第一行代码Android学习（一）_android第一行代码看不懂-优快云博客

本文介绍Android应用开发中Activity的基础用法及不同Activity间的跳转方法，包括显式与隐式Intent的应用，以及如何在Activity间传递和接收数据。

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第一行代码Android学习：第一部分

主要涉及到Activity的基本用法和Activity之间的跳转

1.AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.dyhdm_02_activitytest"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.dyhdm_02_activitytest.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name="com.example.dyhdm_02_activitytest.SecondActivity"
            android:label="@string/title_activity_second" >
            <intent-filter>
                <action android:name="com.example.dyhdm_02_activitytest.Action_START" />

                <category android:name="com.example.dyhdm_02_activitytest.MY_CATEGORY" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>
        <activity
            android:name="com.example.dyhdm_02_activitytest.ThirdActivity"
            android:label="@string/title_activity_third" >
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />

                <category android:name="android.intent.category.DEFAULT" />

                <data android:scheme="http" />
            </intent-filter>
        </activity>
    </application>

</manifest>

2.activity_main.xml

<RelativeLayout 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=".MainActivity" >

    <Button
        android:id="@+id/bt1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="显式" />

    <Button
        android:id="@+id/bt2"
        android:layout_below="@id/bt1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="隐式1" />

    <Button
        android:id="@+id/bt3"
        android:layout_below="@id/bt2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="隐式2" />

    <Button
        android:id="@+id/bt4"
        android:layout_below="@id/bt3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="打开浏览器" />
   <Button
        android:id="@+id/bt5"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/bt4"
        android:text="打开拨号界面" />
      <Button
        android:id="@+id/bt6"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/bt5"
        android:text="显示启动并传递数据" />
            <Button
        android:id="@+id/bt7"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/bt6"
        android:text="显示启动并返回数据" />
</RelativeLayout>

3.activity_second.xml

<RelativeLayout 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=".SecondActivity" >

    <Button
        android:id="@+id/bt1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:text="关闭页面" />

    <Button
        android:id="@+id/bt2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/bt1"
        android:text="显示传递的数据/返回数据给上一个页面" />

    <TextView
        android:id="@+id/tv1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/bt2" />

</RelativeLayout>

4.activity_third.xml

<RelativeLayout 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=".ThirdActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/hello_world" />

</RelativeLayout>

5.activity_main.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android" >

    <item
        android:id="@+id/add_settings"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="add"/>
    <item
        android:id="@+id/remove_settings"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="remove"/>

</menu>

6.MainActivity.java

package com.example.dyhdm_02_activitytest;

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.View.OnClickListener;
import android.view.Window;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {

    private Button bt1;
    private Button bt4;
    private Button bt3;
    private Button bt2;
    private Button bt5;
    private Button bt6;
    private Button bt7;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);
        bt1 = (Button) findViewById(R.id.bt1);
        bt1.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                // 显式
                startActivity(new Intent(MainActivity.this,
                        SecondActivity.class));
            }
        });

        bt2 = (Button) findViewById(R.id.bt2);
        bt2.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // 隐式1
                // 在AndroidManifest.xml为SecondActivity进行注册中加入如下代码
                // <intent-filter>
                // <action
                // android:name="com.example.dyhdm_02_activitytest.Action_START"
                // />
                //
                // <category android:name="android.intent.category.DEFAULT" />
                // </intent-filter>

                startActivity(new Intent(
                        "com.example.dyhdm_02_activitytest.Action_START"));
            }
        });
        bt3 = (Button) findViewById(R.id.bt3);
        bt3.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // 隐式2
                // 每个Activity中只能指定一个action,却能指定多个category
                // 在AndroidManifest.xml为SecondActivity进行注册中加入如下代码
                // <intent-filter>
                // <action
                // android:name="com.example.dyhdm_02_activitytest.Action_START"
                // />
                //
                // <category
                // android:name="com.example.dyhdm_02_activitytest.MY_CATEGORY"
                // />
                // <category android:name="android.intent.category.DEFAULT" />
                // </intent-filter>
                startActivity(new Intent(
                        "com.example.dyhdm_02_activitytest.Action_START")
                        .addCategory("com.example.dyhdm_02_activitytest.MY_CATEGORY"));
            }
        });

        bt4 = (Button) findViewById(R.id.bt4);
        bt4.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // 使用隐式intent打开浏览器
                // public static final String ACTION_VIEW =
                // "android.intent.action.VIEW";
                startActivity(new Intent(Intent.ACTION_VIEW).setData(Uri
                        .parse("http://www.baidu.com")));
            }
        });
        bt5 = (Button) findViewById(R.id.bt5);
        bt5.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // 使用隐式intent打开系统拨号界面
                // public static final String ACTION_DIAL =
                // "android.intent.action.DIAL";
                startActivity(new Intent(Intent.ACTION_DIAL).setData(Uri
                        .parse("tel:10010")));
            }
        });

        bt6 = (Button) findViewById(R.id.bt6);
        bt6.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                startActivity(new Intent(MainActivity.this,
                        SecondActivity.class).putExtra("data", "HelloWorld"));
            }
        });
        bt7 = (Button) findViewById(R.id.bt7);
        bt7.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // 1:请求码
                // @param requestCode If >= 0, this code will be returned in
                // onActivityResult() when the activity exits.
                startActivityForResult(new Intent(MainActivity.this,
                        SecondActivity.class), 1);
            }
        });
    }

    /**
     * 接受返回的数据 重载方法
     */
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch (requestCode) {
        case 1:
            if (resultCode == RESULT_OK) {
                Toast.makeText(MainActivity.this, data.getStringExtra("data"),
                        Toast.LENGTH_SHORT).show();
            }
            break;

        default:
            break;
        }
    }

    /**
     * 在Activity中使用Menu 重载方法
     */
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    /**
     * Menu子项的点击监听 重载方法
     */
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        case R.id.add_settings:
            Toast.makeText(MainActivity.this, "add_settings",
                    Toast.LENGTH_SHORT).show();
            break;
        case R.id.remove_settings:
            Toast.makeText(MainActivity.this, "remove_settings",
                    Toast.LENGTH_SHORT).show();
            break;

        default:
            break;
        }

        return true;
    }
}

7.SecondActivity.java

package com.example.dyhdm_02_activitytest;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class SecondActivity extends Activity {

    private Button bt1;
    private Button bt2;
    private TextView tv1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        bt1 = (Button) findViewById(R.id.bt1);
        bt1.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                finish();
            }
        });
        bt2 = (Button) findViewById(R.id.bt2);
        tv1 = (TextView) findViewById(R.id.tv1);
        bt2.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                if (getIntent().getStringExtra("data") != null) {
                    tv1.setText(getIntent().getStringExtra("data"));
                } else {
                    // RESULT_OK:返回码
                    // @param resultCode The result code to propagate back to
                    // the originating
                    // activity, often RESULT_CANCELED or RESULT_OK
                    // Standard activity result: operation canceled.
                    // public static final int RESULT_CANCELED = 0;
                    // Standard activity result: operation succeeded.
                    // public static final int RESULT_OK = -1;
                    setResult(RESULT_OK,
                            new Intent().putExtra("data", "HelloBoy"));
                    finish();
                }

            }
        });
    }

    /**
     * 按下返回按钮 重载方法
     */
    @Override
    public void onBackPressed() {
        if (getIntent().getStringExtra("data") != null) {
            finish();
        } else {
            setResult(RESULT_OK, new Intent().putExtra("data", "HelloBoy"));
            finish();
        }

    }
}

8.ThirdActivity.java

package com.example.dyhdm_02_activitytest;


import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;


/**
 * 
 * TODO 添加下列代码，配置了一个可以响应打开网页的intent
 * 
 *   <activity
            android:name="com.example.dyhdm_02_activitytest.ThirdActivity"
            android:label="@string/title_activity_third" >
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />

                <category android:name="android.intent.category.DEFAULT" />

                <data android:scheme="http" />
            </intent-filter>
        </activity>
 * @author  zza
 * @data:  2016-8-12 下午3:40:45
 */
public class ThirdActivity extends Activity {

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

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_third, menu);
        return true;
    }

}