第四十六篇--解析和保存xml文件

新建assets资源文件夹，右键app --> new --> Folder --> Assets Folder，将info.xml放入此文件夹下面。

info.xml

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

解析：

MainActivity.java

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();
        }
    }
}

保存：

MainActivity.java

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);
        }
    }
}

activity_main.xml

<?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>

注意：不要忘了在清单文件中添加权限。