[Android]-- Intent (explicit and implicit Intent)

What are Intents?

Intent is a bridge for information communication between various components. It is used for communication between Android components and mainly completes the following tasks:

• Indicate where the communication request comes from, where it goes, and how to go.
• The initiator carries the data content required for this communication, and the receiver parses the data from the received intent.
• If the initiator wants to judge the processing result of the receiver, the intent is responsible for letting the receiver send back the data content of the response.

 Components of Intent

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1. Explicit Intent and Implicit Intent

1. Explicit Intent

Explicit Intent, which directly specifies the source activity and the target activity, is an exact match, and there are three construction methods:

• Specified in the constructor of Intent.
• Call the setClass method of the intent object to specify.
• Call the setComponent method of the intent object to specify.

 (1) Specify in the Intent constructor

example:

Intent intent = new Intent(this,ActNextActivity.class)//创建一个目标确定的意图

(2) Call the setClass method of the intent object to specify

example:

Intent intent = new Intent();//创建新意图
intent.setClass(this,ActNextActivity.class)//设置意图要跳转的目标活动

(3) Call the setComponent method of the intent object to specify

example:

Intent intent = new Intent();//创建新意图
//创建包含目标活动在内的组件名称对象
ComponentName component = new ComponentName(this,ActNextActivity.class);
intent.setComponent(component);//设置意图携带的组件信息

2. Implicit Intent

The target activity to jump to is not clearly specified, but only an action string is given for the system to automatically match, which is a fuzzy match.

Usually the APP does not want to expose the activity name to the outside, but only gives a pre-defined tag string. This action name tag string can be an action defined by itself or an existing system action. Common system action values ​​are as follows:

 example:

java

public class ActionUrlActivity extends AppCompatActivity implements View.OnClickListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_action_url);
        findViewById(R.id.btn_dial).setOnClickListener(this);
        findViewById(R.id.btn_sms).setOnClickListener(this);
        findViewById(R.id.btn_my).setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        String phoneNo = "12345";
        Intent intent = new Intent();
        switch (view.getId()){
            case R.id.btn_dial:
                //设置意图动作为准备拨号
                intent.setAction(Intent.ACTION_DIAL);
                Uri uri = Uri.parse("tel:"+phoneNo);
                intent.setData(uri);
                startActivity(intent);
                break;
            case R.id.btn_sms:
                //设置意图动作为发短信
                intent.setAction(Intent.ACTION_SENDTO);
                Uri uri2 = Uri.parse("smsto:"+phoneNo);
                intent.setData(uri2);
                startActivity(intent);
                break;
            case R.id.btn_my:
                intent.setAction("android.intent.action.NING");
                intent.addCategory(Intent.CATEGORY_DEFAULT);
                startActivity(intent);
                break;
        }
    }
}

xml

<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">
    
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="5dp"
        android:text="点击以下按钮向号码发起请求"/>

    <Button
        android:id="@+id/btn_dial"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="跳到拨号页面"/>

    <Button
        android:id="@+id/btn_sms"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="跳到短信页面"/>

    <Button
        android:id="@+id/btn_my"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="跳到我的页面"/>

</LinearLayout>

The AndroidManifest.xml file of the custom page that needs to be redirected to

        <activity
            android:name=".ButtonClickActivity"
            android:exported="true">//需要设置为true，意为允许其他应用跳转
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
            //添加的代码：
            <intent-filter>
                <action android:name="android.intent.action.NING" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>

        </activity>

 

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