Activity组件：（一）通过显式意图和隐式意图来实现Activity间的跳转

一、通过显式意图来实现Activity间的跳转

显式意图是指在创建Intent对象时就指定接受者组件

 /**
         * 下面是通过显式意图进行跳转，即明确写出要跳转到SecondActivity.class组件中去
         */
        Intent intent =new Intent(this,SecondActivity.class);
        intent.putExtra("account",account);
        intent.putExtra("password",password);
        startActivity(intent);

注意：创建Activity时要在manifests里进行静态注册，示例如下：

<activity android:name=".SecondActivity">

        </activity>

之后再要跳转到的界面接受Intent传递的内容

 //通过getIntent获取MainActivity传来的intent
        Intent intent = getIntent();
        String account = intent.getStringExtra("account");
        String password = intent.getStringExtra("password");

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二、通过隐式意图来实现Activity间的跳转

隐式意图就是通过intent过滤器来进行匹配跳转

 /**
         * 下面是通隐式意图进行跳转,要在manifests里添加意图过滤
         */
        Intent intent = new Intent();
        intent.setAction("com.example.activitydemo.LoginInfo");
        intent.addCategory(Intent.CATEGORY_DEFAULT);
        intent.putExtra("account",account);
        intent.putExtra("password",password);
        startActivity(intent);

进行注册的同时添加intent过滤

<activity android:name=".SecondActivity">
            <intent-filter>
                <action android:name="com.example.activitydemo.LoginInfo"/>
                <category  android:name="android.intent.category.DEFAULT"/>
            </intent-filter>
        </activity>

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三、原码

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.activitydemo">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".SecondActivity">
            <intent-filter>
                <action android:name="com.example.activitydemo.LoginInfo"/>
                <category  android:name="android.intent.category.DEFAULT"/>
            </intent-filter>
        </activity>
    </application>

</manifest>

MainActivity.java

package com.example.activitydemo;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";
    private EditText mAccount;
    private EditText mPassword;
    private Button mLogin;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initView();
        initListener();
    }

    private void initListener() {
        mLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //登录按钮被点击了
                Log.d(TAG,"Login Click。。。");
                handlerLogin();
            }
        });
    }

    private void handlerLogin() {
        //.trim()用于去空格
        String account = mAccount.getText().toString().trim();
        if (TextUtils.isEmpty(account)) {
            Toast.makeText(this,"输入的账号为空",Toast.LENGTH_SHORT).show();
            return;
        }

        String password = mPassword.getText().toString().trim();
        if (TextUtils.isEmpty(password)) {
            Toast.makeText(this,"输入的密码为空",Toast.LENGTH_SHORT).show();;
        }
        //先要创建一个意图对象，然后通过StartActivity()来实现跳转
        /**
         * 下面是通过显式意图进行跳转，即明确写出要跳转到SecondActivity.class组件中去
         */
//        Intent intent =new Intent(this,SecondActivity.class);
//        intent.putExtra("account",account);
//        intent.putExtra("password",password);
//        startActivity(intent);

        /**
         * 下面是通隐式意图进行跳转,要在manifests里添加意图过滤
         */
        Intent intent = new Intent();
        intent.setAction("com.example.activitydemo.LoginInfo");
        intent.addCategory(Intent.CATEGORY_DEFAULT);
        intent.putExtra("account",account);
        intent.putExtra("password",password);
        startActivity(intent);
    }

    private void initView() {
        mAccount = (EditText) this.findViewById(R.id.account);
        mPassword = (EditText) this.findViewById(R.id.password);
        mLogin = (Button)  this.findViewById(R.id.login);
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:text="登录"
        android:textSize="30sp"
        android:layout_gravity="center"
        android:layout_height="wrap_content">

    </TextView>

    <TextView
        android:layout_width="wrap_content"
        android:text="账号："
        android:textSize="25sp"
        android:layout_height="wrap_content">

    </TextView>

    <EditText
        android:id="@+id/account"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

    </EditText>

    <TextView
        android:layout_width="wrap_content"
        android:text="密码："
        android:textSize="25sp"
        android:layout_height="wrap_content">

    </TextView>
    <EditText
        android:id="@+id/password"
        android:layout_width="match_parent"
        android:inputType="textPassword"
        android:layout_height="wrap_content">

    </EditText>
    <Button
        android:id="@+id/login"
        android:layout_width="match_parent"
        android:text="登录"
        android:layout_height="wrap_content">

    </Button>
</LinearLayout>

SecondActivity.java

package com.example.activitydemo;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;

import androidx.annotation.Nullable;

public class SecondActivity extends Activity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);

        TextView info =(TextView) this.findViewById(R.id.info);
        //通过getIntent获取MainActivity传来的intent
        Intent intent = getIntent();
        String account = intent.getStringExtra("account");
        String password = intent.getStringExtra("password");

        info.setText("您的账号为："+account+"您的密码为："+password);
    }
}

activity_second_.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_width="match_parent"
        android:text="登录信息如下："
        android:layout_marginTop="20dp"
        android:textSize="20sp"
        android:layout_height="wrap_content">

    </TextView>
    <TextView
        android:id="@+id/info"
        android:layout_width="match_parent"
        android:textSize="25sp"
        android:text=""
        android:layout_height="wrap_content">

    </TextView>
</LinearLayout>