第四十六篇--解析和保存xml文件

<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<info>
<student id="10011">
<name>lisi</name>
<age>19</age>
</student>
</info>

package com.example.aimee.getfileinfo;import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.util.Xml;
import android.view.View;import org.xmlpull.v1.XmlPullParser;import java.io.InputStream;public class MainActivity extends AppCompatActivity { private static final String TAG = "MainActivity"; @Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
} public void click(View view) {
try {
//1.找到此资产文件并打开
InputStream is = this.getAssets().open("info.xml");//ctrl+shift+方向键可以上下移动
//2.得到xml文件解析器
XmlPullParser parser = Xml.newPullParser();
//3.设置输入流和编码
parser.setInput(is,"utf-8");
//4.解析xml文件，获取当前的事件类型
int type = parser.getEventType();
while (type != XmlPullParser.END_DOCUMENT){
Log.i(TAG,parser.getEventType() + "----" + parser.getName() + "----" + parser.getText());
type = parser.next();
} is.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}

package com.example.aimee.getfileinfo;import android.Manifest;
import android.os.Bundle;
import android.os.Environment;
import android.text.TextUtils;
import android.util.Xml;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;import org.xmlpull.v1.XmlSerializer;import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;public class MainActivity extends com.example.aimee.getfileinfo.BaseActivity { private EditText mEtAge;
private EditText mEtName;
private EditText mEtId; @Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); //1.找到所有需要用到的文件
mEtName = findViewById(R.id.et_name);
mEtAge = (EditText) findViewById(R.id.et_age);
mEtId = (EditText) findViewById(R.id.et_id); //2.将控件内容写到xml文件中
} /**
* 将控件内容写到xml文件中
* @param view
*/
public void save(View view) {
//3.根据控件读取用户输入的文本放入到字符串变量中
final String name = mEtName.getText().toString().trim();
final String age = mEtAge.getText().toString().trim();
final String id = mEtId.getText().toString().trim(); //4.判断是否有空的内容
if (TextUtils.isEmpty(name) || TextUtils.isEmpty(age)){
Toast.makeText(this,"信息不能为空",Toast.LENGTH_SHORT).show();
return;
}else {
//5.将字符串写入到xml文件中
performCodeWithPermission("保存学生信息到sd卡", new PermissionCallback() {
@Override
public void hasPermission() {
//1.创建一个xml文件的序列号器
XmlSerializer serializer = Xml.newSerializer();
//2.设置文件的输出和编码方式
FileOutputStream fos = null;
try {
fos = new FileOutputStream(new File(Environment.getExternalStorageDirectory(), "info.xml"));
serializer.setOutput(fos,"utf-8");
//3.写入xml文件的头
serializer.startDocument("utf-8",true);
//4.写info节点
serializer.startTag(null,"info");
//5.写student节点
serializer.startTag(null,"student");
//6.写属性
serializer.attribute(null,"id",id);
//7.写name
serializer.startTag(null,"name");
serializer.text(name);
serializer.endTag(null,"name");
//8.写age
serializer.startTag(null,"age");
serializer.text(age);
serializer.endTag(null,"age"); serializer.endTag(null,"student");
serializer.endTag(null,"info");
serializer.endDocument();;
} catch (Exception e) {
e.printStackTrace();
}finally {
try {
if (fos !=null)
fos.close();
Toast.makeText(MainActivity.this,"成功保存文件",Toast.LENGTH_SHORT).show();
} catch (IOException e) {
e.printStackTrace();
}
}
} @Override
public void noPermission() {
Toast.makeText(MainActivity.this,"没有运行时权限",Toast.LENGTH_SHORT).show();
}
}, Manifest.permission.WRITE_EXTERNAL_STORAGE);
}
}
}

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"> <EditText
android:id="@+id/et_name"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="60dp"
android:layout_marginEnd="8dp"
android:ems="10"
android:hint="请输入学生的姓名"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" /> <EditText
android:id="@+id/et_age"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="60dp"
android:layout_marginEnd="8dp"
android:ems="10"
android:hint="请输入学生的年龄"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/et_name" /> <EditText
android:id="@+id/et_id"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="60dp"
android:layout_marginEnd="8dp"
android:ems="10"
android:hint="请输入学生的学号"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/et_age" /> <Button
android:id="@+id/button"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="9dp"
android:layout_marginTop="60dp"
android:layout_marginEnd="8dp"
android:text="保存"
android:onClick="save"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/et_id" />
</android.support.constraint.ConstraintLayout>