinfo))=&gt;&nbsp;boolean | No| Callback used to return **tokenValue**.|

## ParseInfo

Provides APIs to manage the parsed XML information.


### getColumnNumber

getColumnNumber(): number

Obtains the column line number, which starts from 1.

**System capability**: SystemCapability.Utils.Lang

**Return value**

| Type| Description|
| -------- | -------- |
| number | Column number obtained.|


### getDepth

getDepth(): number

Obtains the depth of this element.

**System capability**: SystemCapability.Utils.Lang

**Return value**

| Type| Description|
| -------- | -------- |
| number | Depth obtained.|


### getLineNumber

getLineNumber(): number

Obtains the current line number, starting from 1.

**System capability**: SystemCapability.Utils.Lang

**Return value**

| Type| Description|
| -------- | -------- |
| number | Line number obtained.|


### getName

getName(): string

Obtains the name of this element.

**System capability**: SystemCapability.Utils.Lang

**Return value**

| Type| Description|
| -------- | -------- |
| string | Element name obtained.|


### getNamespace

getNamespace(): string

Obtains the namespace of this element.

**System capability**: SystemCapability.Utils.Lang

**Return value**

| Type| Description|
| -------- | -------- |
| string | Namespace obtained.|


### getPrefix

getPrefix(): string

Obtains the prefix of this element.

**System capability**: SystemCapability.Utils.Lang

**Return value**

| Type| Description|
| -------- | -------- |
| string | Element prefix obtained.|


### getText

getText(): string

Obtains the text of the current event.

**System capability**: SystemCapability.Utils.Lang

**Return value**

| Type| Description|
| -------- | -------- |
| string | Text content obtained.|


### isEmptyElementTag

isEmptyElementTag(): boolean

Checks whether the current element is empty.

**System capability**: SystemCapability.Utils.Lang

**Return value**

| Type| Description|
| -------- | -------- |
| boolean | Returns **true** if the element is empty; returns **false** otherwise.|


### isWhitespace

isWhitespace(): boolean

Checks whether the current text event contains only whitespace characters.

**System capability**: SystemCapability.Utils.Lang

**Return value**

| Type| Description|
| -------- | -------- |
| boolean | Returns **true** if the text event contains only whitespace characters; returns **false** otherwise.|


### getAttributeCount

getAttributeCount(): number

Obtains the number of attributes for the current start tag.

**System capability**: SystemCapability.Utils.Lang

**Return value**
| Type| Description|
| -------- | -------- |
| number | Number of attributes obtained.|


## EventType

Enumerates the events.

**System capability**: SystemCapability.Utils.Lang

| Name| Value| Description|
| -------- | -------- | -------- |
| START_DOCUMENT | 0 | Indicates a start document event.|
| END_DOCUMENT | 1 | Indicates an end document event.|
| START_TAG | 2 | Indicates a start tag event.|
| END_TAG | 3 | Indicates an end tag event.|
| TEXT | 4 | Indicates a text event.|
| CDSECT | 5 | Indicates a CDATA section event.|
| COMMENT | 6 | Indicates an XML comment event.|
| DOCDECL | 7 | Indicates an XML document type declaration event.|
| INSTRUCTION | 8 | Indicates an XML processing instruction event.|
| ENTITY_REFERENCE | 9 | Indicates an entity reference event.|
| WHITESPACE | 10 | Indicates a whitespace character event.|