需要root权限

文件路径/data/system/packages.xml里边的preferred-activities属性！

把自己需要的桌面应用设置上Attribute

<strong>android.intent.category.DEFAULT</strong>

<strong>android.intent.category.HOME</strong>

<strong>android.intent.action.MAIN</strong>

<strong>首先是一个bean类</strong>

<strong>public class </strong>XmlBean {

<strong>public static final </strong>String <strong>

<em>NODE</em></strong>=<strong>"preferred-activities"</strong>;

 <strong>private </strong>String <strong>value</strong>;

<strong>public </strong>String getValue() {

<strong>return </strong><strong>value</strong>; }

<strong>public void </strong>setValue(String value) {

<strong>this</strong>.<strong>value </strong>= value; } }

<strong>工具类</strong>

<em>/** </em><em> * dom解析工具类 </em><em> */ </em><em> </em>

<strong>public class </strong>DomUtils {

<strong>private static </strong>DocumentBuilderFactory

<em>factory </em>= DocumentBuilderFactory.newInstance();

<strong>private static </strong>XPathFactory <em>xpathFactory

</em>= XPathFactory.newInstance();<em>//创建XPath工厂 </em><em>

</em><strong>private static </strong>XPath <em>xpath </em>=

<em>xpathFactory</em>.newXPath();<em>//创建XPath对象 </em><em>

 </em><em> </em><em> /** </em><em> * 修改添加xml文件 </em><em> *

</em><em> * </em><strong><em>@param </em></strong><strong>

<em>filePath </em></strong><em>恢复的xml文件路径 </em><em> */

</em><em> </em><strong>public static void

</strong>writeXml(String filePath, XmlBean bean) { <strong>try

</strong>{ DocumentBuilder db =

<em>factory</em>.newDocumentBuilder(); File file = <strong>new

</strong>File(filePath); Document xmlDoc = db.parse(file);

Element root = xmlDoc.getDocumentElement(); Element son =

(Element) selectSingleNode(<strong>"//preferred-activities"

</strong>, root); <strong>if </strong>(son !=

<strong>null</strong>) { root.removeChild(son); } <em>//如果查不

到意味着要插入 </em><em> </em>Element newElement; newElement =

xmlDoc.createElement(XmlBean.<strong><em>NODE</em></strong>);

Element item = xmlDoc.createElement(<strong>"item"</strong>);

item.setAttribute(<strong>"name"</strong>,

<strong>"com.android.unan.urineanalysis/.activity.MainActivity"

</strong>); item.setAttribute(<strong>"match"</strong>,

<strong>"100000"</strong>); item.setAttribute(<strong>"set"

</strong>, <strong>"2"</strong>); Element set =

xmlDoc.createElement(<strong>"set"</strong>);

set.setAttribute(<strong>"name"</strong>,

<strong>"com.android.unan.urineanalysis/.activity.MainActivity"

</strong>); Element set2 = xmlDoc.createElement(<strong>"set"

</strong>); set2.setAttribute(<strong>"name"</strong>,

<strong>"com.android.launcher/com.android.launcher2.Launcher"

</strong>); Element filter =

xmlDoc.createElement(<strong>"filter"</strong>); Element action

= xmlDoc.createElement(<strong>"action"</strong>);

action.setAttribute(<strong>"name"</strong>,

<strong>"android.intent.action.MAIN"</strong>); Element cat =

xmlDoc.createElement(<strong>"cat"</strong>);

cat.setAttribute(<strong>"name"</strong>,

<strong>"android.intent.category.HOME"</strong>); Element cat2 =xmlDoc.createElement(<strong>"cat"</strong>);

cat2.setAttribute(<strong>"name"</strong>,

<strong>"android.intent.category.DEFAULT"</strong>);

filter.appendChild(action); filter.appendChild(cat);

filter.appendChild(cat2); item.appendChild(set);

item.appendChild(set2); item.appendChild(filter);

newElement.appendChild(item); root.appendChild(newElement);

TransformerFactory factory = TransformerFactory.newInstance();

Transformer former = factory.newTransformer();

former.setOutputProperty(OutputKeys.<strong><em>INDENT</em>

</strong>, <strong>"yes"</strong>);<em>//增加换行 </em><em>//

former.setOutputProperty("{https://xml.apache.org/xslt}indent-

amount", "2");//增加缩进 </em><em>

</em>former.transform(<strong>new </strong>DOMSource(xmlDoc),

<strong>new </strong>StreamResult(file)); } <strong>catch

</strong>(Exception e) { e.printStackTrace(); } } <em>// 获取指

定节点信息 </em><em> </em><strong>private static </strong>Node

selectSingleNode(String express, Element source) { Node result =

<strong>null</strong>; <strong>try </strong>{ result = (Node)

<em>xpath</em>.evaluate(express, source, XPathConstants.<strong>

<em>NODE</em></strong>); } <strong>catch </strong>

(XPathExpressionException e) { System.<strong><em>out</em>

</strong>.println(e.getMessage()); } <strong>return

</strong>result; } }

使用方式十分简单

DomUtils.writeXml(Contents.<strong>

<em>SYSTEM_DEFULTLAUNCHER</em></strong>

<strong>new </strong>XmlBean());

操作前请用root权限修改文件的操作权限！！！！

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