Activity系列讲解---数据传递

  在Android中,不同的Activity实例可能运行在一个进程中,也可能运行在不同的进程中。因此需要一种特别的机制帮助我们在Activity之间传递消息。Android中通过Intent对象来表示一条消息,一个Intent对象不仅包含有这个消息的目的地,还可以包含消息的内容,好比一封Email,其中不仅应该包含收件地址,还可以包含具体的内容。对于一个Intent对象,消息“目的地”是必须的,而内容是可选的。

1.数据传递的两种方式:

 

2.对象的传递:

(1)实现Serializable接口,intent.putExtra(String name,Serializable value)

(2)实现Parcelable接口,intent.putExtra(String name,Parcelable value)

3.代码实现

(1)FirstActivity.class  

/**
 * Activity传递数据的两种方式:
 * 1.直接通过Bundle对象来传递
 * 2.使用Intent定义的Bundle对象
 */
public class FirstActivity extends AppCompatActivity {

    private EditText ed;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_first);

        ed = (EditText) findViewById(R.id.et_data_name);
    }

    //传递基本数据
    public  void sendDataClick(View view){
        String info = ed.getText().toString();
        Intent intent = new Intent(this,SecondActivity.class);
        //1.直接通过Bundle对象来传递
       /* Bundle bundle = new Bundle();
        bundle.putString("info",info);
        intent.putExtra("data",bundle);*/

        //2.使用Intent定义的Bundle对象
        intent.putExtra("info",info);
        startActivity(intent);
    }

    //传递对象一
    public void sendObjectOneClick(View view){
        Cat cat = new Cat();
        cat.name = "波斯猫";
        cat.age = 5;
        cat.type = "英短";

        Intent intent = new Intent(this,SecondActivity.class);
        //putExtra(String name,Serializable value)---Cat.class必须实现Serializable接口
        intent.putExtra("cat",cat);
        startActivity(intent);
    }

    //传递对象二
    public void sendObjectTwoClick(View view){
        Dog dog = new Dog();
        dog.name = "乐乐";
        dog.age = 6;
        dog.type = "哈士奇";

        Intent intent = new Intent(this,SecondActivity.class);
        //putExtra(String name,Parcelable value)---Dog.class必须实现SerializableParcelable接口
        intent.putExtra("dog",dog);
        startActivity(intent);
    }

}

  

(2)SecondActivity.class

public class SecondActivity extends AppCompatActivity {

    private TextView tv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);

        tv = (TextView) findViewById(R.id.tv_data_display);

        Intent intent = getIntent();
        //1.直接通过Bundle对象来传递
       /*
        Bundle data = intent.getBundleExtra("data");
        String ret = data.getString("info");*/

        //2.使用Intent定义的Bundle对象
        String ret = intent.getStringExtra("info");

        Cat cat = (Cat) intent.getSerializableExtra("cat");

        Dog dog = (Dog) intent.getParcelableExtra("dog");

        tv.setText(dog.toString());
    }
}

  

(3)activity_first.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns: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:orientation="vertical"
    tools:context="com.langdon.taiyang.androidtest.activity.FirstActivity">

    <EditText
        android:id="@+id/et_data_name"
        android:hint="请输入信息"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/bt_data_send"
        android:text="发送"
        android:onClick="sendDataClick"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/bt_data_send_object"
        android:text="传递对象一"
        android:onClick="sendObjectOneClick"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/bt_data_send_data"
        android:text="传递对象二"
        android:onClick="sendObjectTwoClick"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

  

(4)activity_second.xml 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns: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"
    tools:context="com.langdon.taiyang.androidtest.activity.SecondActivity">
    <TextView
        android:id="@+id/tv_data_display"
        android:text="no data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

  

(5)Cat.class

  

/**
 * Cat实现Serializable接口,
 * intent.putExtra(String name,Serializable value)---Cat.class必须实现Serializable接口
 */

public class Cat implements Serializable {
    public String name;
    public int age;
    public String type;

    @Override
    public String toString() {
        return "Cat{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", type='" + type + '\'' +
                '}';
    }
}

  

(6)Dog.class

    

/**
 * Dog实现Parcelable接口,
 * intent.putExtra(String name,Parcelable value)---Cat.class必须实现Parcelable接口
 */

public class Dog implements Parcelable{
    public String name;
    public int age;
    public String type;

    @Override
    public String toString() {
        return "Dog{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", type='" + type + '\'' +
                '}';
    }

    //描述内容
    @Override
    public int describeContents() {
        return 0;
    }

    //将传入的数据写到包裹里面(Parcel)
    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(name);
        dest.writeInt(age);
        dest.writeString(type);
    }

    //对象的创建器
    public static final Parcelable.Creator<Dog> CREATOR
            = new Parcelable.Creator<Dog>() {
        public Dog createFromParcel(Parcel in) {
            Dog dog = new Dog();
            dog.name = in.readString();
            dog.age = in.readInt();
            dog.type = in.readString();
            return dog;
        }

        public Dog[] newArray(int size) {
            return new Dog[size];
        }
    };


}

  

posted on 2017-01-05 14:23  泰洋  阅读(255)  评论(0编辑  收藏  举报

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