Android (Java) Learning Note 185:xml file generation

1.xml file:

Use elements to describe data across platforms.

2. Create the XML file in a traditional way, here is a case:

Design ideas: Establish a student management system, create an XML file to save student information;

(1) The first is the layout file Activity_main.xml file, as follows:

<LinearLayoutxmlns:android= "Http://schemas.android.com/apk/res/android"Xmlns:tools= "Http://schemas.android.com/tools"Android:layout_width= "Match_parent"Android:layout_height= "Match_parent"android:gravity= "Center_horizontal"android:orientation= "vertical"Android:paddingleft= "10dip"Android:paddingright= "10dip"Tools:context=". Mainactivity " >    <TextViewAndroid:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"Android:text= "Student Information Management system"Android:textcolor= "#99ff0000"android:textsize= "20SP" />    <TextViewAndroid:layout_width= "Fill_parent"Android:layout_height= "Wrap_content"Android:text= "Name"Android:textcolor= "#9900ff00"android:textsize= "14SP" />    <EditTextAndroid:id= "@+id/et_name"Android:layout_width= "Fill_parent"Android:layout_height= "Wrap_content"Android:hint= "Please enter name"Android:inputtype= "text" />    <TextViewAndroid:layout_width= "Fill_parent"Android:layout_height= "Wrap_content"Android:text= "study number"Android:textcolor= "#9900ff00"android:textsize= "14SP" />    <EditTextAndroid:id= "@+id/et_num"Android:layout_width= "Fill_parent"Android:layout_height= "Wrap_content"Android:hint= "Please enter the school number"Android:inputtype= "Number" />    <TextViewAndroid:layout_width= "Fill_parent"Android:layout_height= "Wrap_content"Android:text= "Gender"Android:textcolor= "#9900ff00"android:textsize= "14SP" />    <RadiogroupAndroid:id= "@+id/rg_sex"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"android:orientation= "Horizontal" >        <RadioButtonAndroid:id= "@+id/rb_male"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"android:checked= "true"Android:text= "Male" />        <RadioButtonAndroid:id= "@+id/rb_female"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"Android:text= "female" />    </Radiogroup>    <RelativelayoutAndroid:layout_width= "Fill_parent"Android:layout_height= "Fill_parent" >        <ButtonAndroid:onclick= "Save"Android:layout_alignparentbottom= "true"Android:layout_width= "Fill_parent"Android:layout_height= "Wrap_content"Android:text= "Save" />    </Relativelayout></LinearLayout>

：

(2) The logic core code is as follows: Mainactivity.java:

 PackageCom.itheima.studentinfo;ImportJava.io.File;ImportJava.io.FileOutputStream;Importandroid.app.Activity;ImportAndroid.os.Bundle;Importandroid.text.TextUtils;ImportAndroid.view.View;ImportAndroid.view.Window;ImportAndroid.widget.EditText;ImportAndroid.widget.RadioGroup;ImportAndroid.widget.Toast; Public classMainactivityextendsActivity {PrivateEditText Et_name; PrivateEditText Et_num; PrivateRadiogroup Rg_sex; @Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate); //No caption for interfacerequestwindowfeature (Window.feature_no_title);        Setcontentview (R.layout.activity_main); Et_name=(EditText) Findviewbyid (r.id.et_name); Et_num=(EditText) Findviewbyid (r.id.et_num); Rg_sex=(Radiogroup) Findviewbyid (r.id.rg_sex); }    /*** Click Save Student's information to generate an XML file *@paramView*/     Public voidSave (View view) {String name=Et_name.gettext (). toString (). Trim (); String Num=Et_num.gettext (). toString (). Trim (); if(Textutils.isempty (num) | |textutils.isempty (name)) {Toast.maketext ( This, "Student name or school number cannot be empty", 0). Show (); return ; }        Try{File File=NewFile (Getfilesdir (), num+ ". xml"); FileOutputStream Fos=Newfileoutputstream (file); StringBuilder SB=NewStringBuilder ();
//Create an XML file in a traditional way Sb.append (             "<?xml version=\" 1.0\ "encoding=\" utf-8\ "?>");            Sb.append ("<student>");            Sb.append ("<name>");            Sb.append (name);            Sb.append ("</name>");            Sb.append ("<num>");            Sb.append (num);            Sb.append ("</num>");            Sb.append ("<sex>");            int id = Rg_sex.getcheckedradiobuttonid ();            if (Id==r.id.rb_male) {//male Sb.append ("male");            }else{//female Sb.append ("female");            } sb.append ("</sex>"); Sb.append ("</student>");

 Fos.write (sb.tostring (). GetBytes ());            Fos.close (); Toast.maketext ( This, "Save data successfully", 0). Show (); } Catch(Exception e) {e.printstacktrace (); Toast.maketext ( This, "Save data Failed", 0). Show (); }    }}

Run the code to the simulator, and then we found the 10001.xml file in the/data/data/com.itheima.studentinfo/files directory, such as:

To export the 10001.xml file to your computer, use your browser to open it as:

The above is a traditional method of building an XML file, but when entering the name, school number and other information, we can not contain illegal characters, such as "/", "<" and so on, so the above code is still flawed. Such as:

Use the browser to open the generated 10002.xml file to report the following error:

It is obvious that the traditional way to create XML files is very limited, but Google's API provides a convenient interface to generate XML files, and do not consider these illegal characters, so it is convenient and secure, the following describes:

Android (Java) Learning Note 185:xml file generation