Android PULL 除了可以解析 XML 文件或字符串外，还可以用来生成 XML 文档

PULL 生成 xml 数据流程

1. 创建 XMLSerializer 类的实例，该类用于序列化 xml

   XMLSerializer serializer  = Xml.newSerializer();
   

2. 为 XMLSerializer 实例设置输出流和编码格式

   serializer.setOutput(out,"UTF-8");
   

3. 为 XMLSerializer 实例设置输出时是否添加 XML 编码格式

   serializer.startDocument("UTF-8",true);
   

4. 设置根元素

   serializer.startTag(null,"languages");
   

5. 使用增强 for 循遍历对象集合，并写入标签与属性

   for (LanguageBean language : languages) {
           serializer.startTag(null, "language");
           serializer.attribute(null, "id", p.getId() + "");
           serializer.startTag(null, "name");
           serializer.text(p.getName());
           serializer.endTag(null, "name");
           serializer.startTag(null, "rank");
           serializer.text(p.getRank() + "");
           serializer.endTag(null, "rank");
           serializer.endTag(null, "language");
       }
   

6. 设置结束根元素

   serializer.endTag(null,"languages");
   

7. 结束文档编写

   serializer.endDocument();
   

8. 调用输出流的 flush() 方法将内存中的数据写入文件，并且关闭输出流

   out.flush();
   out.close();
   

范例

1. 创建一个 空的 Android 项目 cn.twle.android.PULLGenXml

2. 修改 activity_main.xml

   <?xml version="1.0" encoding="utf-8" ?>
   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:padding="16dp"
       android:orientation="vertical" >
   
       <Button
           android:text="生成"
           android:id="@+id/btn_gen"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content" />
   
       <TextView
           android:id="@+id/ms_dst"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:text="" />
   </LinearLayout>
   

3. 创建一个 POJO 业务类 Language.java

   package cn.twle.android.pullgenxml;
   
   public class Language {
       private int id;
       private String name;
       private String rank;
   
       public Language() {
       }
   
       public Language(int id,String name,String rank){
   
           this.id = id;
           this.name = name;
           this.rank = rank;
       }
   
       public void setId(int id) {
           this.id = id;
       }
   
       public int getId() {
           return this.id;
       }
   
       public void setName(String name) {
           this.name = name;
       }
   
       public String getName() {
           return this.name;
       }
   
       public void setRank(String rank) {
           this.rank = rank;
       }
   
       public String getRank() {
           return this.rank;
       }
   }
   

4. 修改 MainActivity.java

   package cn.twle.android.pullgenxml;
   
   import android.os.Bundle;
   import android.support.v7.app.AppCompatActivity;
   import android.util.Xml;
   import android.view.View;
   import android.widget.Button;
   import android.widget.TextView;
   
   import org.xmlpull.v1.XmlSerializer;
   
   import java.io.ByteArrayOutputStream;
   import java.io.OutputStream;
   import java.util.ArrayList;
   import java.util.List;
   
   public class MainActivity extends AppCompatActivity {
   
       private TextView ms_dst;
   
       private Button btn_gen;
   
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
   
           ms_dst = findViewById(R.id.ms_dst);
   
           btn_gen = findViewById(R.id.btn_gen);
           btn_gen.setOnClickListener(new View.OnClickListener() {
   
               @Override
               public void onClick(View v) {
   
                   List<Language> langs = new ArrayList<Language>();
   
                   langs.add(new Language(1, "Java", "1"));
                   langs.add(new Language(2, "C", "2"));
                   langs.add(new Language(3, "C++", "3"));
   
                   ByteArrayOutputStream bs = new ByteArrayOutputStream();
   
                   try {
                       ;
                       save(langs, bs);
   
                       ms_dst.setText(new String(bs.toByteArray()));
                   } catch (Exception e) {
                       e.printStackTrace();
                   }
               }
           });
   
       }
   
       public static void save(List<Language> persons, OutputStream out) throws Exception {
           XmlSerializer serializer = Xml.newSerializer();
           serializer.setOutput(out, "UTF-8");
           serializer.startDocument("UTF-8", true);
           serializer.startTag(null, "languages");
           for (Language p : persons) {
               serializer.startTag(null, "language");
               serializer.attribute(null, "id", p.getId() + "");
               serializer.startTag(null, "name");
               serializer.text(p.getName());
               serializer.endTag(null, "name");
               serializer.startTag(null, "rank");
               serializer.text(p.getRank() + "");
               serializer.endTag(null, "rank");
               serializer.endTag(null, "language");
           }
   
           serializer.endTag(null, "languages");
           serializer.endDocument();
           out.flush();
           out.close();
       }
   }